AndrewMc wrote:
1) Set your meter AC. Measure across the rectifier pins. This is where the twisted red wires from the transformer attach to the board, just above and to the right of the MOSFET - where the diodes are. Make sure your meter can handle 600+ volts. Again, make sure it is set to AC. Put the black probe on one of the eyelets, the red probe on the other eyelet (amp has to be on of course). You should have close to 630VAC here.
333VAC for both.
AndrewMc wrote:
If you put the red probe on one of these eyelets and the black probe to ground, you should have in the neighbourhood of 300-315VAC.
315VAC for both.
AndrewMc wrote:
2) Set your meter to DC. Now measure across the 50uF capacitors. With the VRM all the way up you should have 400V. With the VRM all the way down you will have substantially less. If you have alligator clips on your meter (with the amp off) you can clip the black lead to the negative side and the red lead to the positive side. Then turn the amp on, to idle. Voltage should be fairly low. Slowly turn up the VRM and you can actually watch the voltage rise on your meter
Cap 1 VRM idle: 25DCV
Cap 1 VRM max: 285DCV
Cap 2 VRM idle: 463DCV
Cap 2 VRM max: 460DCV
AndrewMc wrote:
3) Keep the meter set to DC. Measure at the pre-amp side. Pin 6 should have 191 volts, pin 1 should have 203 volts (or close to those numbers). Hold your black probe to the pre-amp ground and the red probe to pin 1 or pin 6 depending on which you are testing
Both pins 288
AndrewMc wrote:
You can check your heater voltages (meter set to AC) at pins 7 & 2 on the power tube side and pins 4 & 9 on the pre-amp side. If I remember correctly, mine were around 6.7V. The manual says they are to be 6.3V.
Pin 7&2: 3.6V
Pin 4&9: 3.6V
AndrewMc wrote:
Actually, then very first thing you should do is check the main voltage coming into the amp. Hold your black lead to ground and the red lead where the wire connects to the fuse holder (or on the 'power' pot where the wire attaches that comes from the fuse holder).
.167V
I see there is a little bit of fixin to do!