Memphis 16-ST1000D

Dr Zeus · 2nd April 2011, 03:33 AM

I've worked on a few of this series already, but this one is the worst. I'm not even close to done digging through but here the starting hit-list:

All IRFZ44 fets are bad. 22 ohm gate resistors are good.

All outputs are bad IRF640/9640

IRF640s are in Q215, Q216, Q225, and Q226.

I'll be placing one of each bank of transistors at a time for evaluation and function and will report back what I find.

Dr Zeus · 2nd April 2011, 05:05 AM

Found Q15 and Q16 drivers on the PS driver board out of spec. A1266 transistors. Amp now holds +-60vDC at the rail with the outputs out of circuit.

I'll work on this little guy some more tomorrow. peace!

amc32 · 2nd April 2011, 12:32 PM

I personally love working on these little amps. PS and Output Driver Cards unplug I have tons of rebuildable cards. The key is to keep a functioning amplifier on hand makes troubleshooting much easier. If you need rebuildable cards or photos let me know. Forget the IRFZ44's and go with the IRF3205's or it will be back again as soon as the customer gets drunk one night.

Dr Zeus · 3rd April 2011, 03:26 PM

What originally came in this amp? I could barely see the identification marking on the PS Fets and could only barely make out IRFZ44. This amp is running with 22ohm gate resistors for the PS fets.

Perry Babin · 3rd April 2011, 03:45 PM

As far back as the board revision PAM280-09, the 3205s were the original parts.

Dr Zeus · 3rd April 2011, 03:47 PM

Hmm so the IRFZ44s are likely not going to work if 3205s were original. I wonder why this amp had them in here? Or perhaps they were IRFZ48s - I cannot tell because all the fets were distroyed.

Dr Zeus · 3rd April 2011, 03:52 PM

In powering up this amp with several IRF640/9640s installed (And IRFZ44s), the new IRF9640s get hot within seconds. Pulled both driver boards and they stay cool. I've narrowed the drive circuit i nthe following photo where you can see the lead is attached, and the trace<s> are leading to the three drivers on the top right corner of the board.

-From Left to Right last three on the right-
Q201: C3503-D
Q202: A1027
Q203: A1023

Perry Babin · 3rd April 2011, 04:01 PM

Is there any DC on the tabs of the outputs with no driver boards installed?

Dr Zeus · 3rd April 2011, 04:10 PM

Yes as follows:

IRF9640s have +64vDC on pads 1 & 3, and 0vDC on pad 2.
IRF640s have -64vDC on pads 1 & 3, and 0vDC on pad 2.

Perry Babin · 3rd April 2011, 04:12 PM

Tab = top of the transistor.

It appears that you have none.

The PNP drivers, the 1 ohm resistors and the 12v zeners are all suspect.

2nd April 2011, 03:33 AM	#1
Dr Zeus diyAudio Member Join Date: Oct 2010	Memphis 16-ST1000D I've worked on a few of this series already, but this one is the worst. I'm not even close to done digging through but here the starting hit-list: All IRFZ44 fets are bad. 22 ohm gate resistors are good. All outputs are bad IRF640/9640 IRF640s are in Q215, Q216, Q225, and Q226. I'll be placing one of each bank of transistors at a time for evaluation and function and will report back what I find.

2nd April 2011, 12:32 PM	#3
amc32 diyAudio Member Join Date: Mar 2008	I personally love working on these little amps. PS and Output Driver Cards unplug I have tons of rebuildable cards. The key is to keep a functioning amplifier on hand makes troubleshooting much easier. If you need rebuildable cards or photos let me know. Forget the IRFZ44's and go with the IRF3205's or it will be back again as soon as the customer gets drunk one night. __________________ ...............I Hear in color.................

3rd April 2011, 03:45 PM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	As far back as the board revision PAM280-09, the 3205s were the original parts. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

3rd April 2011, 04:01 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Is there any DC on the tabs of the outputs with no driver boards installed? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

3rd April 2011, 04:12 PM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Tab = top of the transistor. It appears that you have none. The PNP drivers, the 1 ohm resistors and the 12v zeners are all suspect. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links


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2nd April 2011, 05:05 AM	#2
Dr Zeus diyAudio Member Join Date: Oct 2010	Found Q15 and Q16 drivers on the PS driver board out of spec. A1266 transistors. Amp now holds +-60vDC at the rail with the outputs out of circuit. I'll work on this little guy some more tomorrow. peace!

3rd April 2011, 03:26 PM	#4
Dr Zeus diyAudio Member Join Date: Oct 2010	What originally came in this amp? I could barely see the identification marking on the PS Fets and could only barely make out IRFZ44. This amp is running with 22ohm gate resistors for the PS fets.

3rd April 2011, 03:47 PM	#6
Dr Zeus diyAudio Member Join Date: Oct 2010	Hmm so the IRFZ44s are likely not going to work if 3205s were original. I wonder why this amp had them in here? Or perhaps they were IRFZ48s - I cannot tell because all the fets were distroyed.

3rd April 2011, 03:52 PM	#7
Dr Zeus diyAudio Member Join Date: Oct 2010	In powering up this amp with several IRF640/9640s installed (And IRFZ44s), the new IRF9640s get hot within seconds. Pulled both driver boards and they stay cool. I've narrowed the drive circuit i nthe following photo where you can see the lead is attached, and the trace<s> are leading to the three drivers on the top right corner of the board. -From Left to Right last three on the right- Q201: C3503-D Q202: A1027 Q203: A1023

3rd April 2011, 04:10 PM	#9
Dr Zeus diyAudio Member Join Date: Oct 2010	Yes as follows: IRF9640s have +64vDC on pads 1 & 3, and 0vDC on pad 2. IRF640s have -64vDC on pads 1 & 3, and 0vDC on pad 2.

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