60s / 70s Admiral 'Instant Play' Portable
 

Hi guys. Long story short, my grandpa passed away and I got the honor of cleaning his attic. I found my mom's childhood TV set. A POS Admiral portable that she gives no craps about. He was a top electrical engineer back at Simpson Electric, but I have a sneaking suspicion that this tv was retired because grandpa either couldn't or didn't want to fix it.

I thought it might be a nice set for me to practice my tv-repairing skills on.

So first thing, I tested the picture tube. Huzzah! It tested good! Second, I took out the circuit board and resoldered all the (many) broken joints.

Big Mac disapproves of this filthy circuit board.

Next, I powered it up on a variac, using my new (grandpa's old) Simpson watt/voltage meter to monitor it. It... started smoking. But hey! I fixed that, I think. One of the metal shields around one of the transformer thingies was... improperly installed, and therefore touching (grounding) one leg of a capacitor. I unsoldered it and positioned it the right way and then I resoldered even more joints. The holes in the board are too big for the pins, so it's easy for components to rock around I guess.

Also, the grounding spring that touches the aquadag was hooked to that shield thingy, which seems awfully flimsy to hold that spring. Then again, this set is a POS, so...

Anyway, this time, it didn't smoke, and I got some good high pitch tv-working noises. And actually some kind of display:

The yoke is crooked.

I didn't let it run too long, but it seemed liked the horizontal was getting weaker and weaker.

Best I can guess is the horizontal circuit has a problem. (I'm so smart.) Now, the horizontal output tube (33GY7A) is made in Korea, and this youtube guy says they suck, so I'm guessing this one's gotta go. However, this tube got super hot, as well as the sync. sep(arator?)/vertical oscillator & output tube (23Z9) and the sound det(ection?) & output tube (17BF11). Which are all original Admiral tubes. Ironically, every other tube is another brand, even the HV rectifier tube, which... do those ever go bad? It's just two pieces of metal and some mercury, right?

As far as I understand, a hot tube implies a short or other circuit problem. Most of the caps on this thing are ceramic, with a few that are clear plastic ones I've never seen before, a couple film caps, a couple mylar(?) caps, and then that giant worrysome filter can cap thing, which is made of cardboard painted silver, pretending to be metal. I guess replacing all the not-ceramic caps on this thing wouldn't be too hard. It's probably only 10 or so. But could this be a resistor problem?

And uh, I can't test most of the tubes in this thing because they're 12 pin compactrons, and my Hickok 533A doesn't have this new-fangled socket! /cry I did a little looking into this, and I suppose it wouldn't be too hard to make a direct-wired adapter from a 12-pin socket, but then... how would I know the settings to use on the tester to test them? Well I'm not in a hurry on this one, and who knows? Maybe grandpa has the fancy-shmancy adapter device hidden away in his garage somewhere. Or maybe not, and that's why this set was retired.

Can anyone give me an idea of what the model number might be? The sticker on the bottom is completely obliterated. I tried some searching and came up emtpy handed. I'd kinda like to get a Sam's for this thing, especially if I'm gonna have to start poking circuits.

Big Mac is wearing a yoke and standing on a yoke.

Any advice would be appreciated. Thanks!

HV rects are not mercury arc tubes...They are normal filament type vacuum tube rectifiers, and can go bad.

Power tubes like horizontal, vertical, and audio output often DO get very hot by design...If the plate starts to glow a dull red/orange in a dark or (worse a) light room then the tube is being run well beyond it's plate current rating indicative of major circuit issues...Start by verifying grid bias voltage relative to schematic in those conditions, and avoid running a tube that is 'red plating' for more than needed to warm up and get a reading....You will shorten tube life, or ruin a tube by letting it red plate for more than 1 min on end.

Used to fix & sell tons of these. Not everyone can afford
a Zenith ! And if you think this is cheap you should see a GE !
This will run much better & last longer.......

First thing I see is the horz hold shaft is missing. It goes in
the coil behind the horz osc tube ( 8LT8 ??).
What will happen is some one will adjust it too far & not be
able to get it back to the right spot. The pix will usually be
narrow, have lines & multiple pictures side by side. It will
often make a loud high pitched sound. It can overheat the
33GY7 also.

Best thing is to get a source on it like an old VCR to see if
thats whats going on first.

73 Zeno:smoke:
LFOD !

See if the slug is still in the H.osc/hold coil. Somebody mighta screwed it all the way out and lost it. I've seen that happen before.

It'd be nice if I had a schematic. But you know, no model number. I guess I can fire it up again and see if they're red-plating, but I doubt it. But in terms of temperature, all three were too hot to touch. Like, I'd have blisters if I kept my finger on them.

lol, well... to be honest, the only TV I've really gotten into is a 90s Sony Trinitron. And that thing is built like a Swiss watch made out of plastic and PCBs.

