I saw on his YT channel Bob had a series on a similar chassis. I replaced the power resistors, the electrolytic caps (more on this later!), the tubes in the HV box with known good ones and most of the paper caps. The voltages coming out of the bleeder network are pretty close to what they should be. I actually brought this TV up on original components when I started restoring it and I got a small, dim raster on the 10BP4.

But the TV is only drawing 1.5 amps when it should be drawing about 2.2 A. The high voltage is low at around 5Kv. I do not have any light on the screen of either the 10BP4 (tested OK) or on the technician 5" CRT. The brightness control ohms out close to perfect.

Any suggestions on where I should start looking to run this down? I cleaned the tube sockets in the HV section and checked the pin tabs for good connections and possible shorts but found all OK.

On the electrolytic caps, check out my other thread about the Adapt-A-Cap issue.

TIA all
Chris

Just a quick addition. I haven't traced this out yet but there is an RCA jack on the back for a phono audio input and a sliding switch for selection of TV or Phono. I know similar switches on the Dumont and cloned versions of the chassis with the continuous tuner allowing you to select TV or FM does shut down the TV when FM is selected. I've looked over the schematic for the RCA and it doesn't look like the switch wiring is drawn. If there's a switch that's broken in the phono position, could it be a possible explaination, albeit a remote one, for what I'm seeing?

Obviously 5kv is too low to drive the beam fully to the screen on a 10BP4 , norm is 9k, or so, so there has to be a problem with horizontal output or frequency or drive causing low HV. SOMETHING ain't right in that area, you jut have to track down what it is.

.

Always check Power Supply Voltages.... Especially if you suspect current use is too low...

.

I checked the screen voltage on the 6BG6 horizontal output tube and it's about 25 volts low. It should be 143 V DC without an RF input signal and it's around 118 V. The other voltages are OK.

I'm trying to make sense of this SAMS, and not getting very far...

https://www.earlytelevision.org/pdf/rca_8t241_sams_74-8.pdf

p33

shows pin 8 g2 260 vdc.

pin 5 g1 8v vdc
pin 3 cathode 8 vdc

using p6 v18 as ref.
then it says
pin 6 110 vdc:scratch2:
https://frank.pocnet.net/sheets/093/6/6BG6GA.pdf

huh?

Put the negative lead of the voltmeter on pin 6 of V18 and measure the voltage on the pins of V19.
What are you unsure about?

What I'm getting at, this is another case of the infamous early SAMS errata with ref to pin 6, or it's being used as a tie point not shown on the schematic, as pin 6 is NC, a bit confusing!

Yes, pin6 is used as a tie point. They don't show tie points in the schematic. The is no error in the Sams.

And the Sams is close to the 9TC-240 I have, but not exact. In fact, I don't think the ETF has the specific schematic and service data for this chassis. This chassis is the KCS 28B-1. I'm using the voltages from the Service Manual 51 that says it covers KCS28 but is written in reference to the 8T-241, 243 and 244 models. The voltage on the HO screen is 160v with an input signal and 142v without.
Bob, measure the voltages on the 6AV6 audio amp while connected to pin 6 of the 6AL5 discriminator?

The only referred to exact schematic I have is in a service publication TV shops used (the ones in the 16-9 orientation!) that covers RCA TVs from 1946 to 1950. The info in the ETF technical section for KCS 28 and 9T-240 have some differences in resistor and capacitor values from this publication. When I measure some of these components, they tend to agree with the parts list in the TV shop manual

And the Sams is close to the 9TC-240 I have, but not exact. In fact, I don't think the ETF has the specific schematic and service data for this chassis. This chassis is the KCS 28B-1. I'm using the voltages from the Service Manual 51 that says it covers KCS28 but is written in reference to the 8T-241, 243 and 244 models. The voltage on the HO screen is 160v with an input signal and 142v without.
Bob, measure the voltages on the 6AV6 audio amp while connected to pin 6 of the 6AL5 discriminator?

The only referred to exact schematic I have is in a service publication TV shops used (the ones in the 16-9 orientation!) that covers RCA TVs from 1946 to 1950. The info in the ETF technical section for KCS 28 and 9T-240 have some differences in resistor and capacitor values from this publication. When I measure some of these components, they tend to agree with the parts list in the TV shop manual
The SAMS says to use pin 6 of the 6sn7gt (horizontal oscillator), as the negative lead of the voltmeter, and then to check the voltages listed on page 33 on the SAMS, listed, though it's not exact to what you have, it should give you a sign of the problem, as they should be close to standards.

