Monster Bash Flasher Issue

I picked up a Monster Bash a couple of weeks ago that had been in storage for years and had some issues. I have successfully worked thru all but two of the issues and need some guidance for the Flasher issue.

The problem is when you turn on the machine, it instantly blows F107 fuse for the flashers. I have looked over each flasher to ensure it's not a grounding issue and also removed both the J133 connection & J111 connections - to which the machine still blows the fuse instantly.

So I'm guessing that since I removed both connections and it still blows instantly - it must be a board issue. Is this correct? If so, now how do I diagnose whats wrong with the board. I have no problems with my soldering skills, but the whole multi meter to diagnose is still a skill in progress.

Thanks!

#2 8 years ago

LTG

Pinside member

Check the bridge rectifier for 20 volts, it is likely shorted.

LTG : )™

#3 8 years ago

TOM

Dante

Pinside member

Thanks LTG. But one question, how do I tell which bridge rectifier to test. I googled them up and there's a bunch of them. Also how/what setting do I use on my MM to test them to determine. Thanks!

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#4 8 years ago

TOM

Dante

Pinside member

Quoted from LTG:
Check the bridge rectifier for 20 volts, it is likely shorted

And an additional question, how do you tell if it's shorted? Thanks!

#5 8 years ago

AAA

pintechev

Inactive member

11y 91,300 4,437

Monster bash uses discreet diodes instead of Bridges, which makes this WAY easier. Get a meter on diode test and test each of the large black diodes. One way should read open, and the other between .4 and .6. You will find one diode that reads open in both directions. Replace it when you find it.

Good luck.

Marc

#6 8 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

A bridge rectifier is four diodes wired together to convert AC into DC. Use your DMM set to diode position and place leads on the diode and take the reading and then reverse the leads and take the reading. One reading should be open circuit and the other should read .400 to .600. If it reads zero ohms then it's shorted.

#7 8 years ago

LTG

Pinside member

Quoted from pintechev:
Monster Bash uses discreet diodes instead of Bridges,

You are right. I goofed.

Quoted from pintechev:
You will find one diode that reads open in both directions. Replace it when you find it.

Or dead shorted in both.

LTG : )™

#8 8 years ago

AAA

pintechev

Inactive member

11y 91,300 4,437

Quoted from LTG:
You are right. I goofed.

Or dead shorted in both.
LTG : )™

I always bucketize open and .001 as the same thing, but you're right, they are different. Thanks, Lloyd!

#9 8 years ago

TOM

Dante

Pinside member

Thanks all for the reply, but still one question, what do i actually test. When I look at the board, there are a ton of items to look at. What specifically do I set my MM at to test and where do I test at? Thank in advance.

#10 8 years ago

LTG

Pinside member

OP
Quoted from Dante:
what do i actually test.

The big fat diodes on the upper right side of the board.

Youtube has lots of short how to videos.

LTG : )™

#11 8 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

WPC-95 schematics will have all your answers.

#12 8 years ago

???

RoyF

Pinside member

Highland Heights, OH

12y 40,900 664

Look at D15-D18 for the +20VDC flasher circuit. Your meter should be in diode mode.

#13 8 years ago

TOM

Dante

Pinside member

Thanks again! YouTube and Schematics it is.

edit: for future reference, D17 was the culprit with a 0.0 reading.

#14 8 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

Study Terry B soldering tutorial while you are waiting for the new diodes. P/S replace all four as a set.

#15 8 years ago

AAA

pintechev

Inactive member

11y 91,300 4,437

Quoted from GRUMPY:
Study Terry B soldering tutorial while you are waiting for the new diodes. P/S replace all four as a set.

To each his own, but I would only replace what is broken. Don't add risk to the board by soldering more than is necessary.

#16 8 years ago

TOM

Dante

Pinside member

Quoted from GRUMPY:
P/S replace all four as a set.

Thanks, good advice. I'll order some extras as one of the four was giving some wonky values.

#17 8 years ago

LTG

Pinside member