[AMPS] SB-220 cooling/filaments

2 2@vc.net
Sun, 7 Oct 2001 01:51:14 -0700

>Recently, thinking to help keep my SB-220 cool under contest conditions, I
>added a small 110v muffin fan pulling air from the top front of the tube
>compartment -- my thought was to enhance the overall flow of cooling air.
>The added fan is just sitting on top of the cabinet near the front edge,
>and subjective the cabinet does seem to be staying a bit cooler.
//  This arrangement should work since warm air exhausts on the left side 
of the cabinet and through the top of the cabinet.  For optimal cooling, 
the SB-220 should have breathing room on the left, the top, and the rear 
of the cabinet - plus the fan motor bearings need to be oiled 
periodically.  However, a cooling fan in good working order will keep 
things cool enough - unless max-berserko speech processing is used.  

>Tonight, when I turned on the amplifier, I see only one filament lighting.
>My immediate thought is that I have melted the solder in the filament pins
>on that side from excessive heat.  Is it plausible that the "helper" fan
>could have upset the normal flow sufficiently to have caused this?  Or is
>it likely just a coincidence?  

//  One filament not lit is often caused either by solder melting out of 
pin 1 or 5, or it is caused by not enough spring tension on the 
corresponding socket pins - due to heat-caused loss of temper in the 
spring.  Either condition is typically caused by not oiling the fan 
and/or interfering with the natural flow of cooling air.  
good luck, Pete

-  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  

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