MCR power supply re-build

cmkryzer

Member
Joined
Jan 28, 2011
Messages
214
Reaction score
5
Location
Minnesota
I just went through my Satan's Hollow power supply witha rebuild kit.... and as i was doing one of the caps, c101 i think it was, i notice something that looked funny, JW4, jumper wire 4 was missing...i took a picture of the board before i started, and yep it was missing. So just wondering maybe if this was the problem i was having to start with. I added a piece of wire from one of the caps and put that wire in the JW4 place...and put the board in and fired the game up. I get nothing on the screen but a bunch of colored boxes all over the screen, less action going on before it did the rebuild.
Any sugestions?
 
I just went through my Satan's Hollow power supply witha rebuild kit.... and as i was doing one of the caps, c101 i think it was, i notice something that looked funny, JW4, jumper wire 4 was missing...i took a picture of the board before i started, and yep it was missing. So just wondering maybe if this was the problem i was having to start with. I added a piece of wire from one of the caps and put that wire in the JW4 place...and put the board in and fired the game up. I get nothing on the screen but a bunch of colored boxes all over the screen, less action going on before it did the rebuild.
Any sugestions?

Just throwing this out there; try it with out that jumper.
 
I happen to have a pretty nice photo i took of my D000 version of this board (for my Spy Hunter) and it doesn't have a JW-4 either.
 
Its kinda funny on mine, cause there was still studs in the solder when i cleaned up the old solder out of the joints...and they were cut out..
 
Midway released a service bulletin stating to cut jumper J4.....it's supposed to decrease audio hum.

Edward
 
Midway released a service bulletin stating to cut jumper J4.....it's supposed to decrease audio hum.

Edward

Well then that explains why it looks likeit ws cut out of it. Thanks!
Now, back to find out why it still does not work..
 
If JW4 were present it would tie the logic ground (regulated +5/+12) to the audio ground (unregulated +12).

However MCR is designed for an isolated audio power supply. Notice the audio power supply starts with a separate transformer, separate rectifier, and only powers a few audio chips. So with JW4 disconnected you're keeping the audio ground separate and simple; that avoids a single ground that runs all over the machine and acts like an antenna picking up noise.

No idea why they designed it, but didn't have it enabled right from the beginning.
 
If JW4 were present it would tie the logic ground (regulated +5/+12) to the audio ground (unregulated +12).

However MCR is designed for an isolated audio power supply. Notice the audio power supply starts with a separate transformer, separate rectifier, and only powers a few audio chips. So with JW4 disconnected you're keeping the audio ground separate and simple; that avoids a single ground that runs all over the machine and acts like an antenna picking up noise.

No idea why they designed it, but didn't have it enabled right from the beginning.

So for those of us a little less EE literate, it is better to remove JW4, correct?

And if one is having audio hum/static/etc issues, try connecting JW4 to see if it makes a difference?
 
you know ...i did notice something different when i had it plugged in and the jumper installed. I am working in the garage and had a radio playing and i am pretty sure the game was messing with the radio as far as interference within it when i turned it on and off testing it...
 
So for those of us a little less EE literate, it is better to remove JW4, correct?

And if one is having audio hum/static/etc issues, try connecting JW4 to see if it makes a difference?

It will be best if the jumper is removed.

Edward
 
Back
Top Bottom