Pang repair log #4

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Apr 042016
 

9 years ago I got a Pang for my personal collection. It was still with original battery and I carefully changed it with a new one because I didn’t like the wire wrap mod to desuicide it.

Unfortunately 1 year ago while testing the kabuki desuicider the game didn’t boot anymore, steady blue screen.

After testing succesfully the kabuki desuicider on another board it was clear my Pang developed a problem.

For more than a year I never managed to repair it until I got a Fluke 9010A which showed a problem on the z80 bus, the READ signal was not driveable.

I immeditely noticed that it had a very low resistance to gnd.

Near the Z80 there is a resistor network 4,7kohm.  the read signal was connected to a pin of this network which had only a resistance of 427ohm.

pang

I decided to desolder it and install a new one but the game didn’t boot.

I decided to let the game rest for some more time until one day I discovered that the game sometime booted , sometimes not but when it booted it crashed soon after.

Upon closer inspection I discovered that I soldered very loosy a pin of the network resistance!

After resoldering it better , the game booted without problems!

 

Pang repair log #3

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Mar 232016
 

I desuicided this original PCB but after booting up I got this

Pang Pang2

 

After checking rams and buffer they were all good.

Just to avoid any doubts I dumped without convinction all the graphics eproms which normally are very reliable.

To my surprise when I lifted eprom PWE02 with the pcb in operation, the parts of the background corrupted turned to black revealing that at least the problem was connected to the circuit around the eprom.

Placing the eprom on my programmer I got this:

Foto 20-03-16 10 00 58

 

Turned out that the VCC pin of the eprom was making bad contact internally.

Burned a new eprom and the problem was fixed:

Pang_fix

 

A picture of the bastard before going to the bin:

eprom

Poker Ladies repair log #2

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Mar 062016
 

After receiving news that Eduardo Cruz had updated the code of the Kabuki Desuicider to support also the final games with eeproms that in the past didn’t work (Super Pang and Poker Ladies), I took my Poker Ladies board to desuicide it.

After reprogramming the Kabuki chip

Foto 05-03-16 12 31 01

I fired up the game but I was welcomed with a bad surprise:

Foto 05-03-16 11 22 27

 

I had corrupted graphic on some sprites ( title sprite and back side of the cards).

Luckily after locating the 2 chips responsible for the sprites, one of them ( @2J )had internal damage (programmer warned about missing contact on a data line)

The chip was a 1mbit maskrom but 32pin, that means I could do a 1 to 1 change with a programmed 27c1000 or equivalent without any flying wires.

Foto 05-03-16 13 07 54

Problem was 100% fixed

Foto 05-03-16 13 08 25