CRUNCH BLX1000D, few questions about repairing this amp. - diyAudio
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 29th September 2011, 07:29 PM   #1
djmdp is offline djmdp  Poland
diyAudio Member
 
Join Date: Mar 2011
Default CRUNCH BLX1000D, few questions about repairing this amp.

Hello, I have this amplifier and power mosfets of digital audio is missing. I don't know what mosfets supposing to be there on places: Q161,Q162,Q171,Q172,Q181,Q182? Is it a half bridge with complementary mosfets p and n channel topology? There's an identical amp - CRUNCH BLX2000D and BOSCHMANN PSX-D1. I thought that this is half bridge topology with n channel mosfets and set there irf540N. Now I don't know that gate driver is still ok,but it looks like complementary driver, no bootstrap, no VS connected to driving circuitry.
Attached Images
File Type: jpg dscf0004_191.jpg (198.2 KB, 92 views)
  Reply With Quote
Old 29th September 2011, 08:01 PM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Which legs of the high-side FETs are connected to which legs of the low-side FETs?

What is the voltage rating on the rail filter caps?
  Reply With Quote
Old 29th September 2011, 08:22 PM   #3
djmdp is offline djmdp  Poland
diyAudio Member
 
Join Date: Mar 2011
So, all middle legs are connected together with the filter inductor leg, first on the left mosfets (Q181 and Q182) has right legs connected to -50V rail, left is gate. Next mosfets (Q171 and Q172) has right legs connected to +50V rail, left is gate.
Next mosfets (Q161 and Q162) has right legs connected to +50V rail, left is gate.
Rails are +50V and -50V.
  Reply With Quote
Old 29th September 2011, 09:27 PM   #4
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The two on the negative rail are N-channel FETs. The other 4 are P-channel FETs.

IRF540s and IRF9540s may be the right FETs but 50v is right at the limit of the FETs.
  Reply With Quote
Old 30th September 2011, 06:35 AM   #5
djmdp is offline djmdp  Poland
diyAudio Member
 
Join Date: Mar 2011
So this is complementary power amplifier for 100%? Now I must recheck gate driving, there is square wave of 1V-2V amplitude at -50V DC offset, so N channel seems to be good. I'll check the P channel.
  Reply With Quote
Old 30th September 2011, 09:13 AM   #6
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The amplitude must be greater than that. The drive signal is generally 10v and is driven from a 12v supply referenced to each rail (positive and negative).
  Reply With Quote
Old 8th October 2011, 02:32 PM   #7
djmdp is offline djmdp  Poland
diyAudio Member
 
Join Date: Mar 2011
Hello, I bought 2*IRF640 and 4*IRF9640 as a power fets. I've done a schematic of my drive board. There's a drive signal on P mosfets with amplitude of 7V, but there's no signal on N mosfet drive. So I need a little help I replaced all transistors on this board, comparator and diodes except three diodes named CR1, CR2, CR3, is it zener diodes? Voltages that I measured (subj. to ground):
IC1A 1 -> -50,4V
IC1A 2 -> -35.2V
IC1A 3 -> -42.9V
Q2 base -> -49.9V
Q2 emmiter -> -50.4V
DRIVE signal -> +14.5V
I don't understand how this circuit generates pulses to N mosfet, what's the role of this comparator here? Please ask, I can measure more voltages. Oh there's a little mistake on the schematic, Q11_1G1 transistor is exactly the same like Q4 - BCX56-16
Attached Files
File Type: pdf mosfet_gate_drive.pdf (25.9 KB, 20 views)

Last edited by djmdp; 8th October 2011 at 02:37 PM.
  Reply With Quote
Old 8th October 2011, 03:45 PM   #8
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The comparator is used for over-current protection. When engaged, it drives the emitters of the voltage amplifier/inverter transistors so that the signal from the drive circuit (not the 'drive' indicated in your diagrams) can't drive the transistors 'on'.

The drive signal for the N and P channel FET drive circuits is the same.

The Zener diodes are 1N4742As.

The driver circuit for this amp appears to be in the blue box at the end of the driver board.

This amp is very similar to the JBL BP1200.1. Email me if you want the JBL service manual.
babin_perry@yahoo.com
  Reply With Quote
Old 9th October 2011, 05:44 PM   #9
djmdp is offline djmdp  Poland
diyAudio Member
 
Join Date: Mar 2011
Now, when I've got more info, I figured out that probably a/d converter is damaged. On the schematic we can see PWM_0..4V signal, but I also figured out that this a/d converter circuit is supplied by +5V and -5V. 0..4V PWM signal cannot drive Q9 transistor am I right? I think that PWM signal was -5V..5V. That's why the amplifier has been damaged. Schematic of JBL BP 1200.1/600.1 is almost the same. Now I've got to build my own a/d converter ;( blue box.
  Reply With Quote
Old 9th October 2011, 05:47 PM   #10
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The LM361 operates off of a +3 and -2v supply, generally. If you remove the diver board, do you get a square wave drive signal to the driver board pads?
  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
Crunch 1000.1D amp Hi Speed Car Audio 2 1st August 2014 04:39 PM
Crunch BMX1000 amp, some parts missing Pioneer621 Car Audio 6 1st April 2011 01:55 AM
Crunch amp mike49504 Car Audio 6 22nd January 2010 06:49 AM
Crunch USA amp Kronan Car Audio 0 11th November 2006 08:08 AM
blown crunch amp repair? sctt78 Car Audio 2 6th July 2004 01:06 PM


New To Site? Need Help?

All times are GMT. The time now is 03:11 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