I just finished working on a Bally -17. It was pretty corroded. I replaced all the components in the lower section including U8 socket. I bench tested it yesterday and today. It booted fine - all 7 flashes. Tonight I thought I'd take some photos and a video. Now it's flashing 8 times. After the 7th flash it comes back on and just strobes really fast. The strobing is not showing in the video. I've never seen this before. I don't even know where to look.

Thanks

Bob

I'm getting 330.8 Hz. What is except able?

adalogue, my power supply has a 24 volt output as well as 5 and 12 volts. I only use the 24 volts (connected to TP3) to check for the last flash.

It's not rebooting - after the seventh flash the LED just goes in a constant flicker.

Bob

IMG_3187 (resized).JPG

L2 was replaced because of corrosion

Before

IMG_4518 (resized).JPG

After

IMG_4643 (resized).JPG

The only game I have here at this time is a Meteor - MPU 200.

I'll let you know shortly.

Thanks

Bob

When I boot with 24 Volts connected I get the usual - 7 flashes then flicker. Then I turned off the 24 V at the power supply and it rebooted but only 6 flashes (as expected). Then I booted again with 24 V and it did it's usual thing as before but this time I disconnected the 24 V lead at TP3 and it continued to flicker but the flicker seemed to have a different frequency. It would flicker then stop flickering for a second then start flickering again.

Earlier today I looked over the work I did and I wasn't real happy with the solder joints at C16. Although continuity was good the solder joints didn't look so good. I removed C16, Cleaned the pads and reinstalled it. No difference.

Visually I can't see anything else wrong.

Where to go next?

Thanks

Bob

This thing booted fine last week when I rebuilt everything. Then I installed the headers and it booted fine. Then I painted the bare copper traces and it booted fine. As soon as I got out my camera for a video it starts messing up.

I replaced the socket and cleaned the legs but maybe not very well - it was corroded. I have a fear of breaking off the legs. Any tips on how to clean them?

I think it's the way those ROMs are made. U2 is the same way.

IMG_4648 (resized).JPG

https://www.greatplainselectronics.com/proddetail.asp?prod=LM2-R22K

Can I just put the board in the Meteor and connect MPU J4 only?

Thanks Quench, I'll try that tomorrow.

Isn't this the zero crossing circuit?

zero x (resized).JPG

Could U10 or U14 be causing this problem?

Bob

I replace U10 (I didn't swap). Got the same results.

I checked the voltages as indicated in the above post.

CR49 top = 5.25 (should be 5v)

CR49 bottom = 5.38 (should be 4.9

U14 Pin 14 = 5.38
pin 10 and 5 =4.9
pin 9 and 15 = 336 mV
pin 4 = 336 mV

Now here's the strange thing, after probing those voltages I looked over at the LED and it was off. I rebooted several times and now I get just the seven flashes - no flickering.

After typing this I went back and checked it again - same as before - seven flashes then flickering. I left it on for a minute or so and rebooted - seven flashes then off - no flickering. Seems it needs to warm up before it works right.

Next I turned on only the 24 V and let it warm up for a few minutes (no 5 or 12 V). Then I turned on the 5 & 12 V - same thing seven flashes then flickering. I left it flicker for a few minutes then rebooted. No difference still flickering. (BTW I love this power supply)

I didn't have time today to swap boards in the Meteor. That's next.

Thanks

Bob

I just tried the board in the Meteor. Seven flashes then what looks like solid on. It might be flickering but I can't tell. Attract mode seems to be working - the feature lights seems to be working as normal. Only the left 3 digits on all displays are on but they are flickering. The forth digit (from the left) acts like it wants to join the party but it just don't want to come on. I'd call it half flickering. The last two are dark.

I didn't screw the board down - I just plugged in J1 and J4 and left the board hanging. Dangerous, I know.

Thanks

Bob

I had a little shop time today. I was going to swap U11 but first I thought I'd try to boot it up. It booted fine - seven flashes then off. I tried several times - it worked every time. I left it on for 10 - 15 minutes and tried again. It booted fine. Then I rechecked the voltages as I did above. Same voltages as before. I booted it several more times and it works fine every time.

Now I'm at a real loss. I can't fix it if it ain't broke - but I know it's broke.

I'll try again later.

Thanks

Bob

What I did do was push the U11 down in the socket a little more. I didn't think it made a difference but maybe it did. I think a close look at U11 and perhaps I'll change it next. Not getting any shop time lately.

I'll keep you all advised.

Thanks

Bob

After I cut the grass today I got a little shop time. I booted up the board several times and it worked fine. I removed U11 and the chip was clean. I removed the socket housing and sure enough it was corroded under it. I proceeded to remove the socket pins and clean the solder pads. I hope to clean a little more and install a new socket tomorrow. Maybe we found the problem. I'll let you know.

Thanks

Bob

Friday I replaced the U11 socket and it booted just fine but I didn't want to take any chances so today I replaced the U7 socket. I already replaced the U8 socket. It's booting fine now. I think we got this solved.

Thanks to everyone.

Bob