I have here a Magnum IA.100 which belongs to my parents.
The unit powers on & when the relay kicks in, you get a pop from the speakers (this might sound weird but is usual behavior for this amp). However, you get nothing coming through it from any of the inputs & no pops and crackls from any of the controls.
Because of the sound from the speaker when the amp turns on I have assumed that the output section probably works but I could be wrong & I'm not sure how to test that side of things further.
What Ive done.....
I've given it a general visual inspection and don't see anything obvious on the main board (dry joints, exploded or leaking caps etc). The mosfet based amplifier section is a little more tricky to inspect due to the way the boards are stacked. I will go there if I have to but I wanted some advice and I'm waiting on a few bits and pieces (cheap part tester & some other bits and bobs).
I checked the voltages from the power supply before they get to the main board or the output section and they all seemed to check out. +28v DC, -28v DC to main board (there appears to be 2 x 24v regulators on the board, one for the positive side and one for the negative side) & approx 90v going to the amplifer output section.
I checked the 2 large caps on the mainboard & their uf read fine on my meter (but I dont have an ESR meter at present). I checked them out of circuit but I did notice that the on their seems to be a dead short between the positive and negative connections (where the cap on the left is soldered in) which doesn't seem right to me.
I also checked all the relays were working (out of circuit) but I noticed a short between the audio outputs going to the mosfet output section of the circuit (Ive disconnected those wires to get access to the under side of the board, so the short isn't on the mosfet side), sadly I only noticed this short after I reinstalled the output relay, so perhaps the relay shorts those contacts when it's switched off.
The 2 voltage regulators on the board seem to get very hot but my basic ir laser thermometer read them at about 80 - 90 degrees C which seems high but possibly inspec (ive not been able to find a data sheet on them sadly).
My skills.......
I have a rather basic knowledge of electronics (I know what most components are but not really how they work together). I can solder, know how to use a multimeter have a benchtop power supply & a handful of arduino projects under my belt but thats about the sum of it.
The Amp was a "hand me down" from my Uncle who liked his Audio gear almost as much as he loved his car. It was a great performer for many years but after they moved house, it never really got used. I dragged it out of retirement as my Uncle recently died & I thought it would be nice to get it going again for my parents. It was working after it's last use (maybe 15 - 20 years ago).
Any help would be appreciated as I'm so what out of my depth.
The unit powers on & when the relay kicks in, you get a pop from the speakers (this might sound weird but is usual behavior for this amp). However, you get nothing coming through it from any of the inputs & no pops and crackls from any of the controls.
Because of the sound from the speaker when the amp turns on I have assumed that the output section probably works but I could be wrong & I'm not sure how to test that side of things further.
What Ive done.....
I've given it a general visual inspection and don't see anything obvious on the main board (dry joints, exploded or leaking caps etc). The mosfet based amplifier section is a little more tricky to inspect due to the way the boards are stacked. I will go there if I have to but I wanted some advice and I'm waiting on a few bits and pieces (cheap part tester & some other bits and bobs).
I checked the voltages from the power supply before they get to the main board or the output section and they all seemed to check out. +28v DC, -28v DC to main board (there appears to be 2 x 24v regulators on the board, one for the positive side and one for the negative side) & approx 90v going to the amplifer output section.
I checked the 2 large caps on the mainboard & their uf read fine on my meter (but I dont have an ESR meter at present). I checked them out of circuit but I did notice that the on their seems to be a dead short between the positive and negative connections (where the cap on the left is soldered in) which doesn't seem right to me.
I also checked all the relays were working (out of circuit) but I noticed a short between the audio outputs going to the mosfet output section of the circuit (Ive disconnected those wires to get access to the under side of the board, so the short isn't on the mosfet side), sadly I only noticed this short after I reinstalled the output relay, so perhaps the relay shorts those contacts when it's switched off.
The 2 voltage regulators on the board seem to get very hot but my basic ir laser thermometer read them at about 80 - 90 degrees C which seems high but possibly inspec (ive not been able to find a data sheet on them sadly).
My skills.......
I have a rather basic knowledge of electronics (I know what most components are but not really how they work together). I can solder, know how to use a multimeter have a benchtop power supply & a handful of arduino projects under my belt but thats about the sum of it.
The Amp was a "hand me down" from my Uncle who liked his Audio gear almost as much as he loved his car. It was a great performer for many years but after they moved house, it never really got used. I dragged it out of retirement as my Uncle recently died & I thought it would be nice to get it going again for my parents. It was working after it's last use (maybe 15 - 20 years ago).
Any help would be appreciated as I'm so what out of my depth.