Hi all,

I'm in the midst of restoring a 1966 GE Portacolor and was hoping for some guidance. In replacing one of the can capacitors, I screwed up and installed one of the sections backwards. Now it's gone from mostly working to lighting the tube heaters and doing nothing else.

According to the schematic, there's a .5V fuse just before the capacitor I installed backwards. That would trip if someone did what I did, and would cause the symptoms I've seen. I see it on the tube chart, I see it listed multiple times in the schematic, but I'll be damned if I can see it in the set.

I'm including the schematic. Has anyone worked on one of these before? I'm trying to find fuse M2. Am I losing my mind or something?

https://drive.google.com/file/d/1q4d8QUAmpHeyReDgYK4PvxqaMPiHQKBL/view?usp=sharing

Hi all,

I'm in the midst of restoring a 1966 GE Portacolor and was hoping for some guidance. In replacing one of the can capacitors, I screwed up and installed one of the sections backwards. Now it's gone from mostly working to lighting the tube heaters and doing nothing else.

According to the schematic, there's a .5V fuse just before the capacitor I installed backwards. That would trip if someone did what I did, and would cause the symptoms I've seen. I see it on the tube chart, I see it listed multiple times in the schematic, but I'll be damned if I can see it in the set.

I'm including the schematic. Has anyone worked on one of these before? I'm trying to find fuse M2. Am I losing my mind or something?

https://drive.google.com/file/d/1q4d8QUAmpHeyReDgYK4PvxqaMPiHQKBL/view?usp=sharing

It is shown on the bottom left hand corner of the "printed circuit - top view" diagram, which is the image on the right hand side of page 8.

Find L34, and trace it out - one wire should go to a rectifier diode, the other to fuse M2.

Also, this may not be a normal glass fuse.. sometimes TV sets (no idea about this one) used a hair thin piece of wire as a fuse. If this is the case, put in a normal AGC fuse holder and install a normal 1/2 amp fuse.

Also, this may not be a normal glass fuse.. sometimes TV sets (no idea about this one) used a hair thin piece of wire as a fuse. If this is the case, put in a normal AGC fuse holder and install a normal 1/2 amp fuse.

That might be worth checking. I'll see if that's the case here. Thanks.

Okay, I traced the two ends of L34 and haven't had any luck. Everything has continuity so far. Any other direction?

Okay, I traced the two ends of L34 and haven't had any luck. Everything has continuity so far. Any other direction?

Luck with what? What has continuity? Are you getting B+ when the set is on?

Many times the GE factory literature would dedicate an entire page to "production changes" using a code number generally ink stamped on some large metal part of the chassis,usually 3 digits. Fuses added, fuses removed, resistor/cap values changed. Which section of the cap was mis-wired? (C what?). Will have to back track from that point.

Luck with what? What has continuity? Are you getting B+ when the set is on?

Sorry, should've been clearer. In tracing the line between L34 and the associated 100uF cap, there are no visible fuses and everything has continuity. All the diodes test good, and I run continuity tests on all the wires to see if one of them was meant to work as a fuse. If they are, then none are broken.

Right now the cord is locked into the back of the cabinet, so I haven't been able to run any tests to see where the B+ breakdown is. I'm going to guess I don't, though, since there's no life beyond the filament string. My next step is going to be freeing that cord so I can start doing voltage checks with the set on.

Many times the GE factory literature would dedicate an entire page to "production changes" using a code number generally ink stamped on some large metal part of the chassis,usually 3 digits. Fuses added, fuses removed, resistor/cap values changed. Which section of the cap was mis-wired? (C what?). Will have to back track from that point.

You know, I should check that. I know which cap it was and have since corrected the orientation, but since the schematic showed a fuse there I assumed it was C2-B. However, now that you mention that and I'm actually taking a step back, I think it was C2-D. I'm checking for where that is on the schematic now, and I can also check directly on the unit either late tomorrow or Wednesday.

I was always taught to make diagrams on a piece of paper when changing out a multican capacitor but I suppose in this modern electronic day we all live in a picture taken on a phone is just as good to do too.

Sorry, should've been clearer. In tracing the line between L34 and the associated 100uF cap, there are no visible fuses and everything has continuity. All the diodes test good, and I run continuity tests on all the wires to see if one of them was meant to work as a fuse. If they are, then none are broken.

Right now the cord is locked into the back of the cabinet, so I haven't been able to run any tests to see where the B+ breakdown is. I'm going to guess I don't, though, since there's no life beyond the filament string. My next step is going to be freeing that cord so I can start doing voltage checks with the set on.
The power cord interlock connector is held by a "C" clip, easy to remove. It's the earlier PortaColor chassis.
IIRC, The set has two power supplies, one half wave 140 volt source and one 240 volt, voltage doubler source. It has three power supply diodes and maybe two wire-wound resistors. The power supply is near the HV enclosure and there should be a fuse nearby, as well. :scratch2:

1966 Porta-Color ?!? Could be a very early example. I THINK they introduced these things in fall '65 for the '66 season. My Dad always said he got the 1st one in NE Tennessee, he loved being the 1st one w/a new toy like that. Also, the rather decrepit Zenith 24" B/W we had FINALLY went Ker-Pop! & died.. The little Porta-Potty took up about a 10th of the room, the old battleaxe did, that wasn't a bad thing, either, & it was COLOR !! Whoo-Pee !

There is a resistor shown in series with the fuse. They may have eliminated the fuse & used a fusable resistor instead to save $$. If either are blown
check the 3 rectifiers.

73 Zeno:smoke:
LFOD !

There is a resistor shown in series with the fuse. They may have eliminated the fuse & used a fusable resistor instead to save $$. If either are blown
check the 3 rectifiers.

73 Zeno:smoke:
LFOD !

The rectifiers tested good, but you may be onto something about R119. I'll give that a look the next time I'm at my workbench. It's got some insulation around it, and I wouldn't be surprised if there was something under there.

Okay, so R119 is tested and has continuity. I rechecked the diodes, all appear to behave as expected.

So now I'm looking at the connections around C2 D. It has two wires. One goes to the vertical linearity control, which I checked and it appears to be operating normally. The other goes to the circuit board, and I'm having some trouble finding that on the schematic. Perhaps there's something on the circuit board that's blown?

Still no sign of that fuse. I'm wondering if that wasn't removed on the version I have.

I also plan to pull the power cord tomorrow and do some voltage tests. Maybe that will highlight where the power is failing.

Okay, hold on.

Can someone double check C1 for me. I think I may have figured out what I did wrong.

When I removed the original C1, I directly wired M1 and a few other pieces that were connected to the negative terminal of C1 to ground, and I also connected the negative terminal of the replacement C1 directly to ground.

However, C1 was mounted through an insulating pad, and in looking at the schematic, that's not actually what's going on with it, is it? Should I rewire it to have it floating away from ground? Maybe that's the origin of this whole thing.

Bingo! the negative end of C1 shoud not be grounded. M1 is likely blown also if it was connected to ground.

jr

Bingo! the negative end of C1 shoud not be grounded. M1 is likely blown also if it was connected to ground.

jr

I'll double check, but I've repeatedly verified that M1 still had continuity. I'm thinking I got lucky here and a simple wiring fix will get me back to where I want to be.

Alright. Well, C1 is now lined up correctly and I'm still not seeing any life. The tubes are glowing brighter, for what that's worth, and I'm hearing the hum you normally hear when things are warming up, but nothing else.

So I'm gonna pull that power cord this weekend and prep for taking measurements. Any thoughts on where to start?

Am I wrong to think that M1 could still show continuity if it's in circuit? I'm starting to wonder if that isn't my problem, but I'm measuring continuity across ground instead of across the fuse when I test it. Would it be worthwhile to remove the fuse and recheck?

I would first check the three power supplies and the fuse M1 when removed.

jr

Okay, so diodes x1-x3 were removed from the circuit, tested fine, and reinstalled. M1 was also removed, checked good, and reinstalled. Still no life.

I'm looking at removing R119 and doing a continuity check across it next. This has to be early in the line.

Where would you all recommend I measure next? I have the cord out of the cabinet and I'm ready to take voltage measurements.

Are the 3 power supply (labeled source voltages) in spec?

https://live.staticflickr.com/65535/48996417048_f1c591a18b_c_d.jpg

jr

I'm going to assume no on at least one of them. I'll plan to check them either tonight or tomorrow, depending on my schedule. I think I may also take a look at C1 again, just to see if it's got any amps going across it.

Just check for AC ( to GND) on both sides of C1. If there check the
supplies # 1, 2, & 3 for DC.
Keep in mind most the time things in Sams flow left to right.
Try to find a mid point & test voltage. Go upstream or downstream
from there.

73 Zeno:smoke:
LFOD !

Just check for AC ( to GND) on both sides of C1.

Is C1 AC? I've been checking on the DC setting.

Is C1 AC? I've been checking on the DC setting.

Yeah, I'm thinking C1 is DC because of where it is in relation to the diodes, but please correct me if that's wrong.

Yeah, I'm thinking C1 is DC because of where it is in relation to the diodes, but please correct me if that's wrong.

