TATUNG type66 H size not adjusting.

[mahkeymike]

I posted this in the touchscreen section with very little help so decided to post here.

So anyway, I got this tatung type 66 crt im trying to fix. caps seem to be replaced not long ago as most of them look really new. The only problem i have with one of them is the horizontal size wont adjust. I had another type 66 on hand so i swapped outthe circuit boards and while i can adjust the horiziontal size on this other board, I can not get the H/V hold to stop moving. Usually i can get them tuned in pretty easy but this one i cant so im going to assume theres something faulty with this circuit board aswell.

Now what i would like to do is figure out the issue with the H size and use the parts from the spare to fix it but i dont know what parts are the culprit for a non adjustable H size. Please help if you can.

Thanks.

[Ken Layton]

Merit type 66 monitor (made by Tatung) could have one of the following components bad on the main board:

Q1: type 2SC458 transistor

C1: 3.3 uf @ 50 volts
C2: 1 uf @ 50 volts
C3: 100 uf @ 35 volts
C9: 4.7 uf @ 50 volts
C12: 2.2 uf @ 50 volts
C15: 100 uf @ 35 volts

IC1: type LM358

ZD1: zener diode 24 volts

I'd check Q1 first.

[mahkeymike]

Thanks Ken. I will start replacing them in the order you suggested till i find the culprit.