Fender SPL-6000 / Fan operation

[rahmajik]

Just bought a used Fender SPL-6000. Didn't check the fan operation when I picked it up. Set it up to retest and fan is not spinning. Manual says its a 2 speed fan, but does anyone know if it should be on continuously on low speed or is the fan activated / controlled by a heat sensor? Any help would be appreciated.
Thanks

[52 Bill]

Just bought a used Fender SPL-6000. Didn't check the fan operation when I picked it up. Set it up to retest and fan is not spinning. Manual says its a 2 speed fan, but does anyone know if it should be on continuously on low speed or is the fan activated / controlled by a heat sensor? Any help would be appreciated.
Thanks

Looking at the schematic, the fan should turn on at low speed as soon as the power switch is turned on. When the heat sink for the power transistors hits 95 degrees, the fan should switch to high speed mode.

[rahmajik]

Looking at the schematic, the fan should turn on at low speed as soon as the power switch is turned on. When the heat sink for the power transistors hits 95 degrees, the fan should switch to high speed mode.

52 Bill, thanks for the quick response! So I guess I need to check the power feed to the fan to see if its getting any juice to determine if I have a fan or some type of power supply problem... :-( Bummer, can't even seem to find a parts list online for this old amp...

[52 Bill]

The fan is connected to the incoming line voltage. The slow speed is created by a 1000 ohm power resistor in series with the fan. Across the resistor is a thermal switch that bypasses the resistor when the temperature reaches the 95 degree point.

Check the circuit by reading the resistance of the 1000 ohm resistor (amp unplugged). If it reads correctly, then the wiring or the fan itself is suspect.

[rahmajik]

Thanks again 52 Bill, I will check that out!

[J M Fahey]

*Sometimes* (not sure on that model but check anyway) thereīs two thermal switches, the idea being that a fan is not needed or uselessly sucks dust/lint all the time or noise is plain annoying, even at low speed (think Studio or bedroom use) so first switch is in series with everything, and turns on, at, say, 65C ; second one works as described above, in parallel with a series resistor and turns on at higher temperature.
Personally get nervous above 85C but if they chose 95C, so be it.

[rahmajik]

JM Fahey. Thanks. I've attached the fan section of the schematic. Interesting, now that you mention it, it does show a TS1 and TS2. TS1-248 F, TS2-194 F. Sorry guys, I'm not an electronics guy so not good at reading schematics....what do the #'s mean for each of the TS (Thermal Switch?), the F cannot mean Fahrenheit ???

[J M Fahey]

Ok, in your case, Ts2 controls the fan speed but it should always spin (unless stalled by hardened grease or dirt) but thereīs quite a few connectors in the path, so check itīs not open somewhere.
Ts1 is an entire system thermal safety, if heatsinks get fully blocked (say, a pullover or jacket is carelessly thrown over the vents) then NO fan will blow through that.
In that case whole amp is turned off, Ts1 is in series with main switch.

[g1]

what do the #'s mean for each of the TS (Thermal Switch?), the F cannot mean Fahrenheit ???

Yes it is fahrenheit. The 194 F is about 90C.

[52 Bill]

Yes it is fahrenheit. The 194 F is about 90C.

Sorry, missed the 1 on the drawing.

TS probably stands for thermal switch or sensor, doesn't really matter as long as you know what it does. TS-1 is a normally closed switch that opens when it reaches 248 F and TS-2 is a normally open switch that closes when it reaches 194 F.

The schematic is marked with "CP" points. These are connections on the pc board. They are usually printed right on the board next to the metal spade lug where you can plug on a wire. The 1K resistor will connect between CP4 and CP5, which is where the wires that go to TS-2 will be located.

You can use an ohm meter to read the resistance between these two CP points or you can read directly across the resistor itself. The resistor may be fine, but if it has come unsoldered from the pc board, that will also prevent the fan from running. It may be best to read the resistance both ways terminal to terminal and across the resistor itself to test both possibilities.

Not knowing your skill level, I am suggesting the simplest/safest tests to run to solve your problem.

[rahmajik]

Thanks again guys. My skill level in board level electronics is pretty low so thanks for the 'simple' tests. Wow, those fahrenheit temps just seem extremely high....I would have thought much more damage would happen before those temps are actually reached....anyway... I took the cover off, reseated the fan connections (where the fan wires connect via the spade lug to the board) and blew out the fan pretty good as well. The fan now starts up on power up :-) Seems to start fairly slow, then seems to reach 'normal' low speed operation in about 3 seconds. So I guess that tells me power to the fan is ok. Got the part #'s off the current fan so I might consider trying to find a replacement fan as a precaution.

[J M Fahey]

The fan starts lazy because itīs fed through a 1K dropping resistor.
You would also wake up weak and dizzy if your blood sugar dropped under 70 during the night (donīt ask).

Just as a health test, connect it straight to mains as if thermal switch were triggered ... I guess it starts like Hurricane Irma's little sister
I mean momentarily bypass the resistor or thermal switch contacts.

[rahmajik]

Measured the AC feeding the fan where the cable attaches to the lugs on the circuit board and measured around 50 volts AC. Is that how the multi-speed fan works? When it heats up to close the TS2 switch it would get a full 110 volt feed for high speed. Sometimes when it doesn't start, I give it a 'spin' and it starts up to the low speed. I've ordered a replacement fan unit as a precaution and to test.

[52 Bill]

Yes, reduced voltage = reduced speed. There may be oil points on the fan. Or if it has a paper label covering the center bearing, you might remove the label and directly oil the bearing.

[rahmajik]

Thanks, ill look for the oil points!