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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 ?
 

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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.
 

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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.
 
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...
I did the capkit on the system last week, some times I had glitch sometimes not. When I have glitch, it exactly the same as I had before the capkit. The capkit didn’t help this time. Is there a m72 specialist ?
 
Two more things to check in addition to making sure the M72 Multi boards are fully seated and that the underside of the middle board isn’t rubbing against the top of the Multi daughterboard on the bottom:

- Make sure the board stack is receiving 5.0V of power. The M72 triple board stack draws a lot of power and you may need to bump your power supply up a bit. Try running at 5.1V and see if the glitches stop.

- Make sure the ribbon cables connecting the boards together are fully seated and in good condition. You can use a multimeter set to continuity check to confirm a good connection on each pin. It is possible for one line to develop a short and cause glitching.
 
raffy92 said:
because the system of 3 boards plus multi is really heavy on the middle of the boards with only 4 legs, I am wondering if a little bend can be the cause of the issue. I am looking for 2 others legs to reduce the bending .
Click to expand...
Put it on it's side (vertical) and see if it does it. Mine can be funny if its flexed and I get glitches, most notably missing backgrounds in air duel. I mounted mine super snug in a case and havent had the issue since.
 
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