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Seibu ‘UEC-52’ reproduction

Reproductions 3 Responses »

Nov 092017

This project started when, during my repairs, I came across these two PCBs.

Blood Bros:

Raiden:

Both were faulty.Blood Bros played blind :

While Raiden lacked of the BLUE color:

The culprit was the same in both boards, the ‘UEC-52’ (sometimes silkscreend on PCB as ‘HB-52’):

It was clearly faulty in Raiden and missing at all in Blood Bros:

This custom in SIL package is an RGB DAC responsible to convert the digital signals of color palette circuit into analog, it’s used on some Seibu/TAD Corporation PCBs like :

Raiden
Blood Bros
Sky Smasher

Some time ago I partially figured out the pinout and schematics/parts after removed some of the epoxy resin that encapsulate it :

As you can see it’s a 15 bit DAC whose design resembles the Taito ‘TC0070RGB’ : two octal D-type flip-flops , some printed film resistors forming resistor ladders before the output to JAMMA RGB pins.But there was also a third IC that I could not identify.At first glance I thought about some kind of darlington array to amplify the signals so I made a post on EEVblog asking for some help:

https://www.eevblog.com/forum/projects/how-to-amplify-ttl-logical-levels/

The user ‘stj’ (thanks again to him) pointed me in right direction suggesting that the unknown IC could be a 74LS367 used for video blanking.So I removed the IC from a working custom and was able to identify it as a 74HC368:

At this point I had all the info to complete my schematics in order to design a replacement, obviously I first made some prototyping on breadboard which went fine.Later I sent my project files to China for manufacturing and got the bare PCBs after some weeks:

Time to populate (in my design I used 74HC574 since it has more logical pinout compared to 74HC374)

Here is a side-by-side comparison:

Testing was successful on both boards (excessive brightness of recordings is an issue of camera, video levels are exactly the same of original part)

See you to next reproduction project!

Pac-Mania repair log #2

PCB Repair Logs Comments Off

Nov 092017

I bought a faulty Pac-Mania mainly for spare parts but I gave him a chance and tried to repair it

The game was missing sound roms, after replacing them, game booted and you could play but the screen was totally a mess.

After some blind testing I started test all socketed custom chips and rams against new ones and I eventually found the culprit

in the “text” ram @L5!

It was so bad that it totally covered the screen with junk graphics

Replacing it fixed the game 100%

Pacland repair log #1

PCB Repair Logs Comments Off

Nov 092017

Got this Pacland, Sidam version, in mint conditions for a repair

The game had some color bitplanes of the sprites shifted to the left as you can see from this pic

The sprites are handled by CUS29 and there are two 2149 rams connected.

Piggybacking a good 2149 ram on top of the one @3T restored good colours

Testing it out of circuit confirmed it was bad

The game had no other faults and was 100% fixed

Hard Puncher repair log

PCB Repair Logs 1 Response »

Nov 082017

Received this quite rare Hard Puncher (on Konami Twin16 hardware) for repair:

PCB failed all the time the self-test showing a bad device @10G on CPU board and then resetted, this in an endless loop:

The involved device is a Mitsubishi M5M5165 (8K x 8-bit static RAM) compatible with 6264 :

Its data bus showed no activity:

The chip failed the out-of-circuit test each time in a different address location:

With a good RAM the board successfully booted into game:

But speeches were missing, here is a comparison with a MAME recording:

I quickly pinpointed this fault in a missing 640KHz ceramic resonator, this is for generating clock to the uPD7759 ADPCM speech synthesizer IC.I took a spare from a dead Sega System16B motherboard:

Job done.

Donkey Kong Junior repair log

PCB Repair Logs, Repair Logs Comments Off

Nov 042017

The second of Alex’s board for repair is Donkey Kong Junior.
This board booted to static screen that wouldn’t sync. This ended up being a broken 30k pot on the H-Sync.

As I don’t currently have and 30k or 50k pots I opted to temporarily fit an 18k resistor to the video PCB to let me move on.

The game now booted to a static screen of garbage but when touching the Z80 CPU it booted. The socket looked old and a bit crusty so I replaced it.
The game now played but there was a lot of garbage still on the screen.

I hooked up the Fluke 9010 and did some basic reads and writes to the video RAM that sits between address 0x7400 – 0x77ff.

Clearly bits 0 and 1 were stuck low.
Using the schematics I started checking at a 74LS245 at location 6A which buffers the databus.

Straight away I found although the signals were going to the chip the outputs on DAT0 and DAT1 were floating.
As the outputs were floating I tested by piggybacking a good 245 chip and everything came up good.

Replace the 245 and fitted a new one.

Tested the game and all sound and controls work too.

Another one fixed.

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