IRFZ44N Chip Question? - 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 October 2007, 12:58 AM   #1
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
Default IRFZ44N Chip Question?

Hello, I have a SPL CRM1200-2 and at least one of the IRFZ44n's are blown. So I am planning on replacing them all and just wondered if there is maybe a better chip to replace them with to get a few more watts out of this amp and what other modifications I would have to do like matching the outputs? I have heard it is possible to upgrade some amp's but I don't know to much about it. I would apreciate anybodys help with this.
Thanks.
Attached Images
File Type: jpg amp guts 022.jpg (92.2 KB, 218 views)
  Reply With Quote
Old 29th October 2007, 12:59 AM   #2
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
Here is a pic of the outputs.
Attached Images
File Type: jpg amp guts 023.jpg (82.8 KB, 214 views)
  Reply With Quote
Old 29th October 2007, 01:00 AM   #3
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
Here is another pic.
Attached Images
File Type: jpg amp guts 027.jpg (76.1 KB, 197 views)
  Reply With Quote
Old 29th October 2007, 01:04 AM   #4
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
Last pic.
Attached Images
File Type: jpg amp guts 025.jpg (86.4 KB, 196 views)
  Reply With Quote
Old 29th October 2007, 01:35 AM   #5
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Unless you know an amp well, it's best to get the amp working properly with the original parts. After you 'know' that it's working properly, then you make the substitutions. It may cost a bit more but you don't have to waste time trying to determine if the replacements are the cause of the problem or if there is something else wrong with the amp.

The drive circuit on this amp 'should' be able to drive IRFZ48 FETs. They are rated for more current than the IRFZ44s.

Using a different FET will not cause the amp to make more than a few watts more (nothing audible). If the power supply FETs failed but the outputs didn't, the the Z44s may not be rugged enough. If the power supply died because the outputs failed, there's probably no reason to go to a different FET.

When you power up this amp after replacing the FETs, have them clamped tightly to the sink and have a 10 amp fuse in the B+ line.

If the outputs didn't fail, there may be another reason for the power supply failure. With the amp powered up, twist the transformer. If there are intermittantly shorted windings, the fuse will blow or you'll see sparks between the windings as you twist. You would need to find and insulate any shorted windings.
  Reply With Quote
Old 29th October 2007, 02:10 AM   #6
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
The guy I got the amp from said he had put a bigger fuse in after 1 had blown... He thought he had it under a 2 ohm load bridged after hooking the woofers up wrong.
  Reply With Quote
Old 29th October 2007, 04:23 AM   #7
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
To explain it more. I think it can only be bridged into a 4 ohm load and thats why he blew the fuse the 1st time. And then not being very smart, he put a bigger fuse in and smoked the IRFZ44N.

So should I order IRFZ48N's or go back with the IRFZ44N's? I agree with you Perry to get it working first, than modify if possible. But if it won't hurt anything to put a little stiffer FETS in then I would like to. What do you think?
  Reply With Quote
Old 29th October 2007, 04:45 AM   #8
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
It's going to cost an additional $10 to get it working with the Z44s first then change them to Z48s. I think it's well worth the expense. The Z44s will not be damaged and can be used for other repairs if you'd like.

If I'm not mistaken, this amp has a regulated power supply and unless you have a 12v DC power supply with variable voltage and an amp meter, it may be difficult to tell if the drive circuit is able to turn the FETs off quickly enough at the maximum duty cycle. I think it will be OK with Z48s but I've never tried them in one of these.

Check the output transistors before you order parts. If you find any that read anything near 0 ohms between legs 2 and 3, pull them from the board and check them.


Before you replace the transistors, clean all of the black soot from the board. I'd suggest using acetone and a toothbrush. Don't use a transparent toothbrush. Acetone melts them. Do this outdoors. Read the label on the acetone if you've never used it.
  Reply With Quote
Old 29th October 2007, 04:53 AM   #9
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Do the power supply FETs have circuit board designations of Q41-Q49 (no Q45)?
  Reply With Quote
Old 29th October 2007, 09:37 AM   #10
Itsme is offline Itsme  United States
diyAudio Member
 
Join Date: Oct 2007
Location: Nixa, Mo.
I will get both z44's and z48's. I checked all of the bigger output transistor's but I didn't test the smaller ones in between the z44's and the bigger outputs. Which I think are diodes (FMG222) and (TIP41C),(TIP42C).
All the output trans. were open between leg 2 and 3. Can you explain the maximum duty cycle shutting down the FET's? How can you tell if It has a regulated power supply? Is that the same as a PWM? I did post some pic's above of the multipin controller chips, also there was a white 4 pin chip next to them. Those control the power supply right?
I have a Yellow top Optima battery with inline fuse holder, But no way to make variable voltage. I do have several amp meters and 8 DMM's which 2 are Fluke's. I don't have Osciliscope, but am in the market for one. So do I need to buy a variable power supply? And yes to your question, No Q45. I think they use this same board for their higher wattage amp's, It look's like more Fet's could be added. (Empty slots). Anyway would you suggest I order any other parts to replace? like I see a couple of resistors that look like they have been hot. It's the small resistors in front of the Z44's. And any parts to upgrade after getting amp working? Thanks.
  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
Huf75337p3 in place of irfz44n? spooney Car Audio 10 9th August 2009 06:03 AM
Is there a difference in a IRFZ44 and a IRFZ44N? Itsme Car Audio 7 5th November 2007 11:33 PM
need to find out which IRFZ44N to get..help please Wyldhorse Car Audio 2 14th July 2007 10:46 PM
Questions about mosfets IRF3205 IRFZ44N dB-r Solid State 3 6th December 2006 12:36 PM
Blown IRFZ44N cruck00 Car Audio 26 3rd May 2006 01:11 AM


New To Site? Need Help?

All times are GMT. The time now is 12:41 AM.


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