June 2016 – JAMMArcade.net

Nintendo VS System repair log #1

PCB Repair Logs Comments Off

Jun 302016

In the past days I received this Nintendo VS. System for a repair:

DSCN3625

For the uninitiated the Nintendo VS. System is an arcade platform designed for two-player competitive play using the VS. UniSystem or VS. DualSystem based on the Nintendo Entertainment System.

The system came with his special JAMMA adapter and two game ROM sets installed (Super Mario Bros and Excitebike) so time to power it up and I got this scenario:

wrong_colors

As you can see, screen was all bluish sign that the RED component was missing.This was confirmed by probing the signal, it was stuck LOW on its source which is pin 14 of the RP2C04 PPU @8F :

RED_PIN14_RP2C04

The PPU chip was tested as good in another system so there was something in the path which forced the signal LOW.Before reaching the corresponding pin on edge connector, the signal is converted from digital to analog by a net of resistors and amplfied by a LM324 OP-AMP @1P:

RED_circuitry

DSCN3632

Probing the output pin 8 of this OP-AMP I could measure only +1.4VDC against +10VDC of the output of the other one @3F which is involved in the blue color (which was correctly working)

OUTPUT_LM324@1P_@3F

So I decided to pull out the LM324 and add a rounded machine-tooled socket :

LM324@1P_reworking

When tested out-of-circuit, it failed: DSCN3635

Fitted a new one:

new_LM324_fitted

and red color was restored :

fixed

No further issue were found so board 100% working.End of job.

Spectral Vs Generation PAL dumps added

PAL Updates Comments Off

Jun 262016

Dumped 4x AT22V10 chips today of my Spectral Vs Generation PCB.
All the chips were unlocked. They may need converted to GAL22V10 format if that is your target device, i’m unsure whether the two formats are interchangeable.

Tecmo Knight repair log #2

PCB Repair Logs Comments Off

Jun 252016

Dug this board out today with the view of selling it.
I put it on to test and also fired up MAME for a comparison and noticed that the digital samples weren’t playing at all. It first noticeable on the attract sequence when the lightning strike and you should be able to hear thunder.
This game uses an M6295 chip in order to deal with the samples so it was really easy to make a start trouble shooting. Using the scope I could see all the inputs and outputs were toggling when I would expect and could see one of the enable lines going active when the thunder sample was meant to play but the DAO pin (pin 36) was just dead. I did try to reflow this just in case but it made no difference.
I replaced this with one from a scrap PCB
20160625_190328
20160625_193803

Sounds are all back now

Rainbow Islands – Clock Circuits

Technical Info Comments Off

Jun 242016

A short simple post on two of the clock circuits used on Rainbow Islands.
There are 3 x crystal oscillators on the Rainbow Islands PCB. This post will cover two of them. The third is used for selecting a chip enable line of some RAM in an elaborate way which I don’t fully understand right now.

First lets look at the X2 Oscillator which is 12MHz.
ri-x2osc

This is solely used as the clock for the C-Chip and simply goes though IC54, an inverter, into pin 20 of the C-Chip at 12Mhz. Easy!
CCHIP

Next up is X1. This supplies the clock signals for the Z80 and the 68000.
ri-x1osc

The 16MHz clock signal serves as the clock signal for a 4-bit binary counter at IC30. Output Q1 (pin 13) of this binary counter gives a 4MHz clock which is the clock signal for the Z80 sound CPU.
Output Q0 (pin 14) of this binary counter gives out the 8MHz clock for the main 68000 CPU.
SCLK

Both of these clocks also feed into the custom PC060HA chip at IC45 on pin 14 (SCLK) and on pin 15 (MCLK).
MCLK

That’s all there is to this one.

Osman/Cannon Dancer PAL dumps added

PAL Updates Comments Off

Jun 242016

New PAL dumps still from our member Yves M.

This time we have the ones from a Osman/Cannon Dancer PCB (boards silkscreeneed as ‘DEC-22VO’ and ‘MT5601-0′ and manufactured by Data East).Dumps come from unsecured PALCE16V8H devices and have been successfully tested onto GAL16V8 targeting device.Thanks again to him for this contribution.

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