Nice call that is an 8LT8.

On the horizontal osc. coil, the slug is there, and it turns easily with an allen wrench. It doesn't appear to be too far in or out. I'm pretty sure the extension shaft thing just broke off at some point. But I didn't even think of messing with its adjustment while the set is running. I'll try that later, I have the whole set apart so I could scrub off the rat piss.

Horizontal hold thingy.

Be really careful turning that slug with an allen wrench as it's very fragile powdered iron and cracks easily. There are special tools called alignment tools ('diddle sticks') made for that.

The 33GY7 obviously has grid drive since you have a raster. Taking voltage measurements on the tube wouldn't really gain you anything.

The numbers & letters stamped on top of the flyback box will be your chassis number. You can look up the service data that way. Number will be something like this"4H-1A". All the best,Tom.J

The small Admiral sets built toward the end of the run, seemed to be more trouble-prone.
The one with the 8LT8 seemed to be a GE design. The Admiral designed sets were great. Those used the 8FQ7 and a different design, altogether.

Yeah I initially thought the set was a GE (I have a ~16" that looks similar) and was going to see what the model was on mine thinking it might be the same set as his.

Admiral was good about chassis numbers but they are badly stamped
on often. Also not all of them are in Sams. Looking up on line
is not the best way. You cant drill down through a list but I have
the paper index. IIRC the old Sams index on disc will do MUCH
better searches. Last resort is to find a similar chassis. Any
Admiral with the same tubes will be almost identical. I can help
with that.

73 Zeno:smoke:
LFOD !

Many of those GEs had a problem with the Hor. oscillator not starting because it's supplied from B Boost. The fix was to put a diode between the Boost source to the B+ line. That way, the H.osc starts on B+, then when the Boost comes up, the diode becomes reverse-biased and the osc. then runs on Boost.

I don't remember seeing this particular problem in the Admiral clones, though.

Another frequent problem in both GEs and Admirals was- someone would jam the back on without lining up the H.hold shaft with the hole, thus ripping the coil partway out of the circuit board.

Never seen the 33GY7 actually red-plate though, even under sustained absence of grid drive. Figgered this was due to the low B+ design.

Zeno re: post 10 what you say is quite true, but knowing about this chassis series as in having 6 of them sized 15" to 21" gave a good stab at it(H4-1A). Also these are AOC made not GE. All the best,Tom.J

Ok guys, so today I hooked everything up outside of the cabinet (a little easier for me), and fired it up. First off, in my research I found that 'Instant Play' meant that the tube filaments were always on at a low voltage to give a quick startup... but it looks like they're on 100% filament voltage with the set off, that seems so stupid to me O_o. ANYway. I turned off the lights and watched the tubes for any red-plating, of which I could see none. So I let it run for a bit. Still I think those tubes are getting abnormally hot. I'm aware that tubes are by nature warm, but this set could double as a space heater.

Oh, also, how important is the grounding spring that touches the aquadag on the screen? Could I test-run the set without it? Because it's a pain in the ass to keep the spring in place without the cabinet assembled.

Um, at first power on, I had about 3/4 of the horizontal going. after about 2 minutes, the horizontal was getting weaker noticably, and at about 4 mins, it lost horizontal altogether, leaving just a flat line on the screen, at which point I turned it off.

There's no way this could be caused by a tuner tube, is there? Cuz the VHF RF amp (3HA5) tests very weak. Doubt it, anyway.

I let it rest and turned it on again, it started sparking. I resoldered one joint and that took care of it. This time it again started with about 3/4 of the vertical and slowly lost it. Now I didn't see any red plating, but I did see some blue... plasma arcing whatever, inside the AGC video amp & sound IF amp (14BR11). I'm assuming that means it's gassy? I wasn't able to capture it on camera, but I'm pretty sure I wasn't hallucinating.

No worries mate. It moves very freely and I was gentle with it. Also messing with it made no improvement. :/

Thanks bro! T7H2-1A, so I'd assume H2-1A?

Help? Please? :3 It says T7H2-1A on the flyback box. There are also lots of numbers on the PCB. I do have the serial number, but I doubt that'll help.

MadMan, yes the chassis number is T7H2-1A basic chassis is H2-1A. Sams folder #1062-1. Now there will be minor differences between basic chassis as Admiral built these for a few years. All the best, Tom.J

MadMan!
Look at the back of the power switch. The Instant Play function was a diode across the power switch. Clip it out, as it must be shorted. Then the tubes will not be lit, when the switch is in the off position. Probably, just as well.
I used to see those small sets, where the owner would install an in-line cord switch, as it bothered them, that the set was using power all the time. Also, many thought it was a fire hazard. :scratch2:

OK a little more on Sams crosses.

