Sano Supersonic High Fidelity Amplifier....

[59Pan]

I managed to get a day off, and tried to mow between showers of rain and drizzle. At least while it was wet, I cleared a bench and set the Sano Supersonic project on it for pictures. Though the camera is constantly on the blink, today it worked well enough for some pictures.

The amp originally had casters on the bottom. But at some point, those were moved to one end, and the Sano badge rotated. I removed the casters (one was broken in shipping) when I received it. Here is a picture of it laying on it's proper side:

and another:

the back:

top:

The next few are inside, before and after I removed both chassis':

The original mounting position of the power amp was just under the 15" speaker. No idea why it was moved, but I set the chassis over it's original mounting holes, and tried the tubes. They can be removed and inserted with no problem. I will mount it back in that position, once the cab has been cleaned and repairs made:



Even though I can't dedicate any real repair time to it for another couple months, I can at least begin the cleanup and maybe make some cab repairs. A buddy at work suggested that I just clean it up and leave the old 'Road Warrior' as I found it. I'm considering that, as well.

I have a rather large Ampeg dolly that would extend approximately an inch out, all the way around. But, the rubber feet fit just fine, and those casters are original Ampeg, and in good condition.

Also, on top there is a plate with two 1/4" jacks, that were connected to the stereo input. I may reuse it or fab a nicer one. But, I'm thinking that this is a good spot for an effects loop, instead. For the moment, I don't plan to use the stereo input, though I will leave it completely functional if I should find a need for it.

And, I have a set of replica Ampeg carry handles that I can put on each end. This beast is heavy, and those sure would help. I intend to leave the original handle on top.

I'll report more as the process continues. Have a good one.

Jack

 

[JimmyM]

Very cool! Any idea what year it is?

 

[59Pan]

Very cool! Any idea what year it is?

Not yet. Will get the potentiometer codes off of it, the next time I'm out in the shop. I'm thinking 60's, but no idea as to the time period.

This amp does not match any of the Sano schematics that I can find. However, a fellow on the Hoffman Amp site gave me a schematic for the power amp in the same model Excelsior. It matches the tube count for my power amp. Sano built and branded Excelsior, back in the day.

Jack

 

[59Pan]

Got off work at a decent hour, today (Sun). So, I took a quick peek at a potentiometer code. According to this website:

The Guitar Dater Project - Pot Code Reader

This what I have for a code of 1346350:

Potentiometer Info
This potentiometer was made by
Mepco/CentraLab, Inc.
in the 50th week of 1963

So, this is probably a new year model for 1964.

Jack

 

[JimmyM]

NICE! Can't wait to see how it turns out!

 

[B-string]

I think the main amp chassis was moved because pre-heating (cooking) the 15" speaker with all the heat from tubes is a really bad idea.

 

[59Pan]

I think the main amp chassis was moved because pre-heating (cooking) the 15" speaker with all the heat from tubes is a really bad idea.

Maybe. But, I've got quite a few old amps that have the tubes hugging the speaker. All seem to be in good working order with speakers original to the amps.

It has been suggested that it was moved to put more weight on the other end, as that was the end where the casters were re-mounted. Who knows. No history.

 

[59Pan]

Got out to the shop this morning, and fitted the handles to each end of the cabinet. Also, installed the threaded insert in the center of the bottom of the cabinet. Now, I can mount an Ampeg dolly when I want to roll it around.

Cleaned the two 8" speakers, and installed both, along with the 15" speaker. I kinda got ahead of myself, as the small speakers need to be out of the cabinet, in order for me to install the spring tank. It originally was mounted directly to the wall of the cabinet. I will rubber mount it this time. Then, I can install all speakers permanently.

I need to install the grounded cord and a thermistor in line with the 'hot' lead. Once that's done, I will confirm all speaker connections. I plan to determine the impedance ratio of the main Output Transformer, and the Reverb Output Transformer. I'll do that by connecting my auto-transformer to the primary of each, and calculating the ratio using the input and output voltages. Typically, voltage on the primary is increased, until 1 volt is measured on the secondary winding.

I then plug these values into my small transformer program:

[Invalid or Expired Link Removed]

Once I've done this, I can tell whether the 15" speaker and one 8" speaker will be in parallel or series. It came parallel, but it also had other extra speaker connections tied to them, as well.

Anyway, I'll try to do a bit more this week, as time permits. More to come. Have a good one.

