ovation fuzz from the late 60's/// help me resurrect it?

[Rob Strand]

from what i've been reading on the hifi sites, these can often be replaced with 2 diodes and a current limiter resistor.

Honestly I'd try just two 1N4148's.

The way it's used in the circuit the two diode don't even have to be matched.  Only one diode is used as the variable resistor.

[pinkjimiphoton]

hahahah,
so, in fitting with  everything else, one more example of why the hell would they bother using dual diodes if they coulda just stuck a simple diode in its place?

man... these guys musta been on acid lol

i'm gonna head for the dungeon, dunno if i'll mess with it tonite much tho, kinda burnt and very lazy

[pinkjimiphoton]

found these guys
https://cougarelectronics.com/power-conversion-components/selenium-rectifier-suppressor/

the dual diode i believe is selenium, tho i may be wrong.. it had this to say tho, so i thought it may be relevent:

SELENIUM POWER RECTIFIERS

A selenium rectifier is an electronic component that permits free passage of electric current in one direction, but almost completely blocks the flow of current in the opposite direction. Like a silicon diode, when an alternating current is applied to a selenium rectifier in series with the load, half of the AC cycle is blocked and the load receives a pulsating direct current. by using two or more rectifiers in an appropriate center tap or bridge circuit, both halves of the AC cycle may be rectified !

Main parameters :

    Voltages: Standard Voltages per cell up to 36 v rms. The voltage rating is determined by the number of cells in series
    Current: Ratings are determined by the size of the cell, the number of cells in parallel, the circuit configuration and the type of cooling, Current Ratings of 0.5 amps for a 1.0 X 1.0 cell in a half wave configuration to 270 amps for a 8.0 X 16.0 cell in a 6 phase circuit.
    Circuits:Half wave, Doublers. Center Taps, Full Wave Bridges single and three phase.


this is the thing i found in my junk drawer

https://www.ebay.com/itm/IR-Selenium-Dual-Diode-DD05-repl-GE-K118J966-1-NIP/264197276052?hash=item3d83628194:g:etcAAOSw9GhYao2F

[Rob Strand]

hahahah,
so, in fitting with  everything else, one more example of why the hell would they bother using dual diodes if they coulda just stuck a simple diode in its place?

I'm serious - really!  We should learn from our past and not ask why about anything on that unit.

SELENIUM POWER RECTIFIERS

I've played with a *lot* of selenium rectifiers in my time.   
I seriously doubt that device is selenium.   The part number you quoted doesn't look too far off a General Electric (GE) Silicon Rectifier.    I tried to find a GE datasheet with more complete info, which included that device, but I couldn't find much.

The selenium rectifier normally look like the link you posted,
https://duckduckgo.com/?q=selenium+rectifier&iax=images&ia=images

- open construction as opposed to moulded.
- made from plates (round, square, rectangular) stacked side by side
- a rod, screw, or rivet passing through the plates to hold it together
- the whole thing is usually covered in some sort of paint
- Some had 3 terminals (full-wave) and some had 5 (bridge)
- A very common thing was the outside terminal had to be linked together, like this,
https://www.cehco.com/wp-content/uploads/2015/01/K362B4EC1_SR7-300x235.jpg
(Some smaller ones folded the terminals together across the device.)
- Common ones were about 1"x1" (maybe 2A) but you could easily get 4"x4". 
  The smallest one I've seen was about 3/16" in diameter inside an analog meter.
  (Those little ones need to be fed a lot of electrons before they grow into the full size ones.)

[pinkjimiphoton]

i had a whole box full of them ones. i was just thinking se cuz i saw some being advertised as se, and it seems like the description's kinda in line.

but hey... i know NADA!
i'm a monkey with a breadboard!

[Rob Strand]

i had a whole box full of them ones. i was just thinking se cuz i saw some being advertised as se, and it seems like the description's kinda in line.

I'm sure at some point in the 60's GE produced a document which explained all their rectifiers and part numbers. 

I saw a few possible books and catalogs for sale but no PDF's.   No guarantee those books and catalogs cover the part in the Ovation. 

The sheet I posted comes out of a GE book but it's not a databook so it only contains short form info.

It's amazing how difficult it is to find data on old stuff some times, it quite literally has fallen of the planet.

[Rob Strand]

We need the diode or rectifier version of this document:

https://www.datasheet.live/index.php?title=Special:PdfViewer&url=https%3A%2F%2Fpdf.datasheet.live%2Fa8be1379%2Fgefanuc.com%2FC3513FB1AD1.pdf

https://pdf.datasheet.live/a8be1379/gefanuc.com/C3513FB1AD1.pdf

These page number is 1046 so the databook that came from might also have the rectifiers.

I think it's from this one,

https://archive.org/details/GeneralElectricSemiconductorDataHandbook1977

1977 is a maybe a bit too late?

[Edit:  on (printed) page 152 there is table similar to the one I posted earlier.   It shows configuration D as a "doubler" with two diodes.   The "packages" are different but none match you package.   So basically similar info but not quite enough to decipher you part.

On (printed) page 164 it mentions to contact GE for info.]

