PL700 Series 2 NO bias adjust ?? both channels

So after finding and replacing a bad power transistor on the right channel as I look at it I replaced all the fuses now good to go . I do have proper bias adjust on left channel but still nothing on right channel. Noted voltage across Bias adjust pot on working side was .152 VDC. But on non working side is . 695 VDC …?155D168E-A001-489D-BED9-44834AC0D742.jpeg
 
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Also check the 10 ohm resistor on the back plain. This pesky problem has lead many astray
 
hmmmm !!!?? Looks like the carbon has delaminated from the pot ??AB15EB36-9203-4B2B-B85C-A1BE8A24A1CC.jpeg
 
Measures 350 M ohm across the pot in the board compared to the good side at 210 ohms
 
Checked Bias transistors both with heat gun and are reacting so seems closer to operating Id like to make it function before I tear it apart and do the WOPL upgrade just to have an understanding.
 
Greg said:
Checked Bias transistors both with heat gun and are reacting so seems closer to operating Id like to make it function before I tear it apart and do the WOPL upgrade just to have an understanding.
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Like I said in a previses post, Visual inspection and sometimes I use a Magnifying glass after cleaning w isopropyl alcohol w a tooth brush.
I would clean the board and look for bad solder joint but really look for crack and broken traces and wires. ever time you work on the phase linear and move something, it can cause a broken wire or they come loose and also check the wires to the little Bias transistor and they also tend to break off. And every time you unsolder something the solder pads can lift up, if you are not carefull. A visual inspection has to be done before turning power on every time you work on it. ;)

Than I would check the bias transistor and the pot and than the traces from each leg of the pot and buzz it out to the next component leg. I put the meter lead on the pot leg and than to the component leg and any places that might look bad.
and in any area that might have a bad traces, your problem is in this area first. than you can compare it to the other Left channel
(and ohm the pot out to, I had all of these problems)
Good luck, your getting closer
 
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Back when you could get a non working 400 on ebay for 75.00, i bought quite a few and started learning on those. I had a Spec 2 that had gone into protection mode, didn't know shit. Discovered Audiokarma, Don Imlay, Ed Blackwood and finally Joe. God bless em all!!

Echowars and Markthefixer held my hand through the Spec 2 fix, and the others my Pl stuff.

Greg, I have been exactly where you are and took childlike delight everytime something I did actually fixed something!!

Congratulations bud, now the learning curve steepens....
 
Over the last few months I have amassed quite a stockpile of Phase linear survival supplies and had a bag of the Bias adjust pots on hand lol
And yet I could not find a AGX5 amp fuse in all of Phoenix AZ today lol If anyone knows of good electronics shop here in AZ do tell !
 
Greg said:
Over the last few months I have amassed quite a stockpile of Phase linear survival supplies and had a bag of the Bias adjust pots on hand lol
And yet I could not find a AGX5 amp fuse in all of Phoenix AZ today lol If anyone knows of good electronics shop here in AZ do tell !
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I needed one in a hurry once, I went to Auto Zone and found a AGX5 in one of their assortment kit of fuses. Then I bought a box of 100 on either ebay or Amazon. When you do that be careful to avoid counterfeits, make sure that are Buss or Cooper/Bussman.
 
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