Well after a bit of work here and there over the last few months I finally powered up the Doghouse. I replaced all the electrolytics, all bypass caps (except for micas and about a dozen small, little ceramic pf caps. Also replaced all resistors higher than 1 watt.

Slowly powered up on a variac and got a raster, messed up picture and good sound. Good first power up result for my third project. After tweaking I was able to get a picture that looks ok at the very top and then is severely stretched at the middle and bottom. So I went through the vertical and replaced ALL resistors and any small ceramic pf caps. Well, no change. Below photos show what I have.

Note - I am using a 12KP4 CRT (no ion trap needed) instead of the original 12JP4. Not sure this would be causing any of these these conditions? The picture will not fill out on the right side in addition to the obvious vertical issues. I have the yoke as far forward against the bell of the CRT as it can go. If I slide it back, the picture shrinks away from the top right side. Almost like if the yoke could come farther FWD it would fill out.

I will continue testing and replacing resistors and those small ceramic pf caps, but was hoping to see *some* change after doing this in the vertical circuit and saw no change.

I am going to ohm out the VOT and if that checks out, maybe pull the yoke and test resistors in there/replace any caps.

Any ideas??? Do I appear to be on the right track (VOT and yoke)? Only my third set working on it all by myself - so my diagnostic skills based on what I am seeing are not great yet. Set runs solid (well over an hour combined last night), even with the picture like this. Sound is great and all controls seem to function.

The GEICO GECKO sure looks funny this way. More like a velociraptor in the second photo!!!!

The CRT shouldn't be an issue. All the 12" round B&W CRTs are basically interchangeable and they mostly differ in neck length.

Do you have a scope ? Could be the vertical oscillator is producing a distorted sawtooth waveform.

I'd also double check the vertical output tube, cathode bypass cap and linearity control.

The vertical output transformer and yoke are certainly worth a careful look. I'd also double check the values and wiring of any capacitors you replaced in the vertical section. Also note that the vertical centering coarse adjust switch on these sets often has very dirty contacts, so check to make sure that isn't causing a problem.

Did you replace the big Candohm resistors? They have a high failure rate in this chassis. Since you mentioned replacing all large dissipation resistors, I presume you did.

And almost certainly I imagine you have swapped out the vertical tubes.

Can you check all the voltages on the tube pins in the vertical section and see if there are any significant deviations from the service data?

Thanks for the suggestions. Glad I am learning enough to recognize what sections to concentrate on and my inclinations to concentrate on the vertical circuitry, VOT and yoke were good.

Bob, I do not have a scope yet, so flying blind when it comes to wave forms. :screwy:

Tom, I have replaced all the candohms and resistors over 1 watt in the set. All caps are done (minus micas and some ceramic pf caps). All resistors and ceramic pf caps in vertical are replaced now too. I did try various tube swapping for the vertical section with no change.

I will proceed to test voltages on the vertical tubes, check wiring and controls, then ohm out the VOT and see where that gets me.

One thing that you did mention Tom, is that vertical switch on the back. It does function and adjusts the top part of the picture from WAY OFF the top edge of the CRT in one position, then moves the top part of the picture down in the other position. Which is the position I took the photos in. The overall poor vertical appearance does not change in either switch position however. I will try cleaning that switch too.

This is where the fun begins!!! Trying to track down what is off with my limited experience and knowledge. Thanks again for the nudges in the right directions.

I think it's a sawtooth issue as well, but make sure height + linearity adjustments are OK first, as those way off can produce a similar effect.

Ok, so here is the loaded question. :naughty:

If everything else checks out and tube swapping, caps/resistor checking, etc. fail to change the condition and we are looking at a possible sawtooth waveform issue - where do I go from there? That waveform comes from vertical osc tube, correct? So either the voltages are fine on that tube and the issue is with the tube itself, or the voltages are off and I have to track down where the problem lies feeding that tube, right? So test voltages back from tube to tube in vertical before osc tube until I get to a point where they are correct. Then my issue lies between osc and where they test fine.