There is ac on both sides of the cap, but the output is shifted up dc wise. See video of voltage doubler circuit.

https://m.youtube.com/watch?v=Iq-5PPpVHNw

jr

Okay, I found my problem!

R119 is several million ohms. It's supposed to be 3.6 ohms. I jumped it with some alligator clips (briefly) and the TV came back to life!

So I'm going to order another R119 and get back to work on this.

Thanks for your help so far, everyone. Next step is to make sure it powers up with all that fixed, and replace C3. Hopefully that will close this whole thing down.

Hm, having some trouble with this one. Does anyone have a good source for 3.6 ohm resistors with 7 (or highter) watt ratings? Any thoughts on how flexible this part is going to be? Would a 3 ohm do it?

If I did them in series, I could get a 3 ohm and .5 ohm 10 watt resistor from JustRadios, but I'd prefer to use one part is possible.

RCA used a 3.9 ohm one in a lot of their later sets. The 7 watt part number is 143565, the 10 watt one is 153664. Going up or down 1 ohm should not cause any issues.

I would use the 3.9 ohm. Its there to reduce in rush current at
turn on so the electrolytics charge slower. It also protects the fuse
from random blowing. Most sets do not use a fuse, just the resistor.
In that case it is of a fusable design not just a wirewound resistor.

73 Zeno:smoke:
LFOD !

I would use the 3.9 ohm.

Whoops. I bought a 3.5 ohm at 10 watt last night. Oh well. If I decide I'm not happy with it, I can always switch over.

On the plus side, I also decided to add that missing fuse. I'm real sure GE left it out, so I've ordered one and plan to install it where the schematic calls for it. It's probably not necessary, but it will make me feel a little better.

It looks like once that part comes in I'll be able to get back to where I should be. I'll verify it's still passing video and audio and go from there. One more 3 section can to go.

Okay, well mixed news.

The new resistor (Replacing R119) fixed the power issue. I now have sound, video, and high voltage back.

Only problem: I've lost part of my vertical deflection. I also was hearing a clicking from the flyback, but I'm still getting HV and that seems to have stopped after I tightened a few screws on the HV cage. Not sure why that would fix it, but there we are.

So here's what I'm going to check:

- I'll verify that I'm getting the correct voltages out of the 3 sections of the
power supply. Perhaps they're too low.

- I'll verify my HV is high enough. Could that cause partial loss of vertical?

I know the yoke is okay, because in fiddling with the height I've been able to get the picture to bounce all the way down, but it almost immediately bounces back up.

I'm including a video as well. Perhaps someone can point me towards a suspect section?

https://youtu.be/D5siDbEAvU0

1. good

2. No, If HV is too low the picture would be bigger. (slower moving elections are easier to deflect)

3. Seems reasonable.

4. Have you tried adjusting vertical linearity?

jr

Have you tried adjusting vertical linearity?

I did try this. It definitely reacted, but not enough to fill the screen.

A few more clues before I call it a night:

I'm getting a response from the brightness control. When I decrease the brightness, the flyback starts clicking like mad and fills out the screen, somewhat. It more flickers with each click. The picture does grow larger. The picture was shrinking when I increased the brightness before I started.

Also, now the flyback is ringing at me. I'm not sure what that means, or if that makes sense. I took a video of it.

I'm noticing that, when I stick a screwdriver near the flyback ring, small blue sparks jump to it. I think that's normal, but maybe not? Maybe I need to treat the flyback with some corona dope?

I decided to stop taking voltages since I wasn't sure if the ringing was dangerous. I measured two of the three sources, and noticed they were actually running about 10 VDC higher than they were supposed to. I'm not sure if that's within tolerance or not.

https://www.youtube.com/watch?v=A3hxKIHzXkM&feature=youtu.be

You said in the first post that the tv was “mostly working” before you replaced the electrolytics. So are these new problems, perhaps associated with the rebuilding efforts or were they observed initially?

jr

They existed, but have changed, if that makes sense. When I started, the set had AC hum in the audio from bad electrolytics. The picture would shrink and change size with brightness, and the vertical hold was exceptionally touchy. I was also noticing some flashing on the screen. I'm not sure how to describe it, almost like WWII era flak, if you've ever seen video of that. With the brightness up it looked more like the flickering lines you get with tracking issues on a VCR, but with the brightness down they'd be more visible. That wouldn't start until the set had been on for awhile, though.

Since replacing C1 and C2, plus the two paper caps on the main board, the vertical and horizontal hold is much better and the audio hum is gone, but the picture shrinkage and growth is much worse, and I'm hearing sparking from around the flyback. I can't seem to find exactly where it's coming from, though, and I'm not seeing any parts actually failing. I ended up leaving it on for awhile and despite all the sparking noises nothing actually stopped working. It has developed that ringing that I posted earlier, that's new as of last night (and didn't start until quite awhile after replacing C1 and C2.)

I'm wondering if I don't have a problem with the HV rectifier. I ordered a spare to see if that changes anything. I know I have HV from the flyback, since bringing a screwdriver near it and the cap to the HV rectifier causes it to send a healthy spark, so I'm personally inclined to think that the flyback itself is fine.

Any other thoughts? Could this be a yoke problem?

If the rectifier isn't the problem the cup it's socket is in might be...I had a friend's 13" Zenith tube color on the bench a few years ago and that set had HV rect socket cup arc through....the point of the screw that held the socket in the cup was arcing through the cup to the chassis. My solution was clean the living daylight out of the cup to confirm condition, drill out the arc hole and carbon path near it, fill the drill hole with RTV silicone to block the arcing path, and shorten the screw and round it's point to avoid a relapse....worked like a charm, and hasn't failed yet.

If the rectifier isn't the problem the cup it's socket is in might be

Okay, so I'm potentially on the right track that my HV rectifier might be suspect, then? I was more or less shooting in the dark, but I figured it's a cheap part and an easy swap, and worst case I have a spare I can access.

I've heard of something called "Bloom" Does that sound similar to what I'm describing?

Okay, so I'm potentially on the right track that my HV rectifier might be suspect, then? I was more or less shooting in the dark, but I figured it's a cheap part and an easy swap, and worst case I have a spare I can access.

I've heard of something called "Bloom" Does that sound similar to what I'm describing?

What you describe is hard to understand...

If you had a blank raster or unchanging test pattern the set should not flicker of change brightness. What blooming typically manifests as is an overload of the HV supply. Less HV makes for dimmer picture and bigger deflection since less HV means slower electrons that hang out longer in the yokes deflection field. Blooming is typically either constant (beam current set far too high) or dependant on average brightness of the video image displayed.

I've never seen a set display something that looks like a tape artifact unless connected to a tape deck....there is a phenomenon known as retrace lines that occurs when screens and or brightness is too high....

You need to post some pictures.

I would also check the condition of the external dag on the CRT to assure that it is not flaking off and is properly grounded to the chassis. Examine the operating set in a darkened room, with dark adapted vision, to look for the arcs.

jr

If you had a blank raster or unchanging test pattern the set should not flicker of change brightness.

The entire screen flickering is new. It does that when I hear a spark from the HV section. Before it was just the lines I was seeing.

I've never seen a set display something that looks like a tape artifact unless connected to a tape deck....there is a phenomenon known as retrace lines that occurs when screens and or brightness is too high....

No, it wouldn't be that, then. These actually get more visible when the brightness is all the way down. They looked like lines when a picture was displayed, but when I turned the brightness down they appeared as larger blotches across the screen. I don't think the artifacts themselves were changing, I think the video signal was hiding it. It's almost as if these were electrical spikes going straight to the picture tube that had nothing to do with the rest of the circuity, which again makes me think HV.

You need to post some pictures.

I'll plan to either Friday evening or this weekend. I won't get a chance to get to my workbench before then.

I would also check the condition of the external dag on the CRT to assure that it is not flaking off and is properly grounded to the chassis. Examine the operating set in a darkened room, with dark adapted vision, to look for the arcs.

I'll give that a try. As far as the CRT goes, I didn't notice any obvious flaking, but I can definitely check whether it's solidly grounded.

Just to make sure we're on the same page:

When I started, here's what was wrong:

- Audio Hum from bad filter caps.
- The picture would grow larger when I turned the brightness down, and
smaller when I turned it up.
- After being on for a few minutes, lines that resembled tape artifact lines
would appear on the screen. With the brightness turned all the way down
(and the picture not visible) it appeared that these lines were actually
bright splotches flashing on random parts of the screen. These were not
impacted by changing the brightness.
- The vertical and horizontal hold was exceptionally touchy.

What happened when I replaced C1:

- So, I actually technically got this right the first time. I intended to
connect the negative end of my new C1 to ground, along with all the
ground connections that had connected to the negative lug of the can I
replaced. When I soldered it to the terminal strip, I miscounted and
ended up soldering the negative end of C1 and the connections that had
gone to the negative lug of the can to each other on a spare, ungrounded
terminal connection.
- At the time, I also replaced C67 and C105, which are paper capacitors on
the main board. I believe they're related to the vertical and horizontal
holds.
- I tested my C1 replacement and it worked (thanks to my faulty
connection.) I was able to connect a signal and tweak the horizontal and
vertical holds. They seemed much more stable than before. The flashing
on the screen and fluctuating picture size (when I fiddled with the
brightness) were still there at this point, but nothing had gotten worse.
- I recognized my "mistake" later and reworked the connection. I moved
the negative end of my C1 to a ground point, and connected the
connections that were meant to connect to the negative end of C1 to a
ground point on a different terminal strip. That was a mistake, but it also
meant that almost all of the chassis was cut out of the circuit.

