Portacolor Troubles
 

I have a portacolor, made about 1968 or so. Its original, never having been serviced. Its in use everyday about 12-14 hours a day. it produces a nice picture, I've posted a screen shot elsewhere and can link to it here. The problem I'm having is that its moody. I'll be watching it and every once in a while it will lose vertical hold. Its not all the time. It can go days without problems. Someone elsewhere said to test the vertical hold pot, but it seems to be within spec. The tubes are stable, all checked good. The caps seem to be healthy. I'm at a loss as to what its current problem is, or more particularly what makes it fail. it doesn't seem to be temperature, as its in an air conditioned office, and keeps at a fairly even operating temperature (no over heating and no tube scorch on the PCB). Anyone have any ideas of what to look for next?

David

In my Portacolor which was built in 1977, the boost voltage(several hundred volts) is on some of the rear adjustment controls. These controls are in a common package, with some controls seeing the boost, some not. This caused carbon tracking in the controls. In my particular set, the AGC control was affected. The TV would work, then the AGC would overload. Then it would work again.

After I took the ganged rear adjustment control apart a cleaned it completely, the problem disappeard. This is a tedious process as these are crimped together in my set and care must be taken not to break the metal tabs when unbending/rebending them.

Did you replace that big cap next to the HOT? It's a paper cap and I've seen a few bad (exploded) ones. Even 10 years ago I always replaced that cap when I got a Portacolor. I think it's in the B+ boost circuit, so that would affect the vertical.

I would second both suggestions, as I've seen both problems. I had one of those caps blow. Funny, the set kept right on chugging away, but with a messed up picture. I think it's one of those El-Men-Co ceramic tubular caps.

Those 3-in-one controls were a favorite of GE and are trouble. I have had a couple Portacolors with intemittents related to these.

Hmmm isnt 12-14 hours a day a bit too much for a 40 yrs old tube set?

the portacolor's CRT is likely going to get weak pretty quickly this way.

That's the thing about Porta-Pottys...THEY don't know they're cheap, nasty, & not-sposed-to-work after 40 years, they just keep chuggin' on...

If anyone is ambitious and needs a 11SP22 CRT for a Portacolor, PM me with a post to let me know. It's NOS and available for shipping costs. First in gets it.

Dave A

A friend of mine who had an antique / junk shop back in the '90's had a late run portacolor (11/76, I think) and he ran it all day for a couple of years until it died one day. He gave it to me and all I did was solder the mess out of it and got it back going. No, I don't still have it. I guess I should have kept it since it was a later tube set. Of course, if I find another '76 or later model; I'll probably get it for keeps this time.

The 11SP22 winner is Zenith2134 at 11:09pm Monday night. I will PM you back tonight. Got my hands full with playoff baseball today.

Dave

It would appear that I've opened a monster here. I took off the forum for a couple of days for my birthday (9/30) and returned to a lot of messages.

I'm gratified that everyone has an opinion on my Portacolor. I've had a few people to mention that it might not be wise to run one so much. But, it runs at my work, and makes my day a little happier. So, I think its worth having around. My only problem is keeping it going.

As far as the CRT strength, I've noticed no degration in the picture brightness. Its not exactly the brightest of sets to begin with, but its still as bright as when I got it.

I'm going to have to go back and study some of the replies. A few of them are complex, although intriguing. I actually didn't know the Portacolor had an AGC circuit in it. I know it has no DC restoration. I got a schematic from a guy on how to fix that problem. But, I figure one thing at a time.

Thanks,
David

Keeping the brightness and contrast low is the key for CRT longevity...

Turn them up just a little and your CRT will last half as much...

That's probably why the portacolor CRT lasts so long. It has a huge electron gun, but a tiny screen. Even at high brightness, it's running under less load than a full size CRT.

One of the portacolors I had, which I have since sold, spent years demonstrating nintendo games at a flea market. Despite lots of long days it still looked fine. I don't guess spare crts are too hard to come by. I have a pair of them in the attic, for instance.

Did any other manufacturers use the same CRT?

I have a buddy who had a houseboat that developed a leak & sank...He had a Porta-Color on board; THAT particular one floated. We fished it out, took it home, I got the CRT out of it, but didn't have any way then to test it. It still had vacuum, the getter was nice & silver. Betcha a nickel it woulda worked...

Sandy, that is one of the best vintage-TV stories I've heard! Never occured to me that a crt would float :scratch2::yes:

My port-a-color has definitely seen a LOT of use... Its original owner claims he got it for his 18th birthday.. Now he is nearing retirement. The CRT sticker is marked 52 1966, so, Last week of 1966 I assume? Story checks out. Anyway I don't watch this one much, especially since it pulls 200watts from the wall, and I have to push the brightness too far before It is really watchable. Not to mention the heat this little fella throws. Red is also weak, about 30% weaker than G&Bl. Have the red gain cranked up just to get decent greyscale. Cosmetically I cannot complain. Can't wait to slap the new CRT in it and really see what it can do (I know guys, I won't expect too much out of it).

I cleaned that CRT up & kept it for years-Didn't have the heart to toss it...Porta-Colors were Hot Stuff when they 1st came out...A Color TV that was SMALL & portable-Well, "luggable" anyhow...and they were fairly cheap. You gotta remember, rectangular color sets had only been around about a year, & about all the sizes you could get was a funky old 21" roundie-Who wants one of them old ugly obsolete things, anyhow ?- a 23" snazzy new rectangular, or the Porta-Color...The "mid-size" sets, IIRC, were still a year or 2 down the road.

