PCB Repair Logs – Page 99

Captain America and the Avengers repair log

Aug 122014

My friend Silvio kindly donated me a couple of faulty boards, this ‘Captain America and the Avengers’ was one of them:

I was expecting some boot troubles but when I fired up it I got this:

All was OK except for sprites that were all missing.Since I already worked in the past on similar Data East hardware I knew that sprites are generated by some ASIC, in particular the one marked ‘DATA EAST 52’:

Infact, when I firmly pressed this ASIC, sprites were restored.Proving the tightness of the individual pins with a needle as I usually do confirmed that some pins were lifted.So time was to do a reflow of this chip and this was enough to fix the board completely.

Thanks again, Silvio!

Superman repair log #1

Aug 112014

I got this board always from Ebay sold as faulty:

When I first powered up it I got a solid black screen.Probing the CPU I noticed some strange activity on 68000 address/data lines and watchdog was indeed active.So I piggybacked the two 62256 work RAMs @U1 and U4 and I got this:

Despite the message error,this was a good sign of life so I desoldered the two RAMs and I found them really bad:

Replaced them but still black screen and watchdog active.So, I noticed there were other two RAMs connected to 68000 CPU but not directly but through two 74LS245 and enable pin of these were stuck high.I traced back it to an output of a 74HC4075 so I started to test it with logic probe and while I was probing it suddendly the PCB succesfully booted to title screen:

I can’t really explain this but now the PCB is now working perfectly every time I power it on and this is the most important thing.See you next repair!

X Multiply repair log #3

PCB Repair Logs, Repair Logs Comments Off

Aug 112014

Yes, again.
During some playing of this recently repaired board the game froze up.
On reset I was greeted with this static screen.

Non booting boards are generally quite easy to fault find but due to the V30 I was having problems. This is when I came across a post on KLOV from some time ago with someone asking if an 8086 Fluke POD could be used to test a V30 based system. The general thinking was that it could but no one ever tried it, until now!
Im pleased to say it does work (excluding the RUN UUT function).

Very quickly I found that the main ROM’s could not be read properly. The correct signature was 6A03 and I was getting 6935.
Following my schematics I found that there is a 74LS373 at location IC51 that is used as the latch to address the ROM’s.

This input was confirmed good but there was a stuck bit on the output.
I replaced this and the game was back once again. Ive left this soak testing and hopefully it will be rock solid now.

So just to confirm. The 8086 pod for a Fluke 9010/9100 can be used to check V30 based systems.

Cadash repair log #1

PCB Repair Logs, Repair Logs Comments Off

Aug 062014

This one came from the same lot of faulty PCBs (seven in total) as the previously repaired Growl.For the uninitiated, Cadash is an action game with some RPG elements.

Board was in good shape (it has also additional hardware for multi-link game) .

When powered on I got this screen:

There was a clear problem with main code execution so I dumped the four program ROMs and none of them matched the ones in MAME.I ran these dumped ROMs in MAME and I got a similar error (different memory address due not perfect emulation of 68000 core, I guess):

This was enough to lead me to reprogram the four program ROMs from cadash World set into 27C010 devices.And this was the winning move which fixed the board.

Growl repair log

PCB Repair Logs, Repair Logs Comments Off

Aug 062014

Yesterday I got a lot of faulty original PCBs.Among these there was a clean Growl PCB.I always like this game (and played it in MAME) where the player controls a forest ranger who must protect the local wildlife from a group of evil poachers who are driving the animals to extinction.

As said, PCB was in mint state:

but once powered up it showed garbled sprites:

I noticed that, if I press the PCB in the area near the ASIC marked ‘TC0540OBN’ @IC25, all the sprites were restored.

So ,after a quick consultation of MAME source that confirmed this ASIC as a sprites generator ( the letters ‘OB’ in the ASIC name stand for objects a.k.a. sprites), I understood this was the way to follow in my repair.Probing the tightness of the individual pins with a needle I found some lifted ones.A reflow with my hot air station at 390° and a bit of flux was enough to fix the sprites issue completely.

Older Entries Newer Entries