Replacing C2:
- I replaced C2 at the same time that I "corrected" my "mistake" on C1. I
was very careful to label which wire went where, and have checked
repeatedly to ensure that I did not miswire anything. C2 should be
correct.
- After replacing C2, I noticed that I was getting filament lights, and
nothing else. It was then that I realized that I had miswired C1.

Fixing my "Correction" on C1:
- I then corrected C1 to match the schematic, but still saw no change.
Voltage measurements indicated that power wasn't even getting through
fuse M1, so I measured R119 and discovered that it had drifted millions of
ohms above what it should have been.
- To verify my hunch that R119 was the source of my problem, I bypassed
it with a pair of alligator clips. The set came back to life, but I began to
hear sparking from the HV section, and noticed that video was now
compressed from the bottom third of the screen. I didn't leave it on too
long like this, since I didn't want to run it for long with R119 bypassed.
- I replaced R119 (3.6 ohms at 7 watts) with a 3.5 ohm at 10 watt resistor.

Where I am now:
- C3 is still untouched. I prefer to test my set after replacing major
components so I know when a problem started.
- Since replacing R119 and C2 (and correcting C1, though that hadn't had
any impact before) the picture has been squished, and a raster doesn't
appear on the bottom third of the screen. There's sparking noises from
the HV section, but the flyback itself still produces sparks when I place a
screwdriver next to it.
- The picture flickers (and sometimes stretches to fill the entire screen, but
only for a moment) when I hear a spark.
- I need to see if the splotches are still present.
- The picture grows much larger, almost to the point of filling the whole
screen (it may actually, but at a certain point it's too dark to tell) when I
turn the brightness down.
- My audio hum is gone. :thmbsp:

Excellent! I think that is a very good idea to periodically summarize the steps taken and observations made, especially when the thread starts to get somewhat long, to keep everybody on the same page. :thmbsp:

jr

Excellent! I think that is a very good idea to periodically summarize the steps taken and observations made, especially when the thread starts to get somewhat long, to keep everybody on the same page. :thmbsp:

jr

The irony being the summary was the last possible post on its page, and in complementing it putting us on the same page the post being complemented is now on the previous page:D....

Unfortunate but true, I am so embarrassed and sorry.

https://live.staticflickr.com/4867/31682407707_4cdb2567b4_w_d.jpg

jr

Okay, I finally had a chance to do some tests.

I have a video coming. It's a bit long since I tried to document everything I could.

Actually there's two videos, and I may have confirmed my issue. The first has the ringing, some sparking, and shows the "tape artifacts" that I mentioned before. In the second, I removed the HV rectifier, and the sparking etc went away. Obviously some of that will be because there's no power to the tube, but the ringing was definitely around the flyback and that also disappeared when I removed the HV rectifier, so I'm leaning towards that.

One other mystery: Should the HV rectifier tube hold static electricity? I removed it from the tv while wearing gloves (the set was turned off, but I didn't want to risk anything) and put it aside. Later, I went to pick it up without gloves and it sparked when I touched it. Could that be confirmation?

https://www.youtube.com/watch?v=dgotiiv-bJQ&feature=youtu.be

That's the primary overview. Sorry for the length, I was trying to make sure I caught everything.

https://www.youtube.com/watch?v=MQcN5ynW9wQ&feature=youtu.be

Here's when I removed the HV rectifier.

The ringing is probably mechanical vibration of the ferrite core of the flyback. It's usually curable by tightening those two nuts on the big C clamp that goes around the core (not too tight as the core can crack easily).

Your HV rectifier tube is good (if it was weak the raster would 'bloom' and fade out when you turn up the briteness).

The blue arcing when you touch the screwdriver to the glass and top cap of the HV rect is quite normal.

Insufficient height is usually a bad electrolytic coming off the cathode of the vert.output tube (although GE portacolors might not have this cap; other more knowledgable folks will chime in).

“Insufficient height is usually a bad electrolytic coming off the cathode of the vert.output tube ”

That would be c-2, which was replaced.... possible error? :scratch2:

jr

I checked C2 again. Still not finding an error.

Is there a specific section of C2 I should be looking at?

I did a few measurements by the way. I noticed my HV is hoving around 12KV when it's listed as being between 15 and 18KV. Also, my 670V boost voltage coming off of pin 3 on the flyback is measuring around 650V. Not sure if any of that could be related, but maybe that's a clue?

I tightened the core a bit. Ringing is gone, at least so far.

Does anyone have any thoughts on this?

I'm going to try replacing C1 and possibly C2D. I wonder if they didn't get damaged when I installed them incorrectly.

Does anyone have any thoughts on this?

I'm going to try replacing C1 and possibly C2D. I wonder if they didn't get damaged when I installed them incorrectly.

Any lytic that has seen reverse polarity should be immediately round filed and unless you have equipment to test for leakage current at rated voltage.

Any lytic that has seen reverse polarity should be immediately round filed and unless you have equipment to test for leakage current at rated voltage.

Hm. Well now I'm wondering if that's my issue with the height. C2D is definitely a potential culprit.

I had figured that if an Electrolytic didn't explode or smoke, it was fine. Obviously that's not true with the older dried out ones, but these are new. Perhaps I'm wrong?

I've got those parts on order. I'll see what happens when I swap them in. The rest of C2 should be okay.

I had figured that if an Electrolytic didn't explode or smoke, it was fine.





No! That is not a rule-of-thumb.

No! That is not a rule-of-thumb.

Noted. Then I may be on the right track. Recalling that I:

- Attached the line going through R119 and M1 to ground, and attached the negative end of C1 to ground

and that I

- Swapped the polarity of C2D

At the same time. I'm thinking it's very likely that I damaged C2D at that time, which could explain my height issue.

Parts are on order. I'll see what changes once I swap everything in.

Still waiting on C2D to come in. I was doing some work in the power supply tonight.

I've got a new issue. It's my fault. I won't get too into it, I did something stupid trying to check a component and learned my lesson. Blew out R119, M1, C1, and X1. X2 still looks okay, but X1 is now measuring 0 ohms regardless of the polarity. The set blows M1 immediately upon power up. I disconnected the 270V line between C2A and L34 and it still blows, so I know the problem is in the voltage doubler circuit with X1 and X2.

R119, M1, and C1 are now replaced. R119 is now 3.9 ohm 10 watt, and M1 is a 2.5A 250V fast blow fuse. I also took the opportunity to install M2 as it's listed in the schematic, so I'll have that extra protection.

I'm not sure what diode to get to replace X1. Any suggestions? I'm trying to decide if I should go ahead and replace C103 while I'm at it.

Would this replace X1?

https://www.ebay.com/itm/5pcs-1N2071-Original-New-Zener-Diode-Replaces-NTE116/121120656927?hash=item1c335a8e1f:g:ZjUAAOxynhFRBp5 P

Would this replace X1?

https://www.ebay.com/itm/5pcs-1N2071-Original-New-Zener-Diode-Replaces-NTE116/121120656927?hash=item1c335a8e1f:g:ZjUAAOxynhFRBp5 P

No... the diode you listed is a zener diode, you just need a common rectifier diode like a 1N4007.
https://www.amazon.com/MIC-Silastic-Junction-Standard-Rectifier/dp/B00W17LOBO/ref=sr_1_4?crid=THEWCTZTSQGS&keywords=1n4007+diode&qid=1573967003&sprefix=%2Caps%2C358&sr=8-4

not affiliated,
jr

Good thing I asked, then. I'm sure the codes in the service manual match specific products that are long out of production.

Part ordered. I needed to pick some of those up anyway. Fingers crossed this fixes my power supply issue.

X1 is replaced and I have life again. Out of circuit, it tested completely open.

Still having the height issue. I'll update once C2D comes in and I do the swap.

Okay,

C2D has been replaced. I'm not seeing any change.

For good measure I also swapped in a new vertical output tube. Also nothing.

I measured the ohms on R5. It peaks just around 2K, which I belive is what it's supposed to be. When I measure the voltage output coming off of R5, which is listed at 15V in the schematic, I'm seeing it maxing around 22-25V and brushing at 15V at the lowest.

Any suggestions for what to check next?

Shouldn’t the cathode go to zero volts when the pot is at one end? :scratch2:

jr

Let me double check. I know it looked like it dropped off right at the tail end.

I'll grab a video of the voltage and resistance readings today. Maybe you'll be able to interpret it better than I can.

I'm wondering if my issue isn't in R5. I have no idea how likely that is, but could I have damaged that?

Portacolor sets are somewhat prone to tin whiskers in the pots...I had one which had the AGC pot dead shorted to ground via a tin whisker. The set had ZERO reception and it took some time troubleshooting the dead IF to trace it back to the AGC and then the pot...if a whisker developed on a pot connected to B+ or boost it could make the set really unhappy.

