Thanks for the reply Perry How are you doing tonight? I didn' put any compound on the transistors due to I didn't think it was required since the other chips did not have compound underneath the output transistors there are pads underneath the output transistors they only used compound underneath the rectifiers. I feel the heatsinks are pretty tight without cracking the transistors. It just seemed like it was lacking power trying to push a 12" thunder 6000 250rms bridged only 1 of them maybe it was just the power wire not being big enough however the transistor were not getting nearly as hot as the transistors that were in my orion amp
When replacing any of the transistors, you should use heatsink compound. The sil-pads are not intended to be re-used. If you look at them, they have an indentation from the original transistors. If the replacements don't fit/lay precisely in that location, they will not make good thermal contact with the pad and won't be able to efficiently transfer heat to the sink.
You also need to make sure that the clamps are applying pressure evenly. Many times, they get bent and the transistor is only held down tightly on the part of the clamp closest to the screw.
Although unlikely, it's possible that there are biasing issues with the repaired channel. Measure the DC voltage directly across the emitter resistors. It should read 0.000 on both channels. Check it again after driving it hard for a few minutes and again when the amp is hot. It should not change.
You also need to make sure that the clamps are applying pressure evenly. Many times, they get bent and the transistor is only held down tightly on the part of the clamp closest to the screw.
Although unlikely, it's possible that there are biasing issues with the repaired channel. Measure the DC voltage directly across the emitter resistors. It should read 0.000 on both channels. Check it again after driving it hard for a few minutes and again when the amp is hot. It should not change.
Thanks for the input Perry so your saying remove the pads and place the compound between the transistors and the amp casing itself? Also ill check the voltage on the emitter resistors and see what i get cold and hot as for the bias i didnt see any adjuster screws for the bias on the board but ill check the voltage and compound and see what i find out. The rectifiers don't heat up nore does the Power transistors just the output transistors so your probably right.
Thanks again ill keep you posted
Thanks again ill keep you posted
I didn't say anything about removing them. If there is no insulator, the amp will fail the instant that power is applied. The compound is applied between the transistor and the sil-pad. If the sil-pad has been lifted from the heatsink, apply compound between the sink and the pad as well.
You need to take the time to write things out. You stated that the power transistors were no longer getting hot. All of the transistors clamped to the heatsink are power transistor (transistors capable of dissipating significant power in the form of heat). That's different than 'power supply transistors'.
You need to take the time to write things out. You stated that the power transistors were no longer getting hot. All of the transistors clamped to the heatsink are power transistor (transistors capable of dissipating significant power in the form of heat). That's different than 'power supply transistors'.
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