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Arkanoid repair - ROMStar bootleg Arkanoid


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Arkanoid (ROMSTAR bootleg) 22 pin edge connector (PCB marked as AB030)

 

Fault reported: not working

 

Parts used;

 

Capacitors

Z80 CPU

YM2149 (AY-3-8910) sound chip

BEI H20DB (see notes for details)

 

 

My brother in the UK recently sent me a box full of stuff, mostly Commodore64 cartridges and parts plus there where some arcade boards too. I’ll bet they are faulty.

My brother didn’t tell me what games these boards where, so I picked one out and removed the EPROMS to check with ROMIDENT. Turns out this one is Arkanoid bootleg – nice!!

 

Ark1.jpg

 

The board also has MC60705, and found out it was an MCU however my VP-280 reader was not able to open it so not sure if it was good or bad. I went searching data sheets and a schematic of the original Taito board that looks mostly similar to this one.

I cleaned the board with compressed air and checked for any signs of damage, it looked in good condition. I removed and replaced the 220uf capacitors just as a precaution then checked for short circuits, all good.

This board has a 22 way edge connector that seems identical to the “RomStar” version of Arkanoid. The difference being the +5V on the edge connector pin 13 &14 and ground on pin 6 & 7 on the board I had also had position for the header plug, but I prefer to just use the single connector. Easier to manage.

 

Ark2.jpg

 

I made a basic harness connector for DC and fed it +5v, my bench supply indicated it was consuming steady 2.5Amp. OK so far.

 

Ark3.jpg

 

Using the oscilloscope started probing around the crystal oscillator circuit showed plenty of normal looking signals. Probing parts of the circuit with RAM and EPROM showing activity on the address and data bus. The RGB monitor was showing a screen full of random graphics but with good horizontal stability so far I guess the timing circuits might be working OK.

I went probing on the single Z80 CPU and found pretty much everything was in a floating state except CLOCK pin (6) was receiving a good looking 6mHz. RESET in (26) was bouncing Hi-Lo about every second so I started checking back through the RESET circuit.

 

Ark4.jpg

 

The Taito RESET schematics call out a TL7700 in the design, but on the bootleg board I have this chip is not there, however the board has provision but the space is empty and seemed to have been produced that way. I wonder what controls the RESET timer? Not sure.

 

Ark5.jpg

 

The LS08 pin (10) and that was held high at all time. The other input pin (9) was bouncing Hi-Lo. But the drawings show nothing connecting on that pin. Frustrating. I traced it back to LS393 pin (8) and the inputs there look OK. Tracing back further led me back to this unusual Motorola 4584 buffer again, I’ve gone around in a loop. I must have missed a branch somewhere, but then I notice the Z80 blazing hot temperature. It’s got no activity on the data or address line doing the chip is doing no work at all, strange.

 

Ark6.jpg

 

So I have an idea. Clip the Z80 pin 26 from the board and wire a pull-up resistor directly so to bypass the board RESET. Powering up now pin (20) shows pulses, and the CPU control lines are normal but nothing on data or address lines that are still floating and the Z80 quickly very hot very quickly.

The Z80 is soldered directly onto the board, I decided to remove it by cutting off the legs and cleaning out the vias, since this was going to destroy the chip I had a spare Z80 from an old MSX computer that I could use.

I soldered in a 40 -pin socket and just to be safe I powered up the board without the CPU to measure the RESET line was still bouncing. I powered off and pushed in the replacement Z80 and now Arkanoid boots up and runs. All signals look normal and everything seems to be working. Yay! Fixed! or so I thought.

 

Ark8.jpg

 

Ark7.jpg

 

 

Until now I had not paid much attention to the input controls for Arkanoid and realised that a spinner is required, I don’t have a spinner. That sucks. I started to investigate, and it looks like the best option is to purchase one from Ultimarc.

However something else was not quite right, the board would randomly boot up in screen alignment mode, I could sometimes coin-up and start the game normally. I thought it might be a stuck line and checked the dip switches and edge connector settings but these looked OK, checked the input mux IC’s and these seemed OK too.

Also I wanted if the sound was working but all I got was static noise. I replaced all the capacitors in the audio circuit, but problem remained, this board needs +12V for the audio but does not need -5V

I tried starting the board with DIP switch 6 “Test Mode” and noticed the DIP switches status rapidly flickering between states Low and High. I looked on the schematic the DIPS are connected to I/O on the YM2149F sound chip, this might explain why the sound was not working. However I didn’t have a spare YM2149

 

Ark9.jpg

 

I went searching for information on YM2149F and read WIKI page that it’s mostly compatible with AY-3-8910, the difference being a clock mode state can be set to 50% if pin (26) is tied low, and when I checked the board that was not the case here, so I pulled the AY-3-8910 out of the Frogger sound board I was recently playing around with and pushed it in to the Arkanoid board. Now the sound and music started working. Yay.

 

Ark10.jpg

 

Great! The board was 100% working OK, it would coin-up, start and run the game reliably with music and sound but I had no way to actually play the game as I didn’t have a spinner input device.

By complete good luck I found a solution that worked out very well. Now follows a long story I’ll try to keep short. My day job I work as an electrical engineer for a large OEM who design and produce autonomous vehicles. I was chatting with a colleague about sensor design changes, one of the superseded components an industrial encoder made by BEI, it’s got a really long part number which is H20DB-37-F5-SS-500-ABC-7272-SM16-24V-S. The datasheet caught my attention when I noticed the device would work at +5v with TTL and CMOS compatible outputs, so I checked that on my scope and behold it might just work. The diagram shows extract from the datasheet and the pins used from the sensor to the Arkanoid board.

 

Ark11.jpg

 

At this point I was able to play the game and was super happy the BEI sensor works perfectly as spinner controller, it’s got nice resolution (500) and the device is solid and weighted well.

 

Ark12.jpg

 

I highly recommend this, it’s certainly strong enough to take the abuse and has a bolt pattern that could fit under a control panel.

 

Ark13.jpg

 

Ark14.jpg

 

All I need now is a head for the spinner shaft as a finishing touch but that’s for another day in the mean time Arkanoid is great fun to play, no high scores here though…

 

Ark15.jpg

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