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Multi Namco system 1 black screen

raffy92

raffy92

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Hi, everyone,

Three weeks ago, I successfully installed the Namco System 1 multi.

Two days ago, I switched on the system after adjusting the 5V on my Supergun. I got a black screen and the Supergun was buzzing. I switched off the Supergun, removed and reseated the JAMMA harness, and switched it on again. This time, the system booted normally.

I played Splatterhouse, reached the second level, and then an unexpected reboot occurred. The game restarted, but I didn’t pay much attention to it and continued playing.

I switched off the system and swapped the EXCEL EEPROM for the SEEQ EEPROM that I had received the previous week.

I switched the game on, and this time I got a black screen again, with the Supergun buzzing. The LED on the multi was also off.

I switched off the system, checked that the JAMMA harness was properly connected, and switched it on again. Still the same problem: black screen and buzzing Supergun.

I checked the 5V with my multimeter, but it was reading around 1.5V and didn’t seem stable.

I switched everything off and tried reseating the multi again, but the problem remained. I also swapped the SEEQ EEPROM back to the EXCEL EEPROM, but there was no improvement.

I then decided to go back to the original game by reinstalling the original EPROMs, etc. I did that, and this time a RAM test appeared for about one second, followed by the same black screen and buzzing Supergun.

It seems that a chip may have died

also then I used the supergun with my M92 and other games without issue
I’m going to try the Namco Sys 1 with another Supergun and see what happens.

I am open to any advice
 
The namco PCB has a protection (zener) diode (D1) which trips at a voltage (5.6V) and short-circuits the PSU.

In doing so, it becomes permanently conductive because its through-alloyed.
It's located next to the large capacitor C1.

Check that out.................
 
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Astro X said:
The namco PCB has a protection (zener) diode (D1) which trips at a voltage (5.6V) and short-circuits the PSU.

In doing so, it becomes permanently conductive because its through-alloyed.
It's located next to the large capacitor C1.

Check that out.................
Click to expand...
Thanks for your message, I going to check this out

So, would this basically be a safety feature? And could it be that, despite my precautions, my Supergun delivered a voltage higher than 5.6V?
 
yes,
its a safety feature.
Check the diode first, then we'll see..........
 
Is it enough to prove that the diode is shorted ?
 

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I think so,
to be sure, you have to desolder or cut one leg...........
 
The board runs even without the diode,
hopefully, nothing else is broken...........
 
I’m currently gathering the capacitors for a Namco System 1 cap kit. The radial capacitors are relatively easy to find, but I’m having a much harder time sourcing the axial ones.

Does anyone have any tips on where to find suitable axial capacitors, and especially, are there any brands or series that should be avoided? Thanks
 
By the way do you have any suggestion, whether I want to replace the Zener diode 1z6.2, by a new functional one. Should be 6.2 V , 1 W, right ?
 
First, get the board working again,
it will work even without the diode...........
 
The diode was still functional. When I plugged the jamma board and power on, I measured the 5V with my meter and it was 0.87v. I calibrated the meter to 5V before plugging the jamma to the board
 

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Then there is a short circuit somewhere else,
you have to find it...........
 
It will be very difficult to locate the fault without specialized equipment.
I suggest sending the board to a professional..........
 
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