PL700B buzzing with volume increase????

Turboj5525

Turboj5525

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Ok guys so here is a rookie question.... I have searched for 2 weeks for a simular question or thread to no avail.

I have a PL 700 that I installed the watts abundant speaker protection board in. Other than that it is all factory. It worked fine before the install. Now when I power everything up it sounds great until you increase the volume a bit (not crazy loud) and it starts buzzing through my speakers. It goes away if I kill the volume. Music is clear and sounds great and as you start to turn it up on the preamp it starts buzzing loud. It still pops when I power the Amp off as well. I installed new rca jacks when I put the board in. They are the brand everyone on here suggests in multiple post I read. I don't recall the brand offhand. I have both gains turned up although it does the same thing even if I run the gains at 1/2 or 3/4 as well.

I have changed rca cables. Speaker wires, used my pioneer spec 1 and also ran the Amp through my Marantz 2325. I have flipped the plug in the outlet, made sure the transformer bolts were tight. Made sure the conections on the main power caps were tight, inspected the boards for burned or over heated caps, transistors and the like. All of this has done nothing. Boards all look good. Someone at some point has replaced power transistors I beleive. I'm beyond stumped. Also of note I am no electronic whiz.

I don't know anyone in my area (Tulsa, Ok) who could repair or inspect it. I have basic tools including a multimeter, soldering iron ect. I also have the service manual but I struggle to read wiring schematics.

Any and all help would be greatly appreciated.
 
G

George S.

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Well, since it worked well before installing the DCP(Watts Abundant DC Protect Board), I have to assume there is a issue with your wiring. If wiring is correct, then temporarily remove the DCP, tack solder the speaker jack wires back on, tape off the two AC and one ground wires you installed and see if it still buzzes. If the process of elimination shows the DCP is bad(doubtful) Don will replace it.
Also post some good photos of the DCP, your 2 AC wire connections at the rectifier, the ground wire connection. Work carefully and methodically.
 

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George S.

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Also, you mentioned you replaced the RCA jacks(probably Switchcraft). These need to be insulated from chassis ground with the original or replacement fiber washers. Each jack requires two.
 
mlucitt

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Most of us have experienced "buzzing" AKA 60Hz hum. There are many causes, in addition to what George said above, the most common are:
1. Bad AC wire connection. Attaching the DCP AC sense wire on to the Bridge Rectifier transformer secondary connection can be tricky.
2. AC wire or wires routed too close to a audio signal wire. Sometimes you have to reroute (and reroute) to get the lowest noise levels.
3. Faulty ground. This is complicated, but there are some 'rules' that Phase Linear did not always follow: a) There should be a Single Termination At Reference (STAR) Ground, that means all proper grounds go to a single point; which is the bus bar between the main Power Supply capacitors.
b) the chassis should be signal grounded at only one point and a wire leads from that point to STAR Ground. c) The chassis Ground should have the paint or anodized coating removed to ensure good electrical contact. d) Input Grounds (shields) and Output Grounds should not be connected together. e) Original thermostatic switches and power switches can buzz, you can test this by installing a temporary insulated wire across each switch and see if the buzzing goes away (don't forget to remove these!). f) RCA jacks are joined together inside the amplifier and are grounded only at the connection to the control board. g) Finally, there are coincidences. You may now have a bad capacitor on your control board or a broken solder connection, it happens. The best way to solve those problems is to invest in a new White Oak Audio Rev G1 Control Board. If you are handy with wire cutters, wire strippers, and a soldering pencil; you can install this yourself. https://www.whiteoakaudio.com/estore.aspx
 
Gepetto

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You have created a ground loop with the work you have done. Take and post pictures on this site, in particular around the new RCA jacks. Did you retain the isolation from the chassis for the RCA jacks?
 
Gepetto

Gepetto

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Turboj5525 said:
Ok guys so here is a rookie question.... I have searched for 2 weeks for a simular question or thread to no avail.

I have a PL 700 that I installed the watts abundant speaker protection board in. Other than that it is all factory. It worked fine before the install. Now when I power everything up it sounds great until you increase the volume a bit (not crazy loud) and it starts buzzing through my speakers. It goes away if I kill the volume. Music is clear and sounds great and as you start to turn it up on the preamp it starts buzzing loud. It still pops when I power the Amp off as well. I installed new rca jacks when I put the board in. They are the brand everyone on here suggests in multiple post I read. I don't recall the brand offhand. I have both gains turned up although it does the same thing even if I run the gains at 1/2 or 3/4 as well.

I have changed rca cables. Speaker wires, used my pioneer spec 1 and also ran the Amp through my Marantz 2325. I have flipped the plug in the outlet, made sure the transformer bolts were tight. Made sure the conections on the main power caps were tight, inspected the boards for burned or over heated caps, transistors and the like. All of this has done nothing. Boards all look good. Someone at some point has replaced power transistors I beleive. I'm beyond stumped. Also of note I am no electronic whiz.

I don't know anyone in my area (Tulsa, Ok) who could repair or inspect it. I have basic tools including a multimeter, soldering iron ect. I also have the service manual but I struggle to read wiring schematics.

Any and all help would be greatly appreciated.
Click to expand...
If you have the DCP installed properly, there should be no popping in the speakers during turn off. Seems you have something amiss
 
Turboj5525

Turboj5525

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Thank you guys. Ok I will take pics tonight and post them and also perform the suggestions. I checked the instructions multiple times and I beleive it is installed correctly. And yes I beleive they are switchcraft. Thank you to everyone for the suggestions. I also did retain the isolators on the rcas but maybe something is worn or touching they were old. I will have a look at this as well. The relays do click when I power the Amp up.

Also I do want to do the Whiteoak upgrades. What is a good order to go in if I wanted to do this in stages? I would like to eventually do all of them. Backplanes, power transistors. Control board and power caps as well. I beleive that covers everything except the led mod correct?
 
MusicSteve

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Turboj5525 said:
Thank you guys. Ok I will take pics tonight and post them and also perform the suggestions. I checked the instructions multiple times and I beleive it is installed correctly. And yes I beleive they are switchcraft. Thank you to everyone for the suggestions. I also did retain the isolators on the rcas but maybe something is worn or touching they were old. I will have a look at this as well. The relays do click when I power the Amp up.

Also I do want to do the Whiteoak upgrades. What is a good order to go in if I wanted to do this in stages? I would like to eventually do all of them. Backplanes, power transistors. Control board and power caps as well. I beleive that covers everything except the led mod correct?
Click to expand...
Post a Pic of the Speaker Protection Board first Than we will know which one you have.
Also check to make sure the cut ground wire is hooked up to the RCA copper plate and goes back to the 0vdc Capacitor Copper buss Plate
 
mlucitt

mlucitt

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Turboj5525 said:
Also I do want to do the Whiteoak upgrades. What is a good order to go in if I wanted to do this in stages? I would like to eventually do all of them. Backplanes, power transistors. Control board and power caps as well. I beleive that covers everything except the led mod correct?
Click to expand...
Power caps first, the basic upgrade. Control Board next, big improvement. The finale are the backplanes and new output transistors, then stand back!
 
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