(Topic ID: 98163)

TECH HELP: made a dumbass mistake, now no sound from backbox speakers in No Fear

By cosmokramer

9 years ago


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#1 9 years ago

Yes, I am a dumbass....when I was installing a new dmd display in my NF I pinched the two wires for the backbox speakers in between the ground wire for the display where it connects to the bolt that holds the display in place...now I have no sound from the backbox speakers (cab speaker is ok)... I repaired the wires and checked the fuses but still no sound, just a very low crackle sound... any ideas where to troubleshoot?

#2 9 years ago

Audio board, likely something damaged on it.

LTG : )™

#3 9 years ago

Assuming you checked continuity of wires from board to speaker.

LTG : )™

#4 9 years ago
Quoted from cosmokramer:

Yes, I am a dumbass....when I was installing a new dmd display in my NF I pinched the two wires for the backbox speakers in between the ground wire for the display where it connects to the bolt that holds the display in place...now I have no sound from the backbox speakers (cab speaker is ok)... I repaired the wires and checked the fuses but still no sound, just a very low crackle sound... any ideas where to troubleshoot?

likely took out the TDA2030A amp chip. It's the 5 legged transistor looking think on the large heat sink. (after checking continuity in the wire like Lloyd suggested)

#5 9 years ago

Happens to the best of us. Just goes to show double check when done. We have all gotten the whoops did I just do that!!!!!!!! feeling at one time or another....No worries..all part of the pinball experience.
Sounds like you shorted the amp chip out for the BB speakers. Looks like a transistor...well.. kind of. Easy to replace and it should fix the problem. Obviously check all upstream components and down stream components with your eyes and a dmm where possible but that chip is usually the thing to go in this case when it gets shorted out. Of course after checking wires first with said dmm.

#7 9 years ago

continuity checks out ok from board to speakers...visually the board components all look ok including the TDA2030A amp chip...can I test that amp chip or is it most likely fried under these circumstances and should just be replaced? Thanks

#8 9 years ago

you can sometimes verify the short in the amp. Meter out all 5 pins to each other. None of them should be a dead short. If you find one the amp is toast.

#9 9 years ago

ok...I found a dead short in one of the amp chips...luckily a electrical parts house near me had one, It was 3 times the cost as the ones online but without having to pay for shipping and waiting a week it was worth it...I will try to find time today to solder new one on and report back...thanks for all the replies

#10 9 years ago

Good luck!

#11 9 years ago

well new amp chip was soldered in and..........still no backbox sound...continuity is ok, speakers are ok...where do I go from here?

how hard would it be to swap sound board out of my Shadow to test? not sure how many chips I would need to swap in the board?

#12 9 years ago

Check the resistors around the amp for that circuit. Sometimes one will burn with the amp.

#13 9 years ago

I will check it out later today....thanks

#14 9 years ago

A huge thank you to everybody who helped me with this problem. I now have back box speakers working great! Turns out I did a bad job when I soldered the amp chip in...as I was checking resistors as suggested I decided to re solder the amp chip and now all is good. Thanks again for your help!

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