Here's a video where I took some measurements on R5. https://www.youtube.com/watch?v=aBqKyI5KoO8&feature=youtu.be

Could this be tin whiskers? How would I go about correcting that?

That jumping near the end of the pot travel looks highly suspicious... have you tried cleaning the pot with deoxit?

jr

That jumping near the end of the pot travel looks highly suspicious... have you tried cleaning the pot with deoxit?

jr

I did, but I'm not convinced I did it right. I'm thinking I'll take another crack at it.

That being said, if I do need to replace this, does anyone know what replacement part I'd be looking for? Obviously I'll check Moyers with the part number first, but assuming they don't have a replacement.

My standard process for tin whisker infested pots is to remove, and dismantle the pot take a toothbrush then fine sandpaper to the metal parts clean everything with a good control cleaner and paper towels, reassemble the pot, check resistance and range with rotation between all terminals and also case metal, and if all is good reinstall.

My standard process for tin whisker infested pots is to remove, and dismantle the pot take a toothbrush then fine sandpaper to the metal parts clean everything with a good control cleaner and paper towels, reassemble the pot, check resistance and range with rotation between all terminals and also case metal, and if all is good reinstall.

Okay. I'll give this a try. I'm going to just remove the pot, disassemble it, and deep clean it.

One thing I am sort of wondering about, and I can get pictures of this if you need it: I'm noticing that the pot doesn't have the standard three lugs. Instead, it has one that goes to C2D/the main PCB, and two that connect to ground. That matches the schematic just fine, but since this is unusual, is there anything I should be watching out for as I disassemble?

Okay. I'll give this a try. I'm going to just remove the pot, disassemble it, and deep clean it.

One thing I am sort of wondering about, and I can get pictures of this if you need it: I'm noticing that the pot doesn't have the standard three lugs. Instead, it has one that goes to C2D/the main PCB, and two that connect to ground. That matches the schematic just fine, but since this is unusual, is there anything I should be watching out for as I disassemble?

That just means it is configured as a variable resistor instead of a variable voltage divider...One benefit of this configuration is if one of the end lugs is open but center never goes open you can make the open end lug the grounded one and continue to use it(max and min vs rotation may swap).

Okay, well I really went at it with the deoxit on R5. Not seeing any change.

Are we sure this can't be a HV problem? Or maybe a voltage problem? My HV to the CRT is still measuring between 7 and 10 KV. It should be around 15 per the schematic.

I may have something here.

I'm noticing that my voltages are consistently 10 or so volts higher, except the HV which is several KV too low. I traced it back, and discovered that C103 has 0 volts when measured against ground.

I've ordered a replacement. Could that be related to my issue?

Also, if L34 is measuring 36 ohms, could that be an issue?

Also, if L34 is measuring 36 ohms, could that be an issue?

No.

Also re-check your C-103 reading, it can’t be 0 volts, if it is wired correctly and supplies are normal (or slightly high).

What does your boost voltage measure?

jr

C103 should be measured in VDC, correct?

Okay, I think I measured C103 wrong. I was measuring from the ground end of C103 to another ground point, and that was 0 VDC. I measured across C103, and it came out as 152VDC

Boost voltage (from pin 3 of the flyback against ground) is 664VDC

HV is still hoving around 10 V using my high voltage probe. I'm noticing that the image is somewhat dim, and I have to have brightness up above center to see it.

In its present condition what does the picture look like? Can you connect it to a signal source and take a picture?

jr

Sure. I'll take care of that shortly.

Here's a video of the output. Vertical is squished, as expected, but I was able to get everything to lock again.

One thing I noticed, and I mentioned it in the video, is that the picture is moving about like a wave. It reminds me of how a boat moves on the ocean. That's new. No idea what might be causing it, but maybe that's a new clue.

https://www.youtube.com/watch?v=0DmcGd52kpc&feature=youtu.be

Could any of this be caused by a short in C3? I haven't touched that, and it was technically subjected to reverse polarity when I connected M1 to ground awhile back. I need to replace it anyway, but I was sort of holding off until we got all this figured out, since this happened when I replaced C2.

Or, no, maybe not reverse polarity. But it was still incorrectly connected directly to M1. Should I try replacing that and see if that's causing my issue?

That “wave” action looks like good old 60 hertz getting into the horizontal circuit. Could be caused by poor power supply filter caps or perhaps a heater to cathode short in one of the tubes. Scope the supplies and see how much 60 hz ripple is on each one.

jr

Scope with an oscilloscope, you mean? I have one, but I'll have to figure out how to use it. I'm a little fuzzy on the operational theory. The last time I tried to use one, the scales threw me off.

I have a theory that there's something up with the Horizontal Output tube. Maybe I'm off the mark, but I ordered a replacement. It's cheap, and I don't mind having a spare. I'll see if that changes anything.

I may as well go ahead and see what happens if I replace C3. It needs to be done anyway.

I wonder if I should swap in new parts for C2A - C2C? Could those have been damaged when I grounded M1? I'm not sure from the polarity listed, it looks like M1 is actually okay to connect to the negative terminals, and the voltage ratings should be fine, but I'm open to examining my issues here.

You likely know this, but if not it merits saying: The portacolor is a hot-chassis set so to scope it without frying TV and or scope make sure to power the TV and ONLY the TV through an isolation transformer.

Another sidebar/general comment. Are you keeping records of what you replaced and the outcome related to each one? It's getting tough to keep up with all the components you've replaced, and I want to make sure you're methodically tracking the cause-and-effect with each replacement/substitution so that you're not metaphorically chasing your tail in all this. Also, I'm pretty sure you are already doing this, but if not, be sure you're replacing one thing at a time (unless something is very, very obvious like a cascading fault that unequivocally fried multiple components).

Lastly, you may want to consider getting one of the relatively-affordable ESR capacitor testers. You can test caps in-circuit, and it could save you the hassle of shotgunning a lot of them (at least for the sake of diagnostics -- it's good practice to replace the electrolytics at this age).

You likely know this, but if not it merits saying: The portacolor is a hot-chassis set so to scope it without frying TV and or scope make sure to power the TV and ONLY the TV through an isolation transformer.

Good reminder. Thankfully I have one.

Does anyone have an image of what AC ripple looks like? I'm not sure what I'm looking for.

Good reminder. Thankfully I have one.



Does anyone have an image of what AC ripple looks like? I'm not sure what I'm looking for.


You would see a 60 cycle component in the waveform. The more pronounced it is, the more ripple is present.

You would see a 60 cycle component in the waveform. The more pronounced it is, the more ripple is present.

Exact wave shape will vary. (types of rectification and loading applied to it will change it's look). It may also become 120Hz if comming through a voltage doubler.

Post #22 in this thread shows a typical ripple for the 270 volt supply. I suspect the other supplies would be similar. :scratch2:

jr

First off IIRC C1 is a 105 deg C & the others are 85 deg C.
Look at the old C1. If you use a lower rated cap it will NOT last
long. The new C1 probably got stressed out when wired wrong &
is the cause of your ripple.
After the ripple is fixed next step is the vert so if you are ordering parts
you may want to order the vert tube. Should be cheap as its
pretty useless for other apps.

73 Zeno:smoke:
LFOD !

C1 has already been swapped out for a new one, but I'll double check the temp rating on the one I used.

I also tried swapping in the vertical tube, no luck there.

I still have not replaced C3, and considering my HV is low and I'm still hearing sparking from around the horizontal section, I'm not sure my problem is originating directly in the vertical section.

I'm going to replace C3 over the next few days and see what changes. Worst case, C3 needs to be replaced anyway. I wonder if that didn't get damaged.

Okay, finally had some time to sit down and work on this.

C3 is replaced. I didn't notice any change in the vertical behavior, but I hooked up a source and it looks like the waviness is gone.

I've ordered a new C1. It turns out that the C1 I swapped in is a lower temperature rating than it expected, so I've sourced another and will see if that helps. Not sure it will, but maybe it will at least get rid of the buzzing that's come up.

I made another video to show where I am. https://youtu.be/gIrCuJHy9OQ

Any thoughts on what I should check next?

Does fine tuning help, or is that the best you can get the video? Are you on the correct channel? :scratch2:

jr

Did this issue exist from get-go when you started working on the set, or did it arise at some point later?

Did this issue exist from get-go when you started working on the set, or did it arise at some point later?

There was audio buzz, but I had fixed it. The vertical issue is new since I replaced C2, the brightness didn't disappear at the middle of the control, and I believe the color issue I've noticed now is new.

Here's a video I took. I was able to fiddle a bit more with the fine tuning and get the picture stable. I'm noticing that the picture is actually off the edge of the screen horizontally, which is new (I used this exact computer with the tv before I started) and I'm seeing a line of color where there wasn't one before. https://youtu.be/oYJG5Czpvvo

I'm still waiting on a replacement for C1 to come in. I'm also going to see about swapping in new caps for C2A-C2C, since those could have been stressed when I miswired C1 before.

Any thoughts on where I should go next? Could a lot of these be related to stressed caps on C1 and C2?

