Reverse engineering technical question

[hilbi]

I am reverse engineering a certain overdrive pedal, i don't have they actual pedal, i'm trying to copy it from some foto's I have. Now i'm seeing a 10K resistor connected from +9V to pin 5 off the jrc4558 opamp. Now my question is if this technically is ok?

[bancika]

can you post a pic?

[Alex C]

If this is a tube screamer or variant, it looks like the 10k should be between pin 5 of the 4558 and Vref, not 9+.

http://www.kilback.net/homebrewtweaks/pedals/screamer.gif
http://www.sonixtech.co.kr/web/manual/1008_ts808/ts808_sch.gif
http://www.geocities.com/SunsetStrip/Studio/2987/ts9-3.gif

[petemoore]

Now i'm *seeing a 10K resistor connected from +9V to pin 5 off the jrc4558 opamp. Now my question is if this technically is ok?
  If it works...I haven't seen the schematic lately, perhaps there's another resistor keeping pin 5 from being pulled up near +9v, or there's some reason for a 'wierd' bias with this circuit, 10k to V_ or + supply would= strong pull on the idle bias.
  Seeing isn't believing.
  Test that with a DMM !! 1 or two probes [Beep mode] from the 10k's leg to the questionable connection and you'll probably be able to verify where it's connected...

[hilbi]

yes it is a ts variant, i saw indeed that the real ts has a 10k to 4,5 v, but should it harm if in this case it is connected to 9V?

The arrangement around the 22uF is also a bit different.

I'm abit hesitating with posting a pic,'I don't want to ran into legal and ethical issues. Maybe I will post a part of the circuit for questions and technical discussion.

[hilbi]

There is indeed another 10k resistor connected to pin5 and to ground. So this is probably a voltage diveder correct?

[George Giblet]

Almost certainly.

[theman]

Yep ... this is the 10K/10K divider which sets up the VREF voltage which is half the supply. There should also be an electrolytic cap hanging somewhere off the VREF node also -- probably 47 uF. If it's a TS variant and there's input and output buffer transistors, you'll probably see 510K resistors connected between VREF and the base of the NPNs.

[hilbi]

there is a 22uF cap connected from pin 5 Vr to ground.

no in and output buffers.

[theman]

there is a 22uF cap connected from pin 5 Vr to ground.

no in and output buffers.

this is probably fine ... sounds like a ts variant with no input and output transistors -- which sounds like a lot of other boutique pedals ...   

[aron]

How many clones were based off of this???

http://www.geofex.com/Article_Folders/TStech/tsxtech6.gif

and this:

http://www.geofex.com/Article_Folders/TStech/tsxfram.htm