help with a Fan install pictures help wiring? FAN runs slow

[jamme61]

I have an older budda SD18 (no fan ) new ones come with the fan - this amp runs very hot. I ordered this fan kit https://taweber.powweb.com/store/modkits.htm

I haven't received the fan yet but was looking for some help with the wiring. I e-mailed jeff bober (designer of the amp) and he said any 12Vdc fan will work off the low voltage supply used for the switching. I thought I just wire the fan into the heater supply for the 12ax7's? I like to try and do this myself- thanks for any help on this


UPdate - pics show wiring fan runs slow
got the fan in wired it to tag board by PT green wires. Fan runs but runs very slow- did I do anything wrong? added picture showing wiring chopstick trying to point out area. thanks for any help.

[ampgeek]

I wouldn't plan on wiring the fan to the 12 VDC relay supply system until you receive the package from Weber and note the component ratings on the board (capacitors in particular) and max DC voltage limit on the fan itself.

Is there any reason (available space, current limit on your PT filaments winding,etc..) to not just use the filament supply system as Weber intended? The kit includes rectification and filtration which should make it just as good as your typical DC relay supply system.

Good luck,
Dave O.

[jamme61]

no reason at all not to run it the way weber says (off the heaters) that I know of? Looking at the weber schematic I just have to hook up two wires. The new buddas mount the fan right next to the power transformer- I was hoping to be able to tap into the filament power right at the PT. I have to get the kit and open the amp, to make sure. is it this easy two wires to the PT filament supply? thanks for the help

[Phil_S]

Position it as an exhaust fan, not for intake.

[ampgeek]

Yep. It looks to be just that easy!

I would start by positioning the fan just as or as close as Budda does in the upgraded version....unless that is known to be less than satisfactory. No sense in re-inventing the wheel.

Rock on,
Dave O.

[Cantplay]

Position it as an exhaust fan, not for intake.

Wouldn't the increased air density from pressurizing the case transfer heat better?

John

[Phil_S]

I have read that it is a bad idea to position the fan for intake, introducing cooler air directly onto components. It is better to exhaust the hot air and allow room temperature air to replace it gently. Exhaust will get the job done. Why take chances?

[jamme61]

thanks guys I sent a copy of the link to jeff bober and he agrees with you- use the filament supply. I was going to place the fan where budda put it- I figure they should know best. I just have to get the parts- thanks to all you for your time and help on this

tried to post a picture of where budda mounts the fan

[ToneMerc]

I have read that it is a bad idea to position the fan for intake, introducing cooler air directly onto components. It is better to exhaust the hot air and allow room temperature air to replace it gently. Exhaust will get the job done. Why take chances?

Nearly all data and telecom equipment pulls cool air in from the room and directs it over the components.

TM

[ToneMerc]

thanks guys I sent a copy of the link to jeff bober and he agrees with you- use the filament supply. I was going to place the fan where budda put it- I figure they should know best. I just have to get the parts- thanks to all you for your time and help on this

tried to post a picture of where budda mounts the fan

That seems to be placed more for mounting convenience than for cooling effectiveness, especially if there is no additional venting.

TM

[ampgeek]

Jamme,

Do also follow Budda's advice in what direction the air should flow across the chassis.

Again, no need to re-invent something that already works!

Cheers,
Dave O.

[eniam rognab]

also, why buy a kit? does it have to be on a low voltage supply?

we use ~3-4 inch fans at work that run on straight wall voltage.... buy a 120v fan and hook it up to your power switch. cost is like 10 bucks for the fans.

$0.02, sounds like you already bought the kit, but i thought i would throw it out there that there are 120v rated fans....

have fun!

[jamme61]

Yea I just bought the kit thinking I'd be better off. I read that ac fan might cause noise? I have no idea about this stuff. Thanks for the input appreciate it

[eniam rognab]

I read that ac fan might cause noise?

i hadn't thought about it causing noise.... i havent used one in an amp so i cant comment, maybe some of these super smart people can enlighten us.

so yeah, maybe 120v fans aren't the way to go.... i dont know either

i just use them to blow flux fumes away from me at work

[gingertube]

Bridge Rectify a 6V3 Volt Heater Supply add a 10,000uF 16V cap and you get a bit over 7V DC.

That is ideal to run a 12V DC fan at low speed and LOW NOISE. Fan speed is ample to set up an airflow bias to assist natural convection cooling. It is remarkably effective.

Fans are good at pushing against high air presure and crap at sucking from a low air presure so fans should alway blow into your chassis not try to extract air from your chassis.

Chassis will act as a bit of an accoustic baffle too so this will also be the lowest accoustic noise option.

In your example, however, it looks like you just want to direct some airflow across the output tubes and trannies.

Brushless DC Motor Fans are the lowest electrical noise option.

Also - if you live in Denver or somewhere similarly "up high" then consider that your "cooling system" may be up to 40% less effective than for us guys down near sea level.

In the day job I design/build airborne electronic "stuff". Here is the reference I use:
http://www.electronics-cooling.com/1999 ... -altitude/

Cheers,
Ian