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Post by rdr on Jan 21, 2024 14:41:04 GMT -5
Hi. I have to go into my 72 Princeton Reverb to replace the fuse holder.
It has the grounded plug but I don't know if the power wiring is correct inside.
Can someone point me to a diagram of the correct wiring? I want to keep the a/c receptacle working.
Thanks!
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Post by Jim D. on Jan 25, 2024 10:07:01 GMT -5
rdr: If I understand your question correctly, this video guides you step by step. Remember that black is the hot 120 VAC and don't mistakenly rotate black and white! I would definitely use a multimeter to check continuity unplugged, and that black and white are properly landed. The third wire, the ground should be cleanly and firmly bonded to the chassis as shown here. Good luck. If you have the stock "death cap" this method totally disables it. If you are familiar with the method, an incandescent light bulb in series with the black hot wire can be used in place of a variac for a reduced voltage start up test. You would have to rig up a lamp socket, three prong cord, and a receptacle (to plug the amp into) to do this but it's quite straightforward. It's prudent to do this. I can send you something if you have questions.
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Post by rdr on Jan 25, 2024 11:16:37 GMT -5
Thanks so much Jim. I do have a 'dim bulb' tester that I bought (named after me?).
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Post by Jim D. on Jan 25, 2024 13:03:29 GMT -5
Well-I discharged the main capacitors in a Deluxe Reverb once with my fingers. I'm lucky it did not involve both hands. It only took once for me to learn to discharge the caps with a resistor and probes anytime I go near a bare chassis. Here is a schematic if it helps: www.stratopastor.org.uk/strato/amps/prii/schematic/schematic.htmlThis shows the three prong plug. |
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Bopper
Wholenote
Motor City USA
Posts: 506
Age: 72
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Post by Bopper on Jan 26, 2024 11:36:55 GMT -5
Stratopastor (source of the link above) was on the FDP - good guy.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Jan 27, 2024 15:23:37 GMT -5
... this video guides you step by step... Hmm, I'm not keen on the methods shown in that video. 1/ Ground wire too short; it needs to be so that if the cable retention clip fails and the mains cable get severely pulled, the ground termination will be the last to get pulled off its lug. So 50 to 100% longer than he did it. 2/ Chassis safety ground lug retained by mains transformer bolt; those are the most mechanically stressed fasteners on the amp. It's nuts to also trust them with the only safety critical connection on the amp. Plus those bolts can lose their torque over time. Vibration, thermal expansion and contraction, magnetostriction all act against a long term reliable connection. To the point that I've found the mains transformer in a couple of 70s Fenders hanging onto the chassis by 1 loose bolt, the others on the cab floor, their nuts rattling around in the chassis. Basic good electrical practice is to use a dedicated, fastener for the chassis safety connection, and ensure its long term reliability by including a locking mechanism of some kind. Pretty much any item of code / regulation compliant grounded electrical equipment made in the past 20+ years does it like that. 3/ No star washer between chassis and ground lug; any build up of oxidation on the mating surfaces will impair the connection. 4/ Mains switch in the neutral feed; why oh why, it's basic good practice to switch the live and so deenergise more stuff, most pertinently the mains transformer primary. |
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