Pincushion problem but no pincushion adjustment

[MonMotha]

I've got a Hitachi GMK-29FS2 (stock in Neo Candy 29 and Super Neo 29 cabinets) with a pincushion issue, but I don't see any adjustments for pincushion, and the manual (albeit difficult to make sense of since it's in Japanese) doesn't seem to indicate there's an adjustment, either.  What's the procedure for addressing this?

(No, I haven't shotgunned the caps on it, but I was curious if there was anything else I could look at first)

I do NOT have a schematic, but I'd happily accept one if someone's got one as I have two of these things (the other one is fine).

[qrz]

if its a newer chassis, bettin' it will be on a service menu.

i'm guessing there will be two damper diodes (or a combo) to gnd . the gnd side diode will be parallel a cap
this combo produces a dc voltage for pin correction, fed to the pin out xistor.


i'll see what i can find later today and post.

 73 de j

[MonMotha]

Not a digital monitor, so no service menu.  The monitor is from ca. 1994.

I'll see what I can locate.  I haven't dug into it any further than to note it has a pretty serious pin problem.

[grantspain]

is the horizontal size adjustment working?

[MonMotha]

is the horizontal size adjustment working?

Yes.  It works fine.  Has good adjustment range, and I can get it set to something reasonable.  H Position also works.

There is also a "Wide/Narrow" jumper on the chassis that is set to the default of narrow.

And I just noticed while taking some pictures that there's one single lone control on the board that's labeled in katakana.  It reads "saido pin".  I'm guessing that's pincushion.

[lilshawn]

"saido" can mean different things depending on the other words around it. but likely it is "side" since that seems to be the context.

[qrz]

sadly , i'm finding nothing on this (yet) 
 ya'd think being a '94 model, there would be a pdf on it somewhere 

[MonMotha]

Yeah, and it was used until at least the late 90s since the successor "Super Neo 29" used it, too.  There was apparently also a GMK-29FS3 that was very similar.

Best I can do for you is a high quality picture of the boarset and the user manual (in Japanese) from the manual for the cabinet.  Not many details.

I'll tweak that pot when I can get someone to help me watch the thing from the front.  The red cut-off is also wrong, and both adjustments have to be made from the back (no mirror handy).

[qrz]

a pic will be better than nothing . and BOTH sides of the board   
if resolution is high enough , might be able to help ...?
still no joy on a print   

[MonMotha]

That control was indeed a pincushion adjustment.  That combined with about half an hour of tweaking color gains/cutoffs got me a very nice (if a little dim) picture.