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braxR1 26th May 2012 02:22 AM

memphis 16-ST1500d protection mode
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 26th May 2012 03:19 AM

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

timwebb 26th May 2012 03:20 AM

Basic Amplifier Repair - Transistor Test Applet Link

Perry Babin 26th May 2012 05:34 AM

What was the problem before you installed the FETs?

braxR1 26th May 2012 03:39 PM

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

braxR1 26th May 2012 03:40 PM

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

braxR1 27th May 2012 12:29 AM

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


braxR1 27th May 2012 01:52 AM

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 27th May 2012 02:48 AM

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 27th May 2012 02:53 AM

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..


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