spectrum issue - intermittently hanging up

[AlanJ]

so i’ve done a ton of repairs to the new spectrum and it’s working, all feature lights now work and the game boots every time on power on and it works fine.

only issue is that occasionally it will shut down, either mid game or in attract mode.
in both cases all the feature lights go out and there is still power to the score and credit displays although these don’t show any numbers. you can see they still have power as have a bit of orange glow to them. if it was in attract mode then no buttons function. if it was mid game the flippers still work. the green led on the mpu board goes out. the sound board still works. if you press the push button switch it does it’s usual noises.

if i power off and back on the machine reboots ok. it can run sometimes for hours without the problem. other times it can be 10 minutes before it happens.

last time it occurred i tested the various voltages in the main power board, on the sdb/ power regulator board and on the mpu board. all voltages were present and in line with those measured when the machine was functioning normally.

the mpu board looks like it’s had battery leakage damage- see pics below.

anyone got any ideas on what to look at first please? my suspicion is with the mpu board.

many thanks.

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[General Zod]

I would check to see if it has the original 12000uf capacitor on the solenoid driver board as this will definitely be a problem if it's the original one. Spectrum only has 2 flippers so you can use a 10000uf 25v cap as a replacement or a 15000uf too. I would start with that, then start looking at iffy connectors, then your mpu unless par chance you have a known good mpu to eliminate the one photo'd.

 

[General Zod]

Just had another look at your mpu photo it could be that, check for scanbe or augat ic sockets especially the one on the 5101 ram chip as the originals are trash. Also I would get another set of game eproms sorted and get rid of those "probably" corroded pics that are probably in U1, U2 and U6.

 

[AlanJ]

took a good look at the mpu board. it’s been in the war zone[emoji23]

i just added the black ground wire mod

cleaned up a load of crud with ipa.

probably need some of the components replacing, esp lower board area

plan 2 buy an alltek ultimate mpu




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[Toxteth O'Grady]

Looks like the red and white worms are eating your board, knock em off quick!

 

[Arv]

Any pics of the power board Alan?

 

[Slamtilt]

my guess is a dry joint/bad connection on the power board. I have a mpu board with a bad ram chip and the green led still lights.

 

[AlanJ]

Any pics of the power board Alan?

ill take that out this aft and have a closer look & take some pics. i’m still awaiting some capacitors to replace on the power board.


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[myPinballs]

ill take that out this aft and have a closer look & take some pics. i’m still awaiting some capacitors to replace on the power board.


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Replace all the caps I mentioned earlier on the power driver board and rebuild the regulator board in the cab before going any further.

it’s not worth messing about until all your power boards are solid if you are having reset issues. These types of intermittent issues are resolved by logically working trough the boards in a certain order

 

[AlanJ]

Replace all the caps I mentioned earlier on the power driver board and rebuild the regulator board in the cab before going any further.

it’s not worth messing about until all your power boards are solid if you are having reset issues. These types of intermittent issues are resolved by logically working trough the boards in a certain order

the power board had a duff bridge for the 6.5v dc lighting circuit so i replaced that. the other bridge all tested out ok on the 11.9v dc circuit. but i’ll take another look at that part and circuit as it powers the 5v regulator


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[Pick Holder]

Best advice on here so far is to get your power supply sorted. Just replace all the BRs and caps on it.

Then if that doesnt cure it - I would be inclined to go for a replacemement MPU - as you will probably spend hours on that one.

 

[myPinballs]

the power board had a duff bridge for the 6.5v dc lighting circuit so i replaced that. the other bridge all tested out ok on the 11.9v dc circuit. but i’ll take another look at that part and circuit as it powers the 5v regulator


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And the bridge for the 43vdc ( the bridge for the 12vdc is 4 diodes) as this is fed to the cpu via j4 (bottom left) for some boot stuff which is the next step to look at after all the power side stuff is sorted. ie cpu J4 pins and header to be replaced

all the bridge stuff needs changing on the rectifier board regardless in my experience . Just not worth messing about. I have kits if needed but I guess you have the parts already

 

[AlanJ]

And the bridge for the 43vdc ( the bridge for the 12vdc is 4 diodes) as this is fed to the cpu via j4 (bottom left) for some boot stuff which is the next step to look at after all the power side stuff is sorted. ie cpu J4 pins and header to be replaced

all the bridge stuff needs changing on the rectifier board regardless in my experience . Just not worth messing about. I have kits if needed but I guess you have the parts already

Yes thanks Jim, got the bits, I have done the 2 bridges now - using 35A rectifiers. Mounted them on the top with heatsinks. Will next do the 1N5404 diodes. The connectors on that board look good. The J4 MPU connector doesnt look as good ;-(

 

[AlanJ]

i realised my paragon has a alltek mpu board in it so i temporarily put that in soectrum, and it worked fine. no reboots or shutdowns.

so i bought a new alltek for the spectrum.

job sorted


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