Got it. I was looking at the Riders and assuming V18 and V19 in the Sams were V118 and V119 in Riders. Most of the time, they match that way.

Speaking of the Sams, the schematic shows the Phono/TV switch which my TV has despite the Sams saying it's found only in the 9T-246. Inexperience on full display here, what is the switch supposed to do in the phono position and the TV position? When I flip it back and forth between phono and TV, I don't get a blip or any indication the slightest thing has happened on the amp meter (Sencore Isolation Transformer on the 0-4 amp scale). There is no change. Normal?

Speaking of the Sams, the schematic shows the Phono/TV switch which my TV has despite the Sams saying it's found only in the 9T-246. Inexperience on full display here, what is the switch supposed to do in the phono position and the TV position? When I flip it back and forth between phono and TV, I don't get a blip or any indication the slightest thing has happened on the amp meter (Sencore Isolation Transformer on the 0-4 amp scale). There is no change. Normal?

it looks like that when it is set to phono, it cuts out the TV audio, and shunts in the phono audio, and grounds out the CRT brightness. leaving horz and HV alone, rather dumb, the 2 sets I have with the feature had a cutoff for the horizontal output, but then they were made a few years later then this set.

Could a problem with this switch be a possible cause for no light on my screen? I'm using the 5" tube (electrostatic) not the 10BP4. When I turn off the TV, I get the fading central dot.

Depends on what that 5 incher is you are trying to use, you have not said what it is yet, if 5kv is below what it needs to have a full raster with full scan at normal operation, then obviously you won't see anything, and in phono mode, brightness is cut no matter what.

Did you unmount the focus coil? It interferes with the 5AXP4 focus

No I’ll do that

Or at least move it around as see what effect it has. Also do NOT use the ion trap magnet. You should get a glow on the CRT with 5kv

Removed the focus coil...did not have the ion trap on it and there's no change. I hate to keep coming back to this switch but, I measured the voltages on the brightness control (working...ohmed out 10 ohm to 52 Kohm) with the switch in the TV position and I turned the brightness control through the full range while measuring the voltage on all three tabs and had an invariant 135 volts DC reading. No change on the brightness control voltages.

Here's this area:

https://imagizer.imageshack.com/v2/1024x768q70/922/0ngP4C.jpg

what are the voltages on the other pins of the CRT G1 and G2? you say cathode is 135 and wont change?

Short #3 on the brightness control to ground and try

Short #3 on the brightness control to ground and try

yeah. go for broke! :D

that will force it full on! or at least pin 2 of the brightness control should drop to near zero when you turn it to that direction if it's good.

Short #3 on the brightness control to ground and try

That did it! I have light on the screen. No horizontal deflection but there's a line down the center that responds to the brightness control.

I'll get the voltages on V19 from pin 6 of V18 in a few.

Thanks guys. You Let There Be Light!

OK the voltage weirdness is as follows. Black lead from DMM on pin 6 of V18 6SN7GT Horizontal Oscillator and voltages on V19 6BG6 Horizontal Output

Pin #: 0.0V
Pin #2: 0.0V
Pin #3: 4.6V Should be 8V DC
Pin #4: 0.0V
Pin #5: -10.0V Should be 8V DC
Pin #6: 4.7V Should be 110V DC
Pin #7: 6.3V AC
Pin #8: 240V DC Should be 260V DC

There's a jumper installed on V19 between pins 3 and 6 on my TV. Is that supposed to be there? There has been some fiddling with this TV over the years. Why isn't pin 6 over 100V DC?

No horizontal deflection but you have high voltage?!? That can only happen if the horizontal yoke is open or not connected.

No horizontal deflection but you have high voltage?!? That can only happen if the horizontal yoke is open or not connected.

Well there's good news. Tube is correctly oriented because when I adjust height, the line shortens in the vertical aspect. I'll check the connections.

The fact that you have HV, vertical sweep but no horizontal is an indication of a possible problem with the horizontal yoke windings and the path from it to the flyback. al that must be check very closely for it;s a tuned circuit, and when it gets out of wack you are lucky to get any HV at all, the fact you have vertical sweep but no horizontal is a big pointer in the direction of the problem, I dont see where it's stated that the resistance of the horizontal part of the yoke should be, but it has to be someplace, that is a good place to start.

