Maxon - OD-808 (RI) 6 Transistors?

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Maxon - OD-808 (RI) 6 Transistors?

Postby SilviaGold1 » 25 Feb 2008, 17:40

Hi All!
I wonder: Why are there 6 Transistors in my OD808 ?
There is just a 2DPDT in it. I cant find a Schematic. :scratch:

http://www.pic-upload.de/view-430144/Maxon-OD-808-Reissue.JPG.html
Image

I Hope Link or Image works ...(first try in a Forum)

Does anybody Know?
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Re: MAXON OD808 Reissue 6 Transistors?

Postby SilviaGold1 » 25 Feb 2008, 17:59

I must correct there is a SPDT in it. So Transistors are for the LED?
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby analogguru » 25 Feb 2008, 18:20

In the original are 5 transistors:

2 FET´s for the signal-bypassing, 2 transistors for the switching circuit and 1 transistor for the LED-switching.

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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby SilviaGold1 » 25 Feb 2008, 22:23

In the reissue are 2 X K246 Fets and 4 x C1815 Transistors, maby someone knows about the schematic one day,
never mind.
I just solder a bit - "building TS (Clones), compare sounds to the Ibanez Reissue TS9 (with or without Mods) and other Tubescreamers."
The Maxon has still its own Sound (more direct Attack), that could be the MA150 Diodes ?, the circuit here.
In the TS Clones I use 1N4148 or 1N914....just experience bit by bit.
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby jrc4558 » 26 Feb 2008, 15:46

Weren't they using 2SK107 for switching?
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby smanq » 04 May 2008, 23:08

I'm drawing the schematics for this version, I'll post it ASAP.
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby JHS » 05 May 2008, 09:05

Same circuit as the IBZ TS-808.

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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby smanq » 05 May 2008, 14:44

Yes, the differences are uniquely on the switching circuit: the SPDT switch changes the status of the 2 FETs without a F/F circuit.
The schematics can be useful for TB mod of this stompbox (I've just done it for a friend).
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby seniorLoco » 06 May 2008, 04:13

"Curiosity may have killed the cat, but it saved the mice, who ate the cheese."
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby smanq » 06 May 2008, 11:34

The RI schematics is different: there is 1 op-amp (JRC4558D) and 3 transistors for buffering, 2 FETs and a transistor for the switching.
The transistors are all C1815.
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby smanq » 07 May 2008, 01:08

This is the schematics of the OD808 RI (sorry, it's hand drawn).
Maxon OD808.jpg

The switching circuit is in separate file.
Maxon OD808 switching circuit.jpg

Some notes:
1. The supply filter cap is a 100uF/16V, so you can use 9 or 12V supply; for 18V you need to replace it with a 25V cap
2. The output resistors are different (in a slight different configuration) when compared with a real TS808
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby SilviaGold1 » 08 May 2008, 20:14

Big Thanx to smanq :) :thumbsup for the Schematic.

Some months ago I began with DIY Tubescreamers.
I was a little confused with all these different Types of