I was having problems with the sound card blowing the F3 fuse (12 volts to regulator). (see this post: https://pinside.com/pinball/forum/topic/short-in-12-volt-but-where

So I replaced the sound card from another known working Trident - the fuse didn't blow but I have no sound. I checked the 5 volts and 12 volts test points on the card and they are good. I checked continuity from the J3 connector to the speaker and the volume pot and that seems good. Then I replaced the speaker and pot from the known working machine and still no sound.

What to look for next?

Thanks

Bob

This was the first time I didn't replace ALL the header pins when I worked on my MPU. I never had sound problems so I elected not to replace the 32 pin header at J5. I just finished replacing it. Tomorrow I'll check my work again and install the MPU. Hopefully this will solve my problem. I'll keep you posted.

Bob

I installed the MPU with the new J5 header pins. Still no sound. While checking my work I noticed most of the J5 connectors go to the U9 IC. Is it possible that the U9 could allow the MPU to boot but still be bad and not make the sound?

This sound crap is driving me crazy. I now have a known working speaker with volume pot, known working sound card with known working MPU to sound card cables and still no sound.

Please tell me where to look!

Thanks

Bob

I just change the MPU with a known working MPU and now I have sound. I think I have a new U9 and will change it on the non-working MPU.

It doesn't seem possible that the MPU would boot up if the U9 is not working. I thought that what the boot process was for.

Bob

Thanks Andrew,

I replaced the J5 header pins last night and that didn't fix it. The cables are the same used on the MPU with sound and the MPU with no sound. It's got to be something on the MPU and the CPU is the only thing I can see.

Bob

I replaced the U9 with a brand new (un-opened) CPU. Still no sound - The processor is scoring but I just don't get any sound. What else drives the sound on the MPU?

Thanks

Bob

Sorry I can't sleep thinking about this stupid sound problem.

Is it possible that the ROM's could be keeping my sound from working? I believe the ROM's are original.

Thanks

Bob

Thanks guys.

Andrew, you know I'm not very good with a logic probe but I'll give it a shot. Can this be done on the bench? I think I'll probe each of the J5 pins on both boards and compare the difference.

lb45, thanks for the techdose link. I got a lot of chores to do today but maybe I'll read it over tonight.

Thanks guys,

Bob

Thanks Andrew, That would be a much easier way for me. When I installed the headers pins (J5) I did trace most of the lines back to the CPU but I didn't have the schematic out. I got my chores done today (nice weather) so I'll trace the lines tomorrow.

Maybe I'll pull out the MPU and the sound board with the connector cables and trace from the CPU to the chips on the sound board. It'll take me some time but I'll post my results.

Thanks

Bob

My MPU schematic shows 32 pins on J5 - all being used except 29 (key). The schematic for the sound board shows only 18 pins being used on J1. I can't find pins 9, 11, 12, 14, 18-24, 28 or 30.

What am I missing?

Thanks

Bob

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I'm working on a list of all connections from the MPU to the sound board (SB100) - once complete I'll pull both boards and the cables and check everything on the bench.

I only have one 5101 (U8). The PIA's (U10 and U11) have the same numbers and logo but they look a little different. - see photo.

L_satan, I have changed all the crimp connectors and header pins except J5 (to the sound board). I just changed the J5 header a couple of days ago. I haven't changed the J5 crimp connectors because they seem to work OK with the other MPU board. I'll find out if they're bad when I bench test.

Bob

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Andrew don't feel bad - I am VERY embarrassed. I checked the first pin connection - it's supposed to go from SB - U4 pin 2 to MPU - U9 pin 26. - no continuity. Then I checked the next connection - supposed to go to U9 - pin 27 but I got a beep at pin 26 - Then the next one is also one pin off. Then I looked close at the connector. Instead of one 32 pin connector I have two 16 pin connectors. Then I noticed one pin sticking up between to two connectors. I moved the connector over one pin and put the boards back into the game and I have sound.

I apologize for all the trouble I have caused everyone for such a dumb mistake.

Now I can go back to fine out why the original sound card causes the F3 fuse to blow.

Thanks for everyone's help - Especially Andrew

Bob

Thanks for the tips. I thought about replacing the two connectors but I can't find a 32 pin connector - GPE only goes up to 28 pin.

I tried to make the connectors dummy proof by marking "left - up" and "right - up" but even that didn't keep this dummy from missing one pin.

Tonight I re-installed the original sound card. Everything else is the same (MPU, cables, etc.) When I turned it on I got one flash on the MPU then nothing. Tried it again and got nothing - the F3 (12 volt) fuse is blown. I pulled the sound board and gave it a very close inspection. The only thing I found was some minor corrosion (more like oxidation) on the back on the 32 pin connector header. I'll probably replace the header but I don't think that is the problem.

