Repairing a Motorola Cadet

[Billreed79]

Thanks Eric. It does use a slug for the horizontal control, but the pictures I posted were as clear as I could get the picture to become after trying the entire adjustment range.

I'll start checking components in the horizontal oscillator circuit.

[Findm-Keepm]

Higher horizontal frequency, and if all tubes have been replaced, check the capacitors in the horizontal oscillator stage - particularly the one across the Horizontal Hold (Osc) coil - should be about .0022uFd to .0047uFd.

[dieseljeep]

Originally Posted by Billreed79

Thanks Eric. It does use a slug for the horizontal control, but the pictures I posted were as clear as I could get the picture to become after trying the entire adjustment range.

I'll start checking components in the horizontal oscillator circuit.

I haven't seen a set exhibit that problem in probably 40 years.
Make sure that the slug in the coil form isn't stripped, so it doesn't move through the entire range of the coil. I've seen that happen.

[Kamakiri]

Originally Posted by dieseljeep

I haven't seen a set exhibit that problem in probably 40 years.

Common when restoring a set like a 630TS or even an RCA roundie. Synchro guide circuits do that when they're out of whack. Every time I restore a 630 chassis set, power it up.....4 images, turn the synchro guide, 3 images, keep turning, 2, BINGO!

[init4fun]

Originally Posted by Kamakiri

Common when restoring a set like a 630TS or even an RCA roundie. Synchro guide circuits do that when they're out of whack. Every time I restore a 630 chassis set, power it up.....4 images, turn the synchro guide, 3 images, keep turning, 2, BINGO!

The first time I saw the 4 image synchro guide misadjustment trouble it made me wonder , the horizontal , which runs at 15 KHZ (15750 to be exact , yes ?) , could it really be running 4 times too fast , at some 60 odd KHZ (63000 ?) from a circuit optimized for 15 (ish) KHZ ?

[Findm-Keepm]

Here's the schematic for his Horizontal Oscillator.

First check the slug is moving within L500.

I was off a few uFds- the .0068uf (C507) swamping the coil, along with the .022uF (C508) would be my first swaps.

If you have a scope, you can follow the horizontal sync and oscillator waveforms right down the line - just make sure either the scope or the TV is on an isolation transformer - the hot chassis is a problem.

Doug Harmon posted about his TS-454 (same chassis electrically, laid out a bit differently) - his shows those putrid TRW burgundy caps that like to open. All the more reason I think you'll find a cap or two, possibly a resistor to be the culprit.

BTW, the same Horizontal oscillator is used in the TS914 and possibly other Motorola Color Chassis:

http://www.americanradiohistory.com/...-Page-0033.pdf

[jr_tech]

Originally Posted by init4fun

The first time I saw the 4 image synchro guide misadjustment trouble it made me wonder , the horizontal , which runs at 15 KHZ (15750 to be exact , yes ?) , could it really be running 4 times too fast , at some 60 odd KHZ (63000 ?) from a circuit optimized for 15 (ish) KHZ ?

If it were really running too fast I think you would see stretched images... these are narrow and overlapped IMHO, the sweep is running too slow.

jr

[Billreed79]

I'm happy to report that the horizontal problem has been corrected! Dieseljeep's suggestion put me on the right track. The horizontal slug had gotten gummed up, and wasn't moving through the entire adjustment range. After cleaning it up and coaxing it past the sticky spot, I was able to get a good, clear picture!

cadet4.jpg

Thanks to all who replied. This TV will be good for another 50 years now.

-Bill

[init4fun]

Originally Posted by Billreed79

I'm happy to report that the horizontal problem has been corrected! Dieseljeep's suggestion put me on the right track. The horizontal slug had gotten gummed up, and wasn't moving through the entire adjustment range. After cleaning it up and coaxing it past the sticky spot, I was able to get a good, clear picture!

Attachment 195264

Thanks to all who replied. This TV will be good for another 50 years now.

-Bill

Gotta love a success story !

[dieseljeep]

Originally Posted by Kamakiri

Common when restoring a set like a 630TS or even an RCA roundie. Synchro guide circuits do that when they're out of whack. Every time I restore a 630 chassis set, power it up.....4 images, turn the synchro guide, 3 images, keep turning, 2, BINGO!

I just repaired an RCA Synchroguide circuit a few months age and it wasn't off that far. The set wasn't as old as the 630, but the circuit remained pretty much the same from the very begining!