because the bad resistor was directly connected to the SG3525 I also replaced it. I looked after the switched resistor but until now I couldn't find it. After putting everything together and testing again I'm left with one bad channel. That is the rear right channel. The front left and right are ok....

today I powerd up my M44 . When I power up, the red LED is working and after a few seconds the green LED is on (the red LED is out). It pulls no more than 3amps. 2 of the 4 channels are working. The left chanel of the front and rear section are working. The right chanel is making noise (sounds very ...

you can buy them here:
https://www.digikey.com/products/en?keywords=IRFZ44ZPBF

I'm not an expert, the experts are stil on holiday I think :( What I would do: - take out all the components that are not original ( the 4 white ressitors to start...) - take out the 4 IRFZ 44 and test them individual when they are out - take out the 6 PSU caps - take out other components that are l...

seems like a bad connection somewhere. Maybe a bad via.
this is a difficult one...

12v 18A power supply is ok for testing.
if the amp uses more than 3 amps idle than something is wrong.
is the red LED also lighting up?

pictures of the board?
maybe the amp pulls to many current so you have a voltage drop.
Can you measure how many amps it uses? What is your power source?

it sold for 630USD

is this a prototype? https://www.ebay.co.uk/itm/Phoenix-Gold-Car-Truck-Amp-Old-School-POWER-GRID-T/192622442741?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D53530%26meid%3D5ff5443d12bf4920a1630962dd74b7ac%26pid%3D100033%26rk%3D3%26rkt%3D8%26mehot%3Dpp%26sd%3D132632511919%26itm%3D1926224...

it's a two-layer board

take a look at this link:

http://www.phoenixphorum.com/viewtopic.php?f=6&t=11910

you also need to change the rail caps...

Hello
the power supply fets (IRFZ44) and the 2 diode (SF163) are not bolted to the heatsink. If you didn't take out the screws yourself look no further...

Thanks Jason for the info. I've put 4 new gate resistors en 4 new irfz's in, now the power supply works! The BJT's I need to order. Do you think that the resistors are switched during the production of this amp? Could this be the reason that this amp failed? Damn! than I need to find the other one...

did some researche

Sanken 2SA1695
Toshiba 2SA1941

Are these OK? Which are the best?
when using these, are there other components to be changed?

this is the one that is shorted...

there is also an output problem...

there are 4 x A1265 transistors and 4 x C3182 transistors, one A1265 is shorted. What is a good replacement for these?
is it OK to use two different complemantery transistors? Looks like this amp had no repairs before.

Hello everybody for the moment i'm repairing a M44 amp. It has blown powersupply fets and other issues. There are 4 IRFZ44 fets with their gate resistors of 100 Ohm. If you look closely you can see that there are only 3 resistors of 100 Ohm the most left one measures 51 Ohm. Is this normal? (it look...

This is the moment when all the hard work pays off.
This is so damn beautiful.

It’s also thanks to you Eric and a lot of other phorum members (like Jason,Bertje…) that I was able to do this project. It’s a pity that this forum is low on new posts now. My next project will be the restauration of a Cyclone that has been in the closet for +10 years...

Thank you Sir but this is nothing compared to your MS1000 project…

Finally find the time to finish this project.
This amp works like new. The M100 section is very powerful.
It took many hours and parts to finish but I'm glad that I saved this great amp.

Q21: NPN transistor 120V 0.05A 3PIN SPT

Digikey part: 2SC2389STPS-ND

Q20: PNP transistor 120V 0.05A SPT3

Digikey Part: 2SA1038STPS-ND

Mouser part number: 522-ZTX749

Hi Virtue Q34 & Q35: the part has the mark "ZTX749" on it. Maybe other ZPA's have other parts? its a PNP transistor 25V -2A TO-92 link: http://datasheetz.com/data/Discrete%20Semiconductor%20Products/Transistors%20(BJT)%20-%20Single/ZTX749-datasheetz.html are you sure that these are bro...