Electronics > Repair

Sync issue on EV-9031 CRT


I recently got a 9" Green Monochrome CRT off of ebay to go with a Apple II Plus computer, the model is EV-9031 it was manufactured in 1984 for Electronics Associates (Tiawan) LTD by Tiwan Kolin Co.  The number on the back panel is 2101353007, it seems very similar to the Sanyo monitors produced around the same time, but I can't find a circuit diagram.

The monitor has a video sync issue as shown in this video, the video shifts horizontal in a snake like fashion then scrolls vertically but will lock for a half second before repeating.

I replaced some of the electrolytic capacitors although they measured ok with a multimeter capacitor function and a ESR meter, there were some signs of leaking on the PCB, this did not make a difference.  I list some of the capacitors and values below along with which ones I replaced, all replacements were high quality Panasonic or Nichicon.  I also used deoxit on the pins coming off the crt to the connector on the small pcb.

The plug is Europlug type two round pin configuration, so I thought it might be PAL.  I tried a inexpensive NTSC to PAL converter, but could not get any signal with that adapter.  I'm using a Composite to VGA adapter from the Apple II successfully so the output of the Apple II appears OK or at least in spec enough for that adapter to sync.

Capacitor List EV-9031

C605 100uf 35v (replaced)
C310 2200uf 16v (replaced)
C604 3300uf 25v (replaced)
C417 1000uf 16v (replaced)
C314 1000uf 16v (replaced)

C607 220uf 16v
C202 470uf 10v
C503 1uf 160v

C406 4.7uf 16v
C202 470uf 10v
C607 220uf 16v
C305 4.7uf 16v

Any help on finding a circuit diagram or troubleshooting steps would be helpful.

Are there any pots for h-sync and v-sync?

Yes, It has H-Hold and V-Hold pots on the front, the youtube video was after adjusting those.  On the back there are H-Width, V-Line, V-Size and Focus, I did not change any of those.


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