I gotta say, I've never seen a Portacolor with a bad CRT, no matter how beat-up and heavily-used the rest of the set appears.

If you ever actually needed a replacement CRT for a Portacolor, though, I seriously wonder if you could just swap it out (along with the yoke and other neck-mounted stuff) with one from a common 1980's-era 10AA or 10AB chassis GE set. The CRTs look identical except for a shorter neck on the AA/AB sets.
[I should really just try that out sometime just to see if it works...]

I think I checked on that years ago and found out that the pinouts are not the same. Of course, the socket could probably be rewired for the newer tube.

A CRT is an empty shell and as long as it's intact, it will float...

Larger CRT sets are probably useable as lifebuoys in the event of a ship wreck...

It seems like the earlier Portacolor tubes used a low focus voltage CRT and the later tube type Portacolors and the solid state sets used high focus voltage...the later model tube sets probably could use the CRT's from the solid state sets.
Also the filament voltage/current may be different on the solid state sets? I can't remember if the portacolors had the CRT on a seperate filament transformer or was it in series with the other tube filaments? There was some set which had a 2.3 or 2.5 volt CRT filament, maybe that was a Predicta?

I actually have seen what appears to be weak CRT's on some of the earlier Portacolors although perhaps it is a video problem?

Well, its been a couple of weeks since the Portacolor had a problem. Its been reliable. I suppose its just a matter of time before whatever intermittent part will finally go, but for now its well behaved. I appreciate everyone's contribution, its really going to help diagnose this set once it gets a little farther along in its failure. I might just recap it before it does fail, but for now its working.

David

Hi Marty,

I have seen three German Portacolors, made by Kuba but with a GE 11SP22. Two of them had no emission on the red gun. Only one has good emission on all three guns. I assume that the 11SP22 was fitted with regular guns like they were used in the large-screen CRTs. Since the screen of the 11SP22 is very small and needs only 0.2 or 0.3 mA to be full illuminated (compared with 1 to 1.2 mA for large screens), their lifetime lasts much longer.

Regards,
Eckhard

I was playing around with a crt tester the other day and wanted something to hook it up to, so I grabbed a portacolor crt I had in the attic. I think it's a 10VAHP22. This one has a GE label and another that says "made for Montgomery Ward" so I guess it came out of an Airline badged set. The crt tester I have is from the later 60s and didn't have a listing for this tube, but did for the 11SP22. It says the 11SP uses a 12v filament, but the 10v tubes are 6v. (at least this one is) And, of course, older ones are dot matrix.

that's adorable...

too bad there aren't any portacolours on epay

GE Portacolor: AGC troubles
 

Hello,

I have a GE Portacolor, which only displays a raster. No sound, no picture. At the 11BT11 (AGC keying) I found 5V at the cathode and appr. 5V at the grid. With some adjustment at the AGC control I can get 8V. But it has to be 60V. As a consequence I read at the grid of the first video IF tube (pin 10 at the 8AR11) -50V (it should be .1V). Did somebody had AGC troubles with the Portacolor?

- Eckhard

I had AGC troubles with a 1977 vintage Portacolor. The symptoms were intermittant. What would happen is that the picture and sound would go away leaving just a raster. What I found was that the design of this particular Portacolor had controls with the boost voltage (700 volts if I remember correctly) and the AGC controls in the same assembly. Over time, conductive tracts had built up, allowing the boost voltage to leak into the AGC area.

I fixed the problem by very carefully disassembling and cleaning the control assembly. You must be very careful in bending the metal tabs holding the assembly together or they will break. The set still works fine(at least as good as Portacolor ever did) at present.

As this has been a few years back, I do not remember the voltages that were showing up when the problem occurred.

Thanks very much. I believe you are alright. I have operated the set with shortened filaments of the 11BT11 (AGC keying), i.e. the 11BT11 not operating. I found 0.6V at the anode. (Pin 9). With heated 11BT11, I found -60V. In a quiet room I hear some muted cracking noise from the AGC control assembly. I will remove it and clean it like you have suggested.

- Eckhard

Be very careful disassembling/re-assembling the control assembly. The metal tabs are easily broken.

Before disassembling the control assembly, I want to test it with an extern control. I have only to remove the wire from pin 4 to connect it with an extern homebrew control assembly for test reasons. There are only two resistors and a potentiometer, and this is easily build with some alligator clamps. I want to see whether there are other faults.

- Eckhard

Excellent idea!.

Meanwhile I have made a test-assembly for the AGC-control and attached it to the set. It lasts only some minutes. Your hint, peverett, was dead right. The set is working again. Since the AGC control has only few parts, I will make a new one and put it in the set. This seems to be the safer way than disassembling/re-assembling the control assembly and eventually to have broken metal tabs.

This is another example how good Audiokarma is! For myself I would never think of the AGC control assembly as the reason for the fault.

Merry Christmas!

- Eckhard

Good work. Yours is an older model than mine. I was able to disassemle-re-assemble the controls on mine without breaking the metal tabs, but it was time consuming and tedious.

One of the advantages of making a new one with the controls seperate is that the boost voltage is no longer near the agc area.

One thing that I have found with my Portacolor is that it does not work well on cable. I think that the tuner selectivity is not good enougn.

Here is a photo of the new AGC control. I hope that it will not suffer from the heat of the line output tube. I have cut the conducting paths for the original AGC control assembly for ground and +270V to prevent any trouble from booster voltage. This new assembly can easily be removed if I decided to re-activate the original one.

My Portacolor has a time stamp of 4-21-1967. It did not have the label Portacolor, but only "Color". The model is M21THW-1.

- Eckhard