Paradise Builders

Thank you all for the hints
I did the following: I have mounded the heatsink with the 3 screws to the PCB,
soldered all 6 devices with one lead at the proper position, added the isolation pads and used a "glue clamp" to fix the clips one by one, resoldered the 6 leads to minimize mechanical stress and finally soldered the rest of the leads.

I went well and I have no isolation problems.
(Checked with Multimeter)
 
Oké after firing up the pre-regultaor wich worked perfect,it was time to do the same to the phonostage......:D

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


And there was my first real problem.....

Al was going well,but than i had to measure the voltage of de gate/source of the pmos/nmos......


No 2,5v to find.....:scratch1:

What i'm measuring:
-gate 13v
-drain 0v
-source 18v

on both of the units
The output was a perfect 18v.....
 
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No 2,5v to find.....:scratch1:

What i'm measuring:
-gate 13v
-drain 0v
-source 18v

on both of the units
The output was a perfect 18v.....

Hi dre73, have you measured the voltages with a DMM with reference to GND? The sources of both MOSFETs (for the positive and negative shunt regulator) are connected to GND, so the voltage should be zero????

From the picture, it seems the long LED strings are not on, can you please check if you mounted the LEDs the right way?

PS: The 330Ohm vs 120Ohm is no concern right now.
 
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Joined 2005
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Hi dre73, what exactly is the problem? I am lost.....

Did you connect the prereg to the phono stage? Do you measure +18V and -18V at the regulator output, and all LEDs shining`? Then it seems your regulators are OK.

Next step would be to solder the bridges to the amplifier and measure again. Please advise whats happening. By the way, this whole procedure is described in a lot of detail in the assembly guide :D
 
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Joined 2004
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I populated my R3 boards a while back, with the 330 ohms. Will try to reduce them to 120 ohms and report back if this stops the oscillations... Thank you Alfred!
Boy am I slow… Finally got around to do this, on both boards, and they still oscillate. The photo below shows the oscillations, at 0.1 V per division.
B.t.w. I am testing without any load. Am I correct in assuming these should be stable without load?
One one of the board, I have changed every transistor except the two MOSFETs.
Sorry to bother folks with this...
 

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