This is all assuming that controls/caps/resistors, etc are all done and good. Just wanting to make sure I have the concept down really for diagnosing.

The Gecko looks like an ostrich in the first pic :D

SR

Well two rookie mistakes fixed, and the set is rocking!!!

Found two caps that I replaced with incorrect values in the vertical. Put a .047 where there should have been a .0047 and put a .01 where there should have been a .1. Both in the R&C network between the vertical buffer tube and the vertical output transformer. That did it!!!! Plus a little focus coil adjustment to get rid of the neck shadow.

http://youtu.be/k4Un0oL1R6Q

Thanks to everyone that commented. Gonna miss the strange Gecko.

Very nice! The 12KP4 looks pretty good in there. :thmbsp:

Sure does. Thx!!! Just needed to adjust the focus coil a bit to get rid of the CRT neck shadow after switching to a crt with no ion trap.

Played great for over two hours. Power transformer was warm after that. I could keep my hand on it, so was not hot, but definitely warm. Warmer on the side next to the 5U4 and cooler on the back, but warm on the top too.

Just sent you message. Your dials and both gears are ready to go for your tuner.

Thx. Shot you payment. Really appreciate it.

Getting there. Of course will need to readjust when back in cabinet. Going to watch outside the cabinet for now . . .

All resistors that tested bad are replaced. Calling this electronic restoration of the DuMont RA-103 DONE! Next steps - replace dials when parts arrive, finish cabinet restore and reassemble.

Did your dials show up yet? Sent them USPS.

Hey thanks. The dials did show up, they are in perfect shape. Really appreciate it. However, I have encountered an "uh oh!"

Maybe someone here can explain. The attached photo should illustrate my concern. The bottom dial is the damaged one on my set. The top dial that I am holding is the one you sent me. See the difference? They are opposites of each other. Anyone know why this is?? My guess is that I will not be able to use these dials on my set. Anyone explain the difference and why this would be?

Thanks.

Also, the damaged gear on the back of my dial is hard mounted to the dial, with a giant hollow rivet through it (allowing the tuning shaft to pass through it). Also must be glued too because the dial cannot rotate independently of the gear rotation.

So there is no way to swap the gear onto my cracked, but opposite dial. See photo of gear mount on back.

Just when you think you found an extremely hard part to find - BOOM!!! Reality kicks in.

SO - anyone got another spare DuMont RA-103 dial that is in the same configuration as mine (bottom dial photo above)? It's the little things that drive ya NUTS!!!

Thx. :(

Hi I will refund your money if you want no big deal.

No worries, not asking for a refund. More curious as to why the dials are opposite of each other. I would not have even thought to check that as part of our transaction, would you?

So I guess there are continuous tuners that tune opposite directions of each other?!?!

No not really. That is very strange.

A few folks on one of the FB forums said that there are tuners that tune counter-clockwise versus clockwise. But the counter-clockwise ones (like the dials you sent me)are rarer. LOL!

That is about right for my luck, find someone who actually has the rare parts I need, and turns out they are even rarer that I thought. :)

This Dumont Service News from 1952 has an article on the different format of replacement dials and their part numbers.

http://www.earlytelevision.org/pdf/DumontServiceNewsVol23-11.pdf

Thanks for that post about the service bulletins. Interesting stuff. Well pretty much buttoned up the DuMont tonight. Working on a trade for a clockwise dial for this counter-clockwise dial, which I mounted for aesthetics.

http://youtu.be/9ydtqc6gbQ4

http://videokarma.org/attachment.php?attachmentid=184507&d=1412396599

Looks great bigaudioal! Cant wait to get started on mine, just waiting for the replacement crt to arrive. Mine has all wood knobs, did they come with wood or bakelite or either depending on time of production?

Gregb

That does look nice.

Are those dials flat? I would be tempted to lay them down on a scanner to capture a hi-res digital image. It could come in handy for some other collector who is missing the correct dial and wants to make a repro.

Just an idea . . . .

