(Topic ID: 288267)

Data East MPU issues

By Zeegske

3 years ago



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#1 3 years ago

Hi all!

I have a MPU board which had serious corrosion due to batteries.
Removed all bad components, cleaned the board, fixed dead traces and placed sockets and new components.
After soldering everything booted the machine with Leon ROM.
After booting blanking led stayed off and 5V and PIA stayed on. Also PST1 (PST518a - or in my case a MCP120) got hot and after contacting the store they were sure the right MCP120 was sent. Couldn't get any step further so checked the MCP120 myself and it seems I received a wrong version: the D1 instead of the G1. Twisted two legs and after that the blanking led turned on and off and also the PIA turned on and off. So far so good it seemed.
Tested all PIA's and they were fine as well.
After tested some stuff and powering the board on and off a couple of times the relay gets energized but there is no click. You can feel it getting energized though.
Ohm test (relay still soldered on the board) gave a result of 39.2 Ohms so that "seems okay" (I know I should desolder it to be sure 100% it's okay).

Replaced Q80(2n4401) and the diode (parallel over the coil) but same result.
Measured pin 11 and 12 of 7402 (12b) and they are pulsing high which should result in a low pin 13 and it does.
Soldered a lightbulb on pin 13 and 14 of the relay (parallel) but no light so it seems there is either not enough power to energize the relay or the pulse is too short.

What is also weird: my logic probe (Elenco LP-560) pulse led pulses with the testprogram...

Used a heavy duty powersupply for the 5V and a lab powersupply with both the same results.

With the original game ROM the blanking led stays off, 5v and PIA are on. This would indicate there still is a problem on the board....
Ordered a new ROM since I'm not sure this one is okay.

Three questions:
1) is it normal the logic probe pulses with the testprogram? (never used the Leon test ROM before but I cannot explain why the LP pulses);
2) i assume the relay should have a loud click when performing this test? I assume it should but....;
3) any hints on how to continue?

Help!

Thanks!

#2 3 years ago

How about posting a picture of the board?

#3 3 years ago

I fixed a Data East board in similar condition. Check the reset line! It can be damaged and open due to corrosion. I had a problem where the MPU would reset and boot but the RESET never made it to the PIA chips to reset them and it had issues configuring them. Check continuity on the reset to each of the chips it is supposed to reset.

2 months later
#4 2 years ago

I have a Frankenstein MPU board that had corrosion on it. I did my best to clean is off and try to make sure all the line for the chip below the batteries work connected. When I power on the machine there is audio for “Frankenstein” and the GI lights come on but there is no display or attract light on the playfield.
Any help would be appreciated.

#5 2 years ago
Quoted from Modlite_Rain:

I have a Frankenstein MPU board that had corrosion on it. I did my best to clean is off and try to make sure all the line for the chip below the batteries work connected. When I power on the machine there is audio for “Frankenstein” and the GI lights come on but there is no display or attract light on the playfield.
Any help would be appreciated.

Did you do anything besides cleaning the corrosion? Pictures would help.

Typically you end up replacing the CPU socket (sometimes CPU chip), crystal oscillator, some sockets for the ROM and RAM, and an important step is fixing any circuit board trances that have been eaten away by corrosion and are now open. I tyipcally find a few of those on every board with battery damage I've had to fix. One of those is a reset line. If it is open the board can still boot but may not reset all the PIA chips. Ran into that once before myself.

When there is battery damage you really need to strip off a lot of components in order to find the rest of the damage then build it back up.

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