Memphis amp subsonic filter on board

[djtomczak 5]

So the fan was not working off my Memphis 16pr1.5kd so I pulled it out and opened it up. Two lines lead from the fan area to a potentiometer. Then looking around some more I find three pins with a jumper across two. Next to that says subsonic on and off. I don't have any adjustment for a ssf on the outside, but could this be set to "on" then the potentiometer used to adjust the it? Or is this potentiometer linked to the fan somehow? I'll be checking to see if the fan works as I've pulled that out. If someone could link or send me a layout of this board that would be helpful, thanks!

Edit: also the potentiometer is labeled vr1 while the adjustments on the outside are labeled vr01-vr04. Pins for ssf are labeled sw1.

Edited September 5, 2012 by djtomczak

[dbsupra 69]

VR = variable resistor

SW = switch

The numbers 1, 2, 3, etc are just the designation of the component.

I'm not sure why you would need a pot on a fan. Is it temperature controlled or run full time? It could be to tune the cut on/off temperature.

As far as the ssf, if the traces lead to the pot then it could control it perhaps. The pot is just a variable resistor, instead of fixed. There are different ways you can configure it, depending on which legs you use. The wiper is almost always the center pin. Then you can use either or both legs of the resistor. In theory, you can adjust that pot to alter the ssf. It would be the same as the external knob (pot) just mounted internally.

What you can do, is test the ssf to see where it is now. Then carefully count how many turns you make in either direction to see if it makes any changes. If not, then you can put it back where it was by turning it back the same amount of turns. Most pots are 10 turn. Listen carefully, if you turn too many times you will hear a faint click.

Be careful, if there are other components tied to the output it may effect them as well. I used to work on amps back in the day, but Memphis wasn't a brand I have repaired.

Hope this helps