Phase Linear Dual 500 ii Blows fuses right channel

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Mtnman009

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#1
Hello! New guy here on this forum but, have been enjoying the Vintage Audio Addiction for years...I am on the Audio Karma site but my research tells me for Phase linear issues this is the go to spot...


Well, I just added The Phase Linear Dual 500 ii power amp to my collection. Bought it un tested based on the power output and that it is quite rare...Plus, it looks crazy cool even though it's quite beat up.

So I brought it home and realized that it needed Four 10 amp AGX fuses so I couldn't test it right away but I cleaned it up and waited for my order to arrive. Finally a week later and I put the fuses in and and the left channel works great sounds clean, warm yet powerful!

Right channel keeps blowing the 10 amp fuses ( Thankfully I bought 20 fuses) but, there is still a slight music signal coming through the channel with static.

I know this unit has a ton of power so before I start poking around this unit I wanted to seek the advise and counsel of the forum...

Any help would be greatly appreciated!

Thank you!
 
laatsch55

laatsch55

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Halfbiass...Electron Herder and Backass Woof
#2
Sounds like you have a blown output. Is the positive or negative rail fuse blowing?
 
NavLinear

NavLinear

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You'll need a meter to test BJT transistors and something to replace the original Sil-Pads. These are the electrical isolator / heat transfer pads between the output transistors and the heat sink. The Sil-Pads are kind of like a condom - most of us would only use them once and it is prudent that they not be reused when reinstalling working/new transistors.
 
grapplesaw

grapplesaw

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You will have to loosen the large heat sink with the power transistors away from the side plates by revmoving the four screws on the side and both the top and bottom covers in order to remove the screens covering them , if they are even there they are help with some silicon at the ends so you will have to pull a little bit to slide them out sideways. Do not pull it to far apart but if you do the back wants to swings to transformer sides when undone. Pull the transistors on the side which has the problem and check each one with tester there are 18 on each side but two are different from the rest. Note these two and their proper location. Please post photos as you go so we can steer you along. There is a great wealth of information to help you between all the members.
 

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Mtnman009

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#9
Great info! Yes I have some skills and the power of the internet!!! lol...I am looking for a mentor and am not in any hurry with this project. I will be traveling for work over the next couple of weeks. But, once I get back I'll dig in to this project...

Stay tuned!

And thank you for the guidance!

Mtnman009
 
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