R206, 1.5Megohm, something is loading this down, mosfet gates do not draw currents, so anything after R206 is suspect....
could it be that R206 became an open? lift one end and measure resistance...
could it be that R206 became an open? lift one end and measure resistance...
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Hi, I literally just replaced R206! It measure 1.53 in circuit.
I got 99% lol but I did tidy up my work after!
What about the resistor around it? Would a slight drift cause it? I did measure them before and they are about what is on the schematic!
I got 99% lol but I did tidy up my work after!
What about the resistor around it? Would a slight drift cause it? I did measure them before and they are about what is on the schematic!
anything after the R206 is suspect since you are getting 250vdc before that resistor..
you can even replace it with 47k, i do not see why it has to be that high in value..
unless the designer was looking for a delay of 3.3 secs ....did you wait a few secs before you measure output voltage?
you can even replace it with 47k, i do not see why it has to be that high in value..
unless the designer was looking for a delay of 3.3 secs ....did you wait a few secs before you measure output voltage?
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The preamp does take a while to warm up and the light turns green.
Its high voltage I'm scared to even go near it!
Before the pop I was a lot braver, there was 250v at R206 transistor side and 16V after it
Its high voltage I'm scared to even go near it!
Before the pop I was a lot braver, there was 250v at R206 transistor side and 16V after it
can you take out the 3 2.2ufd caps in the meantime? then measure again....
or else your trouble can be found downstream...
or else your trouble can be found downstream...
lift them one lead first then measure again.....
long time ago, i serviced a fisher 400 with one output tube red plating, replacing the cap with a new one got rid of the red plating...mind you i could not find anything wrong with that EROS cap, even bought a megger to test it but no, it tested good..
long time ago, i serviced a fisher 400 with one output tube red plating, replacing the cap with a new one got rid of the red plating...mind you i could not find anything wrong with that EROS cap, even bought a megger to test it but no, it tested good..
I know exactly what you mean. I had a failed amplifier that was caused by a resistor. Test absolutely fine but under strain went hot and and lost or gain resistance and made the circuit not work!
I have a pretty decent meter and all the caps measured about the same. They are expensive type capacitors but if that will certainly fix the problem then it might be worth the investment!
So your suggesting its not any of the resistors or diodes?
I have a pretty decent meter and all the caps measured about the same. They are expensive type capacitors but if that will certainly fix the problem then it might be worth the investment!
So your suggesting its not any of the resistors or diodes?
Attachments
reason i asked you to float one end of the caps is to see how the circuit reacted without them in circuit...prefferably float the end that is not connected to ground...
let us see how it goes...next step is to remove the mosfets....i use the 2sk3565 fully encapsulated mosfets, its got a built in zener gate protection clamps...
let us see how it goes...next step is to remove the mosfets....i use the 2sk3565 fully encapsulated mosfets, its got a built in zener gate protection clamps...
The MOSFETs used are IRF IBE20G
I rather just replace parts then have the circuit go wrong. I will look into replacing the caps and resistors. I may start with the resistors first as they are cheaper and easier and see how it does.
I have not tested those MOSFETs either, I hope they are still OK!
I rather just replace parts then have the circuit go wrong. I will look into replacing the caps and resistors. I may start with the resistors first as they are cheaper and easier and see how it does.
I have not tested those MOSFETs either, I hope they are still OK!
Those Solen caps are like $10/3pcs.
You can even save half of that money and buy those red Audiophiler MKP caps, which are just as good, if not better. They're longer by 5mm though (2.2uF ones), but would probably fit just fine.
You can even save half of that money and buy those red Audiophiler MKP caps, which are just as good, if not better. They're longer by 5mm though (2.2uF ones), but would probably fit just fine.
Thanks. I'm in UK and I have seen those Audiophiler caps. I just want to gather enough information before spending more money to isolate the problem. Last thing I want it to spend money on new caps and resistors which may not be much then then for it to not work again!
Although I have generally found what was causing the issue which is a massive step forward! And its been very helpful with people contributing different ideas and technical expertise!
Although I have generally found what was causing the issue which is a massive step forward! And its been very helpful with people contributing different ideas and technical expertise!
this is what i use for testing parts including mosfets....this tester can tell you if your mosfet is depletion or enhancement type...
M328 Multi-Purpose Transistor Tester Diode Resistor Esr Capacitance Lcr Meter Portable New Component | Lazada PH
M328 Multi-Purpose Transistor Tester Diode Resistor Esr Capacitance Lcr Meter Portable New Component | Lazada PH