Crate K-160XL schematic

[fastback4]

I have a retired ss and tube amplifier repairman available to fix my Crate k-160xl but needs the schematic. Something blew right next to the internal fuse (fuse did not blow) and the repairman needs to know what it is or was. I marked the board (x2) in black where the missing part contacts the board. Thanks to everyone.

[g1]

Whatever it was (cap or surge suppressor of some sort), it is not required for the amp to function. In fact it may have been gone a long time.
The tech seems to be barking up the wrong tree, what is the problem with the amp?

[fastback4]

The amp suddenly started (screaming) when I turned it on with no equipment plugged in. My main volumeand input volume where off when this occurred The green peak light glowed steady until I turned it off. That's when I looked inside and saw this burned??? but the fuse was good. I turned the amp back on after 5 min. plugged in my guitar and it did not scream again and has not since for 2 hours or so. My repairman has not seen the amp but only suggested I get a schematic before he looks at it as he does not have one.
Thanks a lot g-one for all your help again.

[The Dude]

Couldn't find a schematic, but from looking at it's location and how it appears to be connected in the circuit, I'm betting it was a low value cap used to eliminate rectifier switching noise. Probably won't matter much that it's gone.

Edit: Whether you replace the part or not, I would clean up the area and remove all of the charred board and residue so that it does not conduct.

[Jazz P Bass]

It looks like a small value capacitor across the bridge rectifier output, in parallel with the main filter caps.

In pic #3, there appears to be it's brother in the lower right corner.

Can you read the value of it?

[fastback4]

Is this the 'yellow cap' in the lower right you referred to Jazz? Here are some pics. The values are 104k and 100v

[The Dude]

Yes! Nice work. That would be a .1UF/100V capacitor like C41 and C42 in the schematic Jazz posted. Looking at the pads on the board, it appears the other one was stressed also. I would replace them both and maybe go with higher voltage rated caps.

[Jazz P Bass]

Whether you replace the part or not, I would clean up the area and remove all of the charred board and residue so that it does not conduct.

I would resolder that board.
"Most' of the joints look good but some look borderline.

[fastback4]

I have a free parts list and schematic coming in 4 days from Crate. http://www.crateamps.com/support/index.phpThey only asked for a model and s/n from the amp and also digital signature for the disclaimer. I will follow up here with a picture after the repair (if necessary as suggested) is done.

[fastback4]

Today I bought the new cap at Radio Shack for 1.99 and went ahead with installing it myself. New cap is blue. I did up the voltage to 200v as suggested. Turns out a grounding screw and nut on the chassis coming from the power cord was not tight and made this amp pop and scratch. Played my bass through it for over 1 hour no problems. Feels good to accomplish a task such as this and finding there are people whom share the same goals.

[g1]

You still have a possible intermittent problem that may cause the amp to go into squealing again. The AC cord ground would not likely cause the problem that you had.
It would be a good idea to look at the preamp board and make sure you have good solder connections at all the pots and jacks and connectors. Also check that the nuts for all the pots and jacks are snug.

[fastback4]

Thanks G-one...I will ask my repairman that will be re soldering the old joints and ask him to look at your suggested items also

You still have a possible intermittent problem that may cause the amp to go into squealing again. The AC cord ground would not likely cause the problem that you had.
It would be a good idea to look at the preamp board and make sure you have good solder connections at all the pots and jacks and connectors. Also check that the nuts for all the pots and jacks are snug.