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Sigma 22+Dynalo reversed polarity accident.
Sigma 22+Dynalo reversed polarity accident.
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Old 21st July 2012, 12:17 PM   #1
RudeWolf is offline RudeWolf  Latvia
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Join Date: Feb 2012
Location: Riga
Default Sigma 22+Dynalo reversed polarity accident.

Today I finished my first big DIY project- Dynalo powered by a Sigma 22. While hastily troubleshooting a minor problem I accidentally wired the amp in reverse polarity. It didn't stay on for a long time (<6s) but still- it won't work and voltages for most points are all over the place.

Can someone please tell me what parts I should be expecting to replace? Both PCB's look intact and none of the electrolytic caps even went warm.
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Old 21st July 2012, 05:40 PM   #2
RudeWolf is offline RudeWolf  Latvia
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So, it seems that current sources and the input stage have survived (phew!), however the whole output stage is toast.
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Old 23rd July 2012, 06:58 AM   #3
gmphadte is offline gmphadte  India
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Join Date: Jul 2003
Location: Dona paula, Goa
Even if any transistors have survived, it is better u change all of them as u have wrongly biased.

Gajanan Phadte
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Old 23rd July 2012, 01:06 PM   #4
RudeWolf is offline RudeWolf  Latvia
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Today I'll swap out all of the output BJT's and see what happens. According to my measurements probably some of them have even survived but I'm too lazy to check which ones.
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