Hi,
I built an F5 from DIYstore and it is overheating the R3 R4 R5 R6 180R 5W wire wound in the AC softstart Board to the point of smoking and burning the board. The CL60 thermistor that grounds the board to the chassie also gets very hot.
The power supply and SS board work great without the L and R channel boards hooked up.
I can post PICs if this is the place to get assistance.
Any help would be appreciated.
Kurt
I built an F5 from DIYstore and it is overheating the R3 R4 R5 R6 180R 5W wire wound in the AC softstart Board to the point of smoking and burning the board. The CL60 thermistor that grounds the board to the chassie also gets very hot.
The power supply and SS board work great without the L and R channel boards hooked up.
I can post PICs if this is the place to get assistance.
Any help would be appreciated.
Kurt
There must be a short in one of the audio boards. Try each one separately to see which is the problem.
Or it could be a wiring problem.
Or it could be a wiring problem.
Disconnect only the left amplifier board. If the problem persists, connect the left board
and disconnect the right amplifier board.
If only one of the boards causes the problem, check that board.
If the problem happens with either board by itself, check the wiring.
If the wiring is ok, the boards must have assembly mistakes, or bad/wrong parts.
Are the output transistor leads touching the washers on the transistor mounting bolts?
Are the bias pots set for minimum current?
and disconnect the right amplifier board.
If only one of the boards causes the problem, check that board.
If the problem happens with either board by itself, check the wiring.
If the wiring is ok, the boards must have assembly mistakes, or bad/wrong parts.
Are the output transistor leads touching the washers on the transistor mounting bolts?
Are the bias pots set for minimum current?
Yes. My mistake. It is an F6.
Output trans are not touching washers.
I can disassemble and send more PICs.
I will screw the bias pots in before I test again. Just to confirm, to the right/clockwise is lower?
Output trans are not touching washers.
I can disassemble and send more PICs.
I will screw the bias pots in before I test again. Just to confirm, to the right/clockwise is lower?
I don't think you can rely on a particular direction of turning the pot; it depends on the orientation of the pot.
What is important is to make sure the pots are set so that on initial power up, the mosfets aren't wide open and
pulling lots of current. If you are using fairly low voltage zeners (say no more than 6-ish volts), you should be fine with
setting the pots at midway.
What is important is to make sure the pots are set so that on initial power up, the mosfets aren't wide open and
pulling lots of current. If you are using fairly low voltage zeners (say no more than 6-ish volts), you should be fine with
setting the pots at midway.
You can make a dim bulb tester if you like.
The bias across the .47 ohm resistor should be 500 mv or .5 of a volt. If that is correct, check the offset. You should be within 50 mv or so. If not you want to adjust that. Disable One channel and work on the other. Once you get that working, go ahead and reattach the other channel and check.
The illustrated build guide outlines this procedure in greater detail.
Best of luck!
The bias across the .47 ohm resistor should be 500 mv or .5 of a volt. If that is correct, check the offset. You should be within 50 mv or so. If not you want to adjust that. Disable One channel and work on the other. Once you get that working, go ahead and reattach the other channel and check.
The illustrated build guide outlines this procedure in greater detail.
Best of luck!
