What's new
By:

APOCALYPSE Irem M72 Multi, Sales , Installation and Support

raffy92 said:
Some varistor orange, are touching the multi on the a board from below. Can it lead to problem ?
Click to expand...
Anything touching on a pcb bottom I've found can cause errors on my test bench.
So possibly.
You'd think only metal can cause problems because, conductive.
But plastic and whatnot can apply pressure in a way if uneven that can cause glitches.

To be m72 specific the board is an early design they refined to be more reliable in later less complicated versions.

A case or solid spacers really help. As does a recap due to age. And if it doesn't already have them, the front power wires linking the boardstack.
 
ForestOfDreams said:
Anything touching on a pcb bottom I've found can cause errors on my test bench.
So possibly.
You'd think only metal can cause problems because, conductive.
But plastic and whatnot can apply pressure in a way if uneven that can cause glitches.

To be m72 specific the board is an early design they refined to be more reliable in later less complicated versions.

A case or solid spacers really help. As does a recap due to age. And if it doesn't already have them, the front power wires linking the boardstack.
Click to expand...
I actually changed the plastic solid spacer (attached with screws) of 3 cm I had, to metal hexagonal ones of 3 cm too, in both cases pcb eprom were not touching the upper pcb b board. Do you think that changing plastic spacers to metal ones can cause problems (even if there is no contact between boards) ?
I noticed some contact between a board flat orange varistors and the upper multi. How do you proceed in this case? Is safe to gently bend those varistors to avoid contact?
Thanks
 
ForestOfDreams said:
Anything touching on a pcb bottom I've found can cause errors on my test bench.
So possibly.
You'd think only metal can cause problems because, conductive.
But plastic and whatnot can apply pressure in a way if uneven that can cause glitches.

To be m72 specific the board is an early design they refined to be more reliable in later less complicated versions.

A case or solid spacers really help. As does a recap due to age. And if it doesn't already have them, the front power wires linking the boardstack.
Click to expand...
Ok I will order a M72 cap kit
 
raffy92 said:
I actually changed the plastic solid spacer (attached with screws) of 3 cm I had, to metal hexagonal ones of 3 cm too, in both cases pcb eprom were not touching the upper pcb b board. Do you think that changing plastic spacers to metal ones can cause problems (even if there is no contact between boards) ?
I noticed some contact between a board flat orange varistors and the upper multi. How do you proceed in this case? Is safe to gently bend those varistors to avoid contact?
Thanks
Click to expand...
I think you'd be okay to gently bend them.
Or use larger spacers.
The metal is fine.
 
Yesterday I went back to the previous plastic and screws spacer, and also I made sure to not have any thing touching the multi especially a board and multi, then no glitch appeared.
Today, after starting the m72 multi again many small glitches appeared again. After 1h no glitch remained. Capacitor problem ? Is there any idea ? Thanks
 
raffy92 said:
Yesterday I went back to the previous plastic and screws spacer, and also I made sure to not have any thing touching the multi especially a board and multi, then no glitch appeared.
Today, after starting the m72 multi again many small glitches appeared again. After 1h no glitch remained. Capacitor problem ? Is there any idea ? Thanks
Click to expand...
See if shimming foam between the eproms and the board helps so they wont touch.
 
Is it what you are recommending to use ?
 

Attachments

  • IMG_4228.png
    IMG_4228.png
    362.2 KB · Views: 17
Caps help but any rubbing on the eproms for the multi still gives me glitches.

The fact it goes away makes me think it isnt a board fault. Regardless the board is old, a recap stabilizes things.

Here's an example of some foam I used to test the pgm carts I am building on my test bench.
I just stick it between the boards so they can't touch.

I've never not had an improvement in sync or stability on an arcade board with a recap.
I can't say the same for all consoles.
 

Attachments

  • 20250525_235059_HDR.jpg
    20250525_235059_HDR.jpg
    181.9 KB · Views: 9
ForestOfDreams said:
Caps help but any rubbing on the eproms for the multi still gives me glitches.

The fact it goes away makes me think it isnt a board fault. Regardless the board is old, a recap stabilizes things.

Here's an example of some foam I used to test the pgm carts I am building on my test bench.
I just stick it between the boards so they can't touch.

I've never not had an improvement in sync or stability on an arcade board with a recap.
I can't say the same for all consoles.
Click to expand...
Thanks for your observations. Does bad quality eprom stickers can make issues ?
The boards are clean but il will do a recap any way.
I don’t think to have anything touching eproms to something else, only some components like capacitors are bent sometimes and can touch other things.
I don’t think it s a sync problem. Some pixels sometimes shows wrong color or blinks.
 
You must log in or register to reply here.
Back
Top