Today ‘coolmod’ sent in dump of a PAL from a Champion Wrestler PCB.Original device was a PAL20L10, I took care of adapting fuse map to a GAL22V10 which he successfully tested back on PCB.Besides, he tested the two dumps we had in database confirming they both work fine.Thanks again to him.
Got for a repair this Raimais PCB , an obscure maze game released by Taito in 1988 :
Board played fine but sound was totally missing.If I put my fingers on solderside of the amplifier I could hear some noises, sign that it was still good.Someone replaced invain the YM3016 DAC but this was not the cause.Ruled out a problem is the analog section, I went to check the digital circuitry.Sound CPU is a Z80 with a ROM and a RAM.When I went to check the RAM @IC25 (a Toshiba TMM2063, 6264 compatible, almost prone to failure in my experience like Fujitsu TTLs) I found irregular activity on some data pins (on the left of the below picture an healthy signal) :
I desoldered the chip:
and tested it out-of-circuit where it failed (my programmer went in protection due a possible short , indeed I could measure few Ohms of resistance across VCC and GND pins of the chip)
Fitted a good chip restored the sound.End of job.
Received today this Fire Shark PCB for a repair:
According to the owner, board would sit on a “OBJECT RAM ERROR” but instead, once powered up, the board entered in game but sprites were almost absent,spread on screen in form of lines and garbage:
Like many other Toplan games, also this one uses the ‘FCU-2’ custom ASIC sprites generator which , due its package, is the first thing to check if you have sprites issue:
Visually I couldn’t see anything wrong with it but when I tested the soldering of each pin with a needle, I found some loose legs on a side :
I promptly reflowed them and sprites were back properly formed:
The other issue reported by owner was that player 2 controls were not responding except for BUTTON#2, COIN and START.The screen of the TEST MODE clearly showed the stuck inputs:
I traced these inputs back to a 4.7K Ohm resistor array used as pull-up and I found it was cracked in two:
The scope confimed that half of pins were floating and not in high state like they should be :
I removed the broken resistor array:
and, after installed a good one, all the player 2 inputs were correctly working again.Board 100% fixed.
Another Out Zone on the bench and with this one we have five repair logs of this PCB.
Board came in not so great condition, quite dirty :
Like all the Out Zone I have troubleshooted, also this PCB suffered from sprites issue, they were garbled and misplaced :
Having a good knowledge of this hardware, I went to probe the involved circuit.All was fine until my logic comparator reported issue on a couple of outputs of a 74ALS163 @17B:
The scope confirmed the outputs were floating compared to inputs:
I removed the IC and the out-of-circuit testing failed miserably:
Another Out Zone saved.See you at the next repair of this great game by Toaplan!
Got this P.O.W. – Prisoners of War PCB since a long time, bought in a lot of faulty boards from USA :
Board was marked by a piece of tape with the words “SPRITE ERROR”.When I first powered the board up, picture could not sync properly on the Philips CM883-II monitor of my supergun (but it did on my Astro City):
I found a workaround by replacing the 100 Ohm resistor connected in series with the SYNC pin of edge connector with a 10 Ohm one.So the sprite error materialized :
As usual I did my visual inspection and found a severed trace on the solderside (involved in the sprites RAM data bus).Patching it cleared the error so game finally booted showing this issue :
I noticed that if I shorted some address/data lines of a row of eight 2018 RAMs, further lines were displayed so this was the part of circuit involved.
I went to probe each RAM with my scope and found some irregular activity on data lines of the chip @9K, here is a comparison with a good signal (on the left of the below picture)
Time to desolder the chip:
The out-of-circuit test failed :
A good RAM chip fixed completely the game.