do have I have to change my guitar amp's zener diodes?

Hello,

First, don't panic. I'd measure the voltage(s) and see if it(they) is(are) correct. They are certainly running warm, as they have baked the board a bit, and they are near some high wattage resistors. If the voltage is correct, you could leave them alone.

If you want to replace them as a precaution, I'd solder the new one is spaced up off the board a bit so that they get more cooling air around them, maybe .25 in or so. Be very careful, as when they bake the board like this the solder foils can get fragile.

Regards, Tim Schwartz Bristol Electronics

All agreed with Tim. What you have there is what typically happens when this simple power resistor / 5 watt zener arrangement is used to derive the + / -

If you really want to do something about it, just check the state of the joints on the other side of the board. You will probably find that they are quite crystalline, so may benefit from being reflowed with some new solder, before they start to go intermittent ( which of course, they will, at the most inopportune time, right in the middle of a gig !! ). But as Tim says, be a liitle careful of the track foils, as they will probably no longer be bonded to the board very well.

Arfa

looks normal for acheap/bad design. if it really bothers you?, buy new diodes and new cement resisters and mount them with longer legs so that the units are not near the board.