Butchered Admiral 19A15 "re-restoration" thread

[cj_reha]

I have wanted an electrostatic set ever since I started collecting TVs a few years ago, and one finally popped up an hour north of me for the paltry sum of $45! It appears to be an Admiral 19A15, one of the more common and easy to restore variants, so I hopped in my car expecting a fairly straightforward and easygoing restoration...or so I thought.

The gentleman I purchased it from informed me it was restored by a shop in Orlando about twenty years ago but that he had not powered it on in a very long time. At first glance it has definitely been tinkered with, as the knobs are not original, the grill cloth was replaced with what looks like burlap sack material, and all of the decals are missing (I think the cabinet may have been refinished).



It gets worse inside...the original speaker was replaced with an ill-fitting oval speaker secured in place by a single nut, and the original grill cloth is apparently still present, just crudely covered up by the sack material. It does not appear to have been damaged so I do not know why this was done, but I have not pulled apart the speaker assembly yet so maybe there is something I'm not seeing yet.



The chassis is an absolute disaster. Ceramic capacitors EVERYWHERE! They replaced all of the HV caps, most of the paper caps and even a few mica caps (!!) with regular, non-stabilized ceramics. I am unsure how a professional shop could be so unaware of the drifty nature of these caps and use them willy-nilly in the deflection circuits, even in the circuits extremely sensitive to component drift. The previous owner did mention the set requiring a lot of tweaking to keep a stable image, and perhaps this is why!





Note the pink Cornell capacitor in the audio circuit, which is assuredly paper as it tests very leaky. Perhaps they thought it was good because it isn't covered in wax?



They also replaced the original three-section chassis mount electrolytic with a vintage 1960s Mallory two-section unit, hacking in a third 'lytic underneath to replace the missing section.

I decided at this point I wanted to get a baseline and see if the set even worked at all, and it does produce a picture, though a poor one at that. The focus isn't great and true to the previous owner's word, it requires way too much tweaking to keep some semblance of a stable picture. There is also a mysterious interference problem wherein the jagged line visible in the photo below rolls up the screen rapidly and continuously:



On the bright side though, the 7JP4 is still very watchable in subdued lighting.

All in all, this is going to be a challenging re-restoration. I ordered the proper 6kV film caps from JustRadios for the high voltage section and I plan on replacing most if not all of the ceramics with the original film and mica types (Bob Andersen's meticulous documentation of his 19A15 sets will prove invaluable in my future efforts to replicate the original component dress ). Radio Daze has the decals available so I plan on ordering those as well; the only problem I can see right now is sourcing the knobs. If anyone has any leads on procuring the original knobs for this set I would be very interested!

All comments and suggestions are welcomed, as this is my first foray into these early electrostatic TVs. Has anyone ever encountered bodge repair work like this before? I did a bit of research and discovered the place that did this is still in business, though the original owner passed away a few years back unfortunately. I suppose in any case it makes me feel better about my own work

[Tony F]

Yep,..kind of a let-down when someone else has been hacking away underneath. I hope you can muddle your way through it ok. There is a pair of "outer" knobs on E-Bay right now. They look a little warped though. Have you checked the 7JP4 on a CR-70 ? I'd be curious to know what the "cutoff" response is with a picture that looks that good.
https://www.ebay.com/itm/ADMIRAL-Tub...3bd8%7Ciid%3A8
Tony

[cj_reha]

Originally Posted by Tony F

Yep,..kind of a let-down when someone else has been hacking away underneath. I hope you can muddle your way through it ok. There is a pair of "outer" knobs on E-Bay right now. They look a little warped though. Have you checked the 7JP4 on a CR-70 ? I'd be curious to know what the "cutoff" response is with a picture that looks that good.
https://www.ebay.com/itm/ADMIRAL-Tub...3bd8%7Ciid%3A8
Tony

Thank you for the heads up on the knobs! Ended up buying them, I don't mind a bit of warpage...gives the set character

As for testing the CRT, I dug out the CR-70 since I was a bit curious too. Cutoff is mediocre and does not reach the "black box" even with the control maxed, however emissions are quite strong:





I have heard much about how CRT testers cannot accurately test these electrostatic tubes, so I am taking it with a grain of salt. The tube obviously has decent contrast functioning inside the set in any case

[Tony F]

Thanks for posting the cutoff response pics. I have accumulated 3 of these sets. I've tested all 3 crt's. One has excellent cutoff with lots of meter swing. The other one is just like yours. It barely comes up to the same spot you show. The last comes up about halfway to where yours shows. I was thinking that only 1 was restore-able that would produce a watchable picture, without having to invest in another good 7JP4. I've seen a lot of Bob A's video's to kind of know what to expect. Hopefully you will keep us up to date with your progress. I guess unless you swap all crt's into a good working set, you don't know how they are going to perform. Cheers.
Tony

[kramden66]

I've seen the 6kv caps done like that and the set worked fine but not other caps ceramic , that's crazy

[Yamamaya42]

That dirty blue wire on the electrolytic cap is just fugly, if someone is gonna use a radial capacitor like that, they should heatshrink and not use crappy wire.
That 180 ohm 1w resistor looks like it was replaced, but did a very poor job trimming the leads, and why use 10% when much better tol film ones are out there? Or were they not around that much when they did this?

[Notimetolooz]

The smaller yellowish disc cap with the squarish extension on it that is located to the left of the group of red HV disc caps, has a spark gap built in. As far as I know those spark gap disc caps appeared in color TVs in the late 1960s. They were for circuit protection and are out of place in this TV.
I get the impression that the person that did the work got his parts at a surplus store. Low cost but you have to choose what the store happens to have.

[Electronic M]

Originally Posted by Notimetolooz

The smaller yellowish disc cap with the squarish extension on it that is located to the left of the group of red HV disc caps, has a spark gap built in. As far as I know those spark gap disc caps appeared in color TVs in the late 1960s. They were for circuit protection and are out of place in this TV.
I get the impression that the person that did the work got his parts at a surplus store. Low cost but you have to choose what the store happens to have.

He probably got his parts from Skycraft Surplus in Orlando FL.... Before my family had a decent computer and before we trusted buying parts online that's where I got my capacitors from. I even recognize some of the caps in there from Skycrafts inventory circa 2007.

[dtvmcdonald]

Its quite OK to use HV ceramic caps for the coupling to the deflection plates.
If using tthe rated voltage use three of the rated value in poarallel, if using twice the voltage, use just two.
I've done that and it works fine.

I have that type Sencore. Did you use the 68 volt setting on cutoff and the "scope" setting for type? I've
used that on electrostatic scope tubes, electrostatic TV tubes, as well as iconoscopes and an
image orthicon and it works fine for cutoff. Sometimes modestly low emission is OK. If a slight increase in filament voltage
gives good emission you'll be at least passable.