What components would cause the F3 fuse to blow?

Thanks

Bob

I’ve been studying the schematic for the sound board. It has 12 volts coming in at J2 pins 5 and 6. And 5 volts coming in at J1 pin 30. Because I got one flash on the MPU before the fuse blew, I don’t think the problem in on the 12 volt line. Seems to me if the 12 volt line was shorted then the fuse would blow before the MPU got a chance to flash.

Would a short on the 5 volt line cause the 12 volt fuse to blow? The 5 volts are made from the 12 volts at the regulator. I don’t see any fuse protection for the 5 volt line anywhere.

Thanks

Bob

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The capacitors look OK. Not leaking or puffed up.

I'm sure the problem is in the 5 volt line. Today I plugged in the 12 volt J2 connector and the J3 speaker connector and turned on the machine and it booted.

Then I connected the left plug of the J1 that has the 5 volt line. When I turned it on I got one flash and the fuse blew.

I have no idea what to look for or how to test it for a short.

Thanks

Bob

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Using my DMM I get a beep between TP1 (5 volts) to TP4 (ground). The schematic shows 5 volts supply for IC U1 thru U5. Is that the only place the 5 volts goes? I don't see anything else on the schematic that uses 5 volts.

I've looked over the board very close for any trace or solder connection that might be shorted but I didn't find anything that looks suspect. Could one of those IC's be shorted?

Thanks

Bob

Thanks for the idea Lionel. I used a PC power supply before and found it unreliable. I don't think the capacitors or zener diodes are my problem. I'm pretty sure I have a short in the 5 volt line somewhere. The only thing I can find powered by the 5 volt line are IC's U1 - U4. I guess I'll be changing them unless someone has another idea.

Thanks

Bob

I've traced out the 5 volt line that I think is shorted - see first photo. The red lines are the 5 volt - the broken red lines are the jumpers on the front of the board. Looks like the only things connected are U1 - U4 and C1 - C4.

Are any of those items subject to shorting out to ground?

Bob

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Thanks Lionel, I'll try that.

This isn't the board I was using when the connectors got mixed up. That board is working now.

Where is the regulator?

Can I cut the jumper wires on the component side to reduce the search area? The jumpers would be easy to replace.

Thanks

Bob

Thanks Lionel, I found the regulator - it looks OK but I don't know how to test it. And I don't think that's the problem because it's on the 12 volt side. My short seems to be on the 5 volts from the MPU.

I cut the jumpers as shown by the "X"'s in the photos. I still show a short between TP1 and TP4. (no short on the side after the cuts). Looks to me like a bad C1 or a bad U1.

Tomorrow I pull one leg of C1 and see if that's my problem, else it's U1.

Bob

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I pulled up one leg of C1 and my short went away. I removed it and tested it with my DMM and it beeps.

The schematic shows C1 as 4.7 mfd. GPE has "Capacitor, Radial Tantalum, 4.7uF, 16V" - is that the same?

Is mfd the same as uF?

Sometimes this electronics stuff is really strange.

Thanks

Bob

Wow, Thanks Andrew, I didn't know that - That would be C5. I'll check after dinner. It would be great to get it going tonight.

Thanks

Bob

I do have a C5. But which side is positive?

Thanks

Bob

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On these both legs are the same length. I do see a small + 25 on the right side.

I just don't need an explosion - that would ruin my day.

Thanks

Bob

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Quick update - sound card works and no explosion!

Last week when I was trying to diagnose the problem I had plugged in the speaker and volume control from the other machine. Once I had sound I plugged in the original speaker and volume control. No sound.

It's got to be a connection problem, bad speaker or bad pot. I can't believe I'm making a career out of this sound thing. I've had less problems getting the MPU to boot.

More work to do tonight.

Thanks for your help.

Bob

Andrew, I want to thank you for all your help and for sticking with me through all this. Together WE now have working sound. I don't know what I did but tonight I checked the continuity from the connector to the speaker and pot - it checked out fine. Then I turned it back on and it worked! I didn't fix anything and it worked. I even played a few games (old dried out rubbers and all) and it still worked.

I still have a few items that need work (stuck on feature light and a sling-shot don't work) but I really feel proud of myself for getting through this sound problem. I couldn't have done it without all your help.

Thanks

Bob

Hi cutlass,

If you read all the problems I had with my sound you know I'm not the "go to" guy to fix your sound card. I would suggest you contact Andrew (barakandl) - I'm sure he could fix it. Just remove the card and send it to him. You can still play the game while it's gone.

By the way I love your part of the country. When I grew up I had an aunt in Kenosha. I spent many summers there - just a few blocks from the lake.

Bob