MCR power chassis/brick and supply overview

Was searching Mid-Atlantic Arcade group on facebook and found this which is 1000 times better than my description of the components in the video. I briefly reviewed and the only thing that I think is incorrect is the Gray sync ckt reference. That is actually the "pump charger" which feeds the "one shot", both of which are part of the reset ckt....based on my understanding.

Not sure how the AC sync ckt truly works but only U4 &R202 are involved in the below diagram. U4 feeds the rest of the AC sync components (u6, c207, r219, etc) which are not shown.

<<edit>> Also will mention, for those that don't watch the video :), that the fuse F1 is actually part of the +5 regulation ckt. U2 and Q105 get their power from the unreg +12 straight from game transformer. here is where I discover that https://youtu.be/OpBOEqojOJY?t=3m48s

Anyway still nice little diagram.

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Nice job on this. Just bumping it to subscribe.
 
and the reason I even started down this MCR discovery path. MCR Hum issue solved. Might do at least one more, in the future, on a different power supply that has a reset ckt issue.


Ok this is strange and it took me a bit to figure out the history, so documenting here mostly for myself, but the rev. D board at end of above video, from spy hunter, ended up in my Tron cab.

In between like Jan - Feb my Tron developed an issue (i think it was hum actually but not certain) and I put in the fixed rev C board (beg of video) into it (didn't have caps on hand to address tron power board) but subsequently sold that rev. C board and put my fixed spy hunter rev D board (from above video) into Tron. I sold the rev.C board knowing I had other MCR boards ready to be fixed up, had already done the battery mod, was still working on spy hunter, wasn't original to any of my games, blah blah..anyway.

So a few weeks ago my Tron develops Hum (likely again) just like the spy hunter. It turns out to be the same c102 cap (+12 reg ckt) I replaced in previous video. Again the ESR and capacitance (@ 540uf instead of 470uf) wasn't that far off but was not great. I guess I either used bad caps (<likely) or something else is causing them to degrade prematurely (< filter caps??).

Long story but another MCR Hum issue addressed by replacing c102.

 
Major thanks for taking the time to shoot this and detail everything. I must have watched it two dozens times this weekend as I went over my suitcase.
 
Question... if you have this setup can you eliminate the power brick completely?
 

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In this video that TT did it looked like he eliminated everything in a Solar Fox cocktail...

https://www.youtube.com/watch?v=iRlOp4c2A-A

TNT took out the non-isolated components for the +5v and +12v. There was no metal "brick" here; more like a Tron set up with all the same components but exposed. Likely left the isolation transformer in there for Monitor.
 
and the reason I even started down this MCR discovery path. MCR Hum issue solved. Might do at least one more, in the future, on a different power supply that has a reset ckt issue.


That's pretty cool; glad you found the issue!

It's kind of odd; those caps weren't reading that far off from the new ones you used...

Ok this is strange and it took me a bit to figure out the history, so documenting here mostly for myself, but the rev. D board at end of above video, from spy hunter, ended up in my Tron cab.

In between like Jan - Feb my Tron developed an issue (i think it was hum actually but not certain) and I put in the fixed rev C board (beg of video) into it (didn't have caps on hand to address tron power board) but subsequently sold that rev. C board and put my fixed spy hunter rev D board (from above video) into Tron. I sold the rev.C board knowing I had other MCR boards ready to be fixed up, had already done the battery mod, was still working on spy hunter, wasn't original to any of my games, blah blah..anyway.

So a few weeks ago my Tron develops Hum (likely again) just like the spy hunter. It turns out to be the same c102 cap (+12 reg ckt) I replaced in previous video. Again the ESR and capacitance (@ 540uf instead of 470uf) wasn't that far off but was not great. I guess I either used bad caps (<likely) or something else is causing them to degrade prematurely (< filter caps??).

Long story but another MCR Hum issue addressed by replacing c102.


Well even though it appeared replacement caps fixed the issue (they were at least questionable), I again had a hum issue with the same power supply board. I should have been more thorough on checking connector J5 which had some questionable work done on it. Referenced in first video. Fairly certain the hum issue is now finally fixed although my repair makes Frankenstein's Monster look good and original repair less questionable.

 
Can someone tell me why they engineered the +12vdc for the Cheap Squeak on Spy Hunter from the +12vdc going to the rest of the game? Why not use the +12vdc on everything? I had found this to be the cause of my hum the other day. I am using a switcher with the newer mcr conversion board but the hum remains. Almost like the filter cap is not doing what it is supposed to.
 
I can't tell you why it's engineered the way it is but I can tell you that an hour of having a switcher in my Spy Hunter convinced me to go back to the linear power board and I've never regretted it.
 
Testing for a couple errors on my EDOT restoration (using the correct D version P/S). Wanted to confirm a voltage question before going down other paths.

With my harness connected (new from Ken) and the game powered on, should I have 5v and 12v regulated at the test points indicated in Jacklick's video at 24 minutes? Or, should these voltage adjustments occur with the harness disconnected from the P/S? With the harness connected and powered on, the voltages are less than the 5v and 12v regulated shown in his video.

Should I be testing elsewhere in the harness to confirm voltage is set correctly?

 
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If you have the harness connected you should have full voltages. I didn't look at the video, but I think the voltages are measure across the + side of the capactiors? (IIRC).
 
I haven't rewatched video but my tests were out of cabinet...no harness connected. What is your voltage?

Ultimately, with game board connected you want to measure voltage at game board and adjust till you get correct voltages at game board.

Report back with voltage at game board adjusted to 5v and 12v compared to voltage at ps.
 
Thanks Tron Guy and Jacklick. I adjusted them initially after I rebuilt the power chassis and power supply, and had to crank the pots to their minimum to (barely) reach the regulated voltages with the harness not attached.

Just received Ken's harness from Golden Age, and after getting most things connected, noted my previously set voltages were now below the required. That makes sense with load applied, but I wanted to double-check before adjusting them up.

Appreciate your feedback! Will get back shortly.

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Measured at capacitors 106 and 102 on PS:
Without harness:
5.05v on 5v regulated cap
12.02v on 12v regulated cap

With harness attached:
4.87v on 5v regulated cap
6.17v on 12v regulated cap

Measured at CPU connector:
4.82v on pin 3 red (5v)
6.12v on pin 18 orange (12v)

I'll adjust the PS in the morning and retest.
 
That voltage drop on 12v line is concerning, assuming you are measuring at correct location.
You have almost no voltage drop due to connectors and harness, which is good.
 
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