Working on a project Cyclone I recently picked up - you all were very helpful last time I had a question so I figured I'd try here again. I have the machine up and running after relocating the battery box. However, the flippers only work intermittently. When they don't work, there is often (but not always) a loud buzzing coming from what I believe is relay K1 on the CPU board (the orange/yellow box in the photo below). If I lightly tap this relay, or restart the machine, eventually the flippers will start working again.

I have a feeling someone more experienced than me knows what's going on here. I have a DMM at my disposal, what can I do to further diagnose (and fix) this issue? Any help is much appreciated!

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Thanks wayout! I do have a soldering iron and while I've only soldered the battery relocation and a new coil, I think I might be able to handle it. I assume I'll need to remove the CPU board again to tell for sure, correct?

Thanks again wayout, I really appreciate the help. I pulled the board and noticed that nothing seems to be loose, corroded or broken. I've attached pics in case I've missed anything. I'm thinking at this point it might be worth it just to replace the relay?

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Thanks, for $15 or whatever the relay costs, I think I'll just go with that option. Appreciate your help!

Edit: can someone confirm this is the correct relay? http://www.marcospecialties.com/pinball-parts/5580-09555-01

Got it - I have a lot to learn!

Thanks for all of your help.

I finally got around to replacing this, and now another relay (I think "Relay, DPDT, 13A on the Aux Power Unit Driver board) is making the same loud buzzing noise on startup, and in general the machine acts strange. The machine will power up, GI comes on, and I can start a game, however power seems very diminished - the ball return coil isnt powerful enough to kick the ball into the shooter lane, flippers dont work, etc.

Any ideas on how I can figure out what's actually going on? It seems very odd that the other relay would just stop working after replacing the first.

This is the relay that is now buzzing:

relay1.png

I didn't do that - the machine had been working (except for the intermittent flippers and another GI issue that I believe is unrelated), but I noticed low power on startup before removing the MPU to replace the flipper relay. Sounds like my next step is to check the Power Supply.

That would entail checking both the large box on the bottom of the cabinet as well as the board with the large heatsink on it, correct? I've also heard the bridge rectifiers (I believe those gray squares on the board pictured) can be a problem area - anything I should do to check those while I'm in there?

Thank you!

Great information, thank you! Wayout - you've been insanely helpful. I'm grateful to have this place as a resource, otherwise I'd be spending a lot more on troubleshooting this machine.

I'll give those test points a try next time I get a block of time to put into the machine.

Thanks!

I finally got some time to work on this, however, I have a few questions.

I tested with the machine on, with connector IJ17 unplugged and I was testing the pins on the MPU. I had the multimeter set on the 20 VDC setting (is this correct?).

I tested with the black lead on one of the ground pins (1, 2, 3 - mostly used pin 1) and the red lead on 4/5/6/8/9. The readings did not match the schematic:

Pin 4: 5V specified, 0.5V measured (assuming the aforementioned multimeter setting was correct)
Pin 5: 5V specified, 0.5V measured
Pin 6: 5V specified, 0.5V measured
Pin 8: -12V specified, -0.4V measured
Pin 9: 12V specified, 5.6V measured

Assuming I tested correctly, it seems like the voltages are a problem here. I will continue to test the other points Wayout mentioned, but I want to make sure my methodology is sound.

Thanks!

Oh, okay. Forgive the stupid question, but how can I test the pins with the connector plugged in? On the solder side of the MPU? Thanks again, as always!

TP2 (which I believe is the one near the speech roms you mention) is reading +5VDC, and the TP's on the power board tested for the correct readings also. When looking for the 1458 8 pin amp IC (had to google that one), I went to test one and noticed corrosion all over the legs. I don't think I did a sufficient enough job cleaning it off when relocating the battery pack, and when I touched the DMM lead to one of the legs the machine's condition seemed to change. I was able to get a game started with the coils firing at what seemed to be full power.

I think I'm going to take the MPU board back out and give it a much better cleaning and see if that improves things.