Threshold 400a manual/schematic needed.

harhaug · 23rd June 2004, 07:18 PM

Hi.

I would like to get my hands on a schematic, or better yet, a service manual for the Threshold 400a. Mr. Pass didn't have it. Anyone?

- Thanks

Harald

gl · 23rd June 2004, 08:09 PM

harhaug,

I have a factory schematic for this and the 4000A. This is the second request to come up in the last week or so. I don't have the facilities to scan files so I have put these and others into the snail mail to Mr. Pass. He should have them in a few days. Perhaps he would be kind enough to post them.

Graeme

Nelson Pass · 23rd June 2004, 08:21 PM

I believe Jon Soderberg at vintageamp@earthlink.net sells
copies. If not, maybe Jam has it. If all else fails, I can reconstruct
most of it from memory.

jam · 23rd June 2004, 08:35 PM

Mr. Pass and Harland,

I might have it. Let me check and I will let you know tomorrow.

Regards,

Jam

Tom2 · 24th June 2004, 02:17 AM

Mr. Pass,
I also have a 400A schematic. I reversed engineered the main
circuit board along with the power output stage board/heasink
assembly of one of the channels some time ago.

It shows all the components.(I think)
It has all the resistor values, some of the semiconductor numbers
and some of the capacitor values.

Perhaps you could fill in the unknown electrolytic capacitor values.
I am planning to change the electrolytics soon in my 400A.

I can copy it and send it to you.

Tom

Nelson Pass · 26th June 2004, 07:04 PM

Gl has graciously sent a number of schematics. I'll post
them shortly.

Nelson Pass · 30th June 2004, 08:29 PM

Sorry about the delay. I edited a swell copy of this schematic
but I keep forgetting to bring it in and I can't ftp from home.

so use the original 500K tif:

www.passlabs.com/np/400a-4000.tif

jan.didden · 30th June 2004, 08:40 PM

Quote:

Originally posted by Nelson Pass
Sorry about the delay. I edited a swell copy of this schematic
but I keep forgetting to bring it in and I can't ftp from home.

so use the original 500K tif:

www.passlabs.com/np/400a-4000.tif

My god Mr Pass, you've come a long way indeed!

Jan Didden

Nelson Pass · 30th June 2004, 08:50 PM

Progress is our most important product.

anatech · 1st July 2004, 02:36 AM

Many Thanks Nelson!
Got one for a Nakamichi PA-7?

23rd June 2004, 07:18 PM	#1
harhaug diyAudio Member Join Date: May 2004 Location: Oslo, Norway	Threshold 400a manual/schematic needed. Hi. I would like to get my hands on a schematic, or better yet, a service manual for the Threshold 400a. Mr. Pass didn't have it. Anyone? - Thanks Harald

24th June 2004, 02:17 AM	#5
Tom2 diyAudio Member Join Date: Jun 2004 Location: Central CA	400A schematic Mr. Pass, I also have a 400A schematic. I reversed engineered the main circuit board along with the power output stage board/heasink assembly of one of the channels some time ago. It shows all the components.(I think) It has all the resistor values, some of the semiconductor numbers and some of the capacitor values. Perhaps you could fill in the unknown electrolytic capacitor values. I am planning to change the electrolytics soon in my 400A. I can copy it and send it to you. Tom

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23rd June 2004, 08:09 PM	#2
gl diyAudio Member Join Date: Dec 2003 Location: Sierra Foothills - California	harhaug, I have a factory schematic for this and the 4000A. This is the second request to come up in the last week or so. I don't have the facilities to scan files so I have put these and others into the snail mail to Mr. Pass. He should have them in a few days. Perhaps he would be kind enough to post them. Graeme

23rd June 2004, 08:21 PM	#3
Nelson Pass The one and only Join Date: Mar 2001	I believe Jon Soderberg at vintageamp@earthlink.net sells copies. If not, maybe Jam has it. If all else fails, I can reconstruct most of it from memory.

23rd June 2004, 08:35 PM	#4
jam diyAudio Member Join Date: May 2001 Location: Charlotte,NC,USA	Mr. Pass and Harland, I might have it. Let me check and I will let you know tomorrow. Regards, Jam

26th June 2004, 07:04 PM	#6
Nelson Pass The one and only Join Date: Mar 2001	Gl has graciously sent a number of schematics. I'll post them shortly.

30th June 2004, 08:29 PM	#7
Nelson Pass The one and only Join Date: Mar 2001	Sorry about the delay. I edited a swell copy of this schematic but I keep forgetting to bring it in and I can't ftp from home. so use the original 500K tif: www.passlabs.com/np/400a-4000.tif

30th June 2004, 08:50 PM	#9
Nelson Pass The one and only Join Date: Mar 2001	Progress is our most important product.

1st July 2004, 02:36 AM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Many Thanks Nelson! Got one for a Nakamichi PA-7?