The fact that you have HV, vertical sweep but no horizontal is an indication of a possible problem with the horizontal yoke windings and the path from it to the flyback. al that must be check very closely for it;s a tuned circuit, and when it gets out of wack you are lucky to get any HV at all, the fact you have vertical sweep but no horizontal is a big pointer in the direction of the problem, I dont see where it's stated that the resistance of the horizontal part of the yoke should be, but it has to be someplace, that is a good place to start.

13.5 ohms. I will check

15 ohms on the horizontal yoke. I measured from pin 6 of the 5V4 damper to the other side.

Flyback tests fine

15 ohms on the horizontal yoke. I measured from pin 6 of the 5V4 damper to the other side.

That is well within tolerance, the problem must be some place where the yoke hooks to, a bad cap or resistor, or solder joint.

Yes the solder joints in the HV cage do look terrible so I'll go through them tomorrow. I don't like soldered in fuses much. I'll add a fuse holder for the 0.25 amp fuse as well. Headed for bed. Thank you guys so much. We'll get it run down.

one side of the horizontal part of the yoke goes to the plates of the damper tube, the other goes to a power point same as the focus coil it look like.

Yeah the RCA schematic for the 240 is drawn out differently than the Sams. The fuse is directly in line with the yoke and pin 6 on the 5V4 is on the other side. I also ohmed it out from the focus control. I got 13.5 and 15 ohms from multiple places and I doubt a reading that close to the actual value from 2 spots is a coincidence. But with my luck, it could be! I need to get into the HV cage and do a complete service. Haven’t done anything in there yet. Need to resolder and clean and check values.

OK, I know why there's no horizontal deflection. It grew out of working with multiple schematics from various models, direct replacement of capacitors in the chassis, value for value, and confusion regarding the Sams chassis photos of the bottom.

This chassis had a number of those weird caps in it...not waxies but almost like a cylindrical ceramic with coding stripes, in fact, they look like giant resistors only light in color. I can't replace these value for value because I can't read them (color blind). I depend on the sams photos to identify color coded stuff like this.

The problem with the horizontal yoke is that one side isn't connected. If you look closely at the picture, you can see the thick yoke wire attached to the highest lug of the bottom terminal strip. There was one of those funky caps attached to it running down into the terminal strip that has the large 0.47uf cap soldered in. The sams photo does not have the cap I cut out pictured.

https://imagizer.imageshack.com/v2/1024x768q70/922/xBGJwK.jpg

You can see the yoke lead soldered to the terminal but there's nothing attached to it after I cut out the mystery cap

Here is a wider view. The striped lead running horizontally across the center goes to the yoke. The large diameter yellow modern cap is the 0.47uf I put in to replace another large old cap...but not the one I previously cut out. It is C199 in the schematic down at the end.

https://imagizer.imageshack.com/v2/1024x768q70/924/BrvumL.jpg

Here is the section of the schematic I'm using. The sams is depicted so differently.

https://imagizer.imageshack.com/v2/1024x768q70/924/MC6Jmf.jpg

So, I need to connect the yoke lead to something. Like I said, someone has been in here before so I'm not sure what I saw when I opened it was what rolled out of the RCA factory. The other side of the horizontal yoke is connected in the HV cage fine.

so that must be the .047 cap on the RED/BLACK wire to the fuse line that is missing, it gets hit pretty hard, not sure what DC rating is called for, must be rather high.

this is prob overkill. but..
598-474MWR102K mouser part.

Those caps you describe are simply paper caps inside plastic like bumblebee caps.
I'm confused - you say the .47uF cap pictured is C199?
This is the one that connects to the yoke. What do you have it going to?

There are two .47, 200v volt caps in this set. C190 and C199 in the RCA service info. One is used for AGC the other is for the yoke .

Check out the RCA wiring diagram. C199 is located in the middle at the bottom.

The yoke connects on the left side of C199

https://live.staticflickr.com/65535/53896492528_21bf79f89a_z.jpg (https://flic.kr/p/2q7DBvb)

C199 on the schematic picture I posted. Lemme take a look at this. I did not have a cap bridging those terminals when I started.

