Go Back   Home > Forums > General Interest > Car Audio

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 27th August 2012, 10:54 PM   #21
diyAudio Member
 
Join Date: Dec 2005
Location: Northern California
0.1 mv will work and not cause any undue heating of the semi's after that you can raise it as you like I am thinking...
  Reply With Quote
Old 27th August 2012, 11:08 PM   #22
diyAudio Member
 
Join Date: Apr 2011
Location: Anchorage AK
i generally set them using the current meter. perry has a little interactive simulation. back them off to zero, then slowly raise to the point that current starts to barely draw, and repeat.
  Reply With Quote
Old 28th August 2012, 01:32 AM   #23
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
Got it... So since it a 4 channel amp, I thinking turn all 4 pots down, start with one and bring it up until the current draw is 1/2 amp, then do this to the remaining 3 channels so I get a total of 2 amps idle?

Originally Posted by Perry Babin

As was suggested, you need to bias the transistors. If you have a power supply with an amp meter, set it as is shown in the following demo.
http://www.bcae1.com/temp/ausettingbias.swf

Last edited by 90scaraudio; 28th August 2012 at 02:01 AM.
  Reply With Quote
Old 28th August 2012, 06:10 AM   #24
diyAudio Member
 
Join Date: Apr 2011
Location: Anchorage AK
i pay less attention to how much it is, as long as it is in a good range at idle. it could be 1.5-3a idle typically, but anyways, it goes like the demo x4. back all off, like you mentioned, and raise them until the current just starts to pick-up. sometimes i do it a few times to be sure. then move to the next, and repeat until all are done.
  Reply With Quote
Old 2nd September 2012, 09:02 PM   #25
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
Think I'm finished...
On channel 3 which is rear left, I replaced the MPSA06 near the finals, replaced a TIP102 and 107 Which are part of the finals. Pulled a TIP35C but it was good.

I really don't think the problem was in the final area as everything I pulled was good. So on to the next...

I replaced the 2N6715 and 10uf 50v, part of the PWM, don't think they were bad.

Pulled the 4700uf 50v caps, they are good.

Around the NAND Gates, I replaced two MPSA06 and one MPSA56, again, don't think they were bad.

Replaced the two J109 on channel three, they weren't bad but I could smell capacitor liquid. Cleaned it the best I could.

Replaced the two NAND Gates

Replaced 12 OP-Amps, No more static noise now.

OK, When I pulled the CENU-07 and CENU-57 from channels one and three, I did not use enough heat and pulled small traces off the board. Spent about 4 hours repairing them

Idle current is back to 2Amps.

Adjusted bias so now Idle is about 2.2 amps.

Not sure what fixed it, maybe cleaning the rest of the leaky cap off the board?

Now just have to put it all back together
Attached Images
File Type: jpg IMG_2130.JPG (298.6 KB, 61 views)
File Type: jpg 1a.JPG (284.1 KB, 56 views)
File Type: jpg 2a.JPG (290.3 KB, 54 views)
File Type: jpg 3a.JPG (323.1 KB, 55 views)
  Reply With Quote
Old 2nd September 2012, 10:58 PM   #26
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
These are the traces that pulled and ripped off the board.
Also when cleaning this transistor and resistor came off and the pads were very corroded. NOT FUN!!!

Also the semi and cap I changed by the PWM

And the Semis plus NAND Gates.
Attached Images
File Type: jpg Traces.jpg (502.1 KB, 49 views)
File Type: jpg PWM.jpg (172.7 KB, 32 views)
File Type: jpg Nand.jpg (231.4 KB, 33 views)

Last edited by 90scaraudio; 2nd September 2012 at 11:11 PM.
  Reply With Quote
Old 3rd September 2012, 03:55 PM   #27
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
OK, For testing, I pulled two of the four 4700uf caps out. When I reinstalled them, it went back to protect mode. Every thing I've read and most Soundstreams use 1000uf caps for filtering. Is it ok to use 1000uf caps on this Zapco?
  Reply With Quote
Old 3rd September 2012, 07:56 PM   #28
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
Well I put in 4 new 1000uf 50v caps and it turns on with no faults and no big surge of current. Now I have to push it to almost clip to see if I made any mistakes, so far I've run it to the limit of one of my power supplies and the wife yelled at me...OOOPPPPs. Its a 12 amp supply.

Thanks all about the bias adjust info, really works...
  Reply With Quote
Old 3rd September 2012, 10:29 PM   #29
diyAudio Member
 
Join Date: Apr 2011
Location: Anchorage AK
not sure about pushing it ti clip yet. you may encounter a little noise there, since you now have less that a quarter of the capacitance at the rail, and some of the lower frequencies may come through, like the a/c ripple (alt whine) which might come through the power supply. not sure, but it is a possibility. are you planning on going back to larger caps? did you find a bad one?
  Reply With Quote
Old 3rd September 2012, 10:49 PM   #30
diyAudio Member
 
90scaraudio's Avatar
 
Join Date: Aug 2012
Location: ILLINOIS
They are old and they ohm out ok but with them in circuit the amp struggles to start. Plus these boards are so fricken delicate, when I was pulling two of the caps, two of the circular feed through that sits in the hole came out. The positive rail has the main trace in one of the inner layers and that sucks to fix. The ripple with the old caps was about 30 mv, now its down to 2 or 3 mv. I may get larger value caps at a latter time.

How come the old Soundstream reference 1000s only has two 1000uf 50v caps for its rail? See pic...
Attached Images
File Type: jpg rail caps.jpg (105.9 KB, 27 views)
  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
Zapco Z400C4-SL noisegate jumperboard? gisewhcs Car Audio 1 6th January 2012 07:04 PM
Zapco Z400C4-SL missing it's fan gisewhcs Car Audio 4 10th May 2011 04:28 PM
Zapco Z400c4-SL no power supply fongman Car Audio 36 15th March 2010 06:00 PM
Zapco z400c4-vx problem shallowfu Car Audio 17 4th November 2006 04:14 PM
Zapco Z400C4-SL scott-leanne Car Audio 23 13th May 2006 07:44 PM


New To Site? Need Help?

All times are GMT. The time now is 04:32 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