[crossroadazn]

Hi all. My friend has bought a used AN M2 preamp from A'gon and it's a lemon, first the right channel has a thump sound when turn on and lightly tap on the input selector switch and the balance didn't work. He sent the unit to local audio repair shop and they fixed the balance and the thump sound but now when turn on the right channel signal jumps wildly with the valume at zero ( it shows on the meter of my McIntosh amp ) and another problem is it picks up radio signal that I can hear when the valume turn on. He then returned to the shop and they said nothing's wrong with the unit and the same said when he sent it to another audio repair shop. Anyone has any idea what's wrong and know where he can send the unit for repair ? Greatly appreciated any input.

Cr.

[Bill Baker]

Hmmm, curious if this is a manufactured product or a kit design? There are a few things that could be going on here from a bad/cold solder joint to a tube going bad. I have built a few of the M2 units based on the kit design but haven't been inside a production M2 yet to become familiar with it's design.
 Where are you (your friend) located.

[crossroadazn]

This's a kit design and all the solder joints has been retouch up ( as repair shop ) and we're in Arizona. We'll try to change the 2 12AU7 tubes to see if it helps.
Thank you.
Cr.

[Bill Baker]

Take a look at the SS regulators and make sure they are not shorting out on the aluminum heat sink. There is a small plastic insulator (that the hold down screw goes through) that is all too often over tightened causing problems.

[jrebman]

Just for future reference, Nick Gowan in the bay area is the guy for AN amp repair (don't send digital to him though).

Bill,  the AN M2 and the audionotekits M2 share not a whole lot more than the designation in common.  As is the case for the rest of the kit lineup i.e. - the dac2.1x is not the same as the one from te factory.

This does not mean they aren't good -- in fact, there are a number of those pieces I'd really like to have myself (M3 phono for starters), but they are not necessarily the same as the components from the factory with the same designations.

-- Jim

[Bill Baker]

Bill,  the AN M2 and the audionotekits M2 share not a whole lot more than the designation in common.  As is the case for the rest of the kit lineup i.e. - the dac2.1x is not the same as the one from te factory.

 Yes, I realize this but as CR mentions,

This's a kit design 

his is a M2 kit. This is why I mentioned the regulators as I have experienced this myself.

 The kits can be exceptional for the dollar and I was once an AN dealer so have heard production pieces as well.

 A visit and searching at the AN Kits forum may also help you out.