Do you have a signal that drives from the negative rail to about 10v above the negative rail on pin 1 of the 21844s?
What is the DC voltage on pin 2 of the 21844 (with reference to the negative rail)?
What is the DC voltage on pin 2 of the 21844 (with reference to the negative rail)?
For most any measurements on the 21844, you use the negative rail since that's the reference for that IC.
The negative rail is -100v? The negative speaker terminal is likely the secondary ground (0v). Use pin 17 of the driver board or the shunt resistors that are on the negative rail.
Using pin 17 as ground, pin 1 reads .7mv dc however there is a squarewave on it. Pin 2 reads 383mv dc
What's the amplitude of the signal on pin 1?
Pin 2 is too low.
What components did you find that failed in this amp?
Pin 2 is too low.
What components did you find that failed in this amp?
You can NOT use a mains powered scope with the ground on the negative rail without risking damage to the scope or amp. To use your mains powered scope, you'd have to use it in differential mode. If you have a battery powered scope use it if you don't know how to set the mains scope up in differential mode.
Give a quick check to the 21844s (rail caps discharged) using the attached diagram.
Are all of the outputs out of the circuit?
Give a quick check to the 21844s (rail caps discharged) using the attached diagram.
Are all of the outputs out of the circuit?
Attachments
You can take it out. You should be aware that those should not be used for permanent installation and can even cause problems when testing. If you remove the driver board, discharge the rail caps before installing or removing the board.
In an amp like this one, the driver board never needs to be removed. To replace the ICs, stand the amp on end and do the work (IF anything needs to be replaced).
In an amp like this one, the driver board never needs to be removed. To replace the ICs, stand the amp on end and do the work (IF anything needs to be replaced).