chipamp PSU problem, need help

sith · 24th February 2006, 01:01 PM

Hi there, I already asked question on ChipAmps forum , but nobody seems to know how to solve problem...

Just finished, PA100, chipamp and snuberized regulated PSU.

Testing one chanel (board) everything is beautiful, rail voltage is steady +/-27V, dc-offset 15mV, testing other the same thing... Absolutely beautiful...

Now the funny part, when I connected both channels(boards) to a PSU I got massive voltage drop and negative LM388 got too hot to touch... I used a single power tranny (separate windings), a single PSU, two rectifiers (ready made, rated 7A) LM388 regulators... So, every board works perfectly, but when they are both in system sh.. hits the fan...

Alexw amp.
http://shine7.com/audio/pa100.htm

Regulated psu , nuuk's pages http://myweb.tiscali.co.uk/nuukspot...gainclone6.html

Leolabs · 26th February 2006, 03:14 PM

Did you test each board separately???

sith · 26th February 2006, 06:22 PM

Quote:

Did you test each board separately???

Yes, each board works perfectly, but when they r connected together they don't work...

I want to try 'classic' PSU (no regulators, just cappacitors) but I get +/- 38 volts at rails, is that too much for 3886 (2x2 per channel)???

Bazukaz · 26th February 2006, 06:55 PM

LM3886 does not need a regulated power supply.Feel free to try +-38 volts(These chips can handle +-42V).However , continous operation at +-38 Volts is only considerable if your loadspeaker impedance is >=8 ohms.LM3886's has an unique Spike protection , which is annoying when turns on , but keeps output transistor array in safe temperature range.

Regards,
Lukas.

sith · 1st March 2006, 06:35 AM

Just tryed 'classic' (unregulated) PSU everything worked perfectly

Funny thing, regulated PSU works with 3775

Nordic · 1st March 2006, 06:47 AM

Just how much current can that regulator deliver?

sith · 1st March 2006, 08:24 AM

Quote:

Just how much current can that regulator deliver?

5A peak 12.... according LM338 datasheet

Nordic · 1st March 2006, 10:19 AM

Yeah, thats plenty, and did you add the caps as per the datasheet for stability etc...?

Also as per usual with error checking new stuff, grab your multimeter and check every single resistor!

Good luck.

jimbo1968 · 2nd March 2006, 12:11 PM

sith, Are you monster/shine7? or did you buy his PCBs? Or did you fabricate the pcbs?

Afraid I can't help with your problem, just interested in the above.

sith · 3rd March 2006, 06:22 AM

Quote:

sith, Are you monster/shine7? or did you buy his PCBs? Or did you fabricate the pcbs?

no Monster/Shine7 is AlexW from forum here, and no i didn't buy PCB , just did plain old p2p using euro board...

24th February 2006, 01:01 PM	#1
sith diyAudio Member Join Date: Nov 2003 Location: Split	chipamp PSU problem, need help Hi there, I already asked question on ChipAmps forum , but nobody seems to know how to solve problem... Just finished, PA100, chipamp and snuberized regulated PSU. Testing one chanel (board) everything is beautiful, rail voltage is steady +/-27V, dc-offset 15mV, testing other the same thing... Absolutely beautiful... Now the funny part, when I connected both channels(boards) to a PSU I got massive voltage drop and negative LM388 got too hot to touch... I used a single power tranny (separate windings), a single PSU, two rectifiers (ready made, rated 7A) LM388 regulators... So, every board works perfectly, but when they are both in system sh.. hits the fan... Alexw amp. http://shine7.com/audio/pa100.htm Regulated psu , nuuk's pages http://myweb.tiscali.co.uk/nuukspot...gainclone6.html __________________ There is no spoon...there is a fork!!!

1st March 2006, 06:35 AM	#5
sith diyAudio Member Join Date: Nov 2003 Location: Split	Just tryed 'classic' (unregulated) PSU everything worked perfectly Funny thing, regulated PSU works with 3775 __________________ There is no spoon...there is a fork!!!

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26th February 2006, 03:14 PM	#2
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Did you test each board separately???

26th February 2006, 06:55 PM	#4
Bazukaz diyAudio Member Join Date: Nov 2005 Location: Vilnius	LM3886 does not need a regulated power supply.Feel free to try +-38 volts(These chips can handle +-42V).However , continous operation at +-38 Volts is only considerable if your loadspeaker impedance is >=8 ohms.LM3886's has an unique Spike protection , which is annoying when turns on , but keeps output transistor array in safe temperature range. Regards, Lukas.

1st March 2006, 06:47 AM	#6
Nordic diyAudio Member Join Date: Sep 2005	Just how much current can that regulator deliver?

1st March 2006, 10:19 AM	#8
Nordic diyAudio Member Join Date: Sep 2005	Yeah, thats plenty, and did you add the caps as per the datasheet for stability etc...? Also as per usual with error checking new stuff, grab your multimeter and check every single resistor! Good luck.

2nd March 2006, 12:11 PM	#9
jimbo1968 diyAudio Member Join Date: Nov 2004 Location: UK, bristol	sith, Are you monster/shine7? or did you buy his PCBs? Or did you fabricate the pcbs? Afraid I can't help with your problem, just interested in the above.

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