Schematic for oddball Sano amp
Moderators: pompeiisneaks, Colossal
Schematic for oddball Sano amp
Hello all,
I just received an eccentric Sano tube amp for repair, appears to be a stereo accordion amp with reverb and tremolo, with a single 15” and a pair of 8” speakers.
Needs filter caps and updated power cord. The rectifier is a 5U4 and the amp has two 60/20/20/20uF cap cans but I cannot find a modern replacement in these exact values, I’m wondering what I can substitute without exceeding the rectifier tube’s max input capacitance. The 5U4 data sheet lists 40uF here so I’m already skeptical about the original can values being higher. The closest modern cans I can find are 60/40/40/40uF, or 40/20/20/20uF by CE.
I’m also having difficulty locating a schematic (Schematic Heaven had some Sano amps but not this one. This model appears to be called the 500R.
I just received an eccentric Sano tube amp for repair, appears to be a stereo accordion amp with reverb and tremolo, with a single 15” and a pair of 8” speakers.
Needs filter caps and updated power cord. The rectifier is a 5U4 and the amp has two 60/20/20/20uF cap cans but I cannot find a modern replacement in these exact values, I’m wondering what I can substitute without exceeding the rectifier tube’s max input capacitance. The 5U4 data sheet lists 40uF here so I’m already skeptical about the original can values being higher. The closest modern cans I can find are 60/40/40/40uF, or 40/20/20/20uF by CE.
I’m also having difficulty locating a schematic (Schematic Heaven had some Sano amps but not this one. This model appears to be called the 500R.
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Re: Schematic for oddball Sano amp
This thread claims to have the preamp schematic (last photo).
Cheers
Edited to add: From this reverb posting there is this which seems better a better quality photo:
Cheers
Edited to add: From this reverb posting there is this which seems better a better quality photo:
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Re: Schematic for oddball Sano amp
If you have the room to glue down separate preamp filters on fish paper go that route.
Then you can run a somewhat star ground set up from the high current output stage filter and have a lower 120 hz noise floor.
Then you can run a somewhat star ground set up from the high current output stage filter and have a lower 120 hz noise floor.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Schematic for oddball Sano amp
That looks very close, thank you so much! I can’t find anything better than that on the web.
There is a page that supposedly has it but you have to send $20 via PayPal, not sure how I feel about that.
I really appreciate the help guys you guys are a gold mine.
There is a page that supposedly has it but you have to send $20 via PayPal, not sure how I feel about that.
I really appreciate the help guys you guys are a gold mine.
Re: Schematic for oddball Sano amp
Sometimes the reverb works, sometimes it doesn’t.
Re: Schematic for oddball Sano amp
The reverb tank tests good but there’s no reverb, not sure what happened because it was working and now all of a sudden it’s not.
Re: Schematic for oddball Sano amp
Where would you guys start in diagnosing the reverb? The schematic posted above for the 500R appears is correct. I can post pics of the guts but it’s point-to-point so it looks like a rats nest.
Thank you.
Thank you.
- Kagliostro
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Re: Schematic for oddball Sano amp
p.s.:I aplogize, when I posted I linked a wrong version of the file, now it is correct
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Last edited by Kagliostro on Sat Jan 13, 2024 12:08 pm, edited 2 times in total.
Re: Schematic for oddball Sano amp
Work on enough rat's nests and they start to make sense. First step is to figure out if the problem is before or after the tank. Smack the tank and get a crash, the output is fine, look at the driver side. No crash, look at the return side. Can swap the input and output on the tank and check for a crash again. If you get a crash on both sides the tank is fine but the driver side has problems. You can jumper around the tank to see if the rest of the circuitry passes signal, should get a volume boost. Do voltages look normal? If it's intermittent, chopstick around, wiggle tubes, twist and wiggle rca connectors, check cables, etc.. Do all the normal troubleshooting stuff.
Re: Schematic for oddball Sano amp
The schematic is not imho showing the jfet correctly for the tremelo function. Afaik, the jfet input would be driven by the low frequency oscillator, and would be shunting V1A or B's cathode to ground, or not. Also the Depth setting introduces feedback to the oscillator, which is interesting.
Re: Schematic for oddball Sano amp
I would trace the whole reverb circuit and verify what tube it is wired for vs what is in there. I have a 250R and while the schematic shows 6CS7 as yours does, it was wired for and had a 6CG7 installed. I just found a 300R on Reverb that has a picture of the tubes (last photo) and, you guessed it, it's a 6CG7.
https://reverb.com/item/77702988-1979-s ... e-tube-set
The cap coupled reverb is fantastic though, and if yours doesn't already have a proper reverb pan I highly suggest getting one. Mine had the little OC Electronics pan in it which did sound nice, but the 3 spring Gibbs pan I replaced it with made it even sweeter.
https://reverb.com/item/77702988-1979-s ... e-tube-set
The cap coupled reverb is fantastic though, and if yours doesn't already have a proper reverb pan I highly suggest getting one. Mine had the little OC Electronics pan in it which did sound nice, but the 3 spring Gibbs pan I replaced it with made it even sweeter.
- Kagliostro
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Re: Schematic for oddball Sano amp
I agree with you, the simbol that was used is the simbol of an SCR Diode.... The schematic is not imho showing the jfet correctly ....
As I'm not confident with Jfet and other Solid State components, if someone can put on the actual schematic where are placed the Source - Drain - Gate connections I'll try to revise the schematic with the correct Jfet simbol
Franco
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Re: Schematic for oddball Sano amp
Franco, I'm not too sure - will have a look.
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Re: Schematic for oddball Sano amp
Kagliostro wrote: ↑Sat Jan 13, 2024 11:55 am if someone can put on the actual schematic where are placed the Source - Drain - Gate connections I'll try to revise the schematic with the correct Jfet simbol
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- Kagliostro
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Re: Schematic for oddball Sano amp
Thanks again Steve
Franco
Franco