Also I forgot to mention. I forgot to replace a .002 uf paper cap on the output plate bypass. That could be a potential problem!

With the power supply disconnected from the TV and the radio but turned on everything seems to be fine now. No smoke, nothing..

Anyone have a spare 20b1 combo power supply I could have?

If the supply don't smoke running disconnected from the TV and radio chassis, and is producing rated or higher voltage at all outputs, then the power supply chassis is fine. There is likely a short or excessive power consumption in the TV and or radio chassis.

Will check for anything this weekend. Didnt think I'd have so much trouble working on this. :thumbsdn:

This set is really confusing me. The power supply is no longer smoking but I STILL can't get a raster on the CRT i have about 6 to 7 KV but the CRT is weak. But I can't even get a very dim raster. This is really puzzling and I am not sure where to start with diagnosing and fixing this problem. All filter caps stay cool (I will replace them when I can get a raster). All tubes have been replaced except for the horiz out tube that is somewhat weak and is only a quarter way through the good zone and fails the trans-conductance on my hickok 600a. Any ideas where to start?

That's definitely enough HV to produce a raster. Try moving the ion trap magnet around. If it's the typically dual blue/black Admiral magnet, the black magnet goes towards the base of the CRT.

Also, check the voltages on G1, G2 and the cathode of the CRT. Could also be an issue with the focus coil. Check it's resistance.

You can rotate the ion trap magnet as well as push it forward or back along the neck.

There should be a definite sweet spot where the CRT achieves maximum brightness with no shadows around the screen edges.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

I'm restoring a DuMont RA-113. It was totally dead when I got it. Someone had burned up the power transformer when they plugged it in. I have replaced most of the electrolytics, and some of the other caps. So far, I've now got sound, and FM radio! I've also got no image on the screen. My CRT checks fine, and I now have 12kv at the anode after replacing the HV capacitors. I can hear the vertical running. I'm not seeing any signal from the video output tube, yet. It's a challenge that I like. I'll get it going, yet!!

Good news!! Got a raster and picture finally! Was an adjustment of the ion trap. The picture is lacking vertical height,lack of focus,and the vertical and horizontal holds are pretty bad and barely lock at all and dont lock for long. I also noticed that a small little portion of the h out tube plate is glowing red. It is concentrated in the middle of the plate on two sides and is a small dot. Picture is nice and bright. I did a full recap of all the paper caps in the TV and some off value resistors. I have not replaced the filter caps on the TV but none of the caps are getting warm but one does get a bit hotter than room temp which is part of the vertical sweep. Any suggestions on where to go from here? I would assume restuffing the filter caps would be a good idea.

Wow. I don't even put power to the chassis of a set of this vintage without doing the filter caps......

I don't like the red-plating horizontal output.

Most likely the filter caps not powering it on again till they are replaced.

Hope there's room for the new capacitors. There's plenty of room under the hood on the DuMont, so I used regular radial lead capacitors and anchored them in place.

For the record, feeling caps to see if they're hot is not a scientific (or reliable) method of testing whether they are good. If you have ever watched a power transformer burn up before your eyes -- ask me how I know this -- you will be very careful about powering up with 50-year old or 60-year old electrolytic caps in your power supply.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

There's a ton of room to route caps under the chassis of this set.

SwizzyMan, you do good work, but there are no shortcuts on something like this. On a 1940s/early 50s set, you *have* to start by recapping the whole thing, then work from there. Even if for some reason the old wax caps and cans are good, the chances of the set being a reliable performer are close to zero....let alone the damage that might be caused.

At this point in the set's life, you are doing something the engineers never designed the set to do....operate after 60 plus years. You have to throw the diagnosis and repair paradigm out the window until after all the caps of every style are replaced (except micas, which are fine about 90% of the time). I usually replace all resistors with a value of 5 watts and over, as well, before the first power up.

Will be sure to restuff those filter caps Saturday and then continue troubleshooting my current raster imperfections. I do hope you all knew that I had no intention to ever leave those filter caps in. But now that I know there is hope I can continue. I think I am just going to restuff the electrolytics instead of route them under the chassis, I have a particular fascination of sawing the filter caps off and seeing how bad they have deteriorated over the years. Also thanks for the advice kamakiri!

You can restuff them if you want, as many people do. Just bear in mind the sizes of the caps you're getting.....they all have to fit inside that tube.

When you cut apart the can, you're going to find that the wire terminals are attached to a thin ribbon of aluminum which won't take solder. You'll need to drill holes in the phenolic wafer and feed the wires down through the chassis. Doing so successfully is an art form.

Myself, I'm a mechanic ;) . I do the filters by snipping the wire terminals off the can one at a time, and use the can ground to anchor the new cap in place (most of the mounting tabs already have holes in them....some unused). I then trim and de-solder the cut terminal, which leaves a ring that I can slide right over the terminal wire of the new cap...then solder in place. Naturally, I use all axials for this.

With practice, the repair is neat and clean, and doesn't disturb too much underneath, facilitating future diagnoses if you ever need to.

Routed the caps under the chassis after I ditched the restuffing idea. Have full vertical and horizontal deflection now. But I cant get the horizontal or vertical to lock. I can get both pretty close to locking but I just cant get it to stay. Any ideas on where to start since I have recapped the chassis and replaced a few resistors.

check resistors in the synch separator.

Also, see if you can get it to lock by reducing your width and vertical size. Remember, once in the cabinet it won't take up 100% of the picture tube face.

