I just checked with 9V battery and get 8.9V on both devices. I also checked with a 100 ohm resistor and measured across it and both are closely matched.
Actually, I just checked again and it appears the 2 Fets are about 3ma different where the K170 measures 7.3ma and the j74 measures 7.7ma.
I resoldered everything, checked my resistor values, and put the board back in. Still have issues with one channel louder than the other...
Any other ideas?
Any other ideas?
there are so many parts inside ....... best to check them all , at least visually 🙂
after JFets, R3 and R4 being first candidates, ref. to schm Jim posted in #1
with power off, after visual inspection of all parts, waste some time fiddling with ohmmeter - checking all resistors m comparing good and bad channel
most of measurements will be inconclusive (absolutely) with parts still in circuit, but maybe somewhere you'll spot a difference between channels
after JFets, R3 and R4 being first candidates, ref. to schm Jim posted in #1
with power off, after visual inspection of all parts, waste some time fiddling with ohmmeter - checking all resistors m comparing good and bad channel
most of measurements will be inconclusive (absolutely) with parts still in circuit, but maybe somewhere you'll spot a difference between channels
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R1 and R2 are good. I’ll check resistances like you said and see if I can find the differences.
if you were able to properly set Iq and Offset, no doubts in xformer secondaries
just in case, check continuity of primary
just in case, check continuity of primary
What do you mean by that? Are you referring to the Jensen transformer or the Antek Power transfomer?
Yes. I am easily able to set BIAS and Dc Offset.
Yes. I am easily able to set BIAS and Dc Offset.
I’m reviewing the Jensen PIN-out. The bottom of the transformer which faces up in the amp
matches continuity tests on on both sides. I can’t easily get to the opposite side of the transformer so I’ll try tomorrow.
matches continuity tests on on both sides. I can’t easily get to the opposite side of the transformer so I’ll try tomorrow.
it is recommended to test every component out of the board , it may takes some time , but what is properly made has not to be made again 😉
and at the end you will have all your solder joint new 😀
.
and at the end you will have all your solder joint new 😀
.
Im trying to bias channel B.
Channel A is fine.
Each time i power up, R4 starts to smoke.
Bias voltage is low at 0.98mv
Any ideas.
Thanks.
Channel A is fine.
Each time i power up, R4 starts to smoke.
Bias voltage is low at 0.98mv
Any ideas.
Thanks.
R4 smoking means you have a bad (shorted) Jfet, a solder bridge near the jfets, or a short in the transformer.
I figured out my problem.... one of my 1000uf caps had a broken leg from me trimming/bending it to fit the board.. after replacing it the right channel now matches the left.
This cap I had to move around quite a bit to install the trimmer pot so I know that’s how I snapped it.
Amp sounds great and biased fine to .6V. I may try .65V after letting it play for a week.
This cap I had to move around quite a bit to install the trimmer pot so I know that’s how I snapped it.
Amp sounds great and biased fine to .6V. I may try .65V after letting it play for a week.
I would like to say thank you to
Nelson Pass,2picoDumbs,meanie,6L6 and people who support for build and
diyaudio forum.
I could not build without support but learned a lot from trouble,also apologize for my mess.
Now my fullranges sounding fantastic. Biased 1.5A
Vocal is soft and smooth and slapping percussions tight.
I have changed some parts for my taste,still waiting for Panasonic erx.
I also addicted to build so I ordered aleph J and Ba-3 PCB...
Nelson Pass,2picoDumbs,meanie,6L6 and people who support for build and
diyaudio forum.
I could not build without support but learned a lot from trouble,also apologize for my mess.
Now my fullranges sounding fantastic. Biased 1.5A
Vocal is soft and smooth and slapping percussions tight.
I have changed some parts for my taste,still waiting for Panasonic erx.
I also addicted to build so I ordered aleph J and Ba-3 PCB...
