Sano Supersonic High Fidelity Amplifier......

[Jack_Hester]

I have a Sano Supersonic High Fidelity, that has been in a very dusty storage for possibly several decades.  Even though it came out of NY state, it has all the appearances of a number of other old amps that I bought from estates out of Texas.  Very dusty, but no rust. 

The closest schematic that I can find to this one is for a 50WR(T).  That one has 5 tubes in the power amp chassis, and 5 tubes in the pre-amp.  Mine has 7 tubes in the power amp chassis, and 4 tubes on the pre-amp chassis.  That one has 8417 power tubes, where mine has 6CA7/EL34's. 

Mine has one 15" Utah and two 8" Utah speakers.  Each 8" speaker is different. 

I can see no model number on either chassis or the faceplate.  I'm suspecting a model a model other than the 50WR(T), but won't know until I have removed each chassis for a close inspection. 

It also appears that the power amp chassis has been moved from what may have been it's original position in the bottom left of the cabinet (looking in the rear), just under the 15" speaker.  At present, it is on the right. 

Whenever I find the time (too busy at work, and very long hours until June), I intend to remove everything from the cabinet for a closer inspection.  No pictures, for now.  Camera is on the blink for maybe the last time.  I'm shopping for it's replacement.  This is a somewhat unconventional build, by other amp standards.  Very neat, point-to-point.  All the appearances of a fun restoration, thought the cabinet will needs lot's of TLC.  Tolex is sound, but has a few extra cabinet holes to fix.  It had casters on one end, but originally mounted on the bottom.  Lots of screw holes there. 

I know that Jack Gentul worked for Sano in his early career, and left to begin his own line (Hilgen - I have a few of those):

http://www.hilgenamplifiers.net/the-genius-behind-hilgen-jack-gentul.html

So, I'm thinking that this amp layout reflects his handy work, as his Higen amps have the same cleanness of layout that this amp has. 

Anyway, if anyone knows of a schematic for the tube-count of mine, please post.  Would save me a lot of work of making my own, when I am able to start on this amp.  Thanks.  Have a good one. 

Jack

[eleventeen]

Wow, he worked at Brook Amplifiers. Pretty cool. Those are definite cult items.


Thanks as well for posting that link with the bio. I grew up about 10 miles away from Newark NJ. I always wanted to go visit the Tung-Sol factory on Bloomfield Ave but never did. I *did* get to go see the RCA tube factory in Harrrison, NJ.

[Ritchie200]

Jack,

Is this the one you have?  Although this references 6CA7/EL34's.  Does yours have trem?  If so, maybe that accounts for the additional tube count over this one.  Maybe this one will get you close?

Good luck!
Jim

http://davidguilbault.typepad.com/ExcelsiorAmp/ExcelsiorSchematic.JPG

[Jack_Hester]

Jack,

Is this the one you have?  Although this references 6CA7/EL34's.  Does yours have trem?  If so, maybe that accounts for the additional tube count over this one.  Maybe this one will get you close?

Good luck!
Jim

http://davidguilbault.typepad.com/ExcelsiorAmp/ExcelsiorSchematic.JPG

Jim -

Thank you ever so much!  Yes, mine has Tremolo.  That looks like it takes care of the tube count for the power amp chassis. 

Both pre-amp channels leave that chassis as two shielded cables with RCA plugs on the ends.  They combine in a two-into-one RCA adapter, and enter the power amp chassis. 

Jack

[Jack_Hester]

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

Jack

[Jack_Hester]

An idea occurred to me.  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. 

Anyway, more to come. 

Jack

[eleventeen]

Well whaddya know?

[Jack_Hester]

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

According to this website:

http://www.guitardaterproject.org/potcodereader.aspx

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

[Jack_Hester]

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. 

One more thing.  It's very clean now.  And as alluded to previously, cleaner than it has been in possibly decades.    Have a good one. 

Jack

[Jack_Hester]

Got out to the shop yesterday morning (19Jun), before the sweltering heat could run me out.  Replaced one of the power supply canned caps (the one 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.  Nowhere near as loud as before.  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'll locate the oscillator and see if it has a bypass cap on the cathode.  I've got some 20 and 25uf electrolytics on hand.  The Sano 50WRT schematic (tube count doesn't match mine) shows a 20uf on the oscillator. 

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 previously.  Will do so, the next time out.   

This amp makes it easy to add an effects loop.  I have a small die-cast box that I've installed two closed circuit phone jacks, and two RCA jacks.  It will mount in the hole on top, where there was a plate with jacks for a stereo input (two phone jacks).  It was paralleled to the onboard stereo jack.  Already have the holes drilled and tapped to match the mounting holes in the cabinet.  Will be much cleaner than the previous setup.  I won't install this, until all else is working and no more troubleshooting to be done. 
 
The amp is really loud and clean.  Sounding better and better, with each small fix.  More to come.  Have a good one. 

Jack

[kagliostro]

I missed this tread before


Nice Score Jack 


Franco

[Jack_Hester]

Thanks, Franco -

I'm drawing the line.  No more heavy amps.  This one is a beast.  The side handles are an absolute must.  Two people to carry will be the best way to move.  Carrying this with the top handle is very difficult. 

I picked up a Westco hand-truck at a decent price.  With folding platform and wheels, and collapsible handle.  At least now, I can move some of this stuff with a minimal of lifting. 

Anyway, this one will find a spot to rest in the house, with easy access.  The old road warrior will have an easy life from now on. 

Jack

[Ritchie200]

Jack, that is too cool!  That beast cleaned up really nice!  Yeah, just think how old those cap cans are...  I'm sure they are the source of your hmmmmm.  Now you need to post some jazzy-type tunes to showcase your new baby!

Jim

[Jack_Hester]

Thanks, Jim -

Methinks this will be an ongoing repair.  At least thru the Summer.  Once I'm done with the lower chassis, the upper will need some head scratching.  Even though it works, it still not quite there.  When I first started taking it apart, and labeling each cable, making sketches of the guts, I could tell that someone with more than just a working knowledge of electronics had their hands in it. 

The wiring mods appear to be very old, probably when the amp was close to new.  And, with an intent like a multi-purpose studio amp.  Or, the same in a performing amp.  But, it was modded with more than a stock amp in mind.  It had a pre-amp output.  External speaker jacks.  Stereo input jacks.  It is a very clean sounding amp, way up on the volume.  Accordion?  I believe that was by original design.  Organ, maybe?  I always think guitar, but that would only be just another guess.  The amp has no history from the past owner. 

I believe it is an earlier model 50WR/WRT, 1964.  It's been a very interesting mystery so far.  I'll post each new find, as I go.  I've got a couple more days off this week.  Maybe I'll get in some early hours on it, tomorrow.  At least, I can get the other large canned cap removed.  Not sure I have a correct replacement, as I can't read the values.  That side hugs the transformer very closely.  I have a 20, 20, 20, 40uf cap.  But, it may very well be just like the other, (20uf x 4). 

The next time I do roll that chassis out, I will inspect closer for other electrolytics.  And, plan their possible replacement.  The same for the upper chassis.  And, test all the tubes.  I know the rectifier is good.  I put that one in, after the first power up.  The rest are as they were found, except cleaner.  Maybe I'll have something to report after tomorrow morning.  Have a good one. 

Jack

[Jack_Hester]

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

[HotBluePlates]

I'm impressed by the quality of the assembly. That amp shows how to do terminals strips properly.

[Jack_Hester]

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.  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

[smackoj]

Love the look of that old home wrecker. I'm really into 'loud' and 'clean' so this is a true diamond in the rough.  thanks for documenting the restoration Jack. In case any of the forum brothers are interested. Here is a link to a Sano with quite a few similar features that is for sale on sneezbay right now.


http://www.ebay.com/itm/201401643609?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[Jack_Hester]

Love the look of that old home wrecker. I'm really into 'loud' and 'clean' so this is a true diamond in the rough.

Loud and clean is a good description for this one.  But, it can thump, with the big 15" speaker. 

Got some short-bat SPST Carling toggle switches in the mail, today.  So next week, I'll install one to clean up the make-shift setup it has. 

I also noticed a 3-cap can on the Pre-amp chassis.  Right now, the amp is working fine (not counting Tremolo), but I'll identify it and see if I can't have one on hand.  It's rather small, so I don't know if it will be an easy find.  I'll know next week when I'm replacing the switch, and can have a closer look.

Jack

[Ritchie200]

These resurrection threads are so cool!  It's like a historical novel.  Jack, I was just looking at the pics again.  Is it the light/angle of the picture or does that rectifier getter look like that tube's been through hell?

Jim

[HotBluePlates]

Is it the light/angle of the picture or does that rectifier getter look like that tube's been through hell?

The getter is faded and has shrunk in overall diameter. That only means it's been doing its job of combining with gas molecules in the tube.

I've had a lot of input on getter fading from various old-timers, including a tube t.v. repairman. Everyone knows that a brand new tube should have a big shiny getter flash (except for some euro-tubes, like a particular-era Mullard whose getter flash looks almost black when you view it straight-on). The disagreement is over what a faded getter flash means...

The only thing it tells you conclusively is there were gas molecules in the tube and the getter flash recombined with and trapped those molecules. Some point out that extreme tube abuse, redplating, etc could drive gas molecules out of the metal structures in the tube, so a faded getter could be a sign of extreme abuse. However, no vacuum is perfect and some amount of gas could have been in the tube from the day of manufacture. So a faded getter equally indicates an old tube that's been sitting for decades, and a getter that's doing its job.

Outside the guitar realm a faded flash is just seen as proof the tube is old, and not an external indicator of the tube's condition or performance capability.

[Jack_Hester]

One thing that I'm guilty of on this amp is not testing the tubes before using.  Considering the physical abuse that it has had at some point, and the layers of barn dust, the actual repairs have been minimal.  When first on the lamp limiter, the rectifier looked strange.  I don't remember what caught my eye, but I saw and heard something that made me shut it down.  I had another tube close by.  Next time, it came up I knew that I had a working amp. 

No idea at this point where the replacement rectifier came from, but it was on the bench, and not original to this amp.  All other tubes are.  That being said, the first pictures do have the rectifier that came with it.  The pictures of the cleaned amp have the replacement.  Now I need to go back and look at the pictures again. 

Jack

[trobbins]

Jack, you haven't indicated if you have tested any circuit voltages for at least typically ok idle DC voltage levels?

[Jack_Hester]

Jack, you haven't indicated if you have tested any circuit voltages for at least typically ok idle DC voltage levels?

No I haven't done so.  I only powered it up for short periods, as it's been an ongoing project to make it closer to it's original configuration.  I like to make a voltage chart of the whole amp, when I take readings.  The Pre-amp sockets are easy access, as they face out.  The lower chassis will have to come out (relatively easy to remove) for access to those.  I have socket adapters, but the big 15" speaker is in the way to use such, on three of the small tubes.  I'm thinking that I will have to roll it out onto a cradle, in order to hook everything else up for proper loading when I take the readings. 

Also, I've decided that this is a keeper, for sure (like everything else seems to be).  So, I've ordered a complete set of tubes.  Kinda like giving an old stray dog it's first good home.  I used to do that as a kid, here on the farm.  They turned out to be some of the best dogs a kid could ever want.  That's just how much I'm liking this amp.

Jack

[Jack_Hester]

First time since Spring that I've had a whole 'do nothing' day.  So, I began the laborious process of tracing the Pre-amp and Tremolo circuit.  I decided to not follow convention in drawing the schematic.  Instead, I made a literal drawing from the chassis, though I didn't try to make it to scale.  Just the basic layout, as it is a point-to-point build.  I'm about 90% finished with the first draft.  And, it really won't be complete, until I make a drawing of the Power Supply and Reverb circuit.  I'm sure it's the same as the one that Jim posted in Reply #2.  I'll use it as a basis for my first draft of it, and reconcile it with the actual circuit. 

Anyway, much more proof-reading to do.  But, it's time to call it a day.  More to come.  Have a good one. 

Jack

Update: 21Sep15 - See Reply #30 for the latest drawing.

[jazbo8]

Since you have the tremolo, shouldn't the model number be 50WRT? Why does the tremolo circuit contain a transformer? Wouldn't that be for the reverb? Also, could you please confirm whether there is a 6U10 in the tube line up on the preamp or the power amp chassis?

[Jack_Hester]

Since you have the tremolo, shouldn't the model number be 50WRT?

Probably should be, but I can find no Sano listing for anything other than the 30-50WR.  No WRT.

Why does the tremolo circuit contain a transformer? Wouldn't that be for the reverb? Also, could you please confirm whether there is a 6U10 in the tube line up on the preamp or the power amp chassis?

No idea, as of yet, as to the choke being in there.  Not in the Reverb, as all that resides entirely in the other chassis (Power Amp/Reverb).  There is no 6U10 in either lineup, or 12-pin socket.  There is a 6AN8A and and EL84 in the Reverb circuit.  Only 9-pin sockets in both chassis', except for the rectifier octal and the two power tube octals. 

I'm now thinking that once I get the remaining components in place, and have given it a proof-read, I'll spread it out and make it follow convention a bit closer.  This was some kinda slow to draw, with everything so packed together.  Won't be quite as bad next draft, as I'll have my first draft to follow. 

Jack

[Jack_Hester]

Made a quick cleanup of V1, and got rid of some components drawn on Pin-8.  No idea where they came from.  Just stared too long at the packed build.  I replaced the drawing in Reply #24, to reflect this cleanup. 

Also note, 'D' and 'E' of the Master Volume leave this chassis by means of a shielded cable, and connect to the Power Amp chassis. 

Jack

[sluckey]

V3A is the tremolo oscillator. There's a very necessary resistor missing on V3-2 (grid). The missing resistor would connect to ground or back to pin 3 (cathode).

[Jack_Hester]

V3A is the tremolo oscillator. There's a very necessary resistor missing on V3-2 (grid). The missing resistor would connect to ground or back to pin 3 (cathode).

Steve -

Thanks for the sharp eye.  There is a 470K resistor to ground, on Pin-2.  The drawing above has been corrected and replaced.  Actually, I had the 470K in the wrong place.  I had it drawn before the .02uf cap.  It's in the right place, now.

I expect to find more oversights, when I proof-read this afternoon.  Headed out for Church.  Will check in later.  Have a good one. 

Jack

[Jack_Hester]

Ok.  Some more proof-reading and adding missing components.  Plus, the first draft of a different schematic.  Not the cleanest, but making more sense. 

I also appended the Excelsior Reverb / Power Amp schematic.  Time to call it a night.  Have a good one. 

Jack

[jazbo8]

The tremolo bit threw me off, not sure if there was any model with the "WRT" suffix (there is a mistake in the labeling on the el34world schematic database), anyway, it appears that you have the Excelsior 30WR_50WR preamp, and the power amp posted by Richie2000 earlier. I still don't see the choke on the preamp board, could you please highlight it on the photo?


Below is the schematic for the preamp section, I think it matches your description.

[Jack_Hester]

Well, Sano and Excelsior have turned out to be somewhat confusing brands.  Thanks for your pre-amp picture, but that's not mine.  Notice that your picture has two tone stacks.  Mine has only the one.  And, no stereo input jack as drawn in yours.  Mine has a 4-pin (XLR?), and I've spent all my time looking at the backside of it.  I will have to look to see if it's a male of female on the front. 

But, thanks again.  I've filed this one away for reference.  I've got a couple other Supersonics, waiting their turn. 

One has a Leslie cabinet, and was heavily modified by Sano.  I got it from the original owner.  His father bought it for him in 1970, when he was 15 years old.  He was born and raised in New Jersey, and said that the music store that sold it to them had it modified for his Leslie and Sanovox accordion.  I have that, too.  I've confirmed the operation of the amp and Leslie.  They work just fine.  Have not touched the Sanovox, but he told me that it did not work when he tried it.  First time it has ever failed, though he's been playing a Roland setup, and hasn't touched the Sanovox in 10 years or so.  I don't mind, for now.  Not a top priority.

The other is unmodified, but pops and crackles badly.  Have not done any troubleshooting on it. 

So, I'll continue on with my final (hopefully) repair on the pre-amp, and maybe modify the schematic one more time, to spread it out to look more like the one you posted.  I'll be back.  Have a good one. 

Jack

[jazbo8]

So, I'll continue on with my final (hopefully) repair on the pre-amp, and maybe modify the schematic one more time, to spread it out to look more like the one you posted.

Ah, yours must be a special version. Very rare I suppose... Anyway, I encourage you make change to the Sano scheamtic that I posted, it will be easier to follow instead of your layout version, since we don't have the amp in front us like you do.

[Ritchie200]

Jack

Looking at the power amp schematic that I sent you (if correct for yours), am I seeing this right.....?  It looks like a separate channel/EL84 output section/tranny driving a single speaker for just the reverb?  If so, that is truly unique!  Lots of blend options for dry and wet.

Jim

[Jack_Hester]

Jack

Looking at the power amp schematic that I sent you (if correct for yours), am I seeing this right.....?  It looks like a separate channel/EL84 output section/tranny driving a single speaker for just the reverb?  If so, that is truly unique!  Lots of blend options for dry and wet.

Jim

Yes, I'm satisfied it is correct for mine.  I will hand-trace that as well, and confirm it with your drawing.  Same tube lineup as mine. 

Yes, a completely separate S-E amp for Reverb.  It is unique in that it is really strong, from a subtle echo to that of bed springs loud echo.  Ever so nice configuration. 

However, Ampeg has a similar setup in their B-12-X and XY models, though their 'Echo' is very tame as compared to this one and most others.  I did try one of my 'XY' models with a 12" P12Q Jensen, on the 'Echo'.  Much better, but still no comparison with this Sano. 

Jack

[sluckey]

This schematic has nothing in common with your amp, BUT, it has an unusual tremolo circuit that uses a choke. I thought you might find that interesting.

     http://el34world.com/charts/Schematics/files/premier/premier_76.pdf

[Jack_Hester]

Thanks, Steve.  I filed that one, as I have no schematics on any Premier.  I'll take a look at it this afternoon.  Have a good one.

Jack

[Jack_Hester]

Made one more drawing, closer to convention.  Plus, I replaced the pre-amp power supply de-coupling capacitors.  As well as the cathode bypass cap on V3a. 

Depending on my work hours this week, I will try to install the pre-amp in the cabinet.  I'm anxious to see if the minor hum is gone.  But mainly, will the Tremolo come alive for the first time.  I'll be back with the results.  Have a good one. 

Jack

Update: 28Sep15 - See Reply #39 for the latest drawing.

[Jack_Hester]

I got home in time to mount the Pre-amp chassis in the cabinet, and get everything connected.  Warmed the amp up for a bit, and tried out the Guitar and Instrument channels.  Both sound really good.  The Reverb is likewise very strong and has a really good range. 

However, no Tremolo.  I made no further tests.  But, before I go tearing into the amp again, I want to put my VTVM on the oscillator and check for a voltage swing.  As stated before, the oscillator has a new cathode bypass cap.  But, no other component changes.  If I don't find an oscillation, I will see if I have the caps on hand, to change out C3 thru C7. 

I made a drawing update to try and clean up the Tremolo circuit.  Other than that, the circuit is unchanged. 

Jack

Update: 04Oct15 - See Reply #51 for the latest drawing.

[Jack_Hester]

Made a quick check of my spreadsheet for components on hand.  I have some .047uf-630v and some .022uf-630v caps.  Just don't know how many, as I don't keep my spreadsheet up to date on quantities.  I'll check that tomorrow. 

Jack

[Jack_Hester]

Looking at my last drawing (rev D), and at the circuit between V1b and V3a, I replaced capacitors C3, C4, C5, and C6.  C10 (cathode bypass on V3a)  was replaced previously, when I replaced the PS de-coupling caps in the Pre-amp.  No oscillation, when tested. 

Before I begin replacing more caps, I'm open for suggestions.  I don't understand this oscillator circuit, and replaced the easy-to-get-to caps.  The others will have a bit more difficulty involved.  Thanks for any suggestions.  Have a good one. 

Jack

[jazbo8]

On some of the Sano hi-fi amps, the tremolo only works on the stereo (aka accordion) input, try plugging the guitar into that input, you also want to check if there is an input jack with TRS (tip-ring-sleeve), instead of just TS. Also which the value of the small choke in the tremolo circuit?

[Jack_Hester]

On some of the Sano hi-fi amps, the tremolo only works on the stereo (aka accordion) input, try plugging the guitar into that input, you also want to check if there is an input jack with TRS (tip-ring-sleeve), instead of just TS. Also which the value of the small choke in the tremolo circuit?

All channels eventually connect to the Tone Stack at R37, in this amp.  And, that same common is connected to R14, which in turn connects to C2 at V1b-pin 8. 

I replaced C1, C2, and C7.  Connected my DMM to V1b-pin 7 and observed a voltage swing of -0.25vDC to +0.25vDC.  So, I'm getting my oscillation.  I'll warm up the VTVM later and check more points back to V3a.  At V1b-pin 8, I read 9vDC with the Tremolo switch in one position, and 4.5vDC, when in the other.  No oscillation in either position.  I may have damaged C2, as I had the iron against it while replacing either C1 or C7.  I'll dig out another .022uf out when I get the VTVM out. 

I don't have an adapter made up, to test the stereo input.  One of the terminals connects to R4, at V1a-pin 2.  The only way that I can see that signal leaving is out the cathode, through C2, and on through R14. The other two inputs on this connector go through individual channels.  One of them leaves V2a (C8) and connects directly to V1a-pin 2, and should pass to C2 like the previous.  The other goes to V4b, to V4a, and to the Tone Stack. 

No TRS jack. 

No idea of the value of the choke. 

The Guitar and Instrument channels are working really good, so when I resolve this Tremolo issue, all channels should be affected by it. 

Anyway, We'll see what happens with another C2.  Thanks for looking the circuit over.  I'll be back in a little while.  Have a good one. 

Jack

[sluckey]

Divide and conquer. This is the entire oscillator circuit. It doesn't need a footswitch. It runs continuously. Make the oscillator work first.

Monitor the plate voltage of V3A. Use an analog voltmeter if you have one. You should see the plate voltage swinging up and down around some dc voltage. A digital meter will just show some erratic numbers that keep changing. This is good, but if the plate is steady, the oscillator is not working. A strong 12AX7 is needed so rotate several through the socket. R15 (330K) is the plate load. Measure dc voltages on plate, grid, and cathode. What have you?

If you have a scope you can monitor the LFO output at that cap or directly on the plate. Use AC coupling, slow timebase speed, and expect a 50VACpp (or larger) low freq sinewave.

[Jack_Hester]

I stand corrected.  It was C1, a .05uf cap that got burned by the iron.  I can see foil, but I'm leaving it alone for now. 

I'm getting ready to warm up the VTVM and will be back with readings.  Thanks, Steve.

Jack

[Jack_Hester]

Divide and conquer. This is the entire oscillator circuit. It doesn't need a footswitch. It runs continuously. Make the oscillator work first.

Monitor the plate voltage of V3A. Use an analog voltmeter if you have one. You should see the plate voltage swinging up and down around some dc voltage. A digital meter will just show some erratic numbers that keep changing. This is good, but if the plate is steady, the oscillator is not working. A strong 12AX7 is needed so rotate several through the socket. R15 (330K) is the plate load. Measure dc voltages on plate, grid, and cathode. What have you?

If you have a scope you can monitor the LFO output at that cap or directly on the plate. Use AC coupling, slow timebase speed, and expect a 50VACpp (or larger) low freq sinewave.

Readings with VTVM:  V3a
pin 1: oscillation +120v to +124vDC
pin 2: oscillation -0.24v to +0.32vDC
pin 3: oscillation +0.9v to +0.94vDC

Also, I took a DC readings on V1b
pin 6: no noticeable oscillation with a reading of +150vDC
pin 7: oscillation from zero (0) to +0.06vDC
pin 8: no noticeable oscillation with a reading of +0.34vDC

All readings with Depth pot at max and Speed pot at min.  So, it's oscillating. 

Jack

[jazbo8]

Why are ther readings in DCV? In Steve's last post, he mentioned that you should be getting about 50VAC at the output of the V1b after the coupling capacitor.

[Jack_Hester]

Why are ther readings in DCV? In Steve's last post, he mentioned that you should be getting about 50VAC at the output of the V1b after the coupling capacitor.

Oversight.  I only read the scope part.  I'm using an analog meter.  I warmed the amp up a bit, and rather than warm up the Eico 232, I used the Simpson 260 for an AC reading.  On the lowest scale, I'm getting 0.5vAC RMS. 

Here's a new set of DC readings with the 260.

V3a -
pin 1: oscillation around +125vDC
pin 2: no noticeable oscillation, where the Eico shows oscillation around the zero mark.
pin 3: oscillation around +0.9vDC

V1b
pin 6: no noticeable oscillation with a reading of +170vDC
pin 7: oscillation around the zero mark. -0.05v to +0.05vDC
pin 8: no noticeable oscillation with a reading of +9vDC

I can't explain the difference between readings on V1b-pin 8, between the two meters.  I'll check again this afternoon, when I get home from Church.  The 260 pegged on the 2.5v scale, and had to switch to the 10v scale.  I'm confident that it's correct.  I think that I'll rely on it for further readings. 

Jack

[Jack_Hester]

I forgot to mention that all tubes are new JJ, with the exception of the 6AN8A.  So, I've swapped the two 12AX7's and find the same results.

Jack