Repair Logs – Page 104 – JAMMArcade.net

Space Invasion repair log

Sep 212014

Another one of Ben’s boards.
Had the usual graphics issues you normally get associated with those four 2114 RAM’s only this time the RAM’s had already been replaced and all four were good.

Following the inputs and outputs from these RAM chips I found some broken traces, probably a result of desoldering them originally.
Pin 1 of the RAM at location 3H was not connected to anything. I patched this and it fixed the solider sprite on the title screen but some in-game graphics were all messed up.

After confirming all other connections were good I noticed two other 2114 RAM chips that had been worked one and socketed so I checked those too.
Initially I found pins 3 and 4 of the RAM chip at 1B. Patching these gave me this result

Getting there but not quite.
A little further inspecting these chips and I also found pin 15 of the same chip not connected to GND like it should be.
Patching this one gave me a perfectly working game.

Master of Weapon repair log

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Sep 112014

Got this PCB as usual from Ebay as faulty, seller said it was missing some sounds.PCB was in a clean state:

Once powered up, actually, all sound FXs were present but music was missing at all.Sound hardware is formed by a Z80 CPU which controls a YM2203 FM synthesis IC coupled with a YM3014B DAC and all sound (music+ FX) are pre-amplified by a NEC uPC4556C OP-AMP before going to the main MB3735 amplifier.Connecting the analog output (pin2) of the YM3014B to an external amplifier I could hear the music, this was still present on the OP-AMP input (pin5) but not on the output (pin7).So, I desoldered it and tested it in my chinese tester which reported it as good.But this did not convince me so I replaced it with an equivalent Mitsubishi M5218 and this was the winning move since music was fully restored.

End of job, see you next repair!

Pang repair log #1

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Sep 102014

Tired of all the (bad engineered) Pang bootlegs I have had in the past, I bought this mint not working original one:

As you know Pang is one of the CAPCOM Pre-CPS games that use a battery to supply power to a RAM that holds a decryption table. This table is the key to decrypting the encrypted program stored in the board’s ROMs.When the battery runs out, this table goes away and the program code can no longer be decrypted so the board stops working.And, since the board is manifactured in 1989 and mid lifespan of a battery is 3-4 years, nowadays most of the Pang boards suffer from this issue.

Powered up my board, I got this static brown screen, clear symptom that also my board ‘suicided’:

For some years it’s possible to revive this (and others) board thanks to the work of Tim from Arcadecollecting.Infact I followed the instructions on his site (keep only attention to use the proper ROM set specific for your game revision):

https://www.arcadecollecting.com/dead/pre-cps.html

and I could add a full working original Pang PCB to my collection:

Star Jacker repair log

PCB Repair Logs, Repair Logs 2 Responses »

Aug 302014

Got a mammoth box of boards from Ben76 the other day. This Star Jacker PCB is one of them.
Game gave a black screen when powered up and there was no sync signal.
Ben also gave me a scan of the schematics for this board so was quickly able to determine where the sync came from.
My heart sank a little bit as the sync comes from a PAL16R4 chip

On investigating I found the VCC pin was not making a good contact in the socket so I removed both of the PAL sockets and replaced them.

So booting now gave me sync but solid white screen. Ive seen this before on quite a few boards and its almost been RAM issues. I started probing the RAM chips and found a 2016 SRAM at location IC151 had completely dead outputs despite being enabled and having active inputs. I desoldered it and replaced it with a 6116 SRAM chip.

Now I get this (NOTE: the red colour is actually present but I have to edit my pictures these days as the HTC One makes low light pictures all purple)

All fully working again.

Jigoku Meguri (Bonze Adventure) repair log #1

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Aug 282014

I got this Bonze Adventure (actually, it ended to be Jigoku Meguri, the japanese version) PCB as gift from my friend Silvio:

Board was in decent state but it was missing the YM3016F DAC and the TC0100SCN tilemap generator :

so I used a Drift Out faulty PCB as donor for these two ICs.

Besides, some pads of the TC0100SCN ASIC were missing and the RGB module TC0070RGB fell off in my hands once I touched it.I rebuilt missing pads using some AWG30 wire and I exposed the TC0070RGB pins using my Dremel in order to solder new legs:

RGB module doesn’t use a standard 2.54mm pitch but 1.77mm so I used an half of a 64 pin S-DIP socket for its installation on PCB:

All was set and ready for powering on the PCB.Once done, I got a solid black screen but all activity on 68000 adreess/data bus seemed fine.So I’ve started to think about a video RAM failure and I piggybacked a 62256 RAM over the one @IC4 which had some data lines stuck HIGH, this was the result:

so I desoldered it and tested out of circuit resulting as showed:

But, though I replaced this RAM, I got the same error.So I remembered that my friend Silvio told me a lot of Bonze Adventure had both the tile RAMs bad so I decided to desolder also the other one 62256 RAM @IC5 and he was right, it was really bad!

Fitted another good one and :

I could enjoy this weird game!Thank you again , Silvio, for donating me this PCB and for your precious advices! 🙂

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