Punch 60X2 RT SP distortion

Deadly Sones · 12:11 AM

Hello,

A friend gave me his OS punch 60x2 (trans-ana design)to look at... it appears that the right channel is severely distorted.

I tested the speaker - to the RCA shield ground of both... the left hand is 1K ohms and the right (bad) side is 20K ohms... not sure if that means anything, but I've looked over both sides of the amp and there are no lifted traces and no visible signs of damage.

It powers up fine, left channel sounds o.k. but right side has huge distortion... any ideas how I can go about troubleshooting this amp?

Thanks in advance,
Paul

p.s. I've read over Dr. Zues' thread about his punch problem... this seems to be different.

Deadly Sones · 14th March 2011, 12:28 AM

Should there be a .1 ohm resistor in location R236? I have one in R136, 163 and 263, but the one in R236 appears to be missing... not sure if that could be a problem... just something I noticed on the board...

Perry Babin · 14th March 2011, 04:47 AM

There should be one 0.1 ohm resistor for each output transistor.

If the resistor is missing and the legs aren't still in the solder pads, it likely got hot enough to desolder itself. If that's the case, make sure that you clamp all transistors tightly to the heatsink before applying power (after replacing the resistor).

Deadly Sones · 16th March 2011, 01:31 AM

Thanks Perry. I just got the resistor today, and sure enough it works perfectly with it installed... was really strange... almost like the resistor was never there... I guess it could have heated up and fell out many years ago.

Works great now!!!

On to the next project...

kuzhalevich · 21st March 2011, 03:55 AM

Hi.I got broken amp punch 60x2.Same like you got.If you kan tel me some information.I kant read numbers of the CR1 ,CR2,Q6,Q7.Please help me.

14th March 2011, 12:07 AM	#1
Deadly Sones diyAudio Member Join Date: Feb 2011 Location: Windsor, Ontario	Punch 60X2 RT SP distortion Hello, A friend gave me his OS punch 60x2 (trans-ana design)to look at... it appears that the right channel is severely distorted. I tested the speaker - to the RCA shield ground of both... the left hand is 1K ohms and the right (bad) side is 20K ohms... not sure if that means anything, but I've looked over both sides of the amp and there are no lifted traces and no visible signs of damage. It powers up fine, left channel sounds o.k. but right side has huge distortion... any ideas how I can go about troubleshooting this amp? Thanks in advance, Paul p.s. I've read over Dr. Zues' thread about his punch problem... this seems to be different. Last edited by Deadly Sones; 14th March 2011 at 12:11 AM.

14th March 2011, 04:47 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	There should be one 0.1 ohm resistor for each output transistor. If the resistor is missing and the legs aren't still in the solder pads, it likely got hot enough to desolder itself. If that's the case, make sure that you clamp all transistors tightly to the heatsink before applying power (after replacing the resistor). __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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14th March 2011, 12:28 AM	#2
Deadly Sones diyAudio Member Join Date: Feb 2011 Location: Windsor, Ontario	Should there be a .1 ohm resistor in location R236? I have one in R136, 163 and 263, but the one in R236 appears to be missing... not sure if that could be a problem... just something I noticed on the board...

16th March 2011, 01:31 AM	#4
Deadly Sones diyAudio Member Join Date: Feb 2011 Location: Windsor, Ontario	Thanks Perry. I just got the resistor today, and sure enough it works perfectly with it installed... was really strange... almost like the resistor was never there... I guess it could have heated up and fell out many years ago. Works great now!!! On to the next project...

21st March 2011, 03:55 AM	#5
kuzhalevich diyAudio Member Join Date: Mar 2011	Hi.I got broken amp punch 60x2.Same like you got.If you kan tel me some information.I kant read numbers of the CR1 ,CR2,Q6,Q7.Please help me.

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