I have a motorola tv 1959 I guess...model y21t57ch
no sound, just a hiss, screen lights up but no
picture, and the left side of the screen is
shrunk in a little. I have no idea where to start
or how. since I have a degree in MODERN electronics,
I have never worked on the old stuff. dont have a
signal generator and my oscope is only rated at 20 meg
have not worked on the new radios or tvs either...so
if anybody could lend me a helping hand or
direction to start, that would be greatly
appreciated. Ive got a lot of cool radios I,ve
collected also, but would like to fix them
(some do work), not blow them up doing something
wrong.
So as to the tv do I replace all the really old looking
caps that I can find then start locating the various
troubles(not that I would really know
what they are anyway!) Thats part of the problem
I dont know tv terminology

Hi,
It sounds like there may be more than just a few minor problems, but checking the electrolytics is always a good place to start.

Foremost is the trapezoidal picture which indicates a problem with the deflection yoke (the coils in the form that surround the neck of the picture tube). It may possibly (slight chance) be that there is a shorted cap that might contribute to this, but I do not have schematic of your set, so it is likely only a very slight chance.

The other issue is in the RF stages, likely just that the tubes are in need of replacement.

Unless you are servicing portions of the tuner, a signal generator is not an absolute necessity, but it does help in some instances. For the most part, a television of the era you have, you can assume for the moment that it was still reasonably close to being in tune before it experienced the current problems.

Your scope is still adequate for servicing the set, as you are dealing with sweep signals of 60 hertz and 15750 hertz, and most likely, you will just need it for checking the level of the "blanking pulse", and the waveforms of the signals to the Cathode, and grids.

The modern theories still apply, but instead of a chunk of silicon, your amplifiers have a vacuum and heaters.

: I have a motorola tv 1959 I guess...model y21t57ch
: no sound, just a hiss, screen lights up but no
: picture, and the left side of the screen is
: shrunk in a little. I have no idea where to start
: or how. since I have a degree in MODERN electronics,
: I have never worked on the old stuff. dont have a
: signal generator and my oscope is only rated at 20 meg
: have not worked on the new radios or tvs either...so
: if anybody could lend me a helping hand or
: direction to start, that would be greatly
: appreciated. Ive got a lot of cool radios I,ve
: collected also, but would like to fix them
: (some do work), not blow them up doing something
: wrong.
: So as to the tv do I replace all the really old looking
: caps that I can find then start locating the various
: troubles(not that I would really know
: what they are anyway!) Thats part of the problem
: I dont know tv terminology

Hello Sean.

On the 3 sets I have repaired I have learned to replace all paper caps first. It seems that they leak and cause all sort of problems. Also the filter caps go bad and need to be replaced without question. I have tried to fix just the problem in the set without replacing all the paper or round plactic black caps but always end up replacing them all.

But once that is done 2 set fired up and worked with no problems after that the other needed a contact cleaned in a tube socket.

Also a tube tester is a good tool to have. A shorted or week tube can set you mad. If you don't have one then swaping tubes can also work.

Hope this helps.
Tom Guest

Hi Sean, Try and find a copy of Basic Television by Grob or Television Simplified by Milton S Kiver. They were published in the era of your set and will bring you up to speed on the theory of you set. Hopefully you can find a copy in a second hand bookshop (perhaps Amazon.com?). Good Luck with the set, the other advice it on the money, though I'd suspect the narrow width is something other than the yoke, might even be a weak scan or damper tube. They're fairly straight forward but watch the high voltage if you're used to low voltage solid state. Cheers, Don Black.

: I have a motorola tv 1959 I guess...model y21t57ch
: no sound, just a hiss, screen lights up but no
: picture, and the left side of the screen is
: shrunk in a little. I have no idea where to start
: or how. since I have a degree in MODERN electronics,
: I have never worked on the old stuff. dont have a
: signal generator and my oscope is only rated at 20 meg
: have not worked on the new radios or tvs either...so
: if anybody could lend me a helping hand or
: direction to start, that would be greatly
: appreciated. Ive got a lot of cool radios I,ve
: collected also, but would like to fix them
: (some do work), not blow them up doing something
: wrong.
: So as to the tv do I replace all the really old looking
: caps that I can find then start locating the various
: troubles(not that I would really know
: what they are anyway!) Thats part of the problem
: I dont know tv terminology

Hi! If you can find a copy of practical handymans encyclopedia volume 20 by Greystone press you'll be on your way. Text and pictures in plain language. Repaired family tvs many times with it's help, as I had no alternitive [poor country boy]at the time. Have small pamphlet along same lines, will mail no charge if you can supply snail mail location. terry