Changing The M50

dBincognito · Post by **dBincognito** » Thu May 21, 2009 11:16 pm

This was sent to me not working....in protect mode, with no speaker terminal.....just look at her now....she is ready to go back home, someone should be happy.

freshkryp69 · Post by **freshkryp69** » Fri May 22, 2009 2:04 am

yup that was an easy fix,to my surprize nothing else blew,I found a power supply cap solder'd in with the polarity reversed..
I did the mod to the 4 resisters that are connected to the rec. diodes. I replaced them with some much bigger overall diameter resisters that Randy bo bandy got from digikey, and they now touch the heatsink and are raised high off the board touching the heatsink,I used some good thermal compound on the top of the resisters to help aid in dissipating the heat. the stock 10ohm resisters were burning the board..
did later model m50's fix that prob or do all the m50's suffer this?

dBincognito · Post by **dBincognito** » Fri May 22, 2009 6:02 am

freshkryp69

did later model m50's fix that prob or do all the m50's suffer this?

This is a series II M50, so my guess is yes they all share the same problem

Post by **Eric D** » Fri May 22, 2009 6:18 am

Why did you not put a cap in that fourth socket? PG left it out to save a buck, but more capacitance there would not hurt.

dBincognito · Post by **dBincognito** » Fri May 22, 2009 6:23 am

Eric D wrote:Why did you not put a cap in that fourth socket? PG left it out to save a buck, but more capacitance there would not hurt.

Just so I wouldn't have to deal with the pain of putting the heatsink back on.....it's a tight squeeze getting behind there with a cap there.....my original plan was to put 1 there.....but I was seeing a problem with putting the MOSFETS back on, and the limited amount of space if I put it there. So I voted against it. I don't think anything will ever happen to those rail caps

Post by **Eric D** » Fri May 22, 2009 7:02 am

You are right about getting to the MOSFET.

When the amp is totally finished, you could solder a cap in if you wanted too, with the idea you would never be taking it apart again.

freshkryp69 · Post by **freshkryp69** » Fri May 22, 2009 11:29 am

I would have put in the 4th cap after I bolted the heatsink onto the circuit board,but Bo-bandy only brought me 3 caps..

I can still do it but I think he has to send the amp back to the owner..

getting to some of those mosfet screws are a bitch,the heatsink was painted so I had to be carefull not to scratch it...other than that it was an easy fix..