Blowing Up a TM3030

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sqiddly diddly
Learning to Wiggle
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Joined: Thu Sep 03, 2009 3:10 am

Blowing Up a TM3030

Post by sqiddly diddly » Wed Sep 09, 2009 1:07 am

I just finished making a TM3030, then ran 48v, instead of 24 into it.
Midi and LEDs work, but it isn't passing any sound.

I've gone through the schematic and measured all the voltages. There a few places where it drops to 0v or very low. I checked for solder bridges and that it wasn't being shorted to earth. Then I replaced a few transistors, electrolytic capacitors and ICs that were either side of the 0v readings. However, no change in the readings.

Any suggestions as to compoents that are likely to be damaged by 48v?

Maybe no components are damaged and I've just got some bad solder joints.

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Synthbuilder
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Post by Synthbuilder » Thu Sep 10, 2009 5:43 am

48V is a lot. And it can do quite a lot of damage. However, there are several protection resistors in there that should prevent any major harm from happening.

However, you will need to check U10 and C16. Although, I bet they're probably OK.

Check the voltage at pin 8 of U13. It should be around 15V.
Check the voltage at pin 7 of U13. It should be around 12V.
Check the voltage at pin 1 of U13. It should be around 5V.
Check the voltage at pin 1 of U3. It should be 5V.

All voltages should be measured with respect to ground. ie. your black lead of your meter should be connected to blunt end of D6 or D7. By blunt end I mean the side of the diode without a white stripe.

If all is well with those voltage measurement then you probably have a problem with some wrong components somewhere. The other thing to look at is output socket wiring.

sqiddly diddly
Learning to Wiggle
Posts: 3
Joined: Thu Sep 03, 2009 3:10 am

Post by sqiddly diddly » Sat Sep 12, 2009 9:56 pm

thanks so much for the help.
yep, readings are all correct for those four pins of U13. good to know I haven't blown anything.
i've also triple cehcked the output wiring.

the quest continues.

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