Crate KX-80 Keyboard Amp fuse pops immediately

[ajsemtb]

Re: Crate KX-80 Keyboard Amp fuse pops immediately

oh, and I used the barrel caps on those ones that I asked about because the axial caps had a factory ESR of 44ohm, and that was way more than what was in there before, and the regular caps, though required some creative bending of the contacts, they had a similar ESR to the one that was not damaged. (I replaced both so they matched, but used the non damaged one as a reference.)

[budm]

Re: Crate KX-80 Keyboard Amp fuse pops immediately

There may be leaky audio stage coupling caps that no longer block out the DC voltage between audio stages.
Does it pop when Master volume at '0'?

[ajsemtb]

Re: Crate KX-80 Keyboard Amp fuse pops immediately

It "boofs" when turned on w master at 0 but no pop when turned off. The boof sounds like the speaker getting hit with voltage. I would think it shouldn't be that pronounced when turned on.

[budm]

Re: Crate KX-80 Keyboard Amp fuse pops immediately

If you can see the cone moves forward or backward at full cone extension, then you should fix it.
Did it do this before? By the way, did you use the same value caps, it may be that the caps (in the pre-amp, which supplied by the resistors and the Zener Diodes) are charging up slowly due to higher values after the power amp section is already on.
The rule of powering up sound system is to power up the preamp first then the power amp to avoid popping the speakers. Do in reverse order when powering down.

[ajsemtb]

Re: Crate KX-80 Keyboard Amp fuse pops immediately

Yes it did it before. The high pitched squeal that happened when you shut it off is gone, so that's good . But the pop is still there.