Finished assembling my Pearl 2 yesterday. I started it up with a variac and when I got to about 50% it blew the fuse. Replaced fuse and put a multi-meter on the output and got lots of voltage on the output (2 volts before shutting it down).
I'm using an XLR connector for voltage between two chassis and didn't understand that the shield connected a pin and the sockets. I clipped the wire going to the sockets thinking I had solved my problem.
Started testing again today and am still getting negative voltage on the output (both boards behave the same). Almost as much voltage as is going into the board itself. I have done a lot of testing to make sure I don't have any shorts in the wiring.
I pulled one one board and can't find anything out of place. I'm stumped at this point.
I'm using an XLR connector for voltage between two chassis and didn't understand that the shield connected a pin and the sockets. I clipped the wire going to the sockets thinking I had solved my problem.
Started testing again today and am still getting negative voltage on the output (both boards behave the same). Almost as much voltage as is going into the board itself. I have done a lot of testing to make sure I don't have any shorts in the wiring.
I pulled one one board and can't find anything out of place. I'm stumped at this point.
Attachments
Last edited:
Looks like same setup I have on my pearl. Sent you an IM. I can send you some pics of my setup so you can compare
Check orientation/polarity of red LED. I can see clearly in pic.
Also check polarity of power supply getting into phono box.
Also check polarity of power supply getting into phono box.
I'm pretty sure the LED is orientated correctly...but I pulled it anyway and put one in the opposite direction. I get the same results. (- dc voltage on the outputs).
I know the polarity of the power supply going to the phono box is correct because I've check it numerous times.
I know the polarity of the power supply going to the phono box is correct because I've check it numerous times.
I haven't pushed it past 50% on the variac because I see all that voltage on the output and test pad. I'm sure it would blow the fuse, so no it hasn't been fixed yet. I need to go get an LED and more fuses before testing more.
Well...I have one channel working!
The other channel is the one I switched the polarity of the LED which made R29 smoke. I have the LED back in correctly and replaced three other parts, R29, Q2, and Q11. Now Q11 gets very hot. I had it hooked up and it has very little gain.
The other channel is the one I switched the polarity of the LED which made R29 smoke. I have the LED back in correctly and replaced three other parts, R29, Q2, and Q11. Now Q11 gets very hot. I had it hooked up and it has very little gain.
Looks like Q2 is fully turned on or oscillating, remove C7 if fitted, if that doesn't fix the problem, replace the ZVP3310 - is very sensitive to static.
Here are my Measurements:
R4: 23.66
R31: -23.52
R9: 19.68
Q3/Q7: 5.57
R8/Q3 6.25
R24: .075
Q10: -18.32
R28/C24: -23.51
R6 2 Volt Drop
Q11/R29: -18.65
R4: 23.66
R31: -23.52
R9: 19.68
Q3/Q7: 5.57
R8/Q3 6.25
R24: .075
Q10: -18.32
R28/C24: -23.51
R6 2 Volt Drop
Q11/R29: -18.65
Need voltages at all 3 pins of Q4, Q11 and Q10.
Does twiddling P1 have any effect on the 0 voltage point?
As much as it seems like a good idea at times, it actually doesn't fix the problem at hand. 🙂 😀 🙂 😀
Does twiddling P1 have any effect on the 0 voltage point?
As much as it seems like a good idea at times, it actually doesn't fix the problem at hand. 🙂 😀 🙂 😀
Last edited:
Q4
D 18.52
G 0
S .24
Q10
C .24
B 18.35
E 18.82
Q11
C 22.41
B -18.21
E -18.39
Yes, turning P1 has a large effect on the test pad.
D 18.52
G 0
S .24
Q10
C .24
B 18.35
E 18.82
Q11
C 22.41
B -18.21
E -18.39
Yes, turning P1 has a large effect on the test pad.
Last edited:
I believe that's known as "percussive maintenance"! It often works as a last resort.
I hooked it up to the stereo system and it plays at normal levels now but I don't dare to run it long because Q11 is so hot (touching it for a few seconds becomes uncomfortable).
Could it be the wrong LED (not the same in both channels). I bought the one in the bad channel from Radio Shack thinking a red LED is a red LED.
Could it be the wrong LED (not the same in both channels). I bought the one in the bad channel from Radio Shack thinking a red LED is a red LED.
- Status
- Not open for further replies.