Repair Logs – Page 61 – JAMMArcade.net

Golden Axe 2 – The Revenge of Death Adder repair log #1

Oct 042016

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:

goldenaxe2-1

I borrowed a friend’s working Golden Axe 2 rom board for tests and found out that the security board was the faulty part:

goldenaxe2-2

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).

goldenaxe2-3

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. 🙂

goldenaxe2-4

Muter BMR 95 rejuvenator repair log

Equipment Repair Logs, Repair Logs Comments Off

Oct 032016

Had this for a while now and its been fantastic.
20161003_091804

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.
20161003_091809

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
20160911_132516

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
20160918_170806

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.

Out Zone repair log #5

PCB Repair Logs Comments Off

Sep 292016

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 :

100_8856

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:

100_8858

The scope confirmed the outputs were floating compared to inputs:

74als163_inputs_outpus_comparing

I removed the IC and the out-of-circuit testing failed miserably:

74als16317b_failed

Another Out Zone saved.See you at the next repair of this great game by Toaplan!

P.O.W. – Prisoners of War repair log

PCB Repair Logs Comments Off

Sep 292016

Got this P.O.W. – Prisoners of War PCB since a long time, bought in a lot of faulty boards from USA :

100_8798

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 :

100_8729

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.

100_8733_

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)

data_line_compare

Time to desolder the chip:

100_8946

The out-of-circuit test failed :

20189k_failed

A good RAM chip fixed completely the game.

Blood Bros. repair log

PCB Repair Logs Comments Off

Sep 162016

Got this original Blood Bros. among a lot of untested PCBs:

100_8799

For the uninitiated Blood Bros. was released by Tad Corporation in the 1990 and can be considered the sequel of Cabal since it shares the same gameplay.

When I powered up my board, I didn’t noticed anything abnormal but once started a game the background GFX were flashing until they completely disappeared leaving black this part of screen :

Board uses some customs ASIC to generate GFX.Studying a bit the hardware I figured out that the one marked ‘SEI0200 TC110G21AF’ 8QFP100) addresses the background/foreground 42 pin MASK ROM through some 74LS273 and processes directly its data :

bg_circuit

Piggybacking a programmed 27C800 (equivalent to the 42 pin MASK ROM) had no effect.Since there were no other involved component I was pretty sure the ASIC was bad.Having a Raiden II as donor board I decided to replace this custom:

100_8804

After some work the donor part was in place:

100e8813

Powered up the board again and all the background GFX were back.Board 100% fixed.

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