I don't quite know what you mean?
You want me to test each transistor for continuity: like you suggest here?
http://www.bcae1.com/repairbasicsforbcae1/images/npnbipolartransistor00a.gif
As for leakage, how do I go about doing that?
You want me to test each transistor for continuity: like you suggest here?
http://www.bcae1.com/repairbasicsforbcae1/images/npnbipolartransistor00a.gif
As for leakage, how do I go about doing that?
Use the applet, for the type of transistor you have, on the following page.
Basic Amplifier Repair - Transistor Test Applet Link
Basic Amplifier Repair - Transistor Test Applet Link
Ok, I get conductivity every leg to every other leg on both transistors, 905 and 909.
The value changes quickly though, do you want me to attempt to report back with each combination of leg arrangements as the link?
Is the voltage on the emmiter of 909 a problem? I currently only get 1.5v here, where as on the base and collector I get 10v and 63 respectively?
The value changes quickly though, do you want me to attempt to report back with each combination of leg arrangements as the link?
Is the voltage on the emmiter of 909 a problem? I currently only get 1.5v here, where as on the base and collector I get 10v and 63 respectively?
909 replaced. Sinked back up and powered up, sound came from speaker, then the breaker tripped. Cable warm. Felt the FET's, all cold (the 140's and 9140's) However the device on the end (FX50) was hot. The FS70 was not hot however.
I'm considering removing all of the driver part and replacing it. From Q905-912
I'm considering removing all of the driver part and replacing it. From Q905-912
You should have nothing larger than a 15 amp fuse in the B+ line. If an 80 amp breaker tripped, there is a serious problem which could result in the failure of the outputs (some of which are no longer available). If the outputs fail, the amp may not be repairable.
Are you sure that there are no solder bridges?
Are you sure that no transistors are shorted?
Are you sure that there are no solder bridges?
Are you sure that no transistors are shorted?
Ok i'll get a fuse setup. The transistor I installed had no bridges, no. I'll work my way around the board again, looking for a short, i'm pretty sure there are no solder bridges.
Is it best to remove the output parts of the board, so I can work more easily on the input side, without risk of damage to the FET's, Fx/Fs?
Is it best to remove the output parts of the board, so I can work more easily on the input side, without risk of damage to the FET's, Fx/Fs?
I pulled the FX50 (the one getting hot) here's the results:
With dmm on resistance I get; red lead on drain, black pin on source, 5.56Mohm.
Every other combination I get infinty.
I assume this means it's working ok? As it's a P type FET.
Which then leads me to think that it's further back, either the driver part still playing up, or the IRFP's?
With dmm on resistance I get; red lead on drain, black pin on source, 5.56Mohm.
Every other combination I get infinty.
I assume this means it's working ok? As it's a P type FET.
Which then leads me to think that it's further back, either the driver part still playing up, or the IRFP's?
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