MS8-26 horizontal jitter repair log

[geekmiki]

Hi,

My MS8-26 horror story just wasn't over yet... After all the trouble I went through with my other chassis that shutdown after 20 mins, that I thought I had fixed and that finally shut down for good, I decided to buy another chassis. This one was recapped, so at least that would be done.
After mounting it, I immediately noticed a very unpleasant horizontal jitter that was only affecting the left and right sides of the monitor. It wasn't the usual blooming that you would get on a MS8-26, more like the sides moving left-right every 0.5 to 1 sec. At some point, in between tests it stopped, but then eventually came back.
It couldn't (or shouldn't) be capacitor related. I checked them all and values+polarity were ok.
I looked at the pots. Cleaned them, reflowed them.
Then I started a reflow of critical areas of the chassis, hoping to fix it (yoke connector, flyback, HOT, etc.).
I ended up asking @nem (which I got to meet AFK at his amazing arcade in Helsinki a couple of months ago). He pointed me straight away to the deflection daughter board and particularly the IC HA11423.
I replaced the whole daughter board with the one from my non functional MS8-26 and the jitter was gone.

Thanks again @nem, you're THE man!

 

[xga]

Thanks for posting your repair log, geekmiki.

My guess is that C430 (the blue tantalum capacitor) on the daughter board has gone bad.

 

[geekmiki]

UPDATE:
Since November the monitor had been working great, no problems whatsoever. Suddenly, yesterday the same horizontal jitter was back. Knowing that I had changed the deflection PCB with a spare one and that it had solved the issue, what are the odds that the same issue develops on another board?
Before starting troubleshooting, I just thought about the message above posted by @xga.
I decided to desolder C430, a 1uf 25V tantalum capacitor on the deflection PCB. It tested ok, but I replaced it anyway, reflowed the whole deflection PCB and the problem was once again solved.
Was it the capacitor or the just PCB needing a reflow? I won't know for sure, but the jitter is gone and that's what counts.

 

[JohnRambo'sKnife]

This is super helpful. Thank you both.