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

Is it possible that the Crosleys which used the continuous tuner on the left side of the screen were opposite of right-hand-side tuners? I have a Crosle4y at the shop with the tuner on the left side... should check.

What a pain! Upon reading this post (and also having been vaguely aware of this from the past), I now realize that the nice new dial I brought back from New Jersey this summer is the wrong rotation for my set as well! I'm in the same boat as bigaudioal -- the dial I need is like the bottom picture in his pair, and the good one I have is like the top!

Anyone else out there that would benefit from a swap? Anyone got an Inductuner I can swap to go with my nice new dial?

Damn, that is one cool looking set!

Hey Tom, I thought I had it made too. :)

I have found a clockwise brown dial and am trading the brown counter-clockwise one for it. I guess there are tuners that do tune in opposite directions. Not sure why??? That leaves me still needing the clockwise clear dial. Will keep my counter clear one mounted for now though.

What a pain! Upon reading this post (and also having been vaguely aware of this from the past), I now realize that the nice new dial I brought back from New Jersey this summer is the wrong rotation for my set as well! I'm in the same boat as bigaudioal -- the dial I need is like the bottom picture in his pair, and the good one I have is like the top!

Anyone else out there that would benefit from a swap? Anyone got an Inductuner I can swap to go with my nice new dial?

Not a bad idea Phil. I am going to scan the two brown ones I have and see how they come out.

That does look nice.

Are those dials flat? I would be tempted to lay them down on a scanner to capture a hi-res digital image. It could come in handy for some other collector who is missing the correct dial and wants to make a repro.

Just an idea . . . .

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

A few folks on one of the FB forums said that there are tuners that tune counter-clockwise versus clockwise. But the counter-clockwise ones (like the dials you sent me)are rarer. LOL!


I just purchased a set that is in need of both dials that tune counterclockwise. Please, please, please sell them to me....:):):):):)

Well, let's see if we can make this one of those nice VK moments. I have these two wonderfully pristine counterclockwise dials, and I would like to replace them with two (supposedly more common) clockwise dials. If anybody has one, I'll be delighted to forward these to you! :)

Another option would be if someone would send me a counterclockwise Inductuner, which I can retrofit on my set -- then there will be a clockwise one available.

I just traded my brown counterclockwise dial with a collector that is getting me a clockwise brown dial. However, I am still hunting for a clockwise clear dial. Please PM me if you have a clear clockwise dial that you can part with.

I scanned both brown dials that I have before packing the counter-clockwise one for shipping. Hi-res photo below.

Well, let's see if we can make this one of those nice VK moments. I have these two wonderfully pristine counterclockwise dials, and I would like to replace them with two (supposedly more common) clockwise dials. If anybody has one, I'll be delighted to forward these to you! :)

Another option would be if someone would send me a counterclockwise Inductuner, which I can retrofit on my set -- then there will be a clockwise one available.

I can't offer you the ones you want, but if you would like to sell, I would be happy to purchase.

Time to resurrect this old thread -- we were previously discussing here about how the Inductuners in the Dumont RA-103 and its clones seem to come in two flavors -- one with a dial that has channel numbers increasing in the clockwise direction, and one with numbers increasing in a counterclockwise direction. Very strange!

This appeared to suggest that Dumont had Mallory make two different types of roller inductors with opposite helix directions, for no apparent reason.

Finally figured out why. The basic Inductuner roller inductor is identical in both types of tuners, but the shaft gearing is different. Here are the two variants:

Version A has a direct shaft from the roller inductor out through the front panel, with a reduction gear for the slower rotating of the two concentric dials. Version A looks like this (from my Crosley 9-407, photographed several years ago). Note the side-facing tubes on the right side of the tuner chassis.

http://videokarma.org/attachment.php?attachmentid=189247&d=1450417828

In the above picture, the shaft is actually broken off (more on that later). In the picture below is the Inductuner after it was repaired several years ago, and with the cover removed. Direct shaft clearly visible.

