memphis 16-ST1500d protection mode

[braxR1]

hey guys, picked up a dead 16-ST1500d in protection mode from a guy that said he had it looked at but not repaired, i cracked it open and noticed the two missing mosfet n fet's, ordered two thinking the shop removed them and soldered em in but the amp just flashes the green led and yellow protection stays on,

if anyone can point me in the right direction of what to check first or what to remove, check driver boards? certain areas for voltage? i know my way around a solder gun and a multi meter really well, just new to troubleshooting circuits

thanks guys for any help,

 

[timwebb]

u check the mos fets in the power supply for a short? also pull the driver card and test the output transistors

 

[timwebb]

Basic Amplifier Repair - Transistor Test Applet Link

 

[Perry Babin]

What was the problem before you installed the FETs?

 

[braxR1]

hey thanks ill try and give those a shot anr report back, i bought the amp in protection mode... never worked for me..

 

[braxR1]

so i need to de-solder each transistor to check with meter? correct?

 

[braxR1]

k got some pics, i was not sure which driver card to pull, theres one "capacitor"? that looks melted... other than that theres no other visual bad circuit board connections..

after reading the forums i have realized i need to run lower amp fuses...

oh and i thought the yellow light was flickering, but theres no green led lit just the red protection light..
thanks for any advice

[/IMG]

 

[braxR1]

so obviously after searching the web the blue box is in fact a blown cap, "i never knew caps came in square boxes" just seen the round ones, so i guess ill solder in a new one, should i remove the two factory FET's i soldered in? and also should i test for anything else the blown cap could of effected? thanks guys...

also will any cap with the same rating work if even not the same style?

 

[timwebb]

i think for that u might be able to find one close to it. i think u might be able to use a non polar cap but im not 100% on that.i think that is there to filter the noise out. it is best to go and replace all of the fets in the power supply with new ones and the drive transistors with them. they should a1266.

 

[braxR1]

cool, yeah i see no sign of polarity on the melted cap i removed. so you think the damaged cap could of also caused FET failure? sorry im still reading the forums and gaining knowledge

i guess i need to remove the board and check all the FET's for dead short still surface mounted.. ? as far as the drive transistors, are they in the strip mounted with the cooling pads like the FET's? thanks for the help!

would it be bad to just slap a cap in and bench test it?

as far as the two missing FET's prior to me buying the amp, i read on two other forums of them being removed from the factory for some reason, so i guess they were suppose to not be there..

THANKS! 🙂

 

[braxR1]

oh and would it be bad to just use a jump wire in place of the melted cap to bench test if all it does it just filter out noise?

 

[timwebb]

im sure something would explode. its well over 100v going across that part.

 

[braxR1]

good call! ill just wait till mon - tue and drop the $2-3 and report back 😉

 

[braxR1]

well went to my one and only local wholesale electronics supply and they have nothing close.. anyone have a spare or know where i can order one of these 225k250v caps from? thanks

 

[braxR1]

well bench tested with a smaller rating cap and it made absolutely no difference with the cap in or out... still same protection mode, flashing the green led ever 5 secs or so, is anyone interested in repairing this amp for me thats reasonable? thanks