funkmasterron
New member
- Joined
- Aug 20, 2024
- Messages
- 2
- Reaction score
- 0
I am troubleshooting an Egnater Tweaker 15 guitar amp head, that has no output.
I am tracing the circuit using this schematic: (https://el34world.com/charts/Schematics/files/Egnater/Egnater_tweaker_15.pdf)
R27 (1k 5W resistor) was measuring an open circuit impedance. I am measuring 406VDC at the C26 side of R27, then 0V at the other side of R27. I performed a continuity test and resistance value test of all of the resistors in that power supply circuit and everything checks out. C26 is measuring an infinite impedance when in the circuit which seems odd, so I will replace it. All 4x of the filter caps (C28, C29, C30, C33) are measuring an impedance in the circuit so don't appear to be shorted.
I removed the QC2 - QC5 jumpers connecting the output of the power supply to isolate the issue to the power supply circuit or its load (aka other circuitry).
With the QC2 - QC5 jumpers removed, I replaced R27 with the same resistance/power rating part, and in about 2 seconds, that resistor visibly gets hot and blows again.
I need to purchase some more 1k 5W resistors to run more tests, so I'm typing this post out to get some ideas of what to try next.
My thought is that the problem appears to be in the power supply circuit. My next test would be to remove each "leg" of the R27 output (R28 and R30) to see which "leg" is causing the issue.
Or think this is a problem with the power transformer (ground connections, perhaps)?
Any other thoughts?
TIA!
I am tracing the circuit using this schematic: (https://el34world.com/charts/Schematics/files/Egnater/Egnater_tweaker_15.pdf)
R27 (1k 5W resistor) was measuring an open circuit impedance. I am measuring 406VDC at the C26 side of R27, then 0V at the other side of R27. I performed a continuity test and resistance value test of all of the resistors in that power supply circuit and everything checks out. C26 is measuring an infinite impedance when in the circuit which seems odd, so I will replace it. All 4x of the filter caps (C28, C29, C30, C33) are measuring an impedance in the circuit so don't appear to be shorted.
I removed the QC2 - QC5 jumpers connecting the output of the power supply to isolate the issue to the power supply circuit or its load (aka other circuitry).
With the QC2 - QC5 jumpers removed, I replaced R27 with the same resistance/power rating part, and in about 2 seconds, that resistor visibly gets hot and blows again.
I need to purchase some more 1k 5W resistors to run more tests, so I'm typing this post out to get some ideas of what to try next.
My thought is that the problem appears to be in the power supply circuit. My next test would be to remove each "leg" of the R27 output (R28 and R30) to see which "leg" is causing the issue.
Or think this is a problem with the power transformer (ground connections, perhaps)?
Any other thoughts?
TIA!
