Peavey Musician 400G

[The Dude]

No it's not a death cap. The death cap is the cap from line to ground. If it shorts, the chassis becomes hot, if for some reason chassis is not grounded. If the other cap shorts, it won't kill you. It'll just blow the fuse.

[nickbme07]

No it's not a death cap. The death cap is the cap from line to ground. If it shorts, the chassis becomes hot, if for some reason chassis is not grounded. If the other cap shorts, it won't kill you. It'll just blow the fuse.

Ok fuse in this case should blow due to short to ground, rather than energizing the chassis. Got it, ok. Thanks, ill give it a whirl.

[nickbme07]

Any ideas on radio pickup when the flanger is turned on (with or without input cable and flange vol turned down)? Trying not to change out all the lytics

[nickbme07]

A cap in either position does not help. It is worse adding hum even when the post gains are down. Also, the pop is still there when turned off..

[The Dude]

If the cap is causing problems instead of fixing something, leave it out. It certainly isn't critical. A pop at power up or power down is somewhat normal on an older SS amp without a delayed on/off circuit or a speaker relay. If it's not ridiculously loud, I wouldn't worry about it.

[nickbme07]

If the cap is causing problems instead of fixing something, leave it out. It certainly isn't critical. A pop at power up or power down is somewhat normal on an older SS amp without a delayed on/off circuit or a speaker relay. If it's not ridiculously loud, I wouldn't worry about it.

I have left them both out now, as I have with other Peaveys. So there is a 'fade out' lighter pop present at power off if the preamp is disconnected. Id say thats vintage Solid state standard there. Preamp connected, reverb disconnected, there is a very big quick pop. Definitely an issue. I will investigate some of the caps on the preamp.

What should be the culprit for the RF pickup on the phaser circuit when turned on?

[nickbme07]

C49 is listed as Tantalum, is this required or any polarized lytic ok? I ask because I pulled C49 and found this cap (pic attached) with some leakage. I'd like to replace it, but this doesn't seem to be a Tantalum as listed on schematic (10/35 Tant)

[nickbme07]

Ok update today: Replaced C46 with a 1uf/50 sprague tantalum and that fixed the RF be introduced when the flanger is turned on. The peaks are clipping out however. I think it still may be related to C49 being leaky. I don't have any Tants in 10uf so I will have to wait, unless someone can answer my last post?

Pop is still there as well.

[The Dude]

A polarized 'lytic will work just fine. Tantalums have a longer shelf life, but either will work. Keep in mind that this amp has worked for years with the parts that exist in the amp.

[Helmholtz]

C49 is listed as Tantalum, is this required or any polarized lytic ok? I ask because I pulled C49 and found this cap (pic attached) with some leakage. I'd like to replace it, but this doesn't seem to be a Tantalum as listed on schematic (10/35 Tant)

Caps in your pic don't look like tantalums.
In most cases a tantalum can be replaced with an Al electrolytic. Tantalums are better at RF frequencies, though.

[nickbme07]

Ok, great, thanks guys!! I still have to work out this pop coming from preamp. Is there any chance the 2 diodes on the back I took off was helping to suppress the pop? It's definitely only happens when preamp is plugged up.

Well damn. I had the caps changed out and thought the RF was gone and went to check reverb and forgot the tank wasn't plugged. So here's the interesting thing.. With the tank plugged in, reverb works great, no RF etc. Reverb off, doesn't matter,, you turn on the phaser and boom you have RF at any setting on either. Disconnect reverb tank, RF goes away..

[The Dude]

The RF could be because you have the chassis out of the cabinet. Is there shielding in the cabinet?

[nickbme07]

The RF could be because you have the chassis out of the cabinet. Is there shielding in the cabinet?

I have it back in, mounted on face plate as it should.

[nickbme07]

Ok so listening to the RF, all preamp controls do not alter the signal, but moving the eq sliders does change it, but only when channel 1 is engaged to use it (ch2 doesn't change it). Def happening in the phaser circuit, but seems like the ground is not good and using the reverb tan.

The amp is very quiet until you engage phaser. RF is introduced as well as a light hiss. Color control changes tone of hiss.

[nickbme07]

Ok, so Dude was right on for shielding the reverb tank. RF is fine now across the board when tank is plugged in. Ok moving on.

Seems I still cannot get rid of the pop at turn off. It's almost a delayed pop then a high pitched squeak/hiss that fades away. I've replaced a few caps but not all of the lytics.