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Lets get Technical > All Things Tube All about preamp and power amp Tubes.

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Author Topic: New Member - just got an old MP-1 - no sound - it does turn on  (Read 787 times)

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Hi Everybody

I'm Italian and I live in London, UK.

I just received this old MP-1 I got on ebay. Before doing any upgrades or mods I wanted to just make it work.
It's a v1.38
I powered it with a variac at 113vac. The unit turns on and the display says "c xxx" with the numbers going up till 128 and then stops.
I plugged a guitar in the front input (line input jack broke off just by touching it, output A is also broken)
I am connecting outputB to a solid state power amp and a 4x12.
The tubes filaments light up. They are Groove tubes, I haven't pulled them out but i will test them on a tube tester ASAP.
no sound.
The volume knob on the front does nothing I can just hear a little bit of hiss and a slight hum. The transformer is humming slightly.

The controls on the front seem to work properly, I can edit settings, when I switch from DIST to CLEAN I still get no sound from the guitar.

I am waiting for a battery holder from ebay and in the meantime I bought a spare CR2032.

Where should I start first to get this working? Once it does I will proceed with the noise mods and transformer upgrade etc.

Thanks in advance.

EDIT: I forgot to mention that at the end of the sequence it displayed an 'err' message but I don't remember the number. The message did not happen at the second power up.
« Last Edit: Time Format by Overtone85 »


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Ok so dead battery will give C0 to 128 count and err 1,2,3, this is normal with a dead battery.
Also normal if you change voicing dist to cln the master volume resets to zero so you have to manually raise the master volume.

Maybe you could start with the factory presets, just push store then push bank and 1 at the same time, display will read "LP"
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