Yeah, i was a bit perplexed too, not sure if the cap in question is just missing, or just in the wrong place. :scratch2:

I'm just a bit surprised it got any HV without it! :D

The schematic pic posted is from an RCA publication specifically for 9TC-240 model

I think the WD I'm using is a bit different. Same values but different component numbers

https://imagizer.imageshack.com/v2/1024x768q70/922/GwzX7c.jpg

That's weird. The one I posted is specifically for this model too - KCS28B model 9TC240

Yeah, i was a bit perplexed too, not sure if the cap in question is just missing, or just in the wrong place. :scratch2:

I'm just a bit surprised it got any HV without it! :D

Not surprising at all. It just means the yoke is disconnected. The HV comes from an autoformer on the primary side.

Bob can you show a slightly broader picture of the WD so I can see where C190 should be? I have a 0.47 there but IDK if it's hooked up correctly. I will install C199 as shown

C190 is about in the middle
https://live.staticflickr.com/65535/53895368502_b1960d7128_c.jpg (https://flic.kr/p/2q7xRnq)

Did you download that from ETF? I plucked numerous service information packets off it and I don't have a wiring diagram that looks like your's.

It's from Riders volume 4 which is a reprint of the RCA service manual.

It's from Riders volume 4 which is a reprint of the RCA service manual.

Don't have it. OK I'll just have to check through the schematic carefully and track my work. Thanks

What are you working from? Looks like original RCA service info. Is it for chassis KCS28 or 28A. Seems bizarre that RCA would publish two sets of service info with different part designators.

This...and the Sams. My chassis says it's a KCS 28B-1

https://imagizer.imageshack.com/v2/1024x768q70/923/dOMmNc.jpg

https://imagizer.imageshack.com/v2/1024x768q70/922/zVVLii.jpg

Right that only covers KCS-28. Your chassis is a later revision from the following year.

Just went for it. Looks OK...off center but OK :banana::banana::banana:

https://imagizer.imageshack.com/v2/1024x768q70/924/bdEE2r.jpg

Any idea Bob where I can buy and download Riders Television service volumes?

Not sure. The guy who scanned them was selling DVDs on ebay for years. He had manual other manuals too at ke3gk.com

Could be he passed away?

Edit

Yep, Tom passed away a few years ago. Wonder what happened to all that scanned content?

That would be quite a find. I looked on eBay and found a volume 4 in decent shape for $30 including shipping. Like you, most of my restoration likes are in the post-war era

Cool! :D

major step forward, now if you can get video to show up, that would be another step forward!

I don't see any adjustment for centering on the schematics, so it must be purely mechanical, and no doubt will come into play when the 10BP4 is in place.

Just went for it. Looks OK...off center but OK :banana::banana::banana:

https://imagizer.imageshack.com/v2/1024x768q70/924/bdEE2r.jpg

The picture is off center because the CRT is unsupported. Support the tube with a wooden frame or some books or something ensure the neck is centered in the focus coil and it will be much better.

Looks like he has a clamp on the CRT neck. I do the same.
Centering is mechanical by manipulating the focus coil. Do you still have it mounted? It will throw the 5AXP4 image off considerably.

No I removed it

I'd like to devise a way to 3D print a cylinder, about 2" long with an OD that fits in the yoke tunnel and an ID that will accommodate the 5AXP4 neck. The issue is the ID has to be big enough to slide over the base. If it does, then the neck won't be held in the center because there will be some play. Maybe making the ID big enough to get past the base and line the ID with adhesive foam will do the job. It wouldn't be designed to mount the CRT, just to center it. I'd still use the clamp.

It shouldn't really make that much difference though. I'm literally working on one right now with the same setup.

Can you grab the CRT base while the set is running and move it around a little? Can you center the image?

https://live.staticflickr.com/65535/53897640161_2c42f84ec1_c.jpg (https://flic.kr/p/2q7KuDX)

The 5AXP4 and 10BP4 have the same neck diameter from what I see, so the only issue is how the yoke meets to the 5AXP4 and it having no support, this all should be minor stuff in the debug stage, as Bob suggested, just shift it till it is centered.
No where near as tricky as with the 8YP4 I have, :p, for that I did have to use a cardboard spacer, as it has a thin neck.

I use a large clip-on clamp on the neck. Fully supported and snug against the yoke. Works just as well with the 8XP4.
https://live.staticflickr.com/65535/53898275770_2fbf8f02d7_c.jpg (https://flic.kr/p/2q7NKAJ)

It shouldn't really make that much difference though. I'm literally working on one right now with the same setup.