On the color issue: the chroma signal is getting to the CRT, evidenced by your being able to vary it up and down with the color control. But the 3.58 reference signal appears to be missing (per your vid in post# 82). So apparently GE's (in)famous 'ringing crystal' circuit is not ringing. This could be from loss of the burst signal, bad tube, or possibly a bad crystal.

PortaColor gurus can no doubt pursue the issue further. Maybe somebody could post a full schematic and tube layout diagram.

Is DaveWM still active in this forum? He's one of the PortaColor gurus. You might want to send him a DM.

Link to schematic from the first post of this thread:

https://drive.google.com/file/d/1q4d8QUAmpHeyReDgYK4PvxqaMPiHQKBL/view

jr

Is DaveWM still active in this forum? He's one of the PortaColor gurus. You might want to send him a DM.

I feel like I've seen him around. I'll see if I can connect with him.

How would I go about checking the ringing crystal circuit? Could that be related to my vertical issue, or am I looking at multiple broken things here?

nope, color and vertical are totally separate stages.

nope, color and vertical are totally separate stages.

And here I was thinking it just needed some new filter caps in the beginning. This is turning into a fun puzzle after all.

Consider getting a capacitor tester like I mentioned earlier.

I have one, actually. A Heathkit C3. I think I need probes for it, though.

I'll take a look. In the meantime, the caps finally came in. I'm gonna swap those in tomorrow. It's been a hectic weekend.

Okay, new update video: https://youtu.be/WAhnuri57XQ

I've replaced all the remaining caps from C1 and C2. C1 is now within the correct temperature range, and anything that could have been stressed from previous mistakes in C2 is new.

And actually, the buzzing seems better. So I think that was the right move.

Here's my current remaining issues:

- The vertical is still not hitting the bottom half of the screen.
- That color bar is still visible.

I feel like I should say that I really jumped into the deep end with this one. At this point I'm entirely out of my element. But I don't want to give up!

So basically from this point on, I'm standing by to hear what measurements you would all like to see to move forward. Personally, I'm wondering about the health of the yoke and/or flyback. I say that because my HV is several thousand volts too low, and the yoke could be contributing to my vertical issue. Is there a way to check that?

As far as the vertical issue, you need to check all the components around the vertical osc. and output tube. A bad cap or out of tolerance resistor in this area would cause the issue you showed us. I doubt very seriously that it's directly a yoke problem.

“I say that because my HV is several thousand volts too low”

How are you measuring HV? Are you sure the probe/meter is properly calibrated?

jr

I'm using a Heathkit IM-5210. Looks like this: http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/Heathkit%2040%20KV%20Probe%20Meter%20Model%20IM-5210.pdf

Perhaps that's not a good choice for this? I presumed any meter was as good as any other but I could be mistaken.

I wonder if it would be worthwhile to measure the voltages across each pin on the vertical output tube. Is there a tool that would allow me to access those points with the tube in the socket? I've heard of tube extenders but I don't know if I've seen them for compactrons.

I'm using a Heathkit IM-5210. Looks like this: http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/Heathkit%2040%20KV%20Probe%20Meter%20Model%20IM-5210.pdf

Since there's adequate width, adequate brightness and no blooming, I wouldn't be concerned about the HV. Troubleshooting rule 101 is tackle the most obvious problem(s) first. :)

Since there's adequate width, adequate brightness and no blooming, I wouldn't be concerned about the HV. Troubleshooting rule 101 is tackle the most obvious problem(s) first. :)

To be fair, I'm not sure I'd call the brightness adequate. The picture is only visible when I turn the control nearly to the top. That's new, by the way, it wasn't like that when I started, it started doing that around the same time the vertical got wonky.

On the color issue, what voltage do you have on pins 3 and 10 of the 8BU11 (plates of burst amp and sub-carrier amp)? Should be around 200V on both.

What's the voltage on pin 9 (screen grid)? Should be around 120V.

On the vert issue, since replacing C2 didn't fix it, check the plate load resistor of the vert.oscillator. It is a high failure component in all makes/models of tube TVs due to being hammered by high level spike. And by golly Sams shows this set using a thermistor as plate load resistor. Check this. It's designated R64 (R54?). Print is blurry. It goes to the plate (pin 11) of the 11FY7. What's the voltage on pin 11? Blurry print looks like it says 290V (this voltage will vary with the height control setting, since the control is in series with the thermistor).

Okay, I ran some measurements. Here's what I've got. These are all from the test point to ground using DC voltage on the meter unless otherwise noted.

Regarding the 8UB11

Pin 3 is reading around 200 V (it leveled out around 208)
Pin 10 is reading around 200V as well (it leveled out around 216)
Pin 9 is reading just about 0V

Regarding the 11FY7

Pin 11 is reading around 130V

For the thermister (R64 from what I can tell on the SAMS) I measured the resistance across it from cold, and then when the set was running. It measured a little over 1 mohm cold, and then reduced to around 1.4 Kohms.

Obviously there's some wonky voltages on the 8UB11 pin 9 and 11FY7 pin 11. How does R64 look? Shouldn't that reduce to nearly 0 ohms?

Sounds like the thermistor is probably OK since it's not going open. Have you verified there's Boost voltage going to the height control? Should be around 600V or more.

Pin 9 of the 8BU11 is fed thru a resistor (blurry print looks like it's 100 ohms, can't read the R designation). There should be 130V on the supply end of this resistor. Is there? If there is, the resistor must be open, giving you the 0V you're getting on pin 9. Does the resistor look cooked?

There's a .01 cap from pin 9 to ground (can't read the C designation). It might be shorted. Or possibly a short in the tube.

I'll check that the next time I'm at my workbench. Might be tomorrow or Friday night.

I'm still wondering about whether the thermistor is dropping enough. Let's say I were to jumper it with a wire, just to see what would happen with zero resistance. Would I be risking causing any damage?

I'm still wondering about whether the thermistor is dropping enough. Let's say I were to jumper it with a wire, just to see what would happen with zero resistance. Would I be risking causing any damage?

Well, you'd be applying full Boost voltage directly to the plate of the vert osc with the Height control at full rotation, which wouldn't be good.

First, verify that there is Boost at the height control. If there is, try subbbing in a few resistors for the thermistor. I'd try something like 22K, 47K, 100K, 470K, 1 meg. If there's no improvement in the height, then the thermistor's not the problem.

(A decade box for R substitution would be handy.)

“verify that there is Boost at the height control”

Boost voltage is also connected to the Screen pots... perhaps if boost is low, it could be the cause of the perceived brightness problem? :scratch2:

jr

“verify that there is Boost at the height control”

Boost voltage is also connected to the Screen pots... perhaps if boost is low, it could be the cause of the perceived brightness problem? :scratch2:

jr

Make sure the Boost capacitor is good. It's the one on the PC board, .1 @ 1000 volts.

Ran a couple tests tonight. Need to slide the board out a bit to access the resistor for the 8BU11, so I'll plan to do that this weekend when I have more time.

I think I'm getting closer. I tested the boost voltage off of pin 3 on the flyback and the boost point on the height control. I can get 670V on the flyback (it was around 620 when I first tested, but I was able to get it up to 670 by turning the horizontal control) but the pin labeled "boost" on the height control is stuck around 250V. Again, this is all in DC.

So what's in between those two points? Is it just that capacitor? I think I know what you're talking about, and I actually replaced it already. Perhaps it got damaged when I miswired things earlier? I can see about ordering a replacement. Or maybe it's a different cap than the one I'm thinking of.

According to Sams there should be solid continuity (zero ohms) from pin 3 of the flyback to the Height control. Since there's only 250V at the Ht control, find out where the open is. That .1 cap is not a problem if you already replaced it.

Also see if there's Boost at the screen controls. As jr_tech mentioned, if it's low it will knock the brightness down.

WAG.... the wire/run between the HV cage and circuit board that carries the 670v boost voltage to the screen and height pots is broken or cold soldered... the 250 volts measured on the height pot is actually from the 270 volt supply back feeding through the screen pots. :scratch2:

jr

So... if indeed there's no Boost at the scr. controls, turn all 3 down to minimum before the Boost is restored to them. Otherwise, the CRT will be overdriven and may bloom out, an unfamiliar situation for a noob.

Okay, precautions were taken as suggested. Screen controls were minimized before I started poking around again.

Sure enough, no boost voltage at any of them. In fact, the entire boost line on the PCB was dead.

So I checked the wire. Wire was good, but there was no continuity to the board.

It turns out that the same solder joint for the wire linking to pin 3 on T4 is also used for the connection to the .1uf boost capacitor, which I replaced. Apparently when I did that, the solder didn't flow properly around the boost supply wire and left it essentially hanging in midair. It was hard to spot, but when I was actually looking for problems at that joint, it was obvious that the solder had pooled around it and wasn't actually connecting.

Moreover, I've identified the source of that HV sparking, and it wasn't the flyback. As soon as I pulled the board out, I saw sparks shooting from that solder joint. Apparently they were jumping between the gap and periodically supplying boost voltage, which explains why the picture kept filling out.

So anyway, I resoldered that joint. And sure enough, I have full deflection again!

