(Topic ID: 267864)

System 11 - Cyclone - not booting (FIXED)

By Lescell

1 year ago


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  • 20 posts
  • 7 Pinsiders participating
  • Latest reply 1 year ago by Lescell
  • Topic is favorited by 1 Pinsider

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#1 1 year ago

Hey all, figured I would post here for some help as a last resort before sending the board out for repair.

I have a Cyclone MPU that just won't boot. I have good 5V (indicated by LED and DMM), good ROMS and good CPU chips, clean overall. I had a local buddy with the same board so I could swap what was socketed and nothing helped. Neither the diagnostic or blanking LEDs light up. Sometimes I get the start chime, but usually it's no sound at all, or an annoying squealing noise.

The power supply has been recapped. I even tried a brand new rottendog power supply and had the same result. Then put my buddies working MPU in and it booted fine with both power supplies, so I'm confident it's an issue with my board.

I have a DMM and a logic probe so I'd be glad to start probing some chips with your help to narrow this issue down and I have faith that we can do this over the internet I did search quite a bit regarding System 11 boot issues and nothing I checked narrowed it down anymore than where I'm at.

I've attached a few pics of the board, only minimal "corrosion" up near the top resistor packs..

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#2 1 year ago

Have you pulled the fuses and checked them with a meter on the power board to the right of the MPU?

#3 1 year ago

I would recap the power supply and check the 12 pin ac connector going in .

Ive seen bad power supplies properly power a cpu board and not power up others with both cpu boards being good.

#4 1 year ago

Will it boot if you turn it off and back on again quickly?

#5 1 year ago

Thanks all, your replies made me think of a few things I forgot to mention in the original post, it has been updated.

A quick on/off doesn't help, fuses are good.

#6 1 year ago

I had something similar and it was c30. Not sure how to test for sure, but it is a cheap and quick cap to swap out and check until the techs chime in.

#7 1 year ago

Your edit helped - I misread that your friends board also didn’t work. System 11 have tiny traces. I would send this to Chris Hibler for help.

#8 1 year ago
Quoted from Tomass:

I had something similar and it was c30. Not sure how to test for sure, but it is a cheap and quick cap to swap out and check until the techs chime in.

I did test out the c30 theory by clipping another capacitor with the same values in parallel and it didn't help.

#9 1 year ago

Yes, the edit helped me to understand better too. I was wondering about C30. I recommend Chris Hibler.

#10 1 year ago

check all of your socketed chips. rule out the easy stuff first. if you have a chip puller and are comfortable pulling and reseating the chips.

#11 1 year ago
Quoted from Bax1:

check all of your socketed chips. rule out the easy stuff first. if you have a chip puller and are comfortable pulling and reseating the chips.

Thanks for the recommendation. All socketed chips have been pulled and reseated half a dozen times but unfortunately nothing has helped. It still doesn't rule out the sockets themselves but I figured at least once I would get something out of it.

#12 1 year ago
Quoted from Lescell:

Thanks for the recommendation. All socketed chips have been pulled and reseated half a dozen times but unfortunately nothing has helped. It still doesn't rule out the sockets themselves but I figured at least once I would get something out of it.

Start tracing with continuity. Tedious but the answer might be there.

#13 1 year ago
Quoted from Lescell:

Thanks for the recommendation. All socketed chips have been pulled and reseated half a dozen times but unfortunately nothing has helped. It still doesn't rule out the sockets themselves but I figured at least once I would get something out of it.

If they’ve been inserted a bunch of times, are they still tight? But agree with post above on checking continuity. You may have a broken trace causing no boot

#14 1 year ago
Quoted from Bax1:

If they’ve been inserted a bunch of times, are they still tight? But agree with post above on checking continuity. You may have a broken trace causing no boot

They are still nice and tight. I did some continuity checks last night and a good visual and I'm not confident that could be the problem but of course, you never know.

Does somebody have Chris's contact info?

#16 1 year ago

Well, I contacted Chris but he's a month or two out so before I make the dive, can anyone help me check for the initial sequence (blanking, reset, ect) and see what that tells us since it seems to be getting hung up real early.. I have a logic probe but not much understanding of the theory of operation, so I'm open to learning. Im also open to other repairmen even though Chris came highly recommended.

#17 1 year ago

I would go through Clays guide. Specifically about what to do when it does not boot.

#18 1 year ago

Could try Jerry Clause. He fixed up my RCT MPU real nice. Took about a month, that was a couple years ago. His email...

[email protected]

#19 1 year ago
Quoted from Tomass:

I would go through Clays guide. Specifically about what to do when it does not boot.

Thanks, I revisited the site and somehow missed the whole section on a dead CPU which is essentially what I'm dealing with. I found one issue chip, U51 pin 9 is giving a zero reading, while the other five 6821P chips are all good. I will update with how this turns out.

#20 1 year ago

Just wanted to update this as resolved. The issue ended up being a bad 7404 at U36.

Chris

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