Schaller KV40 Guitar Amp & Pwr XFMR Teardown

thought we had seen everything, but no,

this is the same company that makes the primo guitar tuners,

this amp was used by Roy Nichols while he was playing Vegas with Wyn Stewart, and if you believe that then i have some ocean front property in Arizona thati would like to  sell you,

seen is the foreground is the Guitarbage Can, our top salesman, anything under 80 bucks goes in the can, people like to rescue things, it improves their self esteem, and the Guitarbage Can is full of evidence, it even has it's own parking place as it won the Employee of the Month award for the last year now,

reverb pan is shielded, circuit board is an example of precision german engineering gone wrong, but hey, we'll polish a turd as long as they have money,

all the latest transistors, should be fun to work on,

don't know what's inside that epoxy can as schematics for this thing do not exist,

probably a trem opto or something weird,

ok, we'll let you know as soon as the smoke comes out,

gotta rewind thepwr trans, cooked the bobbin, this had a euro cord on it, 220 volts, or something, somebody might have plugged it in while it was wired for 120,

Is this the one?

http://bmamps.com/Schematics/Schaller/KV40.jpg

holy crap that's it!  where did you find that!  i like scoured every server in the lower 48 ,

full props goin out i will send you this amp when i'm done, let me check with the owner first,  ;D
thank you!

may as well hack the iron, seems like the coil was wound around the lams, no seams, wtf, over?

but we have been down this road before,

those sneaky Bitburger brothers, look what they did, chopped out the middles just for the sake of technical superiority,

edges are held in by those ridges on the bobbin,

this guy smelled like a well done porterhouse steak from a mesquite bar b q,  yumm!

Sometimes it is better to give a search engine less information. Actually I searched Google for "kv40 schematic". I figured it might show up on a German site that wouldn't have the word "amplifier".  This was the resulting search URL:

https://www.google.ca/#q=kv40+schematic

The 3rd URL on the page was this:

(I suspect you might want to bookmark this page, or save a bunch of these schematics.)

http://www.amprepairparts.com/schematics.htm


And there it was. It turns out there is a 2nd KV40 schematic for the tube version:

http://bmamps.com/Schematics/Schaller/KV40Roehre.jpg

yes we found that tube amp and was thinkin that their documentation dept was on the fritz,

awesome link, thanks!

this thing looks like it fell out of a jacked up jimmy with a front end shimy,

not too baked that we can not get the turns ratio and re-construct,

isolation bobbin, pri on one side, low volts sec's on the flip side,

looks like some welding going on with the outside turns, wire insl was pretty sketch back then,

risky strain relief , why not break it out and anchor it to the wrapper?

well the sleeve looks ok so maybe they know what's going on,

had to hack out the center divide because the nylon had melted over the turns, looks like things got warm on the inside winds also, always hotter in the center, they even have diff equations for this can you believe it?  well yeah, if your hooking up a pwr station like Hoover you need to have your thermal down,

since we have an amp that wants 110 in a 120 world, we may as well compensate for safety by changing our turns ratios,

and we can ditch the 220 wind since this will most likely be used in the US for the duration,
they got tour companies that will supply you with amps over there anyways,
you show up and your stuff is all set up for the club tour, how spoiled is that?

so if we have 46.7 vac = 263 turns, and we want the turns for 120, what do we do?

we go  120/46.7=2.569    so 2.569 * 263=675.8
so use 676 turns of #28 or better for the pwr line primary,

here are the original turns and wire size

here is a print for the pwr transformer rewind-US version

we also noticed that the schematic calls for 12 VDC off the low volts wind, however, turns ratio calcs say 63 turns will give too much voltage, close to 16, which is gambling, especially with the leaky lytics from yesteryear, so we will adjust that down to 50 turns, looks like they tried to correct this with the cobbled 22 ohm resistor in the schematic,  so we can get rid of that also,

3055 pwr transistors used, aka Neve,

5 VAC wind powers a 6 volt lamp, which is good for lamp life,

Looking for a Schaller Echo Sound schematic. Anyone there with a proper idea where to get it?

Thanks
Ray