Ibanez Orange Overdrive Repair Shop

[hair force one]

[hair force one]

Purchased on ebay last week for 50 euros . So here is what i got:

- a 30 years old piece of orange metal
- Wires that were all misplaced and/or disconnected
- a not original stompswitch (made in france!)
- a hole in the stompcase with a 5mm LED socket (but no led!)

So today i traced this od-250's shematic and found it was somewhat different to the 2nd series od-250 with fet switch i found on the webb. The tone section is entirely different.

My problem is that there is no output wire on the pcb (and therefore on my schematic) so i think it's going out of one of the tone pot lug to the balance/volume pot and then to ouput jack...

After soldering everithing i plugged in and....it works, with mucho distortion! But the tone pot is not acting very right, as it is 100kA audio tapered i might solder it the other way to get a better range.

By the way does anybody got a shemo to compare with mine?

[hair force one]

Here is the shematic i traced from the pcb:
3 stages straight from big muff Pi (those industrial cloning times...) and a strange tone stage that goes either to tone or balance pots lugs...
But how...

[JimRayden]

Congrats on the 30 years old piece of orange metal. I don't know much about it but by looking at the logo, Ibanez seems like it has been a much more fender-like company. Not what it is today. Cheap and corny. Sorry if I hurt someone's feelings. I love my tubescreamer though.

Sorry, can't help you on the circuit.

---------------
Jimbo

[Mark Hammer]

Looks pretty much like a Big Muff with some component value differences.

[Rob Strand]

If I had to take a guess,  I'd say the tone pot should be wired as:

- CW to the input side of the stage, where the 10k goes
- CCW to the output
- wiper to the 3n3 cap

The circuit is basically a Baxandall type tone control where the Bass control is fixed and the Treble control is the tone control - you could draw it that way for clarity.

The output is take from the output lug that goes to the tone pot - this just saves Ibanez a wire point on the PCB.

With this connection clockwise will be treble boost on the tone control - I don't know if the original were wired that way.  (If it turns out not to be the case and the flip the "outers" of the tone pot don't forget to move the output lug as well).

[Rob Strand]

"input side of the stage" means the input of the third stage not the 10k input to the unit.

Actually you might have a trace error as well:  The tone pot might connect to the junction of the 10k and the 1uF as opposed to the junction of the 10k+42n+47k.  That would make it more like a tone control.

Then again,  my whole argument could be wrong......

[hair force one]

thanks rob i'll give it a try, and redraw the schematic as well (found some errors there)...

[hair force one]

you were right for the junction between 1uf and 10k, i misread the pcb!

[hair force one]

Wired it your way after trying some others. Tone pot is like... acting subtle... Finalize the shematic, gonna put it online on my webpage.

Thanks rob!

[eaze]

Original schematics here
http://mad.topnet.com.au/~hairbear/page.2b.htm
seems to be next version.

[Rob Strand]

I was spending the little free time I have cleaning up my schematics today and I found some more info on the early OD-850.

Ibanez Overdrive OD-850
Narrow Box, Script Logo, Round Switch

Not 100%, but I saw an overlay which indicates the following errors/omissions on the schematic:

- Sustain pot is 100KA (log)
- Tone is 100kB (linear)
- The resistor on the ground end of the Sustain pot is 1k
- Transistors 2SC828
- The Balance pot has a 47k resistor in series with the CW lug.
 The resistor is located off the PCB and wired between the CW wiper
 of the Balance pot and the CCW wiper of the Tone pot.

These could be a result of production variations:
- The Tone (treble) cap was 2n2, not 3n3
- The "Bass" caps were 47n, not 42n

(The Tone pot is wired so that clockwise is High-Boost)

[aron]

Thanks Rob!!!!!!  

[hair force one]

Thanks Rob for your support(i'll redraw til its perfect).

I've tried it at decent amplified volumes in the City Rehearsal Studio last saturdays.
Sounds very cool, creamy loads of buzztortion through humbuckers.
The case is one of the cutest/tiniest i ever plugged through.
It has no rubber back pads (i think it was made this way) and is so light that it follows your every movement.

I've never tried a tranny big muff so can't compare.
The schematic eaze pointed out is for second series, almost an exact copy of the big muff pi, tone stack included, with a buffering stage.
Better replica than the Jumbo Tone Bender!

[d@vide]

look at this
http://digilander.libero.it/6hiwatt/dave/
there's a layout draw by me
I hope be correct!  :roll:

[hair force one]

wow davide, your site is a pure beauty!
(Italians are best designers! i wish i could make my boxes the way Olivetti designs his computing machines in the 70's)
Only thing left is to print your pcb and component sides drawings and glue them on cardboard or copperless bakelite, and then perfboard it the regular way...

[Rob Strand]

Davide's overlay is one I used for reference!



Davide,  what program did you use to draw the parts and wiring.  It looks very cool - they have an almost 3D look to them.

[d@vide]

hair force one and rob, thanx for your comments :oops:
yes looks 3D but I have done it with photoshop
(any 2d paint is useful indeed)
is a little waste of time .... but nice!  

[Rob Strand]

is a little waste of time .... but nice

Thanks Davide.  I had a feeling you put some time into those drawings - the coolness factor is very high though .

[hair force one]

You can't waste our time when you're enjoying what you're doing!