Now I can focus on a few other issues. The color sounds like it won't be hard to tackle, and I'll plan to focus on that next since I have the board loosened and accessible.

I'm also still concerned about the brightness. It seems like the picture goes completely dark for a significant portion of the control. Not as much now that boost has been restored, but still more than I'd like. Maybe that's the nature of these sets? Or does that sound like a tired CRT? I don't have a tester with me, but should I start keeping an eye out for a replacement?

Now that boost is restored, an old issue has come back. I'm noticing those flashes of bright light again, and they aren't impacted by the brightness.

I've taken a video of the progress at this point. I'd like to fix the color next, but I also made sure to capture the flashes so you can see what I'm talking about. Any thoughts on what that might could be?

Here's the video: https://youtu.be/LEAJsa0N-FU

That type of flashing was usually caused by a defective video output tube. Will not show up in a checker, only way to tell for sure will be to sub the tube.

Tap the tubes gingerly with something like a screwdriver handle. It'll usually show up any intermittencies. Tap around on the board too. The 'tap test' was an integral part of troubleshooting back in the day.

Temporarily disconnect anything from the ant. input just to be sure that flashing isn't 'hitchhiking' in from outside the set.

That 'flak' looks a lot like the RF noise from a motor running picked up by the TVs RF system.

Okay, brief update. I'm pretty sure the video output tube is causing it.

I was able to get the lines to start and stop by tapping the 11BT11. I've gone ahead and ordered a NOS one, so I'll see if that fixes it. I've also been noticing that the sound and video keep dipping and then coming back, almost like the signal is being muffled. Tapping that tube seemed to correct that as well.

As far as motor interference being picked up, this happens regardless of the location in the house, and there aren't any nearby motors. So I think it's internal to the set.

Since another section of the 11BT11 also contains the sound/sync amp, that could also be affecting the sound as you mentioned.

Incidently, see if the contrast control varies the intensity of those flashes (it's located on the furthest-to-the-right end of the back apron).

“I'm also still concerned about the brightness. It seems like the picture goes completely dark for a significant portion of the control. Not as much now that boost has been restored, but still more than I'd like”

Where are the screen controls set?

jr

There doesn't appear to be any kine bias or brightness range adjustment. If it turns out more brt range is needed, there's a little bit of "engineering fudgery" that may improve it. Just jump a resistor from brt. control wiper to ground. I'd start with 2 meg to be conservative. Then work downward in R value till desired range is reached.

What it does is make the CRT cathodes more negative, hence the G1s more positive with respect to the cathodes.

Again a decade box would be handy

Pin 9 of the 8BU11 is fed thru a resistor (blurry print looks like it's 100 ohms, can't read the R designation). There should be 130V on the supply end of this resistor. Is there? If there is, the resistor must be open, giving you the 0V you're getting on pin 9. Does the resistor look cooked?

There's a .01 cap from pin 9 to ground (can't read the C designation). It might be shorted. Or possibly a short in the tube.

So jumping all the way back to this. I went ahead and tested the resistor in question. It's hitting around 140V on each side. I'm not seeing any significant drop in between. I'm gonna recheck that. It's buried very deeply in and difficult to reach with the probe. But assuming that's correct, does that sound correct to you all, or does that seem unusual that there's no significant voltage drop across the resistor, even if there is continuity?

As for the .01 cap, how would I go about measuring that?

I suppose I could also sub a tube to be safe as well. I reverified that there's no voltage on pin 9, so somewhere between that resistor and pin 9, I'm losing voltage. Maybe a cold solder joint? I haven't done any soldering there as of yet, but I've heard solder joint issues are a common problem in portacolors.

On the foil side of the board, look for a crystalized joint where that resistor's lead comes thru the foil, or where pin 9 comes thru the foil. If there is, re-flow the joints or tack a wire between the two joints.

I'm still waiting on that video output tube to come in, but I wanted to check in about something I'm noticing.

When I turn the brightness down, the picture grows much larger and the vertical seems to bob up and down. It doesn't lose sync, but it's significantly impacted for a moment.

Is that normal? Is that a sign of an issue?

Also, a quick update on the color problem.

Since my vertical is finally back, I decided to go ahead and plug in a video source to get the geometry locked again. In doing so, I noticed that I was no longer seeing that color line.

I wasn't happy with how cramped measuring on the top was, so I decided to do a few voltage tests from the bottom. I had to remove an RF shield to get there, but I was able to uncover the pins for the 8BU11. Reverified pins 3 and 10, those are still a little above 200V, but now pin 9 is reading just above 130V. So it looks like whatever wasn't working is now working again.

My current theory is that the tube pin itself was dirty. I never did clean those, probably should but I always get so excited to dig into the obviously bad capacitors that I skip that step. I've removed that tube a few times and I'll bet in the process of removing and installing it, I eventually cleared the block. I'll keep an eye out to see if it comes up again but I'm cautiously optimistic.

So right now my only remaining issues are the bad video output tube, which is on its way, and possibly that brightness issue I pointed out. Once I fix those, I can clean up the cabinet a bit, do some geometry and color adjustments, and this thing should be good to go (hopefully).

So... is the set now producing a color picture, with proper tint control range?

I think so. I at least know all the voltages to the tube match.

I may need to call in someone to verify for me on whether it's "proper" though, since I'm color blind.

How do I tell if the range is proper? Would a video help here?

A brief vid would help, showing what the color and tint controls are doing when rotated thru their full range, preferably including a pic containing flesh tone (since flesh tone is center reference for tint range). That brightness problem would be interesting to see also.

Okay, here's a showcase of where I am. Sorry for the long video, I was trying to capture everything that came to mind.

Highlights are:

The new video output tube seems to have cured the issues with those bright lines and the signal loss.

I'm noticing some odd behaviors on channel 8 and 9. 9 got better over time, but the static seems dramatically different on 8 from how it appears on the other channels. I showcase that in the video, but that may be normal.

There's a lot of noise in the picture even when I have a stable input signal. It appears to be a sort of cycling movement, scrolling up, and then scrolling to the side. I'll check a few more signal sources to see if that changes depending on the source, but someone else may recognize that issue.

As I already stated, the vertical wobbles when I lower the brightness, and the picture changes size.

There's audio buzz that I'm noticing, but that may also be a signal thing. It's not AC hum.

The color is off. I know the screen needs to be adjusted, but I'm noticing that the colors also seem to be out of alignment and following the cycling movements I mentioned before. I'm not sure if that's an alignment thing or a sign of a problem.

This isn't showcasing flesh tones yet. I'll need to grab a DVD player and set that up. I'll plan to tackle that this weekend. Right now I'm just focusing on picture stability and RF noise. I guess at this point I'm calling the picture "stable" but I feel like it could be better.

Video: https://youtu.be/XHZcKReAZ6A

I left comments under your video, copied here:

Dark band on channel 2 with no signal - this is probably a slight oscillation coming from the power supply - nothing to worry about, should disappear when you have a normal signal.

Snowy picture with a signal - needs to be diagnosed and fixed. Could be anywhere from a broken antenna wire, or something in the tuner; not likely to be the IF though there is a tiny possibility.

Range of the brightness control with picture completely black may be normal due to sloppy design.

Change of picture size with brightness or fine tuning bringing up stronger image - probably normal. Just make the vertical size a bit bigger to hide the black edges.

Vertical collapse when changing channel - big noise in the signal momentarily kills the vertical - needs to be diagnosed and fixed.

Where you point to color at the bottom, all I see is reflections from the table.

Not sure what the squirmy noise is from, probalby some other nearby equipment? You may have a bad signal connection, as I said above.

The color interference you point at (which I can't see very well) could be an interfering signal of some kind just like the squirmy noise - need to get a good strong noise-free RF connection before going further.

The coarser, stronger interference on channel 8 with no signal is unknown, but again, no use trying to chase something that likely occurs only in a no-signal condition, until you can show that it occurs with a good signal.

In summary, on channels with no signal, you should expect to see snow and hear white noise. You do see snow, so don't worry about it until the strong signal problems are fixed. However, if you don't hear audio white noise, there is something wrong with the sound section.

Thanks for the suggestions. So I take it as far as the blurry picture goes, I should start by looking at my signal going from the antenna inputs to the tuner? I know the internal wiring from the inputs to the tuner is right where I was doing a lot of soldering for the filter caps. I wonder if it got damaged. I try some alligator clips across it and see if anything changes, perhaps?

Any thoughts where the "big noise in the signal" might be coming from? Could that be a tuner tube developing an issue? Or maybe a dirty tuner?

I am hearing static audio on the channels with no signal, by the way. I just had it turned down during recording. Beyond the filter hum when I started, I haven't had any audio issues with this.

The problem is most likely in the antenna leads, but I suppose the signal from your source could be weak - do you have another good TV to try it on as a quick sanity check?

The "big noise" is normal switching transient when you change channels. Even though the sync separator circuit may see it as a momentary erratic sync signal, it should not cause the vertical to collapse. This would lead me to check components between the sync separator and vertical sweep section, as well as components in the vertical section itself.

Thumbs up on the audio noise!

The problem is most likely in the antenna leads, but I suppose the signal from your source could be weak - do you have another good TV to try it on as a quick sanity check?

