No power to tube fan?

ATR1 · Apr 14, 2024

Hello,
Mark V 90w combo amp.
I noticed yesterday my fan stopped working cooling the tubes. Watched video on fan replacement. I ordered a fan. This morning removed the fan in question and tested with a 9v battery.
Fan was working fine?
Need help to troubleshoot why my fan stopped getting power?

Thx

rarebitusa · Apr 14, 2024

Is the fan switch off? If not, then perhaps check the fan leads from the unit for a voltage between 9-12vdc. If it's low then maybe there's a problem the 12v circuit which the fan voltage is tapped from. It's been a known issue on V:90s that the bridge rect diodes can fail.

ATR1 · Apr 14, 2024

Thx.
I have no lights on front of amp also. May have to send in to boogie.

rarebitusa · Apr 14, 2024

Well that a strong clue it's the low voltage diode issue. This is a typically a straightforward fix to replace the 4 bridge rect diodes.

If you can find one within driving distance. For this issue I'd think an authorized Mesa repair shop can take care of that for you.

Find a Mesa Repair Shop

ATR1 · Apr 15, 2024

Thank you my friend! I will search out a amp tech or send back to MB.

No power to tube fan?

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No power to tube fan?

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