Replacement of diodes on bias boards on old Fenders and others

[mresistor]

Wondering how all you techs approach this subject. Is it prudent to replace the old tin can diodes in old Fender amps with newer modern silicon diodes? Do you replace them as a standard proceedure? Do you leave them alone if they are still functioning?  Certainly the modern diodes are much better semiconductors with better ratings..  but then again I have yet to see one of the older ones that has failed, not saying they haven't before but I haven't ran across one failing yet.

[sluckey]

Replace all when one fails. They are adequately rated.

[PRR]

> modern diodes are much better semiconductors with better ratings..

More like price. A 400V diode used to be real money; first more than a half tube then slightly less. Today a 400V part is pennies in bulk, and a 1000V is maybe 2 cents more, maybe same-price.

1N4007-TP    Micro Commercial Co  1KV 1A $0.11
1N4004-TP    Micro Commercial Co  400V 1A $0.11
1N4007-G    Comchip Technology  1KV 1A $0.11
1N4004-T    Diodes Incorporated  400V 1A $0.14
1N4007-T    Diodes Incorporated  1KV 1A $0.16
1N4007T-G    Comchip Technology  1KV 1A $0.16
1N4004RLG    ON Semiconductor  400V 1A $0.20
1N4007RLG    ON Semiconductor  1KV 1A $0.20
("RL" is on reel, "T" or "TP" on tape, "G" is lead-free {though I'm sure all are Pb-free now})

[Ed_Chambley]

If you can, try some of the fast diodes.  Fast switching soft recovery.  I attached a data sheet, but there are many types.  These cost almost 30 cents.  I have been using them in overdrive circuits with nice results.


Can you actually hear a difference in an amp some have asked me.  Always the same answer, sure you can hear it but it may not be what you want.



The 1n-4007 will do the trick as PRR mentioned.