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01-24-2019, 12:03 AM
Hi TiCatFan
Fender goofed with the standby wiring. First, it is a wonder this switch was ever included - see the article about standby switches on my site - the upshot is that standbys are potentially hazardous and they have little relevance in a guitar amp resulting in most people not using them "correctly" (a loaded word since the voltage is not high enough, the power is not high enough nor are the tubes expensive enough to justify adding the s/b). Second, the circuit position for the switch does not help switch life itself as it must make / break DC rather than AC. Really, the standby should be bypassed - shorted and use the switch for something else.
The only good thing Fender did with the s/b wiring was to add bleeder resistors across the main filter caps. These enforce voltage sharing, but they also discharge the caps after the amp is turned off. However, if you are inclined to USE the s/b as people suggest, the other caps in the amp might still have a charge when you open the amp. The best way to assure that all the caps are discharged is to bash on the guitar and turn off ONLY the power switch. The sound will fade down to nothing and the caps will be safe for you to poke around inside the chassis.
It sounds like this amp has not been used for a long time? You should never power an old amp like this directly with full mains voltage. Instead, use a Power Limiting Safety Socket (light bulbs) to limit power. First turn-on should be without power tubes, so you can verify that all the voltages are present ESPECIALLY that bias voltage is present right at the tube sockets.
Your amp seems to need a justifiable cap job.
Fender goofed with the standby wiring. First, it is a wonder this switch was ever included - see the article about standby switches on my site - the upshot is that standbys are potentially hazardous and they have little relevance in a guitar amp resulting in most people not using them "correctly" (a loaded word since the voltage is not high enough, the power is not high enough nor are the tubes expensive enough to justify adding the s/b). Second, the circuit position for the switch does not help switch life itself as it must make / break DC rather than AC. Really, the standby should be bypassed - shorted and use the switch for something else.
The only good thing Fender did with the s/b wiring was to add bleeder resistors across the main filter caps. These enforce voltage sharing, but they also discharge the caps after the amp is turned off. However, if you are inclined to USE the s/b as people suggest, the other caps in the amp might still have a charge when you open the amp. The best way to assure that all the caps are discharged is to bash on the guitar and turn off ONLY the power switch. The sound will fade down to nothing and the caps will be safe for you to poke around inside the chassis.
It sounds like this amp has not been used for a long time? You should never power an old amp like this directly with full mains voltage. Instead, use a Power Limiting Safety Socket (light bulbs) to limit power. First turn-on should be without power tubes, so you can verify that all the voltages are present ESPECIALLY that bias voltage is present right at the tube sockets.
Your amp seems to need a justifiable cap job.
