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.
Got this Golden Axe 2 rom board (here plugged on a working Sega System 32 mother board from an Arabian Fight) with a black screen on boot:
I borrowed a friend’s working Golden Axe 2 rom board for tests and found out that the security board was the faulty part:
This board uses an encrypted V60 CPU to prevent conversions by swapping ROMs between boards. For example, there is the exact same board on Arabian Fight but CPUs have different IDs:
– 315-5533-01 for Arabian Fight
– 315-5533-02 for Golden Axe 2
So obviously, putting the security board from Arabian Fight didn’t make the game working, even with the EPROM from Golden Axe 2 plugged in.
ROM, PAL, oscillator and 75HC04AP were tested good but I found a few address lines which looked inactive with the scope. So the faulty chip could be either the CPU @U2 or the RAM @U1. As the encrypted CPU cannot be retrieved anywhere else than another Golden Axe 2, replacing the RAM was my only chance to repair it.
The RAM is a Fujitsu MB8421 (16 kb CMOS).
I bought a new one (got a MB8421-90L instead of the original MB8421-12L but not a problem as it is a faster 90 ns instead of the original 120 ns), replaced it and luckily the game booted with no other issue. 🙂
Had this for a while now and its been fantastic.
There Is a calculation outlined in the manual around predicting the life expectancy of the tube and ive made a little spreadsheet up to deal with that.
The calculation relies on being able to set the G1 voltage on the pot.
I noticed when I first got this that when I adjusted the G1 pot it was pretty loose feeling and also the reading bounced around everywhere.
Fast forward a year and I’ve come to use this again. I was completely unable to get accurate steady results from the G1 this time so I went to check the pot and found readings like this
I tried cleaning it out with contact cleaner but its had its day.
I ordered a new 250k pot from CPC and it came a few days later
Fitting this gave me solid results from the G1.
One thing I recently noticed about this rejuvenator is it has a switch marked “Soft” and “Strong”. Id not really noticed anything wrong with this before but the BMR 95 doesn’t have this option normally. It is present on the BMR 2005 model though.
Looking at it inside it looks to be a factory mod. The same wiring was used and its all part of the same loom. All solder joints look factory as well. Its either a factory mod or a very well done aftermarket mod. Either way Im pretty sure this give me the functionality of the BMR 2005.