Can you grab the CRT base while the set is running and move it around a little? Can you center the image?

https://live.staticflickr.com/65535/53897640161_2c42f84ec1_c.jpg (https://flic.kr/p/2q7KuDX)

I managed to get the image centered but not low enough. I did expect it to move more when I wiggled it but...it's not great but it's better than it was. I can tilt the image if I roll the yoke left or right. I do have a signal passing through that's horizontally stable but rolls and wont vertically lock and the crosshatch is mostly bunched at the bottom of the image...but I still have several caps to replace in the vertical circuit so, I'll get that done and we'll see where we are.

So, I don't know if there was a consensus regarding the TV/Phono switch. Since grounding the 3rd tab on the brightness control got light on the screen, does that indicate the selection switch is bad and should be repaired/replaced or removed from the circuit? I have no intention of using the phono RCA jack for mono audio amplification so if disabling it is the easier route, I'll do that. Any long term performance or safety issue with soldering in a wire from the brightness control to ground for a permanent solution?

Thanks Guys

No, none at all. The switch is supposed to connect the 3rd tab to ground. That's why I suggested you bypass it.

Better. The vertical hold is quite touchy though. I don't have all the NOS tubes I ordered yet.

https://imagizer.imageshack.com/v2/1024x768q70/923/hZcp5N.jpg

I have no audio. The speaker pops when I move tubes around so I think the output transformer is OK. Other than that it's completely silent.

Could the switch be causing this? If the switch was killing the brightness, could it be diverting the phono input to the volume control and disabling the TV audio? Only issue with this theory is the speaker is still silent if I touch and probe the phono RCA jack on the back with a metal screwdriver.

Yes it absolutely could be

Seems like the best thing would be a fabric belt like the original because these bands slip and have backlash as the stretch from winding relaxes and moves the fine tuning wheel a slight amount. But it's the best thing I can find at this time. I used two 2 1/2" X 1/3" bands held together with a little super glue.

https://imagizer.imageshack.com/v2/1024x768q70/922/rBZjLM.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/MSyoc0.jpg

How in the world do you clean this tuner? It’s in a bank vault!

You have to disconnect the wires and unmount it. I wouldn't bother unless you are having problems.

https://live.staticflickr.com/65535/53902622544_a857cb1f1d_z.jpg (https://flic.kr/p/2q8c2K7)

https://live.staticflickr.com/65535/53902710625_43f3f68691_z.jpg (https://flic.kr/p/2q8ctVK)

Yeah…not gonna do that. It’s just stiff and feels like it has a lot of gunk in there. Maybe I’ll spray a bit of contact cleaner in through one of the holes and be done with it.

I'd like some advice regarding removal of the TV/Phono switch from the circuit. It's not exactly part of the title of this thread but I don't want to start another thread on the same TV...if I understand SOP here. If I should move this to the start of a separate thread, then please let me know.

Yesterday, the Riders service manual I purchased, Volume 4, arrived at my house. In it is the wiring diagram and schematic for the 9TC-240 with the KCS28B1 chassis. The switch on the wiring diagram and schematic is pictured below.

https://imagizer.imageshack.com/v2/800x600q70/924/zkvyw5.jpg

https://imagizer.imageshack.com/v2/800x600q70/922/idADzx.jpg

So if I understand what has been described earlier in the thread, if the switch is moved to the phono position, the TV brightness control ground is interrupted and the screen goes dark. There's still HV however. The sound circuit then comes out of pin 5 of the 6AL5 discriminator as coaxial to the switch where it picks up audio input from the RCA jack and is brought back into the sound circuit as a grounded coax line. Around there I get lost! To me it seems the signal goes to terminal 3 of the volume control and out of terminal 2 as coax to pin 1 of the 6AV6 bias clamp???

Below is the WD at the volume control.

https://imagizer.imageshack.com/v2/800x600q70/923/iAgDx6.jpg

The yellow and green coax are from the switch.

I need to understand how this all works with the goal being removal of all the switch wiring and circuitry interruptions. I'd like to just cut it all out and wire the sound like any TV would be without this feature.

So if I understand what has been described earlier in the thread, if the switch is moved to the phono position, the TV brightness control ground is interrupted and the screen goes dark. There's still HV however. The sound circuit then comes out of pin 5 of the 6AL5 discriminator as coaxial to the switch where it picks up audio input from the RCA jack and is brought back into the sound circuit as a grounded coax line. Around there I get lost! To me it seems the signal goes to terminal 3 of the volume control and out of terminal 2 as coax to pin 1 of the 6AV6 bias clamp???




