Amp gets a bit hot, can i add a small fan?

rg12

Member
2010-08-10 3:52 am
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?
 
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.
 

rg12

Member
2010-08-10 3:52 am
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.
 
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.
 
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)
 

rg12

Member
2010-08-10 3:52 am
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?
 
The easiest thing to do is plug a wallwart into a switched AC outlet on the back of the amp. Ive done this with many vintage Japanese integrateds. You can keep the fans somewhat quiet by using less voltage than normal which keeps the RPMs down. Check the specs though since not all fans like varied supply voltage. If you are truly concerned about the noise aspect, purchase some low db Papst fans. Pricey but quiet.

amt