I've got a Rocky and Bullwinkle that is having some issues, and I'm almost certain I've traced the issues back to a bad power supply. I'm getting a low 5V output from it.

TP1: +0.571Vdc
TP2: Ground
TP3: +12.1 Vdc
TP4: -12.2 Vdc

So from my understanding of the board, 9vac comes in from CN1, and then goes to C2 (100uf 25v) D3 (14001N) and then onto IC1 (MC1723CP) TR5 2n6057, and then finally R6 DIRECTLY to output the 5vdc (just saying that I'm not going to go through and list all the components. If I were to start poking around, where do you think I should guess to point to as the culprit.

I would love to not have to replace the whole board with a new board for cost reasons, but I'm also not sure I want to go buy $50 in parts kits, spend hours desoldering and resoldering and then a few years off my life for breathing in the fumes and pulling every last hair out of my head trying to rebuild it properly.

#2 3 years ago

BTF

PinballManiac40

Pinside+ Frequent

14y 234K 17,632 104

C2 is a sure bet. I also seen other smaller capacitors (4 or 5 total) also leak as well, which also should be replaced on the power supply board. https://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Missing_5VDC

#3 3 years ago

GPE

G-P-E

GPE

Omaha, NE

13y 76,800 2,778 4

Start with voltage doubler circuit that powers the 723 regulator: D2, C2, D3 and C3.
Diodes D2 and D3 are likely still good assuming caps C2 or C3 didn't leak on them.
But if these caps are leaking and go bad - this will disable the 5V regulation circuit.

Also check C7 to see if it's leaking.

Even if C2 and C3 are not leaking - if they are originals, best bet is to replace them. If (when) either of these two go bad, 723 regulator will stop working.

#4 3 years ago

???

KenLayton

In Memoriam

Olympia, WA

12y 83,400 5,965

The 100 uf and 47 uf caps go bad causing very low 5 volts. Even if they look physically good, test them with an ESR meter or simply replace those two capacitors anyway.

#5 3 years ago

TY!

radial_head

Three Knocks Pinball

South Berwick, ME

5y 84,800 1,771 6 2

Capacitors replaced and it boots and plays! Thanks for the help.

What causes these two in particular to go bar so normally?

Now to figure out the DMD and sound issues!!

#6 3 years ago

???

KenLayton

In Memoriam

Olympia, WA

12y 83,400 5,965

Those caps go bad from the heat and old age.

#7 3 years ago

ZIT

Zitt

Pinball-Mods.com

Austin, TX

11y 112K 7,875 15 10

Quoted from KenLayton:
Those caps go bad from the heat and old age.

Exactly what he said.
If you look at the wrapper of the old and new caps; they say 85, 95, or 105 degrees on them.
Most cheap common commodity caps are rated for say 85C for 1000hours. At that point they can be garbage.
So 1000hours assuming 24/7/365 only gives you 3 years.
These games are what; 30 years old? Time to replace those electrolytic caps.

Usually when I recap a game or monitor; I pay for the 105C / >>1000hour caps. Just nice to know I don't have to worry about them for another lifetime.

#8 3 years ago

TY!

radial_head

Three Knocks Pinball

South Berwick, ME

5y 84,800 1,771 6 2

Quoted from Zitt:
Exactly what he said.
If you look at the wrapper of the old and new caps; they say 85, 95, or 105 degrees on them.
Most cheap common commodity caps are rated for say 85C for 1000hours. At that point they can be garbage.
So 1000hours assuming 24/7/365 only gives you 3 years.
These games are what; 30 years old? Time to replace those electrolytic caps.
Usually when I recap a game or monitor; I pay for the 105C / >>1000hour caps. Just nice to know I don't have to worry about them for another lifetime.

Thanks for the info! This is super helpful information. Replacing C2 solidified 5v, it sent the 12v out of wack. I just happened to have one lying around. I'm going to go ahead and order a full cap kit for both the PSU and the Sound Board since they're both giving me issues.

Thanks for all the help everybody. This is a learning experience for me in a lot of ways. Appreciate it.

#9 3 years ago

GTX

gdonovan

Pinside member

7y 185K 13,220 70

OP
Quoted from radial_head:
Thanks for the info! This is super helpful information. Replacing C2 solidified 5v, it sent the 12v out of wack. I just happened to have one lying around. I'm going to go ahead and order a full cap kit for both the PSU and the Sound Board since they're both giving me issues.
Thanks for all the help everybody. This is a learning experience for me in a lot of ways. Appreciate it.

Cap problems in the soundboards are rare and are more apt to cause no or poor sound. The odds of all three channels being off by caps is very slim. I'd inspect the volume pot wiring and make sure it isn't damaged.

Have you tried unplugging the pot? If you have no volume then the problem is pot or wiring.

Error on my part, tested on my Jurrasic Park and unplugging gets you full volume. Here is picture of volume control.

20200526_162000 (resized).jpg

#10 3 years ago

TY!

radial_head

Three Knocks Pinball

South Berwick, ME

5y 84,800 1,771 6 2

With the pot unplugged I still get deafeningly loud sounds. I've seen a few threads started about this deafeningly loud sound issue but none with any resolve. Will do some more digging.

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