Part or Schematic needed for Rodo-Tron CH-281 monitor

TheMaze

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Part or Schematic needed for Rodo-Tron CH-281 monitor

I recently picked up a Mortal Kombat in a converted cabinet, but it has a bad monitor. The monitor in it appears to be a Korean monitor I'm not familiar with - it's marked "Rodo-Tron CH-281" The tube is marked "Pentranic"

I haven't really started looking into this yet (observed that monitor does not seem to have HV or heaters, but haven't tested anything), however, there's a remote adjustment board which has about 10 pots for picture size, positioning, etc. Unfortunately, the adjustment board is physically damaged in this monitor, so I'm looking for a replacement.

Does anyone have a spare one of these boards they would sell, or know a (US) source I can get one from? Worst-case, does anyone have one that would be willing to take a picture of the trace layout on theirs so I can manufacture my own board (I'm missing about 1/4 of the board in mine).

Alternatively, if anyone has a whole chassis for one of these monitors they want to sell, let me know, as I suspect mine has other failures.

Lastly, does anyone have a schematic for this monitor? I've poked around online without success.

Thanks!
 
Just left him a voicemail - thanks. To clarify, do you think he will have parts and service information for this monitor? Or were you suggesting I purchase a replacement monitor from him.
I'm also kicking around the idea of just buying a universal chassis and replacing it - it looks like they are ~$100. By the time I buy a schematic + the control board + whatever parts I need to get it up and running, it may not make financial sense to do so. Thoughts?
 
Randy Fromm used to have the CH-281 schematic on his site....
http://randyfromm.com/amusements/techdept/

It was under pentranic.jpg
I don't know if he pulled them or what. It's been down for several months. I've actually got one of these in need of repair. I wish I'd saved the file in the past when I used it.

Edward
 
So I'm still trying to work my way through this. The schematic is at least similar to this monitor (I found one thing that looked wrong, but maybe it was a running change, or just the blurriness of the schematic) so I'm running with it for now. If anyone has a more legible copy though, please let me know.

Also interesting to note that I don't hear the horizontal sweep unless I have the remote controller board hooked up - part of me wonders if the physical damage to this board is my only problem left (on the monitor...I'm pretty sure the audio amp on the MK1 board in here has a problem).

Posting the values of the POTs on the remote control board as I find them in the schematic (marked Rodo-Tron CH.VR and has connector Y102 on it" 1/2 for my own notes, but maybe they will benefit someone in the future. The variable resistors, from left to right:
Top Row:
R910 H. WIDHT - 5K
R327 V. LINE - 1K
R309 H. HOLD - 5K
R341 H. POSI - 5K

Bottom Row:
R121 BRIGHT - 5K
R909 PIN. CUSH - 20K
R338 V. POSI - 5K
R324 V. SIZE - 2K
R315 V. HOLD - 5K

Board also has R323 (non-variable resistor) and J333 (jumper)

On my board, The board is cracked in such a way that the H. WIDTH control is missing completely, and the BRIGHT control has been cracked in 1/2. I'm starting to wonder if the monitor will fire up if I rebuild this board.

Also any other sources for parts than Nieman Displays? I've called several times this past week, left a few voicemails, and gotten no response.
 
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Update #2: HOT looks shorted. Going to order one, and hope that changing it + re-building the brightness control brings this back to life.
 
Newark order came in today. Rebuilt the control board today, and swapped out the HOT. No change. Old HOT is definitely shorted, but clearly it took out something else. I'll hopefully have some time tomorrow night to poke around a bit more and see if I can figure it out.

I'm still wondering if anyone else knows of another parts/repair source for this chassis. Thanks!
 
Spent some more time with it. I've confirmed that the 12.8V power supply is working, and R331 appears to be good. At this point, I suspect IC301 (the HA11235) or at least something in that area. I will do a little more poking around tonight, but probably save it or another day.

I also determined that all this may be for naught - I took the neck board off the CRT today and the Blue pin is torn from the CRT. Any thoughts if I can somehow put this back in (conductive epoxy?) or I should just give up on this monitor? Socket doesn't appear damaged, just the pin is ripped out.
 
<rant>
OK, this game hates me. PCB is bad + tube has a cracked pin. I 1/2 give up and buy a replacement monitor on eBay - replacement "monitor" comes and it is just a tube - no boards! On top of that, neck is cracked off tube from this "was working" monitor (but the cracked part isn't in the box).
*sigh*
</rant>

Any thoughts on trying to use conductive epoxy to glue the pin back in the tube? It almost seems more ripped out than cracked off.

Failing that, anyone have any monitors for sale near Charlotte, NC, or at least able to ship a 25" monitor cheaply? I'm about to give up on this monitor and move forward.
 
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