WG 19v1001 vertical collapse

kstillin

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OK-

I'm still messing with this issue-
http://forums.arcade-museum.com/showthread.php?t=149192#4

After replacing that programmable unijunction transistor, no change.
(I got no deflection at all, but realized a yoke plug popped off).

Then I replaced the vertical output transistors- Q215 and Q216. Still not enough deflection. All the bias resistors had suitable values as compared to the schematic.

The oscilloscope suggested that the waveforms weren't of the same peak-to-peak values as shown in the manual. I figured some transistor wasn't up to snuff even though they measure reasonably on the diode setting on the voltmeter across the base-emitter.

Everything pretty much looks standard. Luckily I have some 'compatible' replacements and I shotgun most of the transistors in the vertical path.

Q210 - MPSA70- I used a 2N3906
Q211 - not specified in manual, I cannot read the markings - did not replace
Q212 - MPSA06 - have a direct replacement
Q213 - MPSA56 - have a direct replacement
Q214 - MPSU07 - hmm.

For the MPSU07, I read that somebody suggested a MPSW42 for one application. I have a few, so I try this.

Fire it up, nice!
Good deflection. Image is shifted to right, but I had been messing with lin and size pots. figure it just needs adjusting.
I'm on the phone, so I'm taking my time, looking for a drawing, etc. Notice some smoke- I see R261 fry out. It's connected between supply and collector of Q214. Should I figure it was just underrated and look for a better replacement (Q214, that is)?

The MPSU07 looks like it can be replaced blindly with a TIP32C from web notes.

Any help here?

Kerry
 

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