About cart you mentioned the Ortofon Cadenza red. What is the TT? Having a pre with gain?
Paralleled 100r to 16.6r. Value is 14.5-14.4r. Still no lights. Voltage across resistor is zero
So we went through the whole CCS circuit by now. D2X,D3X,D4X you said all light up on individual test and they have cathode on square pad, R1x you restored to typical value, Q1X is 9610 indeed, R6x is 22R indeed, Q2X can't be wrong on both channels, slim chance. This IS weird. Double check the LEDS for a last time.
OK stop for now its late. Tomorrow recheck with a clear head. Its very weird but there should be an explanation. Something with the sinks maybe. Being scratched and having scratched solder mask also? Chasing a ghost. We will find it.
I'm sure Salas will walk you through all this tomorrow, but clearly there is no current passing through R1x (else there would be voltage drop across it) nor through the LED's, hence through Q2x. I would start by isolating the LED circuit by lifting one end of R1x and R2x. If the LED's don't light then either one of the LED's is bad, or Q2x isn't conducting, or R6x is open. You already measured R6x, and we already know there is 49V at the junction of R1x and the diodes. Ergo, if the diodes are OK and R6x is OK, then the ONLY other thing is Q2x, and it is either bad (as Salas said, unlikely on both sides) or the wrong part or installed incorrectly. Either way, Q1x is not going to conduct until Q2x does.
Thank you for such detailed explanation.
I'll might try that technique when my final setup will be locked.
So far, and Salas is right, I need need to test my Folded deeply in order to optimize its gain since my cartridge load vs. output is still hazy.
Gas tight copper to copper is the best connection you can get. Ericsson Telecom wire wrapped their AXE stations because wire wrapping gives a much tighter joint then solder joints. My friends still have the old tools and cable terminators. Heres https://www.youtube.com/watch?v=8SSOKppwpAE a hobbyist video. Ericsson used special tools and wire where the materials were cutting into eachother, making it completely gas tight and impossible to tear apart.
I'm going to test my Folded first time this Sunday.
My biggest concern and question is related to LEDs again....
I'm sure that my 4 LEDs (D1...4) are matched between L and R channels, but I hesitate about 7.75v setup. As you did see, I installed 2 red and 2 green LEDs and theoretically I'm getting about 8v.
When I measured these LEDs, I used 2SK117GR and 18.5V battery pack. I made it as quick test. Now I see if you leave LED longer with 9v batery and 1k5 resistor, V is slightly going up till and during 1 min time-frame is ganning from 1.89v to 1.910v. Will you recommend to re-measure that set or to try to use it as is with assumption that I might have more than 7.75v there?
One more question: do I need to connect it to TT and preamp in order to start biasing it?
My biggest concern and question is related to LEDs again....
I'm sure that my 4 LEDs (D1...4) are matched between L and R channels, but I hesitate about 7.75v setup. As you did see, I installed 2 red and 2 green LEDs and theoretically I'm getting about 8v.
When I measured these LEDs, I used 2SK117GR and 18.5V battery pack. I made it as quick test. Now I see if you leave LED longer with 9v batery and 1k5 resistor, V is slightly going up till and during 1 min time-frame is ganning from 1.89v to 1.910v. Will you recommend to re-measure that set or to try to use it as is with assumption that I might have more than 7.75v there?
One more question: do I need to connect it to TT and preamp in order to start biasing it?
Q2x is the correct type and properly inserted.Posting some closeups for reference. Measured resistance between Drain and Source is 92-93 ohms in both channels. Going to remove heatsinks now
Attachments
So i reheated solder joints and checked continuity up until irf9610 and everything is ok but it still doesnt work.
Im thinking i must have done something incredibly stupid in the PSU, probably the board doesnt get much current.
Im thinking i must have done something incredibly stupid in the PSU, probably the board doesnt get much current.