Yeah, right next to the workbench actually. I'll do that the next time I'm down there.

The "big noise" is normal switching transient when you change channels. Even though the sync separator circuit may see it as a momentary erratic sync signal, it should not cause the vertical to collapse. This would lead me to check components between the sync separator and vertical sweep section, as well as components in the vertical section itself.

That's the 8BU11 again. That's been giving me some strange behavior. I've got a spare coming, I wonder if the tube itself is acting up. I say that because the vertical collapse is a new issue, and that tube only recently started giving me trouble.

When you get your DVD player hooked up and ready to display actual color pics, first you need to set the B&W tracking or 'grey scale'. With the color control full Off, and brightness set very low, adjust the Screens so all three extinguish at exactly the same point.

Okay, here's a big update post.

Of the problems I listed last time, several are now fixed.

I replaced the 8BU11 tube, which has the sync separator. Sure enough, the vertical is no longer collapsing when I change signals. Picture is much more stable.

I also figured out why there was so much interference in the video. My matching transformer had a broken lead. I swapped a new one and the picture has cleared up.

I had forgotten my DTV converter box can play video from USB, so I went ahead and added a clip to check the colors. I haven't done a full greyscale alignment or anything, but I was able to prove that the color and hue controls work, and get the display pretty close to what I'm looking for. So I'd say my color is working fine now, minus the adjustments I need to make.

There's a few outstanding issues. I've taken a video to show them: https://youtu.be/5xGn8A43S5A

There's a lot of buzz in the audio. I can get it to come through clear enough to understand it, but even with fine tuning the buzz never goes away fully. Is there an adjustment I can try somewhere? Maybe in the audio IF?

I'm also noticing a slight ghosting issue, especially when the images are static. It's almost like there's a second image slightly to the side of the color one. I've read about a delay line issue causing that, but I'm not sure how severe that would look. Alternatively, could it be a convergence problem? I tried to showcase that in the video.

Also, what I didn't show on the video, and I can go back and try to find this, is that when my signal isn't tuned in quite right, I often end up with a good image that's only in black and white. I can reliably get the color image adjusting the tuning. This isn't something that happens regularly, it only happens if the signal isn't tuned in properly. Once I lock it in, it's rock solid. I don't know if that's normal or not, but I figured I'd check.

Greyscale adjustment is done. It wasn't far off, but it looks even better now.

I touched up the geometry too. Vertical is much more stable as I adjust brightness. I may do another round later.

I noticed it was a little stretched to the left, though. Does anyone know how to adjust the width?

First off keep in mind what a Portacolor is & isnt. It was built to
sell at $220, later $199. As a rule everything was the cheapest
possible with the lowest parts count. Brand new they "worked"
and thats it. Do not expect perfection from it, GE didnt.
GE stands for "Good Enough" dont you know.....

One thing we found was a PC, especially a first gen like yours after
a few yrs needed a lot of work If we changed one low level tube at a
time you could see improvements with each one. Bad news is
compactrons cost $$ even in 1970. So they were fixed to "work"
again & no more.

Notes
Audio. Put it last. Buzz is detector stage, hiss is audio IF stage.
Vert collapse not normal.
"Blooming" change in pix size probably normal for this set. It is not
highly regulated like in expensive sets.
Tuners have 3 bands. VHF low ( ch 2-6) VHF high ( ch 7-13) &
UHF ( ch 14-83). When the UHF is used 3 things happen.
1) UHF tuner gets power. 2)The VHF osc gets turned off.
3) The RF amp & the mixer in the VHF tuner are turned into two more
stages of IF amps.
So you can get very different performance on different bands with weak tubes. But it can give you clues.
BTW they will usually test good.

IMHO your best next step is to get a good stable source of a color pix
pref a DVD with an RF out.

enuf fer now
73 Zeno:smoke:
LFOD !

I say "width" but on second thought I think horizontal linearity would be what I'm looking for.

Though to be fair, I wouldn't be shocked if there wasn't a way to adjust that. This may be one of those "good enough" things.

0) Glad you found the broken wire

1) Losing color with fine tuning wrong is normal. Nothing to fix except adjust the fine tuning.

2) Things you point at in still pictures are hard to see in a video due to the coding artifacts on YouTube. Post some still pics here and we will be able to see what you mean much better.

3) Nothing wrong with using the USB player for test material. I have one (I think the same model) and it works fine for me

Regarding the buzz, there are two sound coils, the !F and the detector ('quadrature') coil. They're both located right close to the 12BF11. The detector is the one you want to try tweaking first. it's the one located more 'inboard', while the IF is the one out near the corner of the board.

But get the best color picture tuned in first. Then peak the detector for least buzz, and then adjust the IF a bit for best sound. Sometimes you gotta juggle the two a bit.

Sometimes you can minimize buzz with the AGC adjustment too.

As far as picture goes, I'm happy with it at this point. It looks like most of that ghosting went away when I adjusted the greyscale, and I'm thinking that most of that is just the nature of the set. This still has one of those early tubes with much lower resolution.

I'll try adjusting the audio, and if that works I think I'm about ready to declare this set finished, minus a few cabinet cleanups.

Played with both coils. Wasn't able to get things much better.

Would it be worth trying a new audio tube? How reliable is the audio diode?

I tried to grab a few more pictures of that bleed/shadow image. Hopefully these show up. It's kind of hard to see. There's a dark shadow to the right of each image.

Still playing with the audio buzz, but no luck. I can't get it much better than it already was. I've ordered a new audio detector and output tube to check whether that's causing it, but maybe there's another coil I could adjust? It definitely seems like it's impacted by the video.

The buzz may be from your source. Remember when this was built
there were no add ons like VCR, DVD, games, cable boxes & most
old sets dont like them. AGC & fine tune can affect them also.
The DVD with RF out is the best choice but even at that lettering will drive you nuts with buzz & streaking.

Fine tuning acts like this, I will go clockwise the way most do.
First you get a poor B&W pix & weak sound. As you go CW the
pix & sound get better. A little farther & the color pops in.
If you keep going you start getting a wormy pix then it will go away.
If you keep going you will you usually hit the next channel up.
If a set has AFT, AFC or auto color buttons turn them OFF
before FTing. You dont have them, it "works" without them.

73 Zeno:smoke:
LFOD !

I suppose that's possible. Maybe I can swap in another input source and see if the buzzing changes. It still feels like I should be able to get it better than it is, though.

The buzz could possibly be the 'nature of the beast', owing to the highly unusual sound take-off scheme. Both sound and sync are combined in a single triode section of the 11BT11. The actual takeoff point is the plate of the 3rd IF stage, rather than right after the video detector as in conventional designs. It looks like GE's way of going el cheapo and still make it 'work'. It may indeed have worked passably in the days before digital players, digital converter boxes etc.

You might still try subbing the 11BT11 just for the heck of it.

I just swapped in a new 11BT11.

I've heard some tubes have manufacturing variances, though. Maybe I'll swap the old one back in and see if the audio changes? The old one had video issues but I could at least figure out if there's a problem with the new one.

Okay, so, no luck with the 11BT11. Although swapping back and forth allowed me to double verify that the video lines and flickering were coming from that.

However. My environment has changed since I started on this. Over the weekend I finally got my home tv transmitter started. I've only got two channels up at the moment, but I decided to see what happened using that. Sure enough, it improved the audio home dramatically. So I'm going to call this done for the most part. Here's the set working where I plan to use it. https://youtu.be/s2wph0EkvUg

There's a few odds and ends I'd like to wrap. There's a slat broken off on one of the vents in the back. I'm planning to have a replacement 3D printed. Unless someone has a spare. I'll attach a picture.

I'm also having a few issues with my transmitter. Namely, I'm noticing that any television I have hooked up where my portacolor is (this is only happening in one location at home) experiences vertical loss and bouncing periodically. Nowhere else in the house is that happening, and it's only happening on over the air transmissions.

I may start a new thread for that, but does anyone have any experience with that happening?

“ I'm noticing that any television I have hooked up where my portacolor is (this is only happening in one location at home) experiences vertical loss and bouncing periodically. Nowhere else in the house is that happening, and it's only happening on over the air transmissions. “

Sounds like the portapottie is generating a bit if rf interference that is bothering the other tvs... likely in an area of the house with the weakest signal from the modulator. :scratch2:
Might try a snap on ferrite filter on its line cord, it might be helpful to bypass its power supply diodes with high quality caps, 10 nanofarad or so.

jr

First off that set is running very good, about how I remember
one back in the 70's. Well done !

The vert collapse issue is bizarre. Both the vert & horz osc should
be free running at about the right freq without a signal. Only thing
I can imagine is the vert sync pulses from your source arnt right
& the vert is trying to lock way off freq. I do remember a few sets
that "blinked". It was always a bad cap in the vert feedback
( parts running from vert out plate to vert osc grid).

Now that this is wrapped up hows about finding another set for us
to work on :thmbsp:

73 Zeno:smoke:
LFOD !

I think I figured out the vertical issue. I was using a different video source when I adjusted the geometry, and as it turns out some of the black and white broadcast shows I'm watching have significant variance in the darkness between shots. I'd already discovered that the vertical on this set can get touchy when the brightness dips suddenly, and apparently it was still doing that. So I played with the vertical linearity a bit more to find a happier balance. That seems to have fixed it.

