Amp gets a bit hot, can i add a small fan? - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 19th September 2010, 10:23 PM   #1
diyAudio Member
 
Join Date: Aug 2010
Default Amp gets a bit hot, can i add a small fan?

I have a Pioneer SA-7300 amp that is powerful enough to drive my
big speakers, but after some time it get very hot and from my experience
i know it won't last after a few weeks playing like that.

If i add a one or two computer fans blowing at the aluminum transistors heatsink, will it help? and if the temprature does drop, will it prevent future damage or it will just help it run a bit more?
  Reply With Quote
Old 20th September 2010, 12:03 AM   #2
Banned
 
Join Date: Jan 2008
Blog Entries: 2
Yes, it'll help, it'll help prevent future damage.

w
  Reply With Quote
Old 20th September 2010, 12:09 AM   #3
diyAudio Member
 
Join Date: Aug 2010
Good to know, thanks alot.

My next question is, where can i take the electricity to the fan?
It's a 9v computer fan (maybe i will add two if i will find the place).

This is the scematic: http://www.milkbands.co.il/Pioneer-SA-7300-int-sch.pdf

Any ideas?
  Reply With Quote
Old 20th September 2010, 12:16 AM   #4
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
You can use a dropper resistor from B+ and drive the two fans in series.
I have done that a few times.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 20th September 2010, 01:10 AM   #5
diyAudio Member
 
Join Date: Aug 2010
Quote:
Originally Posted by nigelwright7557 View Post
You can use a dropper resistor from B+ and drive the two fans in series.
I have done that a few times.
Im sorry, but my knowledge in electronics is limitted.
Where exactly is the B+? and what value of resistor do i need?
  Reply With Quote
Old 20th September 2010, 05:31 PM   #6
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
I have the same problem after 12 hours on of my ST120, not designed for that. I'm going to put 2 12VDC computer fans under the floor of the amp (slotted ) powered by wall-transformer with rectifier outside amp chassis, so I don't induce AC noise inside. can be done inside chassis if you're careful, but outside the steel box makes it a lot more stupid proof. Adapting a little junk sub chassis to go under the actual amp chassis.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300
  Reply With Quote
Old 20th September 2010, 09:32 PM   #7
diyAudio Member
 
Join Date: Aug 2010
Oh right, i didn't think about the noise the fan motors can cause.

If i do it with external power adapter, how can i connect it to the
amp that it won't add any noise and still start the fans when i power
the amp on?
I don't want to have a separate switch for the fans.
  Reply With Quote
Old 20th September 2010, 09:38 PM   #8
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by rg12 View Post
Oh right, i didn't think about the noise the fan motors can cause.

If i do it with external power adapter, how can i connect it to the
amp that it won't add any noise and still start the fans when i power
the amp on?
I don't want to have a separate switch for the fans.
I have built about half a dozen amps with fans running off the B+ and never had a problem with noise. Could be my amps are more resistant to power supply noise tho.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 20th September 2010, 10:08 PM   #9
diyAudio Member
 
boyofwax's Avatar
 
Join Date: Feb 2004
Location: Arnhem Netherlands
Rg12 you might be lucky if you locate the POP-ON reduction relais on the PCB. In the diagram it is listed as S8 RELAIS. If the coilvoltage is something like 9v or 12v you could use these coilpins to solder the wire's of the fan. (check polarity!) In the worst case you should lower the resistance of R111. (100 Ohm or something)
  Reply With Quote
Old 21st September 2010, 01:45 AM   #10
diyAudio Member
 
Join Date: Aug 2010
Quote:
Originally Posted by boyofwax View Post
Rg12 you might be lucky if you locate the POP-ON reduction relais on the PCB. In the diagram it is listed as S8 RELAIS. If the coilvoltage is something like 9v or 12v you could use these coilpins to solder the wire's of the fan. (check polarity!) In the worst case you should lower the resistance of R111. (100 Ohm or something)
If it is more or less than 9v? what can i do? those fans work on 9v from
what i remember.

What can happen if polarity is reversed? the fan will just spin backwards
right?

What did you mean when you said "In the worst case lower the resistance of R111"? What is the worst case and what does this R111 resistor do
in the schematic?
  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
FS: HTPC, Bit-Perfect Computer Transport, Small PC with a great soundcard wigginjs Swap Meet 8 30th September 2009 07:40 AM
F2 running hot(how hot is hot?) Aron Pass Labs 10 13th February 2009 03:42 PM
Denon DCD 1520 20-bit or 18-bit? beauty_divine Digital Source 0 9th September 2007 06:41 AM
WTB: Small 120V ac fan ccdoggy Vendor's Bazaar 0 1st March 2007 10:07 AM
use digital attenuation to improve 16-bit CD playback on 24 bit DAC capslock Digital Source 7 8th April 2002 11:18 PM


New To Site? Need Help?

All times are GMT. The time now is 10:16 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