Yes, pretty much. They way the drew the switch is a little confusing. The switch element go left/right not up/down.

* Ground lug 3 of the brightness control.

* Connect the two ends of the coax together so that the end of R215 is going to C184.

Yes, pretty much. They way the drew the switch is a little confusing. The switch element go left/right not up/down.

* Ground lug 3 of the brightness control.

* Connect the two ends of the coax together so that the end of R215 is going to C184.

That's what I thought looking at it. So all the capacitor and coaxial stuff going on around the volume control, all of that stays in place? That's where I got lost!?

https://imagizer.imageshack.com/v2/800x600q70/923/iAgDx6.jpg

I guess all that stays there. Just do the coax link at the level of the tube bottoms in the chassis

...and my "Noobieness" exposed...how are these pot terminals numbered again? Are they depicted from the back, non shaft side of the pot? What is that fourth terminal coming out the side of the volume pot?

Once I get sound and a decent picture on the 10BP4, I'd like to do a basic alignment on the sound and video IF circuits just to make certain everything is OK and for my own experience. I've never been able to do one successfully before. Bob, I watched your recent video doing the sound align and all of the changes small movement of the adjustment coils made in the symmetry of the traces. I certainly don't have your HP monster on my bench but I do have an Eico 369 sweep generator that can do the 20-25 mc frequencies needed. I also have a decent HP scope from the mid 1980s. I'll probably start it as a separate thread. Your alignment series on YouTube was very informative but there were some Noob things I didn't understand so as I start that process, I'll be asking the choir for their help and guidance.

I suggest just tracing out the wiring on the pots. 4th terminal would be for tailoring the response of the sound. You could boost low or high end for example. Sometimes called a "loudness" tap.

I suggest just tracing out the wiring on the pots. 4th terminal would be for tailoring the response of the sound. You could boost low or high end for example. Sometimes called a "loudness" tap.

Turn it up to 11! :D :yes:
I have an eico 324 signal generator myself, problem is with these, w/o a frequency counter it's hard to know if they are putting out the frequency you want or how well they are calibrated, not that you need to be THAT precise when you align, but i did mess up the first few times i tried, :sigh: then got a digital unit and got it pretty good on my 4th try on my Arvin.

I too will be watching the Alignment progress, As my FADA needs work and is much harder than the Arvin! :tears:

I don’t have a frequency counter but I’ve been dialing in the RF output using my scope. It does jump around a little but never more than half a megacycle. Last night I checked it trying to get 20.5 of and it bounced around between 20.3 and 20.7 mc. It that too much inaccuracy?

I don’t have a frequency counter but I’ve been dialing in the RF output using my scope. It does jump around a little but never more than half a megacycle. Last night I checked it trying to get 20.5 of and it bounced around between 20.3 and 20.7 mc. It that too much inaccuracy?

Not sure about that, I just know I failed with my attempts with the analog one till I got the much more costly digital unit.
Yours may be OK.
https://www.amazon.com/Generator-Precision-Dual-Channel-Arbitrary-Frequency/dp/B07H8BM2FM

I did not spend that much when I got it 3 years ago! :O

Supposedly the 369 is supposed to be good for this kind of sweep generator stuff but since I’ve never used it successfully who knows. There’s a respected ebayer who makes replacement rf output and demodulator input cables for it and I got them. The scope output is a strange output style though and to be “NoobHonest” I have no idea how to hook this output to my scope. They show X-Y connections and say to use your scope in X-Y mode etc and that’s where my head starts to spin. Frankly my scope experience is hooking the probe to a test point and ground, pushing Autoscale and comparing the trace to a photo. That’s about it.

That frequency is jumping around too much. Foe example the sound needs to be at 21.25MHz so you'll want something stable to at least two decimal places.

Eico scope output is three leads - ground, vertical (Y) and horizontal (X). Eico cable ends with three alligator clips as I recall. Do you have it?

What scope do you have? Needs to be a two channel capable of XY mode. That simply means the electron beam is moved entirely by whatever signals are coming in on the X and Y. Turns you scope into a vector monitor.

For that matter you can use a vector monitor instead of a scope if you have one. Like the Tek 604 or Wavetek 1901

Which way do you look at these controls to read the numbers? The flat back side or the front shaft side?

https://imagizer.imageshack.com/v2/1024x768q70/923/iAgDx6.jpg

Sorry about that!

