(Topic ID: 215044)

1986 sys 11 High Speed : 5 volts is 12.5v


By oneperson

1 year ago



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  • 12 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by CadillacMusic
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High Speed Main (resized).jpg
HS_PS_Chip (resized).jpg

#1 1 year ago

1986 sys 11 High Speed : 5 volts is 12.5v

The game wouldn't come up, felt lots of heat on the sound ROMs and checked 5 volts = reading 12.5v
Replaced the caps on power supply with a 8 electrolytic cap kit, still getting the same voltage.
Took voltage readings at the wires that run to the 2N6059 transistor
B 13.5
E 12.5
C 14.6
Any suggestions ?

#2 1 year ago

Well, first of all, your main board is gonna be fried. If 12v went to your 5v chips, they probably are toast. Have you replaced your bridge?

#3 1 year ago

I put a bridge in temp before I swapped caps, same voltages , so I put original back in - also I swapped the 2N6059 and got same voltage so I put the original one back, before doing the cap kit.
I was thinking that the rest of the boards that use 5 volts will be messed up too after feeling the heat off the eproms. Hoping for some luck on that once the power supply is back at 5 volts.

#4 1 year ago

Unfortunately, all boards will have damage under ghis scenerio.

#5 1 year ago

At this point, there isn't much left you haven't replaced. I'd measure the diodes on the power supply to make sure they're okay, and then replace the IC.

#6 1 year ago

I was plugging in the numbers off the IC on power supply without any luck for a cross reference: 5-09424 or RAYC8306

I had heard the Data East power supply was similar and wondered if the IC was the same type? That one I was able to look up : UA723CN

HS_PS_Chip (resized).jpg

#7 1 year ago
Quoted from oneperson:

Took voltage readings at the wires that run to the 2N6059 transistor
B 13.5

This is your problem, should be @ 6.5 volts. So the regulator chip is not applying any control voltage to Q-5. With no control Q-5 will pass unreg voltage straight thru - a pn junction drop.

1 week later
#8 1 year ago

Got a voltage IC , NTE923D and installed it = much closer to 5 volts now, Thanks cadillacmusic !
So the voltage I read at the base was not from the IC, but passing through the Transistor - Thanks grumpy !
The 5 volts is a bit low 4.86

I did not get lucky, as far as the other boards that use 5 volts are concerned : Looks like they are damaged from the over voltage pinballplusmn . Too bad when the power supply fails it is able to pump higher voltage through the 5 volt system like this.

#9 1 year ago
Quoted from oneperson:

The 5 volts is a bit low 4.86

If you change R-8 to 5.11 k ohm this will rise to 4.96 volts. If you change it to 5.23 k ohm your output will be 5.05 volts. Be sure to only use 1% resistors.

#10 1 year ago

I just had a Pinbot that had the same issue. All of the eeproms were bad. Alot depends on if the game was on for a long period of time under this over voltage condition. You may want to replace your eeproms first and see if the boards come up. You may get lucky.

1 week later
#11 1 year ago

Looks like I got kinda Lucky after all (once I dug up a eprom burner that would halfway work with a PC to copy BIN files from web) replaced all but one of the eproms and the system is back up, even sporting a "0"! Thanks for the tip pinballplusmn

Also got the 5 volts looking much better, under load, with the resister trick, thanks for that info grumpy

High Speed Main (resized).jpg

#12 1 year ago

Wow, I'm impressed that all those chips survived. Thanks for the update.

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