#847-1 H1-1A & H2-1A Nov 66

#894-1 H1-1A, & H2-1A added 1H-1A & 1H-2A July 67

Missed the other, must be my eyes. I probably got that too.
Both mine show a 3GK5 NOT a 3HA5 for RF amp so you may
have a newer one with different tuner assy.

73 Zeno:smoke:
LFOD !

Update: It's lost all horizontal now. I think I'm gonna look into getting the Sams for it, use that to try and poke around a bit. If that fails, I'll use the shotgun approach.

Ah beautiful, thanks much.

That diode is a-going bye-bye. It's doubtful that anyone will ever use this set on a daily basis again... and if they do, they can damn well wait 3 seconds for it to turn on.

Thanks Zeno. The tuner is sort of a separate thingy, so apparently the chassis stayed the same for a long while, but the tuner changed. TomJ suggested 1062-1, I'm assuming a higher set number implies a later date? Idk, it'd be nice if I had a model number. With the Sams index, I can cross those folders to about 8 model numbers, none of which give me any results on google. sadface. Do you suppose any of the 3 Sams folders would work for me? Aside from the tuner, the rest should be mostly the same, right?

The 1062-1 probably the right one. See if you can
find a free one first. If not get back to me. DO NOT
buy it from Sams. Will be a shitty PDF of photocopy.
I have high quality originals. for 1/4 the cost.

BTW these had a lot of bad yokes. Often if you pull
it off the CRT it will start to burn & prove it easily.

73 Zeno:smoke:
LFOD !

Didn't Admiral build this same set, with several variations, until the end of the tube era? The last one I worked on had a single control for brightness and contrast, that they referred to as a video or picture control. Seems to be around 1975 or so. The tube compliment was slightly different.
IIRC, that set had an SSKresge logo on the speaker grill. :scratch2:

Yeah, I looked. No free one is to be had. Hell, no paid one is to be had! Excepting from Sam's, so thanks for the warning, because I was considering dropping $22 on that. I have a friend who may have a Sams collection, and then the library in downtown Chicago has a collection... but it's sketchy as to whether theirs goes above 600 or so. I'm gonna be calling in and seeing if they know, and if my friend has Sams or not. He's a quote-unquote tv repairman, but he's actually a friend of a friend and I don't know him very well.

Although he pissed me off because he shortchanged me on some car repair I did for him. So in my book, he owes me a $150 favor.

But I might take you up on that offer.

Also, the yoke looks pristine, it was the cleanest part of the whole ratshit-covered set. And I've taken it off but not while it was working. But now that you mention it, don't they have capacitors inside of them? Maybe I'll crack it open and check the resistance of the coils anyhow.

A small update. I dug around in my tube box and found 4 empty boxes of the 33GY7A, and one occupied one. I also found a 23Z9, so I just plugged both of them in, but no difference was made.

Also, literally burned myself on the 23Z9.

I'll get back to this project for realzies shortly, I've been working on that radio.

I burnt myself on a 23Z9 in a GE 9". There was a shorted cap in the vertical sweep circuit. It's a low B+ set so the tube won't red-plate, but it's still running extremely hot. Find out what's wrong with the vert circuit or you'll destroy the new tube.

Heh, I took those tubes out immediately. I think what I'm gonna do is order a set of caps, and just replace those cheesy clear plastic ones, and maybe any others that look sketchy. Like the cardboard one.

(PS - Check your PM's)

Capacitor question #1:

The polystyrene(?) capacitors - those clear plastic ones - are marked in 4 digits plus a letter. ie - 6800K. I assume that's 6800pf with K tolerance. But then just one of them is 560K, 3 digits. So is that 560pf or 56pf?

Capacitor question #2:

The giant cardboard can capacitor's ratings are toleranced as follows:
200-250uf
120-200uf
100-150uf

With math, I propose the following:
225uf +/- 11%
160uf +/- 25%
125uf +/- 20%

Which, obviously, are very odd numbers. So should I use the minimums, maximums, or go with the oddball middle values I calculated?

I'm pretty sure that would be 560pF. Those are very stable capacitors and probably don't need to be replaced.

I'd go with modern standard values of:

220uF
150uF
120uF

Dude thanks. Someone else though, mentioned that when the plastic cracks on those polystyrene ones, that they start to go out of whack. And they're all cracked. Idk, besides the can and the polystyrene ones, the rest of the caps are brown dips and ceramic. Original, obivously, but I'm hoping one of those little ones and/or the can will take care of it.