Can kind of get my horizontal to lock now. It wobbles from side to side a bit but the vertical is impossible to lock. I can get it to slow down a bit but it wont lock no matter what I do. Swapped out the already good 6k6 vertical out tube to no effect. Assuming off value resistors in the vertical section or possibly the sync sep circuit.

Man, oh Maniechewicz, I've been following this tale, & I sure do wish you could get this Bad Boy "Pinned Down"... I have a feeling, though, that you are SILLY close, & when its over & done, we'll ALL be going, "Yeah, I FIGGERED it was that D@mn XYZBR-549 gonkulator... They ALWAYS give trouble...

Is it approaching lock mid range, or at one extreme or the other?

Assuming that you can make it "freewheel" in both directions and the picture is linear, I'd check voltages and resistances starting from the 6BA6 sync amp and work my way forward. Since the set's 95% there, let the set tell you what to do.

Eventually you're going to hit a reading that makes you go "ooooh, that's it".

Can get both to come close to locking its either slowly moving vertical and somewhat stable horizontal or both are out of sync. Depends on where I rotate the hold switches.

Riders mentions the AGC can affect the sync on this Admiral - see page 4-13 (26 0f 66 in the PDF on the ETF site). It says the AGC voltage should be about -5 volts, and if not, it can affect the sync.

OK so should I start at the agc or the sync sep? I can barely get the horizontal to lock but the vertical is impossible to lock.

Test the resistances at both tubes, compare them to the chart in the Sams and see what you get.

Found some off value resistors in the vertical section. Put some new resistors in although I am not finished and it almost locks just barely moving up in a slow speed. Now the horizontal is pretty weak I can get it to just barely lock but it loses sync quickly. Off value resistors in the horizontal circuit? I also noticed a broken, cut in half 68 ohm resistor going to the horizontal drive variable capacitor could that be a big issue?

Yes - that 68 ohm resistor feeds the grid of the horizontal output tube. No way can it work without it so there must be another connection to the grid.

Thanks for the input Bob. Will replace that and see what I get!

You should also check to see what is connected to that 6BG6 horizontal output tube grid first. There's no way for you to have any HV or raster with that resistor cut in half unless it's being bypassed somewhere.

replaced pretty much all the resistors in the vertical and sync sep circuits. Vertical still rolls but extremely slow but I still cant get it to lock completely. The horizontal is semi lockable but only at low brightness and contrast settings. This is after I replaced all the paper caps in the whole chassis and all the resistors pretty much in the vertical and sync sep section. Also replaced the 8500 ohm damper cathode resistor after it checked out at 1.5 MEGS! What to do now? I am somewhat confused why my vertical will not lock.

I am not an expert by any stretch of imagination. If you can get the vertical to stop rolling but not lock on, it seems as though you are not getting the sync pulse. Have you checked the sync circuit? If it providing proper sync, you should be able to turn the vertical almost from end to end and still have a stable picture.

Well the sync section which is half of the vertical osc 6sn7 and the 6au6 sync sep have had all of the resistors and capacitors replaced in the circuit. Only thing that might be an issue is that I burned a .1 cap too much with my soldering iron and I think that cap may be bad. But that cap goes from a pin on the vertical output tube to the damper and that cap doesnt seem to have much to do with any vertical or sync circuitry. Should I replace that cap? all of the tubes are new ones that I replaced the old bad ones with so I am not sure where to go from here! :scratch2:

Try swapping around a couple of your 6SN7s just for grins. How are your resistances at the tube pins?

OK I think my agc circuit is a bit off and this may be my sync issue. At the junction of the .5 uf agc filter and the 47k agc dropping resistor the voltage when a signal source is connected should be -5 volts but I read -4.17 volts instead. The problem is that I replaced that resistor and that capacitor. Also I am using only one lead of the antenna connection since the other one broke off yesterday but I had the same issue before the lead broke. What do I do? replace all the agc resistors? I know that the tubes involved in this circuit are in fact good.

Hi Swizzyman,
Do you have a scope to check the waveform at pin 1 (grid) of the 6au6 sync sep?
It should look similar to the waveform at the output of L16 ( where the syn signal is removed from the 6AC7 video amp output). Make sure inductor L16 is not open. The output signal of your 6AU6 syn seperator pin 6 should only
be a pulse without any video image information. If you don't have the enough of a pulse signal going into the sync phase splitter then you will never get the
horizontal or vertical oscillator to lock in. The vertical pulse is the summation of all horizontal pulse after passing through the intergator network R59 thru R61 along with C41 thru C43.
If you don't have a scope, check L16 just in case. It should be a low resistance.
Sam's says to measure the 6AU6 AGC voltages from pin 7 (cathode) to other pins.
pin1 (-6.8vdc)
pin5 (-140vdc)
pin6 (+115vdc)

Ed

Replaced some of the resistors in the agc and the big 1 watt 2.2k filter resistor which checked at 113k. Now it is even harder to maintain vertical and horizontal hold! What is going on? I am out of ideas now.

Are you talking about C61, which is connected from the cathode(pin 3) of the damper to ground? If you melted into it with your soldering iron, it should be replaced. That cap filters your boost voltage, which supply's voltage to the plate circuit of both the vertical and horizontal oscillators, as well as the screen of the ACG amp. It could also have something to do with you low high voltage. Sams says you should have 415 volts DC on pin 3 of the damper.