Help with 50w plexi kit.

Get support and show off your MetroAmp 50 Watt kit builds.

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micahnix1
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Help with 50w plexi kit.

Post by micahnix1 » Tue Jul 25, 2017 12:20 am

Need help troubleshooting my 50w kit from valvestorm. I got the board built and connected, and went to test voltages across my preamp tubes. I'm getting around 400v on pins 1, 6, and 8, and Nothing on pin 3 across all 3 sockets. The power tube sockets test fine except for pin 5, which reads about 5v. I've checked my board, all components and wires seem to be in the right place. I'm at a dead end here. Any suggestions would be greatly appreciated! :oops:

micahnix1
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Re: Help with 50w plexi kit.

Post by micahnix1 » Tue Jul 25, 2017 3:24 pm

*UPDATE*
Found a couple bad solder connections and all tube voltages are fixed except V3, which has the yellow wire jumped across pin 8 and 3. Both those pins should be reading around 35-40, but are reading about 160. Going to check the board one more time in that section. I powered up the amp to see if anything came through the speakers. It's pretty noisy, and doesn't have much volume at all. Going to check my grounds. Any ideas are greatly appreciated!

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neikeel
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Re: Help with 50w plexi kit.

Post by neikeel » Thu Jul 27, 2017 9:17 pm

Check you used 470R on the PI cathodes (common mistake is to use 470k which screws up the voltages in the PI and makes the amp put out little volume).
Neil

stratomite
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Re: Help with 50w plexi kit.

Post by stratomite » Thu Oct 19, 2017 2:00 am

Hi, Did you manage to resolve the issue. I have the same problem, V3 pin 3 and 8 reads 105 instead of around 35. checked the resister value 470R is correct.

Thanks

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neikeel
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Re: Help with 50w plexi kit.

Post by neikeel » Fri Oct 20, 2017 10:11 am

The answer is in another thread - he hadn't grounded the presence pot, so the PI had no ground reference.
Neil

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