Ok, so yesterday after playing around with C7 and messing with the jumping offset it was getting already late, so I was getting upset, removed all the extra parts, adjusted once again the offset and gave it a last listen.
I was pretty stunned and could not and still can not explain what happened. Now everything sounds right as it should, heights are there, dynamics, stereo field.
It is clearly not a perception, as I was A/B-ing couple of times before and switching back and forth between the Pearl and my Rega phono - clearly the Rega had way more superior SQ. The Pearl sounded just "dull".
The only thing what I can imagine is when I put in C7 (and stated that the sound immediately got way better), I might have made an immediate "burn-in" by letting the Q2, or whatever other transistor it might be, oscillate...
I mean I put everything back to stock state as it was before and now it sounds as it should.
Stayed another 2 hours up at night listening to records
Thank you everyone for the effort trying to help me, I guess I'm happy now with my Pearl.
Hope it stays like this when I'm back from work
Btw. my left channel didn't produce any sound because the offset jumped again to -23V.
I was pretty stunned and could not and still can not explain what happened. Now everything sounds right as it should, heights are there, dynamics, stereo field.
It is clearly not a perception, as I was A/B-ing couple of times before and switching back and forth between the Pearl and my Rega phono - clearly the Rega had way more superior SQ. The Pearl sounded just "dull".
The only thing what I can imagine is when I put in C7 (and stated that the sound immediately got way better), I might have made an immediate "burn-in" by letting the Q2, or whatever other transistor it might be, oscillate...
I mean I put everything back to stock state as it was before and now it sounds as it should.
Stayed another 2 hours up at night listening to records
Thank you everyone for the effort trying to help me, I guess I'm happy now with my Pearl.
Hope it stays like this when I'm back from work
Btw. my left channel didn't produce any sound because the offset jumped again to -23V.
Update:
Again same issue on one channel. Dull sound. If I measure and touch either of the pins on Q2 or Q11, sound comes back and is louder, same issue if I touch with the multimeter lead the zero offset point on the board, sound gets louder and opens up.
I have ordered new ZVP3310 and ZTX450 and will replace all of them on the boards
Btw has anyone tried to place a gate resistor on Q2? Why is it not used?
Again same issue on one channel. Dull sound. If I measure and touch either of the pins on Q2 or Q11, sound comes back and is louder, same issue if I touch with the multimeter lead the zero offset point on the board, sound gets louder and opens up.
I have ordered new ZVP3310 and ZTX450 and will replace all of them on the boards
Btw has anyone tried to place a gate resistor on Q2? Why is it not used?
Last edited:
Yes, connections are solid, been checking and re-soldering yesterday. R15 is jumpered.
What I had on the initial powering up of the boards is one defect ZTX450, Q1 I believe leading to no sound. So it seems to the ZVP and the ZTX are prone to failure.
Will need to "earth" myself when I'm ging to replace the transistors just to be sure
What I had on the initial powering up of the boards is one defect ZTX450, Q1 I believe leading to no sound. So it seems to the ZVP and the ZTX are prone to failure.
Will need to "earth" myself when I'm ging to replace the transistors just to be sure
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These little ZVP critters are rather fragile. My suggestions at this point are to replace Q2 and check for cold solder joints (though you've already done this). I had a bit of trouble with a few solder joints in my build because of the size/mass of the copper ground plane on the bottom of the board. I had to use my larger soldering iron and adjust the heat to maximum in order to make good connections here. Beyond these, I don't have any other insights to offer...
As I was reading through this thread I also was thinking that a cold solder joint was probably at play. Usually you don’t get the circuit intermittently working if a device is dead. Are you using flux when you reflow the joints? Ive had cold joints that get some surface oxidation and won’t properly reflow unless flux is used.
Terry
Terry
The solder joints are OK. As I don't have any spare ZVP3310, I swapped Q2 between the boards and the other channel is behaving same. So clearly its the transistor.
I had a similar issue with one 2SK170BL in my F5t. Everything was working fine except I had 100hZ very slight hum on one channel. By measuring the output voltage, the good channel had 200uV AC ripple, the bad one 600uV.
I thought it was a groundloop issue and was trying to fix it over month with no luck.
Changed the input FETs and all was good.
I had a similar issue with one 2SK170BL in my F5t. Everything was working fine except I had 100hZ very slight hum on one channel. By measuring the output voltage, the good channel had 200uV AC ripple, the bad one 600uV.
I thought it was a groundloop issue and was trying to fix it over month with no luck.
Changed the input FETs and all was good.
Is there, by any chance, a parts list/Bill of materials with Mouser/Digikey part numbers on it somewhere in the 1485 posts? I'll look through this if I know it's there. Just don't want to waste my time and I'm also deciding how much of the wheel I have to reinvent to accomplish this potential project. Any info would be greatly appreciated!