FAN Amplifier - S4 & up
06-22-2005, 06:34 PM
#1
Racer
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FAN Amplifier - S4 & up
I've got two amps, both with the driver's fan channel/failed & not working.
My GTS was getting intermittent now it is hooped.
Cracked one open, fixed a bad solder joint, looks like the power transistors are fine, but still does not operate the D-side.
Anyone BTDT with this failure?? There must be bushels full out there.
My GTS was getting intermittent now it is hooped.
Cracked one open, fixed a bad solder joint, looks like the power transistors are fine, but still does not operate the D-side.
Anyone BTDT with this failure?? There must be bushels full out there.
06-23-2005, 12:51 AM
#2
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At Beth's TB party we chased that behavior down to the second fan fuse. It's easy to just read down to the first description that looks right and check that fuse. IIRC, the second fuse was in the next block over from the first one.
06-23-2005, 02:06 PM
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Something I didn't check ..but fuses are good, 12 volt power is present at pin #1 &4 of the plug.
I replaced an amp on an '87 with the same problem, same miles.
I replaced an amp on an '87 with the same problem, same miles.
06-24-2005, 01:08 AM
#4
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http://home.wxs.nl/~Jennit/Technical...0/MyTip011.htm
Theo went through a problem where one fan was on high all the time. The link above takes you to his description of the fan amp rebuild. His was a rare case, since the FET devices typically fail in the open mode as yours has, with one or both fans not running.
Before you dive into the module, try swapping the leads at the rear of the fan console so that the drivers fan is connected to the pass side harness. If the drivers fan now functions, you are on the right track with your search through supply power and the module. If the drivers fan doesn't work plugged into pass side, then the fan motor is done.
To check for power at the fuses (28, 29), be sure to check under load (ie: fan trying to run). You may find that one of the primary fan leads at the battery positive is loose. That happened to a local (to me) owner a couple years ago. Look for two red wires at the battery positive terminal. Connections need to be clean and tight there for the fans to run. With no load, there may be enough current flowing to get 12V at a meter. Under load, you would see the voltage drop through a poor connection.
Theo went through a problem where one fan was on high all the time. The link above takes you to his description of the fan amp rebuild. His was a rare case, since the FET devices typically fail in the open mode as yours has, with one or both fans not running.
Before you dive into the module, try swapping the leads at the rear of the fan console so that the drivers fan is connected to the pass side harness. If the drivers fan now functions, you are on the right track with your search through supply power and the module. If the drivers fan doesn't work plugged into pass side, then the fan motor is done.
To check for power at the fuses (28, 29), be sure to check under load (ie: fan trying to run). You may find that one of the primary fan leads at the battery positive is loose. That happened to a local (to me) owner a couple years ago. Look for two red wires at the battery positive terminal. Connections need to be clean and tight there for the fans to run. With no load, there may be enough current flowing to get 12V at a meter. Under load, you would see the voltage drop through a poor connection.
