Decibel Dungeon Gainclone

Puffin · 30th November 2007, 09:57 AM

NuuK. I have put together an LM3886 as per your circuit (the only change being OR22, for which I used a 1R WW res as it was all I had.

I don't appear to have any output (yet seem to read -5v DC offset ?)

I have put together a power supply to run it with. the DC +V and
-V is 47.3V.

I am getting the following readings :-

Pin 1 - 3 37.3
Pin 1 - 4 40.3
Pin 1 - 7 32.2
Pin 1 - 8 34.6
Pin 1 - 9 36.3
Pin 1 - 10 32.2

By the way I am getting a strange reading from the PS, +V and OV = 32.5, -V and OV = 15V

Any help you can give would be appreciated.

Puffin · 30th November 2007, 11:17 AM

Don't know if photos will help

http://i73.photobucket.com/albums/i2...nsex/chip2.jpg

http://i73.photobucket.com/albums/i2...onsex/chip.jpg

Nuuk · 30th November 2007, 12:27 PM

First off, are your rails +/-47v or +/-37v?

Sherman · 30th November 2007, 12:35 PM

I believe he is saying his V+ rail is 32.5V and his V- rail is -15V for a total difference of 47.5V. Definitely something odd happening there.

Nuuk · 30th November 2007, 01:14 PM

I reckon you have a short somewhere! Disconnect the PSU from the chip and measure it again to make sure it is correct.

Then check for shorts.

The chip isn't insulated from the heatsink is it?

Check for any shorts.

Are you using a muting cap?

Puffin · 30th November 2007, 01:27 PM

It is insulated. I have attached th 100uf cap to pin 8

Nuuk · 30th November 2007, 02:50 PM

And how about the PSU voltages when it is not attached to the chip?

audio1st · 30th November 2007, 02:57 PM

Hello Puffin, i can see no V- connection to pin 4..?The neg side of that 1000uf cap connects to 4 as well, with the pos side to ground..

Nuuk · 30th November 2007, 03:04 PM

I wondered about that as well, but if the neg rail isn't connected, he should be getting the full rail voltage on the output!

Puffin · 30th November 2007, 03:47 PM

NuuK. Voltage with chip disconnected +v and -v = 60.6, +v and Ov =32.8, -v and Ov = 27.8

With chip connected +v and -v is 47.1, +v and Ov is 32.10 , -v and Ov is -15v

30th November 2007, 09:57 AM	#1
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	Decibel Dungeon Gainclone NuuK. I have put together an LM3886 as per your circuit (the only change being OR22, for which I used a 1R WW res as it was all I had. I don't appear to have any output (yet seem to read -5v DC offset ?) I have put together a power supply to run it with. the DC +V and -V is 47.3V. I am getting the following readings :- Pin 1 - 3 37.3 Pin 1 - 4 40.3 Pin 1 - 7 32.2 Pin 1 - 8 34.6 Pin 1 - 9 36.3 Pin 1 - 10 32.2 By the way I am getting a strange reading from the PS, +V and OV = 32.5, -V and OV = 15V Any help you can give would be appreciated.

30th November 2007, 12:27 PM	#3
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	First off, are your rails +/-47v or +/-37v? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

30th November 2007, 12:35 PM	#4
Sherman diyAudio Member Join Date: Feb 2004 Location: Chicago area	I believe he is saying his V+ rail is 32.5V and his V- rail is -15V for a total difference of 47.5V. Definitely something odd happening there. __________________ --Sherman

30th November 2007, 01:14 PM	#5
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	I reckon you have a short somewhere! Disconnect the PSU from the chip and measure it again to make sure it is correct. Then check for shorts. The chip isn't insulated from the heatsink is it? Check for any shorts. Are you using a muting cap? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

30th November 2007, 02:50 PM	#7
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	And how about the PSU voltages when it is not attached to the chip? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.


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30th November 2007, 11:17 AM	#2
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	Don't know if photos will help http://i73.photobucket.com/albums/i2...nsex/chip2.jpg http://i73.photobucket.com/albums/i2...onsex/chip.jpg

30th November 2007, 01:27 PM	#6
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	It is insulated. I have attached th 100uf cap to pin 8

30th November 2007, 02:57 PM	#8
audio1st diyAudio Member Join Date: May 2005 Location: Foxton, CAMBS..	Hello Puffin, i can see no V- connection to pin 4..?The neg side of that 1000uf cap connects to 4 as well, with the pos side to ground..

30th November 2007, 03:04 PM	#9
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	I wondered about that as well, but if the neg rail isn't connected, he should be getting the full rail voltage on the output! __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

30th November 2007, 03:47 PM	#10
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	NuuK. Voltage with chip disconnected +v and -v = 60.6, +v and Ov =32.8, -v and Ov = 27.8 With chip connected +v and -v is 47.1, +v and Ov is 32.10 , -v and Ov is -15v

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