[pinkjimiphoton]

far @#$%in out

thats a nice find. yeah, could call ge but i bet they'll be no help literally 50 years out.

i'm gonna check that archive link.

on the ebay link i think i posted for the one identical to the one i have here, or almost...
if ya look on the back, it lists all kinds of replacement numbers for different appliances, but i don't think its worth going thru all that nitemare to try and match it up if a couple 1n914's will work.

lazy tonite. all i did was epoxy the broken mount back to the chassis, crazy glue'd first to get it to stay put, then hit it with the goo. its nice and solid now.
while watching it dry, i whittled a bigger hole in a very botched les paul  for a middle pickup i found somewhere. i did not do it.
they really buggered this poor thing up. a couple hours with a couple files later, i can fit a humbucker in the damn hole and have room for the pickup rings as long as its an open coil one. i gotta box of buckers, i'll just throw some in.

ya play thru as much fuzz as i do, ya discover them cheap ones got one hell of a sound, a lot closer to the days of yore all the tonehounds with the 22k pickups supposedly pine for

anyways, also gotta proper neutrik 6 pin din plug for the footswitch, the pos plastic one on got on ebay is already falling apart from the weight of the cable, lol.

oyyyyyyyyyy

anyways.. 2:28 been up since this mornin at 7 after gettin home last nite at 2:30 so i'm beat.

peace out and have a pleasant tomorrow, tonite, or whatever it is wherever you may be

[Rob Strand]

but i bet they'll be no help literally 50 years out.

2019: I'm phoning about a rectifier ... What problem do you want rectify? ...

[pinkjimiphoton]

youu cain't get theyah, from heeyahh....

took the nite off finished tom/electric druid's flangealicious. very yummy.

i DID however, tho i forgot to measure that diode <and may have lost it in the debris field in the dungeon> remember to pull the tuner board out of the ovation. i'll scan both sides of it and try and write in the values tomorrow morn....err afternoon when i wake up.
i did check my notes, and other than the actual "on/off" switch and polarity reversal stuff, we got everything documented except for what bulb types and #'s for the strobe tuner and the pilot light. they're both incandescent. we're real close to being done with it i think, so i can finally button it up. i'm dieing to try it live. and its taking up serious bench estate!!
lol

[pinkjimiphoton]

ok rob,
here's the strobe tuner board.
PLEASE let me know if ya think there's any other data we need, i'd love to get this
behemoth off my bench







this sucker is just about ready to sink a fork in

[Rob Strand]

ok rob,
here's the strobe tuner board.
PLEASE let me know if ya think there's any other data we need, i'd love to get this
behemoth off my bench

Wow, awesome.   I think the unknown transistors are female, they have little skirts.

[pinkjimiphoton]

hahah yeah little blue transistor spacers, not even sockets... and burkas made of epoxy

[Rob Strand]

hahah yeah little blue transistor spacers, not even sockets... and burkas made of epoxy

A lot of old equipment had those things.  They come in various colors - for different occasions  .

[pinkjimiphoton]

i thought they were sockets at first, but....

[Rob Strand]

i thought they were sockets at first, but....

I've always understood they improve reliability when you have shock and vibration.   Not sure how well they work since if you don't glue everything the transistor can still move away from the PCB.   For TO-5 & TO-18 packages it can stop the metal can pushing all the way down onto the PCB and shorting on something.

[pinkjimiphoton]

hahahah maybe they're so them stoned ass techs could line up the tabs on the q's so they'd install right

hahah.... man, gonna be good to put this thing back together again

[pinkjimiphoton]

c/p from the fuzz ovation thread...

this thing is the weirdest freekin circuit i've ever freekin seen.

its had me and rob strand scratching our heads for weeks trying to understand how some of the stuff in the preamp this was lifted from can even work. seriously.

anyways, i was dicking around with it tonite and decided the 50k pot gotta go. its just not worth freekin' being there, its more of a damn switch for all intents, and doesn't really affect the tone enough to merit keeping.

that said,...
an
A500k pot is almost kinda cool, if you wire it as a variable resistance with just 1 lug and the wiper... as you mess with the resistance, there's spots in the sweep where it acts like a compressor, and squashes your attack and then swells in... depending on the transistors you used. very sick. not super great sounding, but ok for some sick leads, and not annoying if the piss flanged out of.

i ditched that pot entirely. i also found i liked a diode clipper at the end of the circuit, with a bat41, cathode to ground, and a 1n60ge with anode to ground. loses some volume, but gets a nice squishy overdrivey sound thats really tough to beat. especially when ya read this next part...

this was designed to be a parallel fuzztone with a preamped signal. weird, right?

i'm seriously wondering, after messing with this for weeks if they were freekin high on acid, geniuses, morons, or what... cuz in the original unit it phases against the signal and gets a fairly wide range of sounds.

this thing is WEIRD. i thought it was supposed to be a pnp in q2 and an npn in q1... but i somehow got that backwards. i think. sorta. i don't understand this @#$%ing thing AT ALL and it makes no sense whatsoever to me.

but i've got it running now, and sounding like a nice old-school overdrive/fuzz

for q1,
2n2905A.... pnp, si
https://www.onsemi.com/pub/Collateral/2N2905A-D.PDF
ready?

hfe 166
uF 663mv

reverse beta... c to ground
voltages, 9.26v b+
e  1.54
b   .70
c   0.0


q2, 2n5088 , npn, si
hFE 522 <close to the original bc109 in the original unit>
uF 672mv

ALSO reverse beta, c to ground
e 1.95
b   .57
c  0.0

gives a really nice, warm fuzzy overdrive with much more common parts.

this is a really weird circuit. i will try and get video of it soon.

anyways.. thats the update for now. i'll try n re-jig the layout and schematic accordingly.

i'd love to hear thoughts on why the hell this thing would be so completely different from the original unit, which had two bc109e's and .001u caps other than the 330n input cap... and it sounded like utter ass.

i'm gonna have to reopen the dang headpiece and try the different transistors out and see if it suddenly comes to life like it did tonite messing with it.

peace.

[Rob Strand]

FYI, I've been trying to finish other stuff off so I haven't had a chance to go over the tuner.

[pinkjimiphoton]

i think i'm gonna pop it back open and try different transistors on the fuzz, see if it makes an improvement like it did on the standalone.