Fender Bandmaster

mkran · Newbie Alert Joined: 17 Nov 2005 Posts: 2

Hello,I changed the electrolytics on my 68 bandmaster with some NOS caps and some new.Seems about the same no hum but at about volume 3 or 4 i hear e e e e e e e e e e e e e type sound.I ordered some 1000v 3 amp diodes to try.What is the Grey strip side again.That looks like negative just like on the old film caps but just wanna make sure.The 70 uf caps i used were actually NOS the same exactly paper caps.I'm an electrician from 20 years ago but never read any amp books. Question

polar_electronics · Posted: Thu Dec 15, 2005 6:30 pm Post subject:

Unfortunetly, NOS doesn't usually apply to electrolytic caps. With age, the dielectric usually dries up and can no longer function properly. Amps with old caps can still work, but that can usually be attributed to the fact that they have been played a lot and the caps never had a chance to dry. Either way you look at it: if your caps are truly New Old Stock, they have most likely dried up by now, or if they work properly, there's a good chance that they've been used and therefore aren't truly NOS. Either way, the signs don't look good.

mkran · Newbie Alert Joined: 17 Nov 2005 Posts: 2

O.k. thanks.Have you every seen the rectifier diodes go on a amp and what was the sound the amp made ?

polar_electronics · Posted: Sat Dec 17, 2005 9:26 am Post subject:

Solid state diodes are very sturdy components, as long as they are of the right voltage value. I've actually never seen diodes go bad, but if they did there wouldn't be a sound at all, since the diodes feed the filter caps and on to the high voltage. A good way to test is to see if the pilot light is on but no sound coming from the amp. If you measure the voltage at any positive filter cap point and there is none there, get someone to look at your diodes. Also, a lot of not-so-expensive multimeters have a diode check function that would work. Isn't it great to have a good excuse to buy new toys?