Dropping Cap rating advice.

[Shawnobi]

Will try to keep it short. Picked up a silverface Fender twin (1976 100W). Have got all the usual parts in for a service but I'm struggling with the 20uF 500V in the power section. All my usual places in the UK are on back order for some reason (also 22uF). I want to get the old Mallory's out and I need to be using the amp next week.

Now, I can get some Vishay 20uF 450V in the next day or so. But I'm uncomfortable about dropping 50V on spec which I wouldn't normally do. Looking at the schematic the highest they should see (ignoring spikes) is 443V which seems a bit close for comfort to me. HOwever I know Cap technology has come a long way since the 70's and Vishay are a solid brand so part of me thinks "they'll be fine". Plus it's my own amp so I can change them out when the correct values become available (But you know how we like to put things off when they work).

So I'm looking for a sensible consensus really. Leave the Mallorys in (No signs of bulging) until the correct ones become available? Or throw the 450V's in?


20uF/500V: https://uk.rs-online.com/web/p/alumi...itors/8506317/

[DrGonz78]

Now, I can get some Vishay 20uF 450V in the next day or so. But I'm uncomfortable about dropping 50V on spec which I wouldn't normally do. Looking at the schematic the highest they should see (ignoring spikes) is 443V which seems a bit close for comfort to me.

Don't guess what the voltage is in the amp and don't assume that the B+ voltage is exactly the same as what is listed on the schematic. Chances are that the line voltage was a little bit lower back in the day and it might be more like 460-480v with today's line voltages. I would wait and order the correct parts for the recap job.

[Shawnobi]

Don't guess what the voltage is in the amp and don't assume that the B+ voltage is exactly the same as what is listed on the schematic. Chances are that the line voltage was a little bit lower back in the day and it might be more like 460-480v with today's line voltages. I would wait and order the correct parts for the recap job.

I agree. Impatience raised this question I guess.

However I've just finally found a source of the correct value after much searching so I'm good after all it seems. Phew!

[m1989jmp]

Will try to keep it short. Picked up a silverface Fender twin (1976 100W). Have got all the usual parts in for a service but I'm struggling with the 20uF 500V in the power section. All my usual places in the UK are on back order for some reason (also 22uF). I want to get the old Mallory's out and I need to be using the amp next week.

Now, I can get some Vishay 20uF 450V in the next day or so. But I'm uncomfortable about dropping 50V on spec which I wouldn't normally do. Looking at the schematic the highest they should see (ignoring spikes) is 443V which seems a bit close for comfort to me. HOwever I know Cap technology has come a long way since the 70's and Vishay are a solid brand so part of me thinks "they'll be fine". Plus it's my own amp so I can change them out when the correct values become available (But you know how we like to put things off when they work).

So I'm looking for a sensible consensus really. Leave the Mallorys in (No signs of bulging) until the correct ones become available? Or throw the 450V's in?


20uF/500V: https://uk.rs-online.com/web/p/alumi...itors/8506317/

https://www.tube-town.net/ttstore/Ca...xial::402.html

Used these when I had a Vibrosonic that needed a recap.

Best prices I found by far.

[mozz]

Yes, i was going to say you can probably get F&T somewhere over that side of the pond since they are made over there.

[pdf64]

http://www.die-wuestens.de/eindex.htm