Troubleshooting an humming WOPL : need help!

Gepetto

Gepetto

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Coldsmoke said:
Ah ah ! You know what, I was tonight at a friend's place who used to be the official reseller for ALTEC LANSING and JBL back in the 80's and 90's in Belgium to pick up an AMCRON IC 150 preamp and a DC300 amp.
I have a couple of good news : he borrowed me a variac, and, rarer, a 60W bulb! An other good news is that a good frien of his used to service PL stuff in the 70's and 80's and could have some rare PL parts like this fuck*** IC's for the 2000....
A bad news is that ... The DC300 HUMMMMMS JEEEEZ, I AM CURSED!
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The DC300 is a very good amp, hope you fix it. I have many of them. Unfortunately, the IC150 is not that well regarded, very nice build quality but the sonics need work.
 
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Gepetto said:
The DC300 is a very good amp, hope you fix it. I have many of them. Unfortunately, the IC150 is not that well regarded, very nice build quality but the sonics need work.
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The hum is audible from the transformer and through the speakers, I hope that tightening it might fix the hum. Are your DC300 transfromers noisy somehow?
I listened to the IC 150 through a very good power amp (the name of the brand is "POWER" a french pro audio company from the 70's-80's) and I really enjoyed the sound...
 
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Coldsmoke said:
The hum is audible from the transformer and through the speakers, I hope that tightening it might fix the hum. Are your DC300 transfromers noisy somehow?
I listened to the IC 150 through a very good power amp (the name of the brand is "POWER" a french pro audio company from the 70's-80's) and I really enjoyed the sound...
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They make a low 60Hz mechanical hum if you are very close to them but that hum does not come through the speakers.
 
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Gepetto said:
3. The 22AWG white wire attached to OUT1 on the right channel backplane board goes to PAD1 on the LED light board, the 22AWG white wire attached to OUT1 on the left channel backplane board goes to PAD2 on the LED light board, attach a 22AWG black wire from the bus bar ground to PAD3 of the LED light board (easiest place to grab this is the solder lug provided to tie to chassis ground, solder a second wire into that lug hole.
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Is shortening the grey wires from transformer so that I can tackle them on the lower side of the chassis a good idea ...?
 
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Coldsmoke said:
Is shortening the grey wires from transformer so that I can tackle them on the lower side of the chassis a good idea ...?
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My installs have them exiting along the top back fold of the chassis, tyrap the 2 gray wires together and separate from everything else. The 3 signal wires get likewise tyrapped and over to the LED light board.
 
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I promise this is my last silly question the grounding for L and R chanels for the dc protect board are to be taken at the chassis star point right...
 
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Correct...and the ground for the relay drive. You will have 3 grounds from the DC protect to the star ground point..
 
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Prime PITA, have to make sure before insertion the leads are straight and square off the base of the transistor...
 
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Thanks for the tips guys but... Big disapointement tonight... : I was finaly able to put these transistors in place but the start up didn't passed the dim bubble test... It turns bright arround 100 V or so... Can't figure what could be shorted or what I did wrong... Man I was very enthusiastic but here, I'm about to loose my nerves...
 
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Coldsmoke said:
Thanks for the tips guys but... Big disapointement tonight... : I was finaly able to put these transistors in place but the start up didn't passed the dim bubble test... It turns bright arround 100 V or so... Can't figure what could be shorted or what I did wrong... Man I was very enthusiastic but here, I'm about to loose my nerves...
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Florian
Take the single ground wire off the chassis ground connection stud on the left channel upper heatsink screw and ensure that you have infinity on a resistance reading from the 4 transistor collector cases that are installed when measured to chassis ground. You installed the sil pads under each transistor correct?

You have no other screws in the heatsink except the 8 screws total holding the 4 bottom row transistors in correct?

You have MJ21196 then MJ21195 then MJ21196 then MJ21195 in the bottom row starting from the transformer and going over to the output side of the amp correct?
 
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Gepetto said:
Florian
Take the single ground wire off the chassis ground connection stud on the left channel upper heatsink screw and ensure that you have infinity on a resistance reading from the 4 transistor collector cases that are installed when measured to chassis ground. You installed the sil pads under each transistor correct?

You have no other screws in the heatsink except the 8 screws total holding the 4 bottom row transistors in correct?

You have MJ21196 then MJ21195 then MJ21196 then MJ21195 in the bottom row starting from the transformer and going over to the output side of the amp correct?
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Hello Joe, my answers:
-the 4 collector cases are not shorted with the chassis / silpads are installed
- no other screw in place
- here I am feeling stupid/lost all the transistors wère put back at their original place but are all the same and reading "66546 RCA 7632" ==> what information did I miss?
 
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If you did the 66546 drivers are no longer used. Each column will now be all 96's and 95's..in other words...the column closest to the transformer should be 96 the row next to that 95, the next 96...the last 95's.
 
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Coldsmoke

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Well ok, I guess we ha the reason here... Home I dis not broke anything ... I completely missed this information. Are these transistors easy to find?
 
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