JAMMArcade.net – Page 140

HAL21 repair log

Aug 272015

Got this HAL21 PCB from my frend Josef for a repair.The game is a vertical shoot ’em up produced by SNK in 1985, a mix between Xevious, Terra Cresta and Alcon.

Board was in good shape given its age:

but fautly since it didn’t boot at all, stuck on a static garbage screen:

First thing I noticed (besides the fact that it didn’t boot) was the wrong colors, specifically the red one was missing. My friend Josef gave me an hint pointing me to a missing transistor 2SC1815 @Q1 near the edge connector:

Actually this transistor was for driving the RED ouput (the other two are for BLUE and GREEN) so replacing it restored correct colors:

So, I started my real troubleshooting .Hardware is made of two Z80 CPUs ( a main and sub one) plus a third one for the sound.I decided to hook up my Fluke 9010A in order to perform some test on main CPU.MAME source reports this memory map for the RAMs:

AM_RANGE(0xe000, 0xe7ff) AM_RAM AM_SHARE(“spriteram”) // + work ram
AM_RANGE(0xe800, 0xf7ff) AM_RAM_WRITE(marvins_bg_videoram_w) AM_SHARE(“bg_videoram”)
AM_RANGE(0xf800, 0xffff) AM_RAM_WRITE(snk_tx_videoram_w) AM_SHARE(“tx_videoram”) // + work RAM

When I performed a long RAM test on the first and third address spaces, I get an R/W error from Fluke 9010A.With the help of its probe, I could located the involved chips, eight 2114 of video board:

I probed them with my BK Precision 560A in-circuit tester which reported bad devices for the four ones on the right :

I took this result with reservations, most likely not all four chips were bad but one certainly and this affected the other ones (due the fact they share same address bus) misleading the tester.Not being able to accurately identify the faulty chips I desoldered all the four and I found two bad ones @6L and 7L:

With two good 2114 RAMs fitted, the board properly booted with no further issues.Mission accomplished.

Sunset Riders repair log #1

Aug 252015

Got this Sunset Riders PCB always in a trade with my friend Ifog:

Board was really in mint condition but, as my friend warned me, it was faulty.

Actually when I first powered it up it played perfectly but after some minutes it showed an issue where some parts of graphics had wrong colors (pinkish, I’d say) :

Since I have repaired other similar Konami boards with same issue, I already knew where start to look at.Palette RAMs are two 2018 devices @13D and 14D:

I probed them with my oscilloscope but didn’t notice anything abnormal (though they were hot at touch), also piggybacking them didn’t change anything.So, I went more ahead in the palette circuitry following the path of the data bits of these RAMs.Just before the generation of the three RGB colors there are some open-collector buffers (74LS07):

Probing the one @8C with my scope, I found discrepancies between input pin 3 and output pin 4:

Once desoldered, the IC failed on pin 4 indeed:

Comparing on a tracer the bad output with a good one, you can see how the internal junction was altered (good one on the left of the below picture):

Fitted a good IC fixed the colors.

Success!

PAL dumps update

PAL Updates Comments Off

Aug 232015

Today we can record some PAL dumps.

Layer sent in a handcrafted ‘WL22B’ @1A PAL to use with the japanese 88622B-3 B-board of Willow (Capcom CPS1 hardware).
This PAL is not yet dumped and not in Mame.

Charles MacDonald uploaded on MAME D.U. mailing list the PAL dumps from an Aqua stage PCB, only the one labeled ‘315-5801’ was fully combinatorial, all the remaining were partially registered.

Lastly, always from MAME D.U. mailing list, we had a dump from an Atari Quantum PCB.Original one was from a 82S153 device @1B stamped ‘CF2038N’ (reported by Atari as ‘137290-001’) but I recompiled its equations into a GAL16V8.

All these dumps have been succesfully tested except for the Aqua Stage one.Thanks to respective people for their contributions.

Fluke 90 repair log

Equipment Repair Logs, Repair Logs Comments Off

Aug 232015

I’ve come to the conclusion that I will probably never own the 6809 pod for the Fluke 9010. Accepting this fact led me to find a Fluke 90 6809 tester.
These things are a far cry away from the capabilities that the Fluke 9010 offers but they still offer some decent functionality.

I got one of these from the US quite recently and it was, as far as I could tell, unused. It was still in its wrapping and is in pristine condition.
Ive got a couple of games that use 6809 CPU’s to hand so thought I would give it a try out.
IMAG1483

I first pulled Breywood out and clipped the test clip over the CPU but I got an “ERROR 4 UUT CPU BUS REQUEST FAIL”. This means that the /HALT signal cannot be driven.
Its at this point I found the “Getting Started” guide online.
This states that the /HALT line cannot be tied to VCC. Breywood does indeed have this pin tied directly to VCC (and not even via a resistor).
Thinking about it I probably caused this fault by not reading the manuals prior to using it.

Time to break this thing open.
IMAG1485

The Fluke 90 needs to be able to drive the /HALT pin and it also does a check on startup that it can do this. If it cannot drive the pin then it flags up the fail message.
As you can see in the above picture there are a few discreet components for this section. Doing some quick poking around with the logic probe revealed that the emitter on one of the NPN transistor (towards the top on the picture) was dead. I removed the transistor and checked it out of circuit, sure enough it was dead.
I replaced both of these transistors just in case and tested.
IMAG1482

Everything now seems to be working fine.
I’m really pleased with this unit. It has some nice features like being able to set breakpoints (if connected to a PC)

Knuckle Bash repair log #1

PCB Repair Logs, Repair Logs Comments Off

Aug 212015

Got this faulty Knuckle Bash PCB in a trade with my friend Ifog:

For the uninitiated, it’s a side-scrolling beat ’em up developed and published by Toaplan in Japan in the 1993.

As expected, on the power up I was greeted by this scenario:

Game was playing almost blind, all graphics were totally wrong replaced by colored blocks.All the GFX DATA are stored in four 42 PIN 16Mbit MASK ROMs:

These devices are addressed by the near custom ASIC ‘GP9001’ @U13 which is the graphics processor unit of the system:

Also schematics confirmed this:

When I went to probe address lines of the MASK EPROMs, I found that most of them were silent.A closer inspection revealed the many pins were lifted.Pressing the custom chip with a clamp (a rude method perhaps but always effective) restored all the GFX :

So, I did a reflow of the custom chip passing the iron tip on its pins (with the clamp still in place) and this fix GFX stably.

Last thing to do was replacing some leaking 10mF axial electrolytic capacitors in the audio section (luckily corrosion didn’t involve any traces ) :

Another great game preserved to eternity (well, hopefully…)!

P.S.

This board turned to be an undumped Korean revision.I sent dumps to MAME developers.

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