The pearl 2 phone pre that I just finished is not working and I can not figure out why. The rectified voltages look fine but after that everything goes pear shaped.
I replaced the zvp3310 (which is why they are airborne) in case I had statically damaged those components but that did not make any difference.
I checked all the resistor/cap values and semi placement but everything appears correct.
I attached a picture of one channel (both channels are not working in exactly same way) and a picture of the voltages I am reading (in pencil) compared to the expected values (in red)
If anyone can point me to a likely fault in the build that would be hugely appreciated.
I replaced the zvp3310 (which is why they are airborne) in case I had statically damaged those components but that did not make any difference.
I checked all the resistor/cap values and semi placement but everything appears correct.
I attached a picture of one channel (both channels are not working in exactly same way) and a picture of the voltages I am reading (in pencil) compared to the expected values (in red)
If anyone can point me to a likely fault in the build that would be hugely appreciated.
Last edited:
Please fix the photos.
Unless wrong parts are installed the same way in both channels,
the power supply is most likely the place to start.
Bad solder joints.
Your voltages don't make sense unless it is not really connected according to plan. Some of those solder joints look dubious to me. When there is more than one unrelated wrong reading, you probably have more not-really-connected solder joints than you know.
Get an old VCR and practice on the PCB, taking parts out, putting them back in, and ohm-metering the joints to prove they connect. Technique is everything. A not-crappy iron helps. Flux is essential.
Your voltages don't make sense unless it is not really connected according to plan. Some of those solder joints look dubious to me. When there is more than one unrelated wrong reading, you probably have more not-really-connected solder joints than you know.
Get an old VCR and practice on the PCB, taking parts out, putting them back in, and ohm-metering the joints to prove they connect. Technique is everything. A not-crappy iron helps. Flux is essential.
What do you mean by ''everything goes pear shaped'', and can you post a scope photo of that waveform.
Something's not right around R8 / R10.
Either bad solder joints, as PRR said, or the resistors are bad.
But your soldering technique looks suspicious there.
Suck the old solder with a solder sucker and then apply fresh new one with a suitable tip, heating equally the solder pads and the legs of the resistors.
Use 60/40 solder.
Try to get 9V at the base of that ztx450 first.
Either bad solder joints, as PRR said, or the resistors are bad.
But your soldering technique looks suspicious there.
Suck the old solder with a solder sucker and then apply fresh new one with a suitable tip, heating equally the solder pads and the legs of the resistors.
Use 60/40 solder.
Try to get 9V at the base of that ztx450 first.
I unsoldered the j74 bl9c and replaced them with the sk370. After plugging in I measured 8 volts on one channel at the zero point but I was able to adjust it down to 0v. The other channel was off by 1v and could also be adjusted correctly. A very promising sign.
I pulled an old cyrus amp and speakers and fired up the turntable. Sucess!
I pulled an old cyrus amp and speakers and fired up the turntable. Sucess!
Enjoy!Over the weekend I had a chance to try the Pearl 2 with my main turntable which has a Denon 103R. It was surprisingly good. Very very low background noise and no problems with gain. Based on some other diyaudio threads the 103R/Pearl 2 was suspect due to low output form the 103R but I did not find that to be a problem.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.