Fender Evil Twin (Reed Knob) Impedance Switch Wiring

[mikeydee77]

Would love a second opinion on this one... perhaps someone has a photo of one of these or one on the bench right now?

This amp with a 1989 build sticker on it came in ith a miscellany of faults(caps, jacks etc) and after all fixed it is quite loud on the hiss level but the his is not coming from pre amp but introduced at the effects loop stage. One doubt I have is that the impedance switch has been messed with and I noticed that the hiss is greatly removed when in 4 ohm mode... I don't think the wiring in front of me matches the schematic but the photos i have found on line are not clear enough to tell...

issue is that the NFB (white wire) is out of circuit unless the 4 ohm setting chosen. I would expect a wire link to be present...

Mike

pics coming below

[mikeydee77]

[g1]

Sorry, I think you are right, I just couldn't see clearly on the pic. White wire lug should have link to grn/yel lug.

[mikeydee77]

Sorry, I think you are right, I just couldn't see clearly on the pic. White wire lug should have link to grn/yel lug.

thanks g1 appreciate the second pair of eyes on that that

[g1]

If memory serves, the loop level switch setting will also affect the hiss level in these amps.

[mikeydee77]

If memory serves, the loop level switch setting will also affect the hiss level in these amps.

it certainly does.... and those switches also wear out.. reverb one on the front too which can be a noise source too.

in my case the nfb link must have been removed in some earlier fix. adding it back has tamed it somewhat.

cheers

[Tom Phillips]

Attached are 2 photos of a 1988 and 2 of a 1990 "The Twin" Speaker Impedance Switch.
HTH,
Tom

[mikeydee77]

Attached are 2 photos of a 1988 and 2 of a 1990 "The Twin" Speaker Impedance Switch.
HTH,
Tom

Thanks Tom i believe pic 4 has all the evidence.