I would just go over the solder connections on both boards.
Many of the connections look questionable.
worked for ten years but corrosion finally caught up.
almost looks like no solder on one of Q3 legs
I cant tell if C4 is swollen or just picture angle.
schematic could help
Many of the connections look questionable.
worked for ten years but corrosion finally caught up.
almost looks like no solder on one of Q3 legs
I cant tell if C4 is swollen or just picture angle.
schematic could help
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almost everything looks like cold solder.
I dont know the board looks hole through pads.
most of it could be touched up from the top.
power connections look cold and blue ground looks corroded.
likely just a connection issue.
schematic would help, dont know looking at current sources or small signal.
only guess current sources are hot all their life. so something may have died.
but it just looks like cold cold solder everywhere
I dont know the board looks hole through pads.
most of it could be touched up from the top.
power connections look cold and blue ground looks corroded.
likely just a connection issue.
schematic would help, dont know looking at current sources or small signal.
only guess current sources are hot all their life. so something may have died.
but it just looks like cold cold solder everywhere
FYI the heat sink is ice cold so I am thinking this is related to current.
I will scrub, solder and check voltage drop tonight. Time permitting
Question regarding voltage drop. Can you explain how to measure voltage drop?
Earlier you asked for voltage across. So I put my multi meter probs on either side of the resistor should I be measuring between the resistor and the chassis?
As you can see from the soldering I’ve got a lot to learn and appreciate all the help trouble shooting. I’m learning more repairing than when I assembled it way back when. So I guess I’m lucky to have the opportunity to repair it. I’m hopeful we will find a solution.
Thank you!
I will scrub, solder and check voltage drop tonight. Time permitting
Question regarding voltage drop. Can you explain how to measure voltage drop?
Earlier you asked for voltage across. So I put my multi meter probs on either side of the resistor should I be measuring between the resistor and the chassis?
As you can see from the soldering I’ve got a lot to learn and appreciate all the help trouble shooting. I’m learning more repairing than when I assembled it way back when. So I guess I’m lucky to have the opportunity to repair it. I’m hopeful we will find a solution.
Thank you!
Indeed it is. It can be removed and can be tested without it for now, unless a replacement is at hand. It may have failed open as voltage was still present and the fuse did not blow. So remove C1 and see if it makes a difference.
As for the R1, R3 voltages at 0V, there was no current flowing, hence the cold mosfets. With no current flowing I am not sure how the voltage at the drain of Q1 was adjustable with adjustment of the trimmer.
Reflow the solder joints and see if that makes a difference. If not, then remove Q2 and Q3 and test them. They may need replacing.
Google "testing NPN transistor with multimeter" and "testing N channel mosfet with multimeter".
As for the R1, R3 voltages at 0V, there was no current flowing, hence the cold mosfets. With no current flowing I am not sure how the voltage at the drain of Q1 was adjustable with adjustment of the trimmer.
Reflow the solder joints and see if that makes a difference. If not, then remove Q2 and Q3 and test them. They may need replacing.
Google "testing NPN transistor with multimeter" and "testing N channel mosfet with multimeter".
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