Hi
I fixed power supply. It had a mosfet bad. Now amp comes on a d has all the voltages. Signal is good until R201. After that the signal is very weak on outputs. Tested all transistors but everything looks good. Does it have mute signal any where.
I fixed power supply. It had a mosfet bad. Now amp comes on a d has all the voltages. Signal is good until R201. After that the signal is very weak on outputs. Tested all transistors but everything looks good. Does it have mute signal any where.
Short Q11 C-E with a jumper and power up through a limiter. Does the amp produce audio at a normal level?
Yes amp came on with 1.7amps with limiting resistor and got 15v rms output signal on speaker terminals and it is 100hz signal it is clean.
One channel is pulling current mostly irf9640 0.1 ohm resistor is have 6.8 millions. On one resistor when I remove that mosfet other resistor now having 6.8 to 7 milliohms. I removed all 9640 except one and this mosfet resistor also having same value. Other side channel only has 0.2milliohm. Bias pot turned all to anti clock side.
PC-3083-C.
I removed all the mosfets on that channel now other side one mosfet is pulling 6millivolts across rresistor.So the amp is still pulling current.
See attached.
List which FETs are now out of the circuit and which FET has high current across it's 0.1 ohm resistor with the bias fully CCW.
List which FETs are now out of the circuit and which FET has high current across it's 0.1 ohm resistor with the bias fully CCW.
Out of circuit fets
Q215 Q214 Q212 Q211
Q220 Q219 Q217 Q216
Current across 0.1 resistors
Q213. 5.7mV
Q218. 5.7mV
Q315. 1.2mV
Q314. 2.3mV
Q313. 1.0mg
Q312. 1.1mV
Q311. 1.2mV
Q320. 0.5mV
Q319. 4.1mV
Q318. 0.6mV
Q317. 0.8mV
Q316. 0.6mV
I removed the fet. But the amp still trying to pull current. Other channel still showing 6.4mV across Q213 and Q218 source resistors.
After removing that fet causing high current across resistor and few more gets. I am having balanced current draw on left and right side fets. But the amp still trying to pull current
He is asking what the voltage is now across the source resistor for the fet you pulled out (Q319)
The 300 series parts are marked on the board for example R301,R355 ect if you look at the silk screen printing on the board 1 channel all the resistors diodes ect are marked 3xx and the other channel are marked 2xx
The 300 series parts are marked on the board for example R301,R355 ect if you look at the silk screen printing on the board 1 channel all the resistors diodes ect are marked 3xx and the other channel are marked 2xx
You can't have current flowing through the resistors that have no FETs. You need to post the voltages for the resistors for the remaining FETs.
Q315. Out of board
Q314. Out of board
Q313. 1.7mV
Q312. 1.4mV
Q311. 1.6mV
Q320. Out of board
Q319. out of board
Q318. 1.6mV
Q317. 1.5mV
Q316. 1.7mV
Q314. Out of board
Q313. 1.7mV
Q312. 1.4mV
Q311. 1.6mV
Q320. Out of board
Q319. out of board
Q318. 1.6mV
Q317. 1.5mV
Q316. 1.7mV
Are these the original FETs?
Is the other channel reading about the same?
Bias pots fully CCW still, correct?
Is the other channel reading about the same?
Bias pots fully CCW still, correct?