Jack

 

[59Pan]

Re-assembled the Supersonic and connected to the lamp limiter. It failed before I could go past my 60 watt bulb. I stepped through four bulbs, 25, 40, 60, and 100 watt. So, the first test is to remove the 5U4 rectifier tube and try again. It passed, as I observed the filaments begin to glow. PT is good. I dug out another 5U4 tube and started again. This time it passed, and began showing signs of working with the 60 watt bulb in place. I connected the guitar and the amps does indeed work. However, there was a slight hum, with all volume pots turned down. I stepped to the 100 watt bulb and the amp got louder. So did the hum. But, it works.

Finally, removed the 100 watt and put a plug-fuse circuit breaker in lamp socket. Now the amp is really loud. And, the hum is some loud, but I'm enjoying the amp. The Reverb is really strong, so I've got a good spring tank, and I have the speakers connected correctly.

While I was enjoying it, the amp developed a really loud hum that made playing impossible. Shut it down and put it back on the limiter. It still passed. Fired it up again off of the limiter, and it sounded really good for a few minutes. Then, the loud hum came back with a thud. I shut it down. I won't play it again until I've replaced the two canned capacitors in the power supply. Fortunately, that chassis is easy to remove, and the caps should be easy to get to. I will order the parts and begin work on filling the stripped out screw holes on the back. I have some new black washer-head #6 wood screws to re-install the back panel.

Once the power supply caps are installed, I intend to connect a chassis ground from the bottom chassis to the top pre-amp chassis. A bit more towards de-humming the amp. Also, I will make an effects (FX) loop box to mount to the hole in the top, and fab up a cable to go between the Return and the RCA jack in the power amp. I will connect the pre-Amp output (RCA, as well) to the Send of the loop.

Here's some pictures of my resulting progress:

Note the replica Ampeg sided handles. And, the real Ampeg dolly underneath. The last two pictures are mainly to show the solder terminal (bottom left of the chassis picture) and the thermistor installed in series with the 'hot' line to the power switch.

In my haste to get pictures, I forgot to snap one of the front, and my newly re-installed badge. Though it's missing the white back panel, it still looks good to have it back in its correct orientation. I will have more pictures when the next (and hopefully final) phase is done. Showing real promise.

And, it's really clean for the first time in a very long time. Have a good one.

 

[59Pan]

Got out to the shop yesterday morning (19Jun), before the sweltering heat could run me out. Replaced one of the power supply canned caps (just to the right of the power cord in the above picture), and brought it up on the lamp limiter. Just to ease the new caps into service.

Made a big difference, but there's still some background hum. Disconnected the pre-amp and hum is still there. I'll change the other canned cap out the next time I have a cool moment from the heat. Really strong Reverb. The Tremolo will need cap replacement(s), as the oscillation starts and then decays to none. I've seen this quite a few times before, in a number of old amps. I don't have the correct schematic for this amp, but typically on the Tremolo the bypass cap on the cathode of the oscillator is the culprit. It can be a 20 or 25uf. Either seems to do the job. That'll be the first replacement.

Also, need to troubleshoot the wiring on the power switch that's located on the pre-amp chassis. Power is always on, no matter the switch position. I never gave it a close look for mods or repairs. Will do so, now.

The amp is really loud and clean. Sounding better and better, with each small fix. More to come. Have a good one.

Jack

 

[Drcorey]

Hi jack. Thanks for posting your work I this amp. I'm working on an older excelsior branded Sano. As you diagnose each issue, it's helping me a lot. I'm working on my preamp caps now. Thanks for sharing. Ill post some pictures.

Corey in boston.

 

[Drcorey]

 

[59Pan]

Foolishly, I thought that I would be able to get something done on my amp, since the intense Spring of long hours at the plant. Not so. But, I haven't put it aside. I'm going to have to continue in bits. One more power supply canned capacitor to replace, before moving on. Hopefully, no other issues from the Power Supply / Reverb chassis, before moving on to the Pre-amp chassis.

Jack

 

[Drcorey]

btw- what schematic are you using? Mine seems to be modified from a 30/50wrt but my tubes are all different- It is labeled as an excelsior at 70 watts so it's not running the spec'ed tubes... as a beginner a this, I am learning a lot...

 

[beans-on-toast]

In case you haven't seen this site, some nice Sano amp information: Sano schematics

 

[Drcorey]

Thanks! yea- that is where I found a bunch of schematics though mine seems modified from the one's Larry provides here-In fact, I've yet to find one exactly like mine in any pictures- Looking at 59Pan's pix above, under the 2 filter cap cans in the lower chassis near power cord, I have an output selector (4-8 ohm) right next to another selector marked with "1,2,3"- not sure what this does. I think it is based on the 30wt circuit but modified to 70w as it has a bunch of 6SN7 tubes with pinouts that correspond- no 12ax7, 12au7 to be found in the chassis. I got it to play but the preamps tubes are microphonic so I'm replacing a can cap there (already replaced cans x2 in power section). Any advice??!!

 

[beans-on-toast]

Thanks! yea- that is where I found a bunch of schematics though mine seems modified from the one's Larry provides here-In fact, I've yet to find one exactly like mine in any pictures- Looking at 59Pan's pix above, under the 2 filter cap cans in the lower chassis near power cord, I have an output selector (4-8 ohm) right next to another selector marked with "1,2,3"- not sure what this does. I think it is based on the 30wt circuit but modified to 70w as it has a bunch of 6SN7 tubes with pinouts that correspond- no 12ax7, 12au7 to be found in the chassis. I got it to play but the preamps tubes are microphonic so I'm replacing a can cap there (already replaced cans x2 in power section). Any advice??!!

Sano amps from the 50's did use the 6SN7/6SL7 tubes. Those octal tubes, like the ones that Ampeg used, have a lot of rich harmonic tone in them. I prefer them to the 12A?7 family of tubes. The early schematics are more difficult to find than the later ones.

Fortunately, the amps are simple enough that the circuit can be traced and drawn. My best advice is to take things one step at a time. Test the amp after each change. Keep the original parts so that you can reverse any changes that you make.

I don't know what the function of the 1,2,3 selector is. Some of these old amps used a common chassis and they were predrilled for various options. It isn't unusual to find unused tube socket holes or holes for pots.

 

[59Pan]

Update - 11Aug15:

I didn't realize how long it's been since I put my hands on this amp. Life is just too complicated. I have a couple days off before working an 8-day stretch of long hours. It's a rotating schedule at the plant, so I know when it's coming.

I replaced the second canned capacitor in the power amp, and now that chassis is very quiet. It houses the Power Amp and Reverb. The Pre-amp is connected by means of a shielded cable, RCA plug on the end. I fabbed up a small metal project box with two closed-circuit phone jacks, and two RCA phono jacks. This is for an Effects Loop to mount in a rectangular hole on top of the cabinet. Before, there was a plate with two open-circuit phone jacks, paralleled with the 'Stereo' input. I believe that the onboard, four-pin stereo jack is for an accordion, as Sano catered to the accordion market. The amp is overall very quiet, even though the Pre-amp does not have a chassis around it. It's just mounted to the Faceplate.

Again the Reverb is plenty strong and the Tremolo is weak. I can see that a drawing is in order, at some point, to properly troubleshoot by. There is a Guitar input, Instrument input, and another unlabeled input. I'll inspect closer when I'm making a drawing. It's a lower gain, and is affected by the Master Volume, only. The Reverb, Guitar, and Instrument inputs have their on Volume/Gain pots. I'm thinking this one ties in somewhere downstream of the Guitar and Instrument.

What a really nice sounding amp this has turned out to be. With no history, a very trashy appearance (dirty inside and out), and many input modifications, it has come back to life in a fine way. I believe that I have it very stock, with the exception of my FX Loop. No wiring mods, on my part.

Next fix will be to straighten out the power switch, as it has no affect. Power is always on, if the power cord is connected. I use the switch on my limiter box, when I'm working on it. My limiter has a lamp socket, fuse holder with 3-amp fuse, and a typical wall switch (though I put one in rated for 20 amps). When I want full line voltage/current, I screw in a plug fuse replacement circuit breaker, in place of a lamp. The receptacle is protected by the small fuse, at all times. I also have a ground binding post (green), so that I can run an alligator jumper to a chassis that may not have a grounded cord.

Anyway, I'll snap a couple of pictures when the rest of the fixes are done. Particularly, the FX box and the front with the Sano badge rotated to it's correct position. More to come. Have a good one.

Jack

 

[59Pan]

Found the issue with the power switch. It is a 3-position switch, apparently is not original to the amp. I now have it wired to have one 'Off' position, and two 'On' positions. At least now, I can power it down with the switch. I will pick up a Carling short-bat power switch to replace it.

Also, I tested my FX Loop with the Pitchfork that I received from Doug Hoffman. Sounds really good on this amp. But then, anything would sound really good on this amp, I believe.

I haven't made a drawing of the Pre-amp, yet. But, the unmarked input appears to be an original installation. It jumps way downstream to a point on the Standby switch. Which explains the weaker sound when connected here. Probably an input requiring some signal from an external Pre-amp.

This Standby is like that on the Guild amps that I have, as it grounds the signal.

Anyway, the weak Tremolo is the next issue to resolve. That will have to wait until next week. Too warm in the shop. Glad I had a cool morning out there.

Jack