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Fender Twin Twins

nj pheonix

nj pheonix

Lunatic Member
Hi,
I've been conspicuously absent for while though i poke my head in from time to time. In any event, my brother left 2 fender twins with me (one complete one just the innards).
The complete one blows fuses. As i expected (hoped?) it has shorted diodes in the PS. So my intention is to replace them all (6). The Fender schematic I've seen doesn't have a PN. My thought was to use 1N4007. Is there any reason this isn't suitable or why i should be looking at something different? My intention, was to replace the electrolytics change the caps,, clean the jacks and controls and call it day. Oh, any issue with using D5 Deoxit on the controls? Any comments or commentary welcome.
 
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Have any data on the transformer voltage? Pretty solid bet three 1n4007 in series is plenty adequate. Original were probably less than 1kv

If you feel some kind of way about it, bridge the diodes with a high value resistor, 470k to 1M ought to do. That will ensure the voltage is spread equally
 
nj pheonix said:
Hi,
I've been conspicuously absent for while though i poke my head in from time to time. In any event, my brother left 2 fender twins with me (one complete one just the innards).
The complete one blows fuses. As i expected (hoped?) it has shorted diodes in the PS. So my intention is to replace them all (6). The Fender schematic I've seen doesn't have a PN. My thought was to use 1N4007. Is there any reason this isn't suitable or why i should be looking at something different? My intention, was to replace the electrolytics change the caps,, clean the jacks and controls and call it day. Oh, any issue with using D5 Deoxit on the controls? Any comments or commentary welcome.
Click to expand...
I use 1N5408 (or UF 5408) diodes in these big Fender amps. The extra current capability is nice if you like the super-clean Fender tone to a VERY LOUD volumes. ;)

8041f6d6-4c2c-43b1-97eb-563e69c8d4a6.jpg

Bassman solid-state rectifier board (similar to your TR).

65faa66e-6c01-4f72-8f32-8085b0c506fc.jpg

Be sure to put fresh caps under the doghouse.

DeOxit D5 on all connections and sockets. Fader Lube in the controls.

Good luck!

:thumbsup:
 
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Buck Rogers said:
Yeah, I'd prefer those too.

More is always better with diodes...
Click to expand...
Yup. It won't hurt. Current on-demand sort of thing.

People used to post how plain-jane 1N400X or 1N540X diodes had an audible switching noise. Perhaps in the old days, of the early 1960s. I bought into the hysteria and got two rolls each of UF4007 and UF5408 (really only cost me pennies more per item).

I can hear no difference between the 1N4007 and UF4007. And I use no bypass or snubber caps (another hysteria thing, in my opinion,. when using today's quality diodes).

:)
 
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nj pheonix said:
Other observation . PS has 2 50uf 70v caps. What my early parts search has me looking at is 47 @100 .
Click to expand...
Use 50 µF (or close) @ 100 VDC caps in the BIAS SUPPLY. This compensates for higher wall outlet voltages.

I use high-voltage-rated caps (usually 500VDC) in the MAIN POWER SUPPLY. 100mfd/450VDC for the first two caps, in series — if you have a similar setup to the AV763 circuit.

a2d0b35b-f3f3-4ad5-af39-6026c09ae3cc.jpg


:thumbsup:
 
I've been down a bunch of rabbit holes on the audio side. I've become very pragmatic over the years. Fortunately my brother isn't a lunatic. Just looking for something roughly equivalent to what it might of sounded like when it was new and neither of us will every know.
 
nj pheonix said:
I've been down a bunch of rabbit holes on the audio side. I've become very pragmatic over the years. Fortunately my brother isn't a lunatic. Just looking for something roughly equivalent to what it might of sounded like when it was new and neither of us will every know.
Click to expand...
What speakers does he have in that TR?

00cac2aa-1511-4ca6-b36d-3f208af30f86.jpg


My old Twin with prized orange basket JBLs. I no longer have this monster. :(
 
nj pheonix said:
I've been down a bunch of rabbit holes on the audio side. I've become very pragmatic over the years. Fortunately my brother isn't a lunatic. Just looking for something roughly equivalent to what it might of sounded like when it was new and neither of us will every know.
Click to expand...
Refreshed, he'll like this amp.

:thumbsup:
 
I'll go back and get pics of the speakers ( they're not those for sure . My doghouse cap config is different. I'd bet caps are from around 1970 +/-. So they go.
 

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nj pheonix said:
I'll go back and get pics of the speakers ( they're not those for sure . My doghouse cap config is different. I'd bet caps are from around 1970 +/-. So they go.
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20260404_125805-jpg.3735224

Mid 1970s Twin Reverbs usually came with Oxford or Utah speakers.

___________________________


Cap dates, the 44th and 47th week of 1972.

235-7244A, 235-7247A = 235 (Mallory's EIA manufacturer code). 72 = 1972. 44 (47)= 44th (47th) week. Not sure what the "A" means.

They need replacing. As those are the original cases (the cases may have been restuffed with new caps :idea:). I say this because someone has replaced the resistors on the B+ power rail. I have never seen anyone replace those without replacing the caps.

Use all metal oxide resistors (blue-gray body) (I like 2 or 3-watt rated ones) or wire-wound types in the power rail. They last much longer than the carbon type (the brown-bodied one).

[NOTE: The polarity of the top two caps! They are in series with each other. All other caps are in parallel.]
 
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