Yikes!

I don't know that there is any strict convention for control lug numbering. That's why I suggested you follow the wiring.

I did trace it out and it is all wired correctly...but still no sound so I'm going to need to start tracing backwards through the audio circuit. Before I had some pops and cracks when I moved tubes around but now the speaker is silent...and it was before I did the re-wiring work. Also, somewhere along the line, someone replaced the 6AG5 converter and RF amp in the tuner with two 6BC5 tubes. There doesn't seem to be too much of a difference in performance when I went back to the 6AG5s.

6BC5 is an excellent sub for the 6AG5

I did trace it out and it is all wired correctly...but still no sound so I'm going to need to start tracing backwards through the audio circuit. Before I had some pops and cracks when I moved tubes around but now the speaker is silent...and it was before I did the re-wiring work. Also, somewhere along the line, someone replaced the 6AG5 converter and RF amp in the tuner with two 6BC5 tubes. There doesn't seem to be too much of a difference in performance when I went back to the 6AG5s.

Well, if you touch the center of the pot with a screwdriver (2) with it set midway while touching the screwdriver, you should hear the telltale hum, and you know at lead the pre amp and output works.

Fed a modulated signal into the audio amp tube and could hear it so all from there to the speaker is good. Headed more upstream

Fed the same tone into the pin 5 cathode of the 6AL5 (V118) discriminator and hear a very faint tone with full modulation gain on the generator that isn't changing with the TV volume control in fact, it's the easiest to hear with the volume control turned full down to minimum. It's very faint though I do hear it.

Well...I think I found the answer. There was a 6AU6 in the 1st audio/bias clamp socket and not a 6AV6 that's supposed to be in there.

Working...that was it

Well...I think I found the answer. There was a 6AU6 in the 1st audio/bias clamp socket and not a 6AV6 that's supposed to be in there.

Big dif between the two! :yes::D

Sure is except one partially rubbed off U mistaken for a V. Sound getting through the if but the video and sound are misaligned. Par for the course for me. Now that the bottom of the chassis is sorted, I need to get the bench cleaned up and reorganized and put the focus coil back on and the 10BP4 back in. A reset in my head is needed before I go on the next adventure with this!

Sure is except one partially rubbed off U mistaken for a V. Sound getting through the if but the video and sound are misaligned. Par for the course for me. Now that the bottom of the chassis is sorted, I need to get the bench cleaned up and reorganized and put the focus coil back on and the 10BP4 back in. A reset in my head is needed before I go on the next adventure with this!

Numbering aside, I mean that one is a pentode and the other a duplex-diode, high-mu triode, they look very different from each other, after you have seen many of both, they are easy to tell apart, as they are distinctive.

Looks like the back side to me, since that's a drawing of the inside of the chassis, and the only way the drawing of those terminal strips makes any sense is if you're looking at the back of the controls.

Numbering aside, I mean that one is a pentode and the other a duplex-diode, high-mu triode, they look very different from each other, after you have seen many of both, they are easy to tell apart, as they are distinctive.

Yes I looked them up and saw the difference. That's why I was confident the issue would be resolved by making the substitution. I'm still not happy with the power situation. The TV is still only pulling about 1 1/2 amps when fully functioning. That's why I want to get the 10BP4 installed and see where I am with the picture as it needs to be. I've checked the voltages in and around the bleeder circuit and all of them are close to what they should be. Still I feel like I'm missing something. I need to check the HV again now that everything is sorted correctly on the underside.

Looks like the back side to me, since that's a drawing of the inside of the chassis, and the only way the drawing of those terminal strips makes any sense is if you're looking at the back of the controls.

Yes that's the way I did it. Didn't want maximum volume blasting through at the minimum setting!!!

Keep in mind that the general AC voltage in the USA has risen a bit since the TV was made by 10+ volts, this will tend to make all the bias voltages a bit higher, and the amp draw slightly lower, if it says 2.5 amps @ 117vAC, that will change at higher and lower vAC, and also, no 2 sets are alike! :)

One thing I've noticed is wattage and current of tube gear tends to be based on inrush surge at switch on rather than steady state draw of a warmed up set for most tube gear out there.

One thing I've noticed is wattage and current of tube gear tends to be based on inrush surge at switch on rather than steady state draw of a warmed up set for most tube gear out there.

Well if that's the case, it does zoom up to a bit over 2.0 amps when initially turned on.