Chip tech: you need to check r13. Bad solder joint or unsoldered. It’s the mosfet gate resistor. This could explain a lot.
Chiptech, please reflow R13 as others have asked.
And to follow up on McQuaide's point, unless you have a distortion analyzer for adjustment,
I would suggest leaving out P3.
Also, the only resistor change I remember making was increasing the wattage of R3 and R4.
And to follow up on McQuaide's point, unless you have a distortion analyzer for adjustment,
I would suggest leaving out P3.
Also, the only resistor change I remember making was increasing the wattage of R3 and R4.
I have confirmed that the mosfets and jfets and ztx are in the correct positions.
Thanks
Dennis,
You are correct. I missed a solder joint on R13. Thanks. At least we know what most likely went wrong.
I'm not clear on reference to P3.
Given the bad measures on most of the resistors, I plan to replace them all.
You are correct. I missed a solder joint on R13. Thanks. At least we know what most likely went wrong.
I'm not clear on reference to P3.
Given the bad measures on most of the resistors, I plan to replace them all.
You can’t tell anything by the measurement of the resistors in the circuit, generally. They are connected to other things. You will only be measuring the path of least resistance.
Chiptech,
R3 is bad, but the other resistors may not be bad. Many of the resistors are parallel to other resistors or parallel to circuitry that affect their measured resistance when connected to the circuit. The only way to check many of them is to lift one resistor leg to take it out of the circuit before measurement.
When you were biasing the right channel. was the left channel also connected? Did you attempt biasing the left channel? If no, then probably the left channel is undamaged, and comparing resistances between left and right channels is a good way to check for damage to right channel resistors. Also for R5/P1 and R6/P2, check resistance with pot at maximum in one direction and then turn pot all the way in the opposite direction.
R3 is bad, but the other resistors may not be bad. Many of the resistors are parallel to other resistors or parallel to circuitry that affect their measured resistance when connected to the circuit. The only way to check many of them is to lift one resistor leg to take it out of the circuit before measurement.
When you were biasing the right channel. was the left channel also connected? Did you attempt biasing the left channel? If no, then probably the left channel is undamaged, and comparing resistances between left and right channels is a good way to check for damage to right channel resistors. Also for R5/P1 and R6/P2, check resistance with pot at maximum in one direction and then turn pot all the way in the opposite direction.
When you were biasing the right channel. was the left channel also connected?
Yes it was connected.
The only way to check many of them is to lift one resistor leg to take it out of the circuit before measurement.
I will follow that procedure to test across the board.
Also for R5/P1 and R6/P2, check resistance with pot at maximum in one direction and then turn pot all the way in the opposite direction.
Is this to check the pots? My experience to-date is turning them can go on and on, unless that was because of the missed solder point?
Yes it was connected.
The only way to check many of them is to lift one resistor leg to take it out of the circuit before measurement.
I will follow that procedure to test across the board.
Also for R5/P1 and R6/P2, check resistance with pot at maximum in one direction and then turn pot all the way in the opposite direction.
Is this to check the pots? My experience to-date is turning them can go on and on, unless that was because of the missed solder point?
Twenty five turns from one side to another. The clicks are at the limits when the screw clutches.
The pot clicks at either end of it’s travel. There are 25 turns in between the click at either end. Make sense?
These are much thicker than the Keratherm and smaller than the size of the Mosfet or do I have the wrong item: 4180G-ND: Blocked
Yes, it's an optional adjustment for those with distortion measuring equipment.
If it is removed, it can't be misadjusted and cause problems.
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Can we get this fixed please? First, I am really feeling the pain for Chip. Secondarily, I'm running out of popcorn.
Ok. I have the board off the heat sink on my table and I just went 32 clicks. It still will turn but there is a click after every full turn. So have I traveled all the way to that end? The resistance of R6/P2 is 1.092 ohms. I went 31 turns the other way to a 0.2 ohms reading.
Same results for P1 and R5: 1.089 to 0.2 ohms readings.
Chiptech, the aluminum oxide pads you got are rigid so they also require the
use of thermal grease.
use of thermal grease.
If resistors are not damaged, it should read about 0 Ohm at one extreme and 1532 Ohm at the other end.
So R5 and R6 damaged and/or P1 and P2 damaged. Lift one leg of R5 and R6 and measure them, and then also measure P1 and P2 using the pads for R5 and R6.
If R3, R4, R5, and R5 are damaged, Q1 and Q2 may be toasted too.
So R5 and R6 damaged and/or P1 and P2 damaged. Lift one leg of R5 and R6 and measure them, and then also measure P1 and P2 using the pads for R5 and R6.
If R3, R4, R5, and R5 are damaged, Q1 and Q2 may be toasted too.
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