Working on a 1000bd. This one is pretty tough to crack. I’ve replaced the power supply MOSFETS with IRF 3205 with 47 ohm gate resistors and replaced the driver transistors. I get 6.90V at the gates. One bank of fets get hot nearest the rectifiers. Thoughts on what to check next? I even went as far as replacing the 3526N ic still same results
Attachments
Connect only ground and remote and measure the DC voltage on the gate leg of every PS FET. Are they all the same?
What do you read on them?
What do you read on them?
What's the idle current?
Is the MESHA insulator under the hot FETs getting as hot at the FETs themselves?
Is the MESHA insulator under the hot FETs getting as hot at the FETs themselves?
All fets get very hot. If I apply remote amperage pulls at 15amps that’s when they get very hot instantly. Power led does not turn on. I’ve check all outputs those are fine.
All FETs or just the 4 near the rectifiers?
What is the frequency of the drive signal?
Do you have a current limiter for your 12 v supply?
What is the frequency of the drive signal?
Do you have a current limiter for your 12 v supply?
It’s all of them. I don’t own an O scope unfortunately, is there a possibility I can still get to the issue without?
Maybe.
What is the frequency of the drive signal?
Is this a different problem than the initial problem when you stated:One bank of fets get hot nearest the rectifiers.
What is the frequency of the drive signal?
Is this a different problem than the initial problem when you stated:One bank of fets get hot nearest the rectifiers.
Ok so I removed two fets Q7 & Q8 now the heating up has moved over to the other bank of fets. I was suspecting one of them was leaky but that wasn’t the issue they test out fine.
To answer your first question I’m not sure as I don’t have an o scope on hand.
To answer your first question I’m not sure as I don’t have an o scope on hand.
Be careful though, I've noticed that several meters I own will capacitively load circuits they are attached to when in frequency mode which can throw circuits off depending on where you connect them sometimes.
That's generally on the oscillator itself. On the output of the IC up to the gates of the FETs, it will have no effect.