Power transistor help

I have replaced to power supply using Joes capacitors and bridge rectifier. I have built the back planes panels using Joes kits. I have built a new control board with Joes kits, and I have installed your protection board inside of a new model 400 chassis. I am installing the backplanes and using Joes bring up diagram. Everything was good. I installed first roll of transistor. As I said earlier on in step 18 joe ask us to test the outputs. Without an input or output connected, I'm reading .139 ac of the left output. right side is .000. Hope this helps.
 
gary33030 said:
I have replaced to power supply using Joes capacitors and bridge rectifier. I have built the back planes panels using Joes kits. I have built a new control board with Joes kits, and I have installed your protection board inside of a new model 400 chassis. I am installing the backplanes and using Joes bring up diagram. Everything was good. I installed first roll of transistor. As I said earlier on in step 18 joe ask us to test the outputs. Without an input or output connected, I'm reading .139 ac of the left output. right side is .000. Hope this helps.
Click to expand...
Where are you in the bring up procedure Gary? With control board or without?
 
gary33030 said:
I have replaced to power supply using Joes capacitors and bridge rectifier. I have built the back planes panels using Joes kits. I have built a new control board with Joes kits, and I have installed your protection board inside of a new model 400 chassis. I am installing the backplanes and using Joes bring up diagram. Everything was good. I installed first roll of transistor. As I said earlier on in step 18 joe ask us to test the outputs. Without an input or output connected, I'm reading .139 ac of the left output. right side is .000. Hope this helps.
Click to expand...
ac voltage???
 
Joe,
I know you're going to scold me big time. I install all the transistors, wired everything together, hooked up speakers, etc. Right channel plays perfect and as loud as i want. left channel has distortion that does change with volume level.
It has got to be a missed solder joint, capacitor, or diode installed backwards. I'm going to pull the board and start comparing the good side to the bad side unless you say different.
 
gary33030 said:
Joe,
I know you're going to scold me big time. I install all the transistors, wired everything together, hooked up speakers, etc. Right channel plays perfect and as loud as i want. left channel has distortion that does change with volume level.
It has got to be a missed solder joint, capacitor, or diode installed backwards. I'm going to pull the board and start comparing the good side to the bad side unless you say different.
Click to expand...
Yes sir may I please have another... :-)
 
gary33030 said:
Joe,
I know you're going to scold me big time. I install all the transistors, wired everything together, hooked up speakers, etc. Right channel plays perfect and as loud as i want. left channel has distortion that does change with volume level.
It has got to be a missed solder joint, capacitor, or diode installed backwards. I'm going to pull the board and start comparing the good side to the bad side unless you say different.
Click to expand...
I would recommend you pull the output devices from the misbehaving channel (leave the properly behaving channel in place) and observe if the output stays at 0.139VDC without any outputs installed. That will give us some clues where to look.
 
Joe,
When I removed the control board, my voltage also disappeared from the outputs. I knew its somewhere in the control board. I have a good side, so I just keep looking and measuring. Please take a look at attachment. Terminal #7 on the terminal board was not soldered. Soldered up the connection and touched up some other questionable joints. I have not remounted the control board as of yet. Wife informed me that I need to feed her. Of all the time to be hungry. Ill let everone know after work tomorrow what's happening. I hope I've found it. To everyone who's helped so far, THANKS. I'll see everyone tomorrow after work.
Gary
 

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gary33030 said:
Joe,
When I removed the control board, my voltage also disappeared from the outputs. I knew its somewhere in the control board. I have a good side, so I just keep looking and measuring. Please take a look at attachment. Terminal #7 on the terminal board was not soldered. Soldered up the connection and touched up some other questionable joints. I have not remounted the control board as of yet. Wife informed me that I need to feed her. Of all the time to be hungry. Ill let everone know after work tomorrow what's happening. I hope I've found it. To everyone who's helped so far, THANKS. I'll see everyone tomorrow after work.
Gary
Click to expand...
good catch!!!
 
gary33030 said:
Joe,
When I removed the control board, my voltage also disappeared from the outputs. I knew its somewhere in the control board. I have a good side, so I just keep looking and measuring. Please take a look at attachment. Terminal #7 on the terminal board was not soldered. Soldered up the connection and touched up some other questionable joints. I have not remounted the control board as of yet. Wife informed me that I need to feed her. Of all the time to be hungry. Ill let everone know after work tomorrow what's happening. I hope I've found it. To everyone who's helped so far, THANKS. I'll see everyone tomorrow after work.
Gary
Click to expand...
Gary
#1 I would Visually check everything - Solder Joints and Components (I do not do it generally, but zoom in my eyes on a single connection)
I do this all the time, than again, it easy to miss something somewhere.
Also when cleaning I inspect solder joint and for missed solder components and I also looking for Cold solder joint or even not completely soldered or a tiny hole.
#2 Buzz Meter test- I try to Buzz out all wire to were they go and Color Code are correct (saved me many time and gives me peace of mind) also check components are in the correct location.
#3 Bolt and component test - Losses Part test - Wiggle test - Looses bolts and missed solder Joints
Good Luck
 
I'm sure why I think this is funny. Buy Joe say's "Nothing we do here is wife friendly." Carmen, (my wife) asked me why I keep feeling behind my PL400. I let her know, I'm making sure temps feel right. Asked her to reach around. You and I both know that the transistors conduct electricity. Long story short, she does not think it's funny. I'm in the doghouse again....
 
gary33030 said:
I'm sure why I think this is funny. Buy Joe say's "Nothing we do here is wife friendly." Carmen, (my wife) asked me why I keep feeling behind my PL400. I let her know, I'm making sure temps feel right. Asked her to reach around. You and I both know that the transistors conduct electricity. Long story short, she does not think it's funny. I'm in the doghouse again....
Click to expand...
Just DON'T do that with both hands on alternate columns!
 
Tonight's question for all. (Phase Linear 400, Series II)
Left channels Bias reading .350. Adjustment in little past halfway on the Bias control.
Right channel is reading .343. I cannot raise it anymore as the Bias control is all the way clockwise.
Both speaker's outputs are reading 0.00.
Do I have an issue? Should I just adjust left channel to match right channel? All other voltages are reading correctly.
 
Gary, if you did not change the Bias Transistors from the original 2N3403 devices, that may be the issue. We use newer 2N5088 devices because they track with the heat a little better, and they are current production.

The 350mV Bias setting was a compromise. 300mV gave us a cooler running amplifier with a smidge of distortion; 400mV gave us a hot running amplifier with slightly less distortion.

You are close enough with a reading of 343mV, the voltage will fluctuate as the temperature of the amplifier changes. I find that a amplifier that is just turned on will produce a Bias setting of 338mV and it gradually climbs up to 350mV (previously adjusted, with no input). When you add an input the Bias voltage will vary with the level of the input, naturally.
 
Thank you for the fast response. I used Joes back plane boards, so yes, I have changed both Bias Transistors, but i used NTE192 instead of 2N5088. His new boards accept both transistors? I have a spare which I'll replace tomorrow, and then report back to all.
 
All is well. I replaced the Bias Transistor for the right channel. I have both channels set to .350. Right channel adjustment is still very close to max out clockwise. The amp is playing as I'm typing. Today, I'm building the led boards. The wife wants to know if I can replace the red for blue LEDs? Do I have to do anything different?
 
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