Recondition m50 & fan mod

[BrianUK]

Now finished the case,added a fan as had problems with 4 transistors
Near the bias pots getting hot ,tested all the components as best i could
Just can't find anything wrong,i have set the bias but still they get hot
With the fan on the amp runs for hours and sounds very good
This also keeps the resistors cool and probably help the heat sink as well
Any way it's all a bit of fun

see pics

sorry for the bad pics

[trickyricky]

Hmm I know there is one resistor (large, 5watt) that gets pretty hot but that's normal. The ones your referring to are the pre-drivers (not sure what stage, since its a triple darlington design). How much amperage is it pulling during idle (no load or signal)?


Please tell me you have already replaced the leaky caps labeled "HFZ". Otherwise that would be highly suggested. No matter if they look like they're not leaking...they are and am willing to bet a 6 pack.

[BrianUK]

Hi yes replaced caps I put x4 back in I know you don't need to but I had 4 new ones ,also changed all output trasistors and fets , blown risistors ones with black band at end I am sure these are fuse type, x4 10ohm resistors behind fets, 330ohm upgrade 5 watts resistors ,also had problems with remote turn on input this was n24401 transistor next to the led power lights,so after changing all these parts the amp is now working and sound very good running through my focal speakers, I did try to set the bias both sides were giving out about
18mA but this did not change when turning the pots,it's not the X4 transistors next to the pots that get hot but the 4 below the ones in a row,if you can help that would be fantastic
Thanks

Brian