Pumpkin preamp - ordered by Steen , official making thread - Page 342 - diyAudio
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Old 28th November 2012, 04:54 AM   #3411
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Led string tested with voltage 11.8V, led light up, so i guest led orientation not wrong. Led Vf=1.97V.

Didiet
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Old 28th November 2012, 05:39 AM   #3412
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ZM. how was it with bords for dis thing?
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Old 28th November 2012, 08:22 AM   #3413
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by didiet78 View Post
Led string tested with voltage 11.8V, led light up, so i guest led orientation not wrong. Led Vf=1.97V.

Didiet
I was looking last night at your pcbs and I still can't find what's wrong

will try harder

Quote:
Originally Posted by AudioSan View Post
ZM. how was it with bords for dis thing?
still waiting for Paypal in Serbia

most probably in a month or two , but even then I can't be sure will they include receive money option from start
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Old 28th November 2012, 08:51 AM   #3414
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If i change Led with higher Vf (maybe White or Blue Led) will it make Voltage higher (Gate Q11 and V-) ?
Thank for checking.

Didiet
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Old 28th November 2012, 09:12 AM   #3415
Zen Mod is offline Zen Mod  Serbia
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certainly ;

but - why doing that ?
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Old 28th November 2012, 09:54 AM   #3416
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Because i just use LTSpice to sim Led String CCS, and i got 5V, maybe my sim not right.

Update : i lift Gate resistor of CCS output (Q6 and Q8), Led String light up, measure it 11,4V. Howto check mosfet, good or bad ? check with my ohm meter pin G-S i got 220 ohm ( on both Channel, Q6 and Q8)
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Old 28th November 2012, 10:01 AM   #3417
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Quote:
Originally Posted by Zen Mod View Post
I was looking last night at your pcbs and I still can't find what's wrong

will try harder



still waiting for Paypal in Serbia

most probably in a month or two , but even then I can't be sure will they include receive money option from start
aha. bummer. they need some
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Old 3rd December 2012, 10:44 AM   #3418
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Replace Q6 and Q8 (IRF610), LED string light up (just one channel). I guest Q6 and Q8 on the other channel need replacement too.

Didiet
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Old 5th December 2012, 11:00 AM   #3419
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Q6 and Q8 are faulty. Replace quad of them. On one channel, i can set the offset betwen - gnd and + gnd to get 20mV. Betwen - and + i get 2mV.
On the other chanel i only can get - gnd, + gnd 16V. Betwen - + 2 Volt.

I think Q9 fault too. I'll check again tomorrow

Didiet
Attached Images
File Type: jpg The Pumpkin - Shunty_Page_02.jpg (78.6 KB, 167 views)
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Old 5th December 2012, 09:03 PM   #3420
tonimxp is offline tonimxp  Italy
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Default 2sj310 matching

Hi at all! Please i just make the matching of 2sj310 (Q1 and Q2) jfet of Pumpink with Zen mod's circuit matcher.
I have found those values of Vgs:
180-184-(187-188)-(193-196) mV so i have match as in parenthesis.

I have to ask you your comments for results.
The current draw is set to 5mA for five minutes test time.

In addition I also bought some 2sj109 used (for future aleph j babbelfish project), can you suggest a method to test their genuineness?

Please can you let me know?

In attached some pictures please to know some comments for results.
Attached Images
File Type: jpg IMG_20121203_161118.jpg (589.3 KB, 144 views)
File Type: jpg IMG_20121203_161544.jpg (761.8 KB, 128 views)
File Type: jpg IMG_20121203_161717.jpg (754.0 KB, 118 views)
File Type: jpg IMG_20121203_163929.jpg (385.4 KB, 72 views)
File Type: jpg IMG_20121203_164901.jpg (532.5 KB, 33 views)

Last edited by tonimxp; 5th December 2012 at 09:12 PM.
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