60s / 70s Admiral 'Instant Play' Portable

[Electronic M]

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.

[zeno]

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
LFOD !

[old_coot88]

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.

[MadMan]

Originally Posted by Electronic M

Start by verifying grid bias voltage relative to schematic in those conditions

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.

Originally Posted by zeno

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.......

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.

Originally Posted by zeno

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.

Originally Posted by old_coot88

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.

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.

[old_coot88]

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.

[dieseljeep]

Originally Posted by zeno

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
LFOD !

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.

[Electronic M]

Originally Posted by dieseljeep

The one with the 8LT8 seemed to be a GE design.

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.