BOSOZ Problem - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th July 2007, 02:03 PM   #1
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
Default BOSOZ Problem

Hi All,

I need some troubleshooting help. I finished building the BOSOZ with separate PS and preamp circuit. I tested the PS and it's fine. After connecting the preamp fuses blow. I used 1 & 2 amp slow-blow fuses.

I built the circuit based on the article with a few exceptions:

-Used 2 power supply circuits- one for each channel.

-Used 4- 28.4V + 28.4V transformers at around 3-5 amps each. (I know overkill, but they were cheap.) Too much power on surge maybe??

-The FETs on the preamp are not bedded down on the circuit board. They are upright. The center pin is soldered to the connection where the case would be screwed down.

-The switch has a built-in fuse holder. It requires 2 fuses. The circuit only required one. I used 2 fuses.

The PS output voltage is 58+/-. The zenner array on the PS is set for the 60v setup.

No burn or burn odor emmitted when powered on.

Test equipment I have available: analog meter, 2 digital meters and a dual channel scope and Radio Shack transitor checker. And of course the light bulb socket thingy. I haven't learned how to use the scope yet.

When testing the PS, I used the light bulb trick, and it actual helped fix a ground problem. Can I use it again to help futher troubleshoot this issue?

Your suggestion are greatly appreciated.

Vince
  Reply With Quote
Old 30th July 2007, 02:50 PM   #2
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
A couple of pics of the whole setup and connections would make it easier to figure for us

Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
  Reply With Quote
Old 30th July 2007, 02:57 PM   #3
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Default Re: BOSOZ Problem

Quote:
Originally posted by vdi_nenna


-Used 4- 28.4V + 28.4V transformers at around 3-5 amps each. (I know overkill, but they were cheap.) Too much power on surge maybe??

Without knowing your fuse size, I think most probably . . .
Did you have NTC thermistors on the primary side?
Otherwise, try them.
If this doesn't work, there must be unwanted short circuit.



  Reply With Quote
Old 30th July 2007, 03:50 PM   #4
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
Hi Babowana,

No, there are no NTC thermistors on the front side, just what was indicated on the PS schematic. Should I try one for each side of AC in?

Quote:
A couple of pics of the whole setup and connections would make it easier to figure for us
Oh, I don't know...it's kind of ugly. I don't want to embarrass myself in light of all Your great projects. But, for the sake of fixing it, I will post a few pics.

One other thing-
Also, when I had it plugged in to my amps and speakers, even though there was no power, if I turned up the pot on the preamp, there was some distorted sound coming from the speakers.

V~
  Reply With Quote
Old 1st August 2007, 01:20 PM   #5
Fox is offline Fox  Netherlands
diyAudio Member
 
Fox's Avatar
 
Join Date: Dec 2002
Location: The Netherlands
Quote:
Too much power on surge maybe??
If I understand you correctly, than you use 4 transformers and 1 fuse.

With respect to the fuse: did you increase the value of the fuse, i.e. 4 times the nominal value, or do you use a fuse that is appropriate for only one transformer?

Hope this helps,

Fox
  Reply With Quote
Old 1st August 2007, 02:03 PM   #6
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
Quote:
fuse: did you increase the value of the fuse, i.e. 4 times the nominal value
Hi Fox- I used 2 fuses, one for each AC in after the power plug.
I used 1 amp and 2 amp slow-blow fuses.

There are 4 transformers, 2 for each power supply. These are 3-4 amps each.
  Reply With Quote
Old 1st August 2007, 08:54 PM   #7
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Quote:
Originally posted by vdi_nenna


No, there are no NTC thermistors on the front side, just what was indicated on the PS schematic. Should I try one for each side of AC in?

I would try one for each side of trnsfomers' primaries.
They could be of help for the trouble, or at least for the softer start.


  Reply With Quote
Old 2nd August 2007, 05:34 PM   #8
Mad_K is offline Mad_K  Norway
diyAudio Member
 
Mad_K's Avatar
 
Join Date: Sep 2002
Location: Norway
Have you measured V+ and V- on each channel against (short to) ground?
If the fuses does not blow with only the psus connected it is unlikely to blow when you add the circuit.
__________________
Mads K
  Reply With Quote
Old 3rd August 2007, 05:52 PM   #9
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
No go. There's a major problem. I have to recheck the wiring.
The NTC thermistors didn't help.

Best thing to test the PSUs is use a 15k resistor to ground, correct? I'm going to test everything and use only 1 PSU, instead of 2 to reduce failure points.

I'm really bummed.

Thanks,

Vince
  Reply With Quote
Old 2nd September 2007, 03:29 PM   #10
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
Default Still Blowing Fuses

I wired up the PS with only one PS board and tested it with 15k resistors. I get about 58 volts +- and no blown fuses.

I checked the caps on the audio board by using an analog multimeter. The needle jumps and slowly dropped on all caps.
I'm not sure if this test works for caps when installed on the PCB.
The resistors check out ok. The zeners all show about the same resistance. Their orientation looks ok.

On the audio board I swapped out all 4 IRF610 MosFETs just in case. This time I bolted the FETS and heatsinks to the board. I'm still blowing fuses.

I'm not sure what else to do. I may remove the switch with the built in double fuse holder. Maybe that's the wrong part for this type of circuit?

Should I start with a new PCB and all new parts?

Any suggestions would be nice.

Thanks,

Vince
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
BOSOZ Hum Problem hifileslie Pass Labs 12 18th September 2007 04:28 PM
Bosoz psu problem vit Pass Labs 10 21st August 2005 10:10 PM
more bosoz problem. when will it end! cowanrg Pass Labs 16 20th July 2005 05:51 AM
BOSOZ PSU problem tcl2 Pass Labs 7 5th July 2004 03:08 PM
Bosoz PSU problem CH2 Pass Labs 3 28th June 2003 04:08 PM


New To Site? Need Help?

All times are GMT. The time now is 07:11 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2