That's fancy. I use those sockets over my bench for screw in LED lamps.
Clamp everything to the heatsink until you know that there will be no surprises.
Clamp everything to the heatsink until you know that there will be no surprises.
I installed the bulbs (75watt) in series with the d447 and d444 like you recommended. When I hooked up the remote the amp started to power up and the fuse blew. I didnt see any light from either 75 watt bulb. I then checked the ps fets and get 435 shorted. The 75 watt bulb didnt seem to offer much protection, the fuse blew pretty fast like usual.
I had realized my jumper on that capacitor had been broken on one side so that may have caused the fuse to blow but not sure why the fet would have failed.
I did check the outputs, none of them are shorted. I take it the outout section doesnt get switched on till the remote wire is powered correct?. Also maybe that's why the fuse blew trying to power up the output stage and somehow took out the ps fet when the fuse blew? That wouldn't make sense to me but a lot of things in this amp still dont.
Did you have a replacement for the failed FET?
The lamps were in series with two of the rectifiers but two other rectifiers remain out of the circuit, correct?
When all of the rectifiers were out of the circuit, did you check all of the power supply voltages except for one of the optocouplers?
The lamps were in series with two of the rectifiers but two other rectifiers remain out of the circuit, correct?
When all of the rectifiers were out of the circuit, did you check all of the power supply voltages except for one of the optocouplers?
I did have a replacement for the bad fet.
Yes the 2 rectifiers are in series with the bulbs and the others are not installed.
Idk any other powere supply voltages accept for the 20v on the op amps.
I replaced the rectifier and unhooked the wires to the bulbs just to fire it back up. Now it is blowing fuses without the rectifiers in circuit.
Yes the 2 rectifiers are in series with the bulbs and the others are not installed.
Idk any other powere supply voltages accept for the 20v on the op amps.
I replaced the rectifier and unhooked the wires to the bulbs just to fire it back up. Now it is blowing fuses without the rectifiers in circuit.
Is there possibly a bad solder connection on either of the gate resistors for the PS FETs?
You twisted/pushed/pulled on the main transformer. Do the same for the driver transformer to see if the current draw will change.
Before doing that, confirm that the FETs have drive on their gates.
You twisted/pushed/pulled on the main transformer. Do the same for the driver transformer to see if the current draw will change.
Before doing that, confirm that the FETs have drive on their gates.
Gate resistors are in circuit good.
With the amp powerd up I twisted, pushed, pulled on the driver transformer and cant get that to effect the drive signal or voltage at the amp.
The fets do have drive on there gates.
With the amp powerd up I twisted, pushed, pulled on the driver transformer and cant get that to effect the drive signal or voltage at the amp.
The fets do have drive on there gates.
As it is, power it up/.down about 10 times, discharging the primary caps (shorting between the B+ and ground terminals) before every cycle. Do the PS FETs survive that?
Are the gate resistors within tolerance?
Are the 2 10 ohm resistors and the 1k resistor connected to the driver transistors within tolerance? You may need to desolder the 1k to reliably test it.
Are the 2 10 ohm resistors and the 1k resistor connected to the driver transistors within tolerance? You may need to desolder the 1k to reliably test it.
The gate resistors are in tolerance. I assume those 10 ohm resistors are r430 and r431? If so they are reading 10ohms. R434 is reading .5 ohms. Is r434 the 1k resistor your asking about?
Can you replace the insulators to be absolutely sure that they're not the problem?
Do you see anything that can be causing the problem to be intermittent/inconsistent?
Do you see anything that can be causing the problem to be intermittent/inconsistent?
Ok so I looked over this amp with a magnifying glass and found the tiniest little strand of wire laying over some components near the driver transistors. I removed it and reinstalled fets, with the rectifiers in series with the bulbs I fired it up. The bulbs did glow slightly for a second as the amp came up. It didnt blow any fuses and all seems good. One thing I noticed is before when I had it fired up before shorting the octocoupler IED 238 was lit. It is now not. Maybe that led has somthing to do with the output stage and that was when my jumper on that capacitor had come ome off the one side. What is led 238 for? Also both octocouplers have between 18 and 20v
Another thing I should mention that I dont really think matter is, I was down to only two irfz44n and two 75339p rectifiers. I had the two irfz44n in one bank and the two 75339p on the other bank. This time when I put them back in I put one of each in each bank to kind of split any difference they might have. I dont really think this should have made a difference but I was thinking possibly the amp is sensitive to differences in how fast each bank powers up. Any thoughts?
The jumper prevent the muting from being defeated.
The mixed PS FETs shouldn't matter for this type of testing. For high-power tests, it would.
Flex the board (insulated probe) and push on various components to see if anything intermittent happens. If not, remove the jumper.
The mixed PS FETs shouldn't matter for this type of testing. For high-power tests, it would.
Flex the board (insulated probe) and push on various components to see if anything intermittent happens. If not, remove the jumper.
I flexes the board around , no funny business. I then cut the jumper and let it run for a minute or two and there is about 7vdc on the speaker outputs. Shorting the rca inputs didnt help, I dont know if its possible to short them as I removed d138
Do you have equal positive and negative rail voltage on the output transistors? Drain of one bank and source of other bank.
Is LED238 lit?
Do you have rail-rail oscillation on the output transistors when you drive a 100Hz signal into the amp?
Set the gain to the mid-point. Set the boost to the minimum point.
Positive 7v on all speaker terminals?
Is LED238 lit?
Do you have rail-rail oscillation on the output transistors when you drive a 100Hz signal into the amp?
Set the gain to the mid-point. Set the boost to the minimum point.
Positive 7v on all speaker terminals?