http://videokarma.org/attachment.php?attachmentid=189248&d=1450417828

Version B does not have a direct shaft out the front panel, but instead has a gear drive, which reverses the sense of rotation and is the reason why the two versions have clockwise vs counterclockwise dials. Note that this version has upright tubes on the tuner chassis. This is from the Dumont RA-103 I'm working on now.

http://videokarma.org/attachment.php?attachmentid=189249&d=1450417828

Here's a closeup with the dials removed, showing the reversing gear.

http://videokarma.org/attachment.php?attachmentid=189250&d=1450417828

What's interesting here is that to get the shaft location to be the same for both models (the cabinet is identical for both, with the same dial and tuner shaft position), the whole mechanical layout of the tuner chassis has been redesigned! The reversing gear moves the shaft to the right and higher, so the chassis was modified to move the whole Inductuner subchassis down and to the left.

Why in the world did they do this? I have a hunch it relates to the broken shaft. With the shaft of the Inductuner sticking directly out the front of the set with a big knob on it, the ceramic Inductuner shafts were getting broken in shipping and handling by pressure being put on the big tuning knob. So eventually they redesigned it so that the Inductuner shaft did not protrude directly out to the big knob, but rather a sturdy shaft driving a gear did so instead. This probably helped prevent damage to the Inductuners.

I don't know if that's really the reason, and I don't even really know which model was first and which was second, but now it's clear how the two designs differ. The roller inductor is the same in both models, but the drive shaft arrangement and tuner chassis design is very different between the two.

Mystery solved.

But, to finish restoration of this set, I still need either:

- nice set of dials for the gear-drive tuner in the set, which needs a dial which shows numbers increasing in the clockwise direction when looking at the static dial (turning dial clockwise goes towards channel 1), or

- tuner with direct shaft (like the Crosley set above) that can use the nice dial I have, which shows numbers increasing in the counterclockwise direction when looking at the static dial (turning knob clockwise goes toward Channel 13).

Thanks for posting this Tom.

I am still in need of the clear dial that increases counterclockwise. Bigaudioal has one that does not work on his set, but he is not responsive to my PM's.

I would be happy with a scan so I can make a clear transfer to a fresh piece of acrylic.

Until then, the set sits...

I'll make you a high quality scan this evening or tomorrow. If I manage to come up with the correct dial (opposite of what I current have and what you need), I'll be happy to pass along this really nice dial I have to you. But for now I will keep it, since an alternative that will work for me is to get the other type of tuner (the one with the horizontal tubes and the direct shaft out the front).

Here are two files with scans of the FM and 7-13 (rapid turning clear) dial.

You'll note that these look "backwards" but that will make no difference when you print on clear material -- simply flip it over to make the image correct. Since the disk has a shaft bushing on one side, this was the only side that could go down flat against the scanner.

Took me a few tries to get a nice scan of it. What worked best was to have strong backlighting on white paper against the back of the disk. This helped reduce the amount of shadow from the scanner's own light projecting through the lettering to the paper backing.

I've attached one file with the raw scan and one that I processed to remove as much of the remaining shadows as possible. These have been reduced to much lower resolution by the bulletin board software. The .png files I uploaded are much higher resolution, and I can send them to you by email if you provide the address to me (send a PM if you don't want your email publicly displayed).

I also have .TIF uncompressed versions of both available which I can send by email (but cannot attach here because the format is not allowed).

I also have .TIF uncompressed versions of both available which I can send by email (but cannot attach here because the format is not allowed).

.ZIP files are allowed, and ZIP is a container format. You can get a ZIP program such as JZIP and use it to losslessly compress the .TIF to ZIP. then attach the file, and those that download it can unZIP the file and get the original .TIF out.

Over on AudioKarma it is common to see audio files such as .MP3 .FLAC .WMA etc. attached to posts as ZIP files....

The allowed file size is still very small, even after zipping. So I've attached one of my processed files here, which is actually a pretty good one. Can't attach the raw scans unfortunately. I've sent the whole set of original scans to Polaraligned by email.