Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Punch 851s
Punch 851s
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 March 2020, 03:53 AM   #1
ray9043 is offline ray9043  Mexico
diyAudio Member
 
Join Date: Mar 2008
Default Punch 851s

Hi! I have a punch 851s, it comes with the lm317 shortcircuit. Replace it and again in short. Find d3 in short and replace it, im testing with a lm7815 for the moment.

I pull out all output mosfets, all are ok. Rail caps out of the board for test.

I have +- 47 volts on rail. -20v on 640 gates and +20 v on 9640 gates, so if i put one and one the ps shuts off, both are on at the same time.

The first problem with the lm317 in short was +47 volts instead of +20 volts on the control circuit. 4 47ohm resistors replaced because the high voltage. All 1am and 2a and 1q smd transistor are ok. Bias pots 2k ohm readings are ok. A56 and a06 ok.

I have the 800a2 schematic, are the same board.

Any ideas?
  Reply With Quote
Old 27th March 2020, 05:38 AM   #2
Perry Babin is offline Perry Babin  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
With any of the components inside the feedback loop out of the circuit (including the outputs), you cannot use the voltages for troubleshooting.

Reinstall the outputs, set the bias pots fully CCW and power the amp up through a limiter. Does it power up?
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version.
  Reply With Quote
Old 29th March 2020, 04:27 AM   #3
ray9043 is offline ray9043  Mexico
diyAudio Member
 
Join Date: Mar 2008
One channel installed, 2 1am transistor replaced, q301 and q207. Now the ps only does 14v, no dc voltage at speaker terminals
  Reply With Quote
Old 29th March 2020, 04:39 AM   #4
Perry Babin is offline Perry Babin  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Are you saying that the rail voltage won't go above 14v?

What are you using for a 12v power supply?

How much current is thew amp drawing?

Did you set the bias pots fully CCW after replacing the parts?
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version.
  Reply With Quote
Old 29th March 2020, 08:13 PM   #5
ray9043 is offline ray9043  Mexico
diyAudio Member
 
Join Date: Mar 2008
Bias fully ccw, 20amp ps for test. Nothing above 14v.

With the 9640 source resistors desoldered the ps does 47 volts but i have heat from lm regulator and q304, q305 and q307.
  Reply With Quote
Old 29th March 2020, 09:26 PM   #6
Perry Babin is offline Perry Babin  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
If you powered the amp up with the source resistors out of the circuit, you likely damaged the protection circuit.

Do you have a 2 ohm limiting resistor?

Is that 14v or just 14v?
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version.
  Reply With Quote

Reply


Punch 851sHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Punch 250M vs Punch 500M seankane Car Audio 30 26th January 2016 12:35 PM
rockford 851s rare problem stoke Car Audio 10 9th May 2011 11:32 PM
Help with rockford 851s stoke Car Audio 34 8th February 2011 05:03 PM
Selling a punch 250a2, old punch 75, and ppi epx 205 on EBAY ppia600 Swap Meet 0 23rd February 2008 01:17 AM
My experience: the cheap punch set VS Greenlee punch vax9000 Tubes / Valves 5 21st July 2006 07:52 PM


New To Site? Need Help?

All times are GMT. The time now is 10:40 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki