[sdiy] TB-303 braindead

[Richie Burnett]

I would also suspect one or more broken PCB traces.  I had a TB-303 a few 
years ago that was displaying similar symptoms to yours: switches and LEDs 
not working or working intermittently.  It had developed cracks in three PCB 
traces that crossed a tiny hairline crack in one of the PCBs.  The only way 
that I knew which tracks to scrutinise was by working it out from the 
symptoms whilst looking at a schematic.  But look closely around where the 
plastic PCB supports are, because that's where the force gets transmitted to 
the PCB if a previous owner has dropped it or something heavy has struck the 
front panel, etc.  Those cheap phenolic boards are very prone to cracking 
because they don't have the internal glass-fibre weave that gives strength 
to proper FR-4 PCBs.

-Richie,


-----Original Message----- 
From: cheater00 .
Sent: Wednesday, June 17, 2015 9:42 AM
To: Robin Whittle ; synth-diy ; Analogue Heaven
Subject: [sdiy] TB-303 braindead

Hi guys,
upon replacing the battery wire which broke off in my TB-303, I have
found it to be relatively braindead. It will play some sorta random
patterns when in either song or pattern write mode - which it starts
doing right when turned on. The pattern buttons sometimes change the
pattern, but you can press the same button a few times to get a
different one. A/B obviously doesn't do the right thing either but
changes the pattern as well. Nearly all LEDs are lit up but some are
much brighter. When in either play mode, the same LEDs are on but
pressing the start button turns them off. You can't get it to play
patterns this way. I was wondering if anyone knew what might be wrong
with it.

Cheers
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