Just need to get that slat fixed and I'll be done.

Next up is a small adjustment to my RCA 8-PT. I may not need to make a thread on it, but I'll see about posting pictures at least.

You reach a point on these old sets that you have to draw a line in the sand and say. It’s as good as it’s going to be. When I worked at the shop GE was known as generally defective and Portacolor was Porta potty for a reason. That fact that it’s working with a raster, color, and sound is something that should bring you satisfaction. You’re now tuning in a ‘66 year tv with programs that have state of the art tv studio equipment. All those inherent flaws are going to show up. I watch a Sony KV-1920 from ‘75 era and it buzzes whenever a lot of writing or high contrasty picture is displaying. But I’m overjoyed to watch current television on something that is 45 years old. Enjoy it and draw a line in the sand and say I’ve done enough to it.

Well, I'm not even gonna make another thread about this one. It took me all of 20 minutes to resolve.

This is a set that was previously restored by Phil Nelson of Phil's Old Radios. I bought his RCA 8-PT, and one of his to-be-restored sets a few years back and finally got a chance to fiddle with it. The Horizontal was struggling to sync, the antenna was damaged, and I wanted to swap the restored chassis into a new cabinet so I could get the legs on it. The paper collar around the ion magnet also needed to be replaced.

That's all done now. I had the antenna cabinet worked on when I picked it up, and getting the broadcaster running inspired me to check out the hoizontal sync. It actually fixed itself once I got the antenna connected. I'm not going to call it "rock solid" in any sense of the word, but I attribute that more to RCA trying to design a cheap set than to any outstanding electrical issues. I may tear into it later and tinker with the yoke a bit. It looks angled, even in the new cabinet, but that's something Phil noted in his original restoration so that could be an outstanding issue.

Perhaps some day I'll tackle the other chassis and reunite it with its original cabinet, but that'll be a future project when I have more experience.

The sound issue that disappeared when you switched modulators was probably video over modulation....audio is FM and video is AM...AM modulation at 0% is full carrier strength and at 100% modulation is no carrier ( proper AM normally stops just shy of 100% modulation) when AM modulation exceeds 100% the carrier turns back on but is phase inverted 180degrees (or reverse polarity)....that effectively creates phase modulation of the carrier that depends on video and video has a 60Hz rate. Phase modulation and frequency modulation are closely related...any FM modulator creates phase modulation and any phase modulator creates frequency modulation you can switch a transmitter between sending one or the other by applying an integral or derrivative mathematical function to the signal and the Same applies to a reciever just run the output through a circuit to do the math to make is sound correct... that PM noise will make it through the FM detector as easy as a proper FM signal.
Many cheap modulators over modulate the video and use the same carrier for both audio and video resulting in the PM noise being on the sound carrier and having an EASY path through the set.

And it's done! Found someone who could 3D print a new slat to get the back fixed. It's not perfect - there's blemishes here and there and the audio buzzes with hot signals - but from what I've heard this is as good as it'll get. I may play with my Agile Modulators and see if I can reduce the signal strength a bit to reduce the buzzing.

What part did you have 3D printed? Do you have a picture?

So this has been awhile.

As far as the 3D printing goes - it's not that exciting of a part. One of the slats on the back had broken off and I had it replaced and glued in. Looks much better now.

That being said...

My set has had a relapse. It's been working fairly well for the past few years since restoration. No serious complaints, save for some bad buzzing when I use my Atari 2600 on it which I think is due to the signal strength and not all that fixable. I've never quite gotten the balance right on the quadrature coil for that.

However, a few weeks ago the color went out. It still has audio and an image, but it's completely black and white.

I'm not entirely sure where to start, save for replacing a few of the tubes in the color section. I'm thinking of maybe trying a new Chroma Amp, but that would just be fumbling in the dark. Does anyone have any guidance on where I could start looking?

Ok I've at least isolated the problem to a specific area. Pin 2 of the 8BQ11 Chroma Amp should be around 200V. I'm reading around 180V between it and ground. Willing to bet that tube is weak. I have a new one on the way to confirm, and short of that I'll check the circuit around it.

The problem must be there, though. Luma video displays with no issues, and I've got audio, so anything up through the 11BT11 has to be fine. If the tube itself isn't the issue I'll see if R84 or R85 have gone bad.

Tested tube voltages for the 8BQ11 and 8BU11:

8BQ11: Pin 2 reads around 180V, as does pin 3. These should both read around 200V, so perhaps this tube is weak? I'm surprised I'm getting no color, though, these don't seem low enough to totally kill my color.

8BU11: Pin 9 reads around 130V. Pin 10 reads around 230V and pin 3 reads around 220V. Again, these seem in line with what should be expected voltage wise.

I'm going to confirm that I have around 170V on pins 2, 5 and 10 of the 6AC10. Those appear to be the final point of contact for the red, green and blue color signals before they hit the CRT. It could be that something has shorted in that tube and killed my color signals. If that's not the case, I'll check R84 and R85 to confirm they haven't shorted and then start working backwards from the 6AC10 to find where my signal is dying.

Hey, so any help here would be appreciated. I need some guidance on how I can go about testing this next component.

I've discovered that the SAMS numbers don't line up with the numbers stamped on the bottom of the Portacolor. that's going to make this much more difficult to test at the component level when I'm working from the underside. Does anyone know if there's a rhyme or reason to match them up?

Second point: I'm almost certain my problem is related to the ringing color circuit. It was previously called "infamous" which I assume means this is a common source of trouble. My tube outputs all have the correct voltages, or at least in range, and replacing both the Chroma and Color amps had no impact.

So here's what I'm thinking: knowing that my burst gate signal is present (or at least operating at the right voltage), and pin 10 of the 8BU11 is still outputting a voltage in a tolerable range, my problem is likely to be either:

1. The crystal
2. The 2.4 pf capacitor marked at C80 on the SAMS schematic
3. The 220 ohm resistor marked as R93 on the SAMS schematic.

I have no means of testing the crystal, but Moyers has the part so I'll plan to test the other two and, if those are fine, I'll replace it.

Here's the thing, though. While I've identified R93 on the top of the schematic, it looks like the crystal is buried under a shield which in turn is blocked from the underside by the plastic support running down the center. So that's my second question: Are there any tricks to getting at this thing, or do I need to tear this down further to pull the whole unit apart?

Again, I'd be incredibly appreciative of any help here. I'm eager to get this working and I've made serious progress in figuring out where the problem ISN'T, but I want to make sure that as I get further into the weeds here I'm not doing anything that would damage any parts.

Realized I never updated this thread - the portacolor is working once more. I can't tell you exactly what was wrong, I fiddled around underneath for awhile, swapped the crystal and discovered that the pinout was different, swapped it back to the original and the color was back.

I had also touched up a few solder joints around the tube sockets while I was down there. It's been stable since so without having actually replaced any parts I'll suppose that there was an intermittent cold solder joint somewhere that I caught. Unless it comes back.

How about some pictures?

Photos are a bit too big to share but here's the set!

https://imgur.com/a/7M38RXn

That's a pretty one. The top isn't all scratched up. You should round up as many spare parts as you can especially those compactrons!
Yeah, I've had trouble posting pics here. Probably be going to imgur myself!

That's a pretty one. The top isn't all scratched up. You should round up as many spare parts as you can especially those compactrons!
Yeah, I've had trouble posting pics here. Probably be going to imgur myself!
I got a lot of the tubes needed for my PortaColors from ESRC. RIP, Stan!

That's a pretty one. The top isn't all scratched up. You should round up as many spare parts as you can especially those compactrons!
Yeah, I've had trouble posting pics here. Probably be going to imgur myself!

Flickr is better in that you can seemlessly embed pictures into the text.

It honestly annoys me whenever I have to read a post with imgur and have to click links to view pictures...Makes the threads look blander too.

Flickr is better in that you can seemlessly embed pictures into the text.

Oh cool, I'll give that a try next time! I just upgraded my phone after about 6 years with the old one - I think the default size has gotten too big for the native image sharing setup.

I only wish I could get this to behave a little better with strong signals. Try as I might I've never managed to get rid of the loud buzzing that comes up during colorful segments by fiddling with the internal controls or my transmitter setup. I suppose it's the nature of these beasts, especially with Portacolors as they are.

Oh cool, I'll give that a try next time! I just upgraded my phone after about 6 years with the old one - I think the default size has gotten too big for the native image sharing setup.

I only wish I could get this to behave a little better with strong signals. Try as I might I've never managed to get rid of the loud buzzing that comes up during colorful segments by fiddling with the internal controls or my transmitter setup. I suppose it's the nature of these beasts, especially with Portacolors as they are.

A few months ago the default max image upload size/sites ability to auto rescale got messed with in a server maintenance session and it hasn't been fixed. I've had the same phone since last summer and I can remember when uploads stopped working after the maintenance. I'm almost out of storage on VK anyway so I plan to go back to flicker (which was my go-to after Photobucket imploded and before I had a smartphone.