gslikker
Super Member
Bought myself a dirty and defective SA8100. While troubleshooting a DC-unstable output first, there was a bang and some smoke.
A 50 volts capacitor blew, it was sitting at a location supposed to be 50 volts....
Now, I decided stop troubleshooting before hearing the next bang and just start replacing some components and cleaning up this very nice amp.
I always start the easy way to familiarize myself with the amp. ("Always" is my seventh amp refurbishment, in my case). The first thing to do will be the protection unit. On the internet manuals/schematics I find the AWM027 A board. Mine is AWM027-D, having no R19 resistor compared to -A, and two 0.22 uF electrolytics for C1 and 2. Q1 and Q2 are corroded leads 2SC869
issue 1: The power supply board employs 50 volts caps, where some 50 volts to be measured according the schematics. This is rather odd (no margin).
issue 2: There is no protection diode over the AWM027 relay coil, it may be no good for the transistor.
issue 3: two 0.22 uF 25V caps, C1 and C2, are small electrolytics. The "+" legend on the circuit card is the wrong way around for both. As a result, they were mounted the wrong way around..
This is the first circuit card, guess I'll find more "issues" as I go along.
So, I guess I post the interesting "issues" as I find them, if anybody interested?
A 50 volts capacitor blew, it was sitting at a location supposed to be 50 volts....
Now, I decided stop troubleshooting before hearing the next bang and just start replacing some components and cleaning up this very nice amp.
I always start the easy way to familiarize myself with the amp. ("Always" is my seventh amp refurbishment, in my case). The first thing to do will be the protection unit. On the internet manuals/schematics I find the AWM027 A board. Mine is AWM027-D, having no R19 resistor compared to -A, and two 0.22 uF electrolytics for C1 and 2. Q1 and Q2 are corroded leads 2SC869
issue 1: The power supply board employs 50 volts caps, where some 50 volts to be measured according the schematics. This is rather odd (no margin).
issue 2: There is no protection diode over the AWM027 relay coil, it may be no good for the transistor.
issue 3: two 0.22 uF 25V caps, C1 and C2, are small electrolytics. The "+" legend on the circuit card is the wrong way around for both. As a result, they were mounted the wrong way around..
This is the first circuit card, guess I'll find more "issues" as I go along.
So, I guess I post the interesting "issues" as I find them, if anybody interested?