(Topic ID: 208831)

I fried something but not sure what. I need advice.

By crazybruce10

6 years ago



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#1 6 years ago

So on my 1978 Lost World restoration, I noticed all my score displays were out. I am new to this so after reading up on this forum, I figured it was possibly my F1 fuse on my solenoid board that was bad. Sure enough, that fuse in the high voltage area was blown. Not knowing much about fuses, I installed a 250v 10A fuse instead of a 250v 3/16a fuse. So after 2 seconds I saw smoke so I unplugged and removed fuse. My question : I am not sure what was burning in which area. I just saw smoke. I am wondering if it would have affected the score display boards or somewhere else. Anybody know? And now when I start my machine the test light on the MPU board stays lighted and stuck on the 4th flash. Help if you can. Yup, I'm a dumba$$.

#2 6 years ago

If you deliberately knew that overfusing was a bad idea, that's one thing - if you simply didn't know then what you need is some basic electronics education. You can read and learn some fundamentals on your own (or even better yet take an electronics course)

Then you should get familiar with the systems in your pinball machine before opening the backbox again. I suggest you thoroughly read this series:
http://techniek.flipperwinkel.nl/ballyss/rep/index1.htm
http://techniek.flipperwinkel.nl/ballyss/rep/index2.htm
http://techniek.flipperwinkel.nl/ballyss/rep/index3.htm

All is not lost, but your going to need this info if you are going to fix this on your own. Each board in the game should be gone through systematically, and learning about measuring electronics voltage with a DMM/Voltmeter will also be required.

#3 6 years ago

as for what areas were affected by the over fusing, which I think was your real question, I would start by looking at the circuits and components closest to the fuse and try to identify any burned up parts or brown/black discoloration on the board. It may help to remove the board to identify this as you can look at the back. I do recommend reading the links in the above post as there is some great info in there. I will read over basic electronics all the time as it helps to ingrain a mental flow chart for diagnosing issues.
Thanks
Blake

#4 6 years ago

Disconnect power from MPU, etc... and work on a single board at a time to minimize additional damage as well. Check your rectifier board, make sure that is good. Then you probably will be rebuilding the HV section on the solenoid driver board, at minimum. Don't hook up anything else like MPU or display boards until you are certain the power measurements are within spec.

#5 6 years ago
Quoted from wayout440:

Disconnect power from MPU, etc... and work on a single board at a time to minimize additional damage as well. Check your rectifier board, make sure that is good. Then you probably will be rebuilding the HV section on the solenoid driver board, at minimum. Don't hook up anything else like MPU or display boards until you are certain the power measurements are within spec.

I'm thinking because of his experience level it would be worth mentioning that there are test points on the rectifier board as well as most other pcbs and those are the specific measurements he is looking for. And that he needs to set his meter up to reflect the voltage being measured.
Thanks
Blake

#6 6 years ago

Yes I have been going through the step by step for the boards and have been testing my voltages. When I replaced the fuse i just saw the one I removed said 250v and 3/16 wasn't visible as there was corrosion on the metal, when I picked up the other fuse I just saw 250v and thought they were the same. I will re-check everything tonight. At first glance without the boards removed, i can't see any evidence or melted or burnt wires except on 2 of the displays I can see some 100k resistors are burnt and wondering if this could have been the source of the smoke? Also, now the machine is stuck on the fourth flash, light doesn't go out. Is that a sign of problem with U10 chip?

#7 6 years ago

If you're uncomfortable working on your boards and just want it fixed, there's a few highly reputable guys on here thst do sidework. Drawing a blank on who specifically, but someone I'm sure will chime in. Also Clive at the coin op cauldron does stellar work, but usually has some backlog. If you're in a hurry ask before shipping.

#8 6 years ago

no fifth flash means U11 (6821 PIA) is bad.

The six 100k resistors on the display boards should be upgraded to 1/2 W resistors
http://stevekulpa.net/pinball/bally_disp6r.htm

#9 6 years ago

This is a very cool tip from that write up. I wonder how many people actually do this and how easy it really is?
thanks
Blake

Step 1: Pry up the old socket base. If a black socket, it will come right off easily, leaving the solder-in socket pins in the board. The brown sockets will not pry up (don't even try!); skip right to step number three. On the black sockets be careful not to damage any traces while prying with the screwdriver tip! Once the socket base is pried up, examine the socket pins for any grey/green corrosion. If the socket pins are clean and undamaged, press the socket base back onto the pins.

#10 6 years ago

I am hoping the 100k 1/4w resistors are the only casualties that caused the smoke. I will see later when I attack the problem again.

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