Jolida JD-3000A Schematic

[mgalusha]

Just wondering if anyone has a copy of the Jolida JD-3000A schematic. I recently acquired a pair of these amps and they both are oscillating at about 161kHz at about 5W of power output. Yep, lovely radio transmitters and yes, that is with a non inductive resistor load and the input shorted. I've started tracing out the board but that of course won't tell me if the part values in mine actually match the design and it's not a quick process. Something is obviously amiss since both amps exhibit the same behavior.

So far my request to Jolida has not resulted in much, so if anyone has this I'd be mighty grateful.

Mike

[richidoo]

Sorry about your trouble Mike. Both amps... that sounds fishy.

Maybe this guy has it, or knows who to ask.
http://www.drtube.com/schematics/jolida/sj-502a.gif
http://www.drtube.com/askdrtube.htm

I'll ask some local guys.

[mgalusha]

Thanks Rich, I'm hoping someone will be able to help out.

I've an idea of how to address the problem but a schematic would of course be most helpful.

[Response Audio]

Hello Mike,
I have not forgotten about you. I packed up many of my schematics after doing away with modification work but I know I have it along with hundreds of others.

I just have to get the box out that contains all the Jolida schematics. I will pull through for you. Maybe even by the end of the day

[Response Audio]

Hey there Mike,
A quick question, what speaker cable are you running with these amps? Is it a smaller gauge? Anything smaller that 14 AWG can cause problems with the amps as well as trouble biasing.

[mgalusha]

Thanks Bill. I was determined not to bug you. The last thing I want to do is take advantage of anyone, hence my attempt to purchase them from Jolida.

The cables in the system are Kaplan GS, which is about equivalent to 7GA. They oscillate sitting on my bench as well as in the system. I believe the cables on the resistive load are 16GA but they might be 14. Have to check. I did put the load on my LCR bridge and ran it up to 10Khz, it's highest test freq, and the resistance barely changes from DC, so pretty much non inductive.

Mike

[Response Audio]

No Worries about bugging me Mike. It has been a bit hectic in my brain with the holiday season and gearing up for further Purity production. I just have to ask a favor of you now. I have the schematic in the envelope but your address is on my other computer. Can you PM it to me here?

[mgalusha]

Done, thanks!

[alx_d]

Hi,

I am new to this forum and saw this interesting post.  I would like to know if you ever found out the problem and what was the solution?  I am currently considering buying a used pair and would like as much feedback as I can get before I buy.

Regards
Alexander

[MartyRL]

Hi - I also just purchased a pair of 3000A Monoblocks - one has good bias - the other is running at a little over 1V.  Did you ever find some schematics? 

[Nick B]

Hi - I also just purchased a pair of 3000A Monoblocks - one has good bias - the other is running at a little over 1V.  Did you ever find some schematics? 

It seems Mike hasn't been active on this site for over a year. Good luck re the schematics and welcome to AN
Nick

[sleepyguy24]

Hi - I also just purchased a pair of 3000A Monoblocks - one has good bias - the other is running at a little over 1V.  Did you ever find some schematics? 

Welcome to the forum MartyRL

Try contacting Scott Gramlich of SG Custom Sound

40-33 235th St, Little Neck, NY 11363
(718) 224-5083

http://www.sgcustomsound.com/

Scott REALLY knows Jolida stuff. He worked on my JD-502P amp some years ago.

[rollo]

  Good call Scot has it.


charles