XR-8600 Schematics needed (Mosfet)

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K-B
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XR-8600 Schematics needed (Mosfet)

Post by K-B » Sun Jun 27, 2021 6:38 am

Hey Enzo, Finally getting back into some repair after CV setback. This amp is getting hot and shutting off. Think R1 the temp sensor is getting extremely hot. Fan turns on for a split second then goes off. I found the bi-polar schemo but not Mosfet. Tried contacting Roger through email but got no response is he still the man ?

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Enzo
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Re: XR-8600 Schematics needed (Mosfet)

Post by Enzo » Sun Jun 27, 2021 10:08 am

Read his recent response in the parts department thread. Roger is your guy, there aren't many other guys there any more.

And I do not have that drawing file myself.

K-B
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Re: XR-8600 Schematics needed (Mosfet)

Post by K-B » Sun Jun 27, 2021 10:26 am

Thanks Enzo , I found 4 shorted diodes along that string but doubt they are all shorted likely just one if that. I'll see if I can get Roger tomorrow.

KB

rockbobmel
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Re: XR-8600 Schematics needed (Mosfet)

Post by rockbobmel » Mon Jun 28, 2021 8:55 am

K-B wrote:
Sun Jun 27, 2021 6:38 am
Hey Enzo, Finally getting back into some repair after CV setback. This amp is getting hot and shutting off. Think R1 the temp sensor is getting extremely hot. Fan turns on for a split second then goes off. I found the bi-polar schemo but not Mosfet. Tried contacting Roger through email but got no response is he still the man ?
I am experiencing a similar situation. I had to cool the back with an external fan. I could smell burnt but the amp comes back after cooled.

K-B
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Re: XR-8600 Schematics needed (Mosfet)

Post by K-B » Mon Jun 28, 2021 5:51 pm

Yeah this one too. What you are smelling is R-1 the thermistor or heat sensor getting hot. When it get to a certain temp it shuts down the HV to keep from frying it. aka overload protection. I'm trying to wing it but sure wish Roger would come through with schematics for MOSFET.I've called several times ,left voicemail and messages and no go. Thinking it's similar to the Bi Polar but some differences. This is an H class and uses High voltages of +/- 90vdc and +/- 40 vdc for the low side. I 'll stay on it without the schemo and post what I find.

K-B
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Re: XR-8600 Schematics needed (Mosfet)

Post by K-B » Sun Jul 04, 2021 11:28 am

So here is the correct schematic for this amp and I have to figure out why R1 4.7k 7 watter is getting so hot. My guess is that the bias may be off causing both sides to run at the same time with not enough cut-off, In other words too much current. This resistors see's 330 volts which is not a problem but the current could be so 330 x..021 ma is around 6.93 watts so it must be getting more than that to make it get that hot that it trips the relay off.
Peavey Forum.pdf
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Last edited by K-B on Mon Jul 05, 2021 6:15 am, edited 2 times in total.

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Enzo
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Re: XR-8600 Schematics needed (Mosfet)

Post by Enzo » Sun Jul 04, 2021 8:57 pm

Where in this sea of parts is R1?

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Re: XR-8600 Schematics needed (Mosfet)

Post by K-B » Mon Jul 05, 2021 6:20 am

Sorry Enzo I have so many XR pdf's I downloaded the wrong one. This one on page 2 of 14 at the 2nd block in middle of the page at the top you will see Q5 Mosfet and right above it is R1.

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