PVX-P Service Manual

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dhughes
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PVX-P Service Manual

Post by dhughes » Mon Jan 24, 2022 2:08 pm

Hello Fellow Peavey fans. Does anyone know where I can get a service manual for a PVX-P15? It has the 330v but no +,- 39v or +,- 15v. There is no AC at all on T1. Chris at Cust Svc sent me a schematic for the electronics and I've traced a potential problem to pin 1 of U2. From the 330v feed to the series resistors, there is an appropriate drop on R28, R2, R24, but the output of R20 feeding pin 1 of U2 is 0v, so I'm guessing something is shorted, to pull the voltage down to 0v. The schematic only gives voltage readings at the 330v, 39, and 15v.
If any of you knowledgeable people have any pointers for me, I would certainly appreciate your help. This speaker belongs to a small church, so I'm trying to fix it on the cheap.
Dave Hughes

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Enzo
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Re: PVX-P Service Manual

Post by Enzo » Tue Jan 25, 2022 8:01 pm

I don't have the schematic, so please post it so we can share. And we can tell you how it works.

300v? In a speaker? I suspect you have an SMPS power supply in there. They are VERY dangerous to work on. The primary side directly rectifies and filters the mains, giving oyu that 300vDC. But the whole point of a switcher is that it switches at very high frequency, like 50kHz or 100kHz or more. Your meter will never detect that.

If a switcher won't run, the first thing I look for is a excess load, like a shorted output on the power amp would provide. Otherwise I check the secondary side rectifiers for shorts.

Beyond that I need the diagram. I have no idea at this point where U1, R20 etc might be.

dhughes
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Re: PVX-P Service Manual

Post by dhughes » Tue Jan 25, 2022 10:13 pm

Enzo; Thanks for the reply. I posted (hopefully) the schematic (PVXp_Power_Supply.pdf) that Chris sent me. he said that was the only schematic he had for it. Let me know if the schematic doesn't post.
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PVXp_Power_Supply.pdf
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Enzo
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Re: PVX-P Service Manual

Post by Enzo » Thu Jan 27, 2022 12:52 am

All I see there is a parts list.

dhughes
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Re: PVX-P Service Manual

Post by dhughes » Thu Jan 27, 2022 12:52 pm

Sorry, here's the right one. Should have the schematic, pc brd and parts list.
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PVXp_Power_Supply.pdf
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Enzo
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Re: PVX-P Service Manual

Post by Enzo » Thu Jan 27, 2022 5:53 pm

There, that's better.

Note the bottom end of that 300v is SGND (star ground) Nore further that SGND is NOT NOT NOT earth ground, In fact it is something like -170v to earth. SO if you clip your scope ground clip to that SGND, it will cause damage. We always use an isolation transformer to service these things.

That string of resistors from the 300v down to U2 is the starting voltage. Nore D15 makes that 15v across U2.

dhughes
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Re: PVX-P Service Manual

Post by dhughes » Thu Jan 27, 2022 8:42 pm

Thanks Enzo. The reading I am getting at U2 pin 1 is 0v (to star gnd), where I believe it sb about 15v, set by D15.
I'm thinking some component is shorted, bring the voltage to 0. Do you think I'm on the right track there? The way the boards are stacked I can't get to the components without removing the top pc brd. I appreciate your help! I'm not using a scope yet, just a vom. I'm glad you reminded me about star ground not being earth.
Dave

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Enzo
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Re: PVX-P Service Manual

Post by Enzo » Fri Jan 28, 2022 4:08 am

Well, is D15 shorted? You have the four series resistors 30.1k if I recall? (I don't have the schematic open at the moment.) Is one of them open? Or with power removed and the main filters discharged of their 300v, is there (Oh foo, I opened it anyway, yes 30.1k) 120k betwen pin 1 of the IC and the +330v point? Of course C16 could be shorted instead, or even U2 itself.

You have zero volts there? OK, did you measure resistance to find out if it is shorted or if there is simply no voltage reaching the point.

dhughes
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Re: PVX-P Service Manual

Post by dhughes » Fri Jan 28, 2022 6:46 am

I haven't had a chance the last few days to get to the board to check some of those things. I can see that the series resistors are not open. I should know more soon as I can get the top pc brd off. I'll let you know. Thanks.

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Re: PVX-P Service Manual

Post by dhughes » Sun Jan 30, 2022 10:32 pm

Enzo, I found D15 is shorted. Thanks for your help.

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Re: PVX-P Service Manual

Post by dhughes » Sat Feb 05, 2022 8:50 pm

I had to give up on getting parts from Peavey. Left message after message after message- never got a reply. I found the parts at Amazon- hope they work alright.

soundchaser
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Re: PVX-P Service Manual

Post by soundchaser » Mon Mar 20, 2023 1:46 am

Greetings.
You wouldn't have schematics for the power amp interconnect circuit board for this device or know where I can get it, would you?
The schematic you shared for the PS board is all I've seen so far.
Thanks in advance for any help.

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