Ibanez PT-999 Phaser schematics?

[Dingleberry Electronics]

Hi.

I just recently rehoused old Ibanez phase tone pedal. I didn't want to drill any exess holes to the original box but I wanted true bypass with indicator led and dc-input connector so I decided to fit it inside small ha***nd box.
The thing that I came up was the original bypass confiquration. It had just spst on-off switch. Took a while when I figured out what was going on in it. There was only one wire leading from the input jack hot terminal to the effect board and two "output"-wires coming out from the board. One to the first pole of the switch and another to the second pole of the switch and jumpering from there to the output jack hot terminal.  When the effect was engaged the switch combined two outputs coming from the board. "Dry" and "wet" outputs I assume.
The funny thing that I realized was that if you take only the wet output and leave the dry off, you get nasty pitch vibrato.
I added a switch so now I can choose between vibrato and phaser. It is actually a very mild phase effect. Sort of reminds me of easyvibe by John Hollis. Probably something similar there. Easyvibe is using ldr's and Ibanez fets as variable resistor though.

It probably would be handy to add a blend pot betwee those two outputs. Would something like 10k be a good value to start experimenting with?
If someone has any experience modding that model phaser please reply.
If someone has schematic for that PT-999 phaser that would bemore than awesome.
Thanks.

[Rob Strand]

I know the PT-999 schematic is on the web.

IIRC, there also an older type  PT-909 (or something) - this has the small PCB inserted in the plastic case in the box.  A schematic was put up for this at one stage but I suspect it is gone.

For the switch:  The dry and wet paths mix together using a resistive mixer.  Dry goes through a 30k, wet goes through a 30k then there's 30k a 30k to ground. The point where the resistors meet eventually goes to the output.  The switch breaks the wet signal at the resistors.  The wet signal here is the vibrator signal.  When the wet and dry mix you get a phaser.

Sorry I can't tell you more I don't have my stuff with me - I'm speaking from memory.

[Rob Strand]

Here's one of the schematics:

http://filters.muziq.be/model/ibanez/808/pt909

It says PT909 but I'm pretty sure it's not for the PT909.

The older model I outlined the switching for uses a single opamp for the oscillator, sort of like the MXR stuff.

[Dingleberry Electronics]

The phase tone pt-999 is the older one with just one knob controlling speed. I better check that out what value the resistors are when Iget home. I'm now on a gig...

[captntasty]

Hey DingleB (does that sound right?),

I certainly don't want to be the guy who hijacks threads and usually I'm not - but this one had my sensors going "ding, ding, ding"!
I have what I believe is the same pedal but it was branded Foot System PhaseTone - the Ibanez pt999 PhaseTone, the Greco pt900 PhaseTone and the Pax PhaseTone being the other "brands" - of course, they are all the same circuit which is the Maxon pt900.  Okay, enough with the history lesson.

I got this one off ebay a number of years ago really cheap, it need one wire to be reconnected which I did and it worked great - but the wire used in this effect was incredibly brittle and the slightest movement would break it.  After a number of leads came undone I decided to replace all the wire and in the middle of it I had to put it aside for a few months and when I came back I had no idea what was which.  So, it has been sitting in my "plan to get back to someday" bin.  I've searched high and lo for a schematic but there is bupkus.  I was wondering if you had a gut shot of the insides to guide me in rewiring this one, pretty please?  If I can help in anyway with your circuit I most certainly will...
Thanks
Patrick

[Rob Strand]

If it's any help the circuit when something like this:

It is a 4 stage unit that uses JFETs.  The opamps were all duals LM1458C.

The LFO was a single opamp type like the MXR units (but not exactly the same ckt).  The LFO couples to the JFETs via an electrolytic capacitor, which is unusual.

The biasing for the JFETS is done using a zener and a bias trimpot, pretty standard thing.  The bias trimpot is the large round one.  The bias setting is really critical.

There is another trimpot in series with the signal between the LFO and the JFETS.  It's purpose is to set the LFO magnitude to the JFETS - I found it didn't do much.

The input stage is an opamp with a gain of 2.  The output of this stage feeds the all-pass chain and the dry signal via one of the 30k resistors I mentioned before.

The other details are as I have already mentioned.

I know I have a schematic but I don't know when I'll be able to get it (currently away from home).

[Dingleberry Electronics]

Hi.

Thanks for replies guys.
I worked a lot with the bias trimmer and finally found the "sweet spot".
Actually the factory setting wasn't the best sounding to my ears. Very subtle.
Now it sounds very nice. The biasing seems to be critical and the trimmer is very sensitive...

That was very good description of the circuit Rob. Thanks a lot. I really appreciate.
Gave me a good picture of it.
Of couse If you happen to find the schematic some day feel free to email me.

And  for Capntasty. I dont have a digital camera so I'm not able to send a picture of it but I can draw a some kind of wiring istructions.
Had the same problems with the brittle 25 years old wires... That's the reason why I also rewired it. 
I'll draw the wirings when I come back home from the road. Hope I can do it next week.
   

[captntasty]

I would be forever in your debt.
Thnx
P

[regroth]

Anyone found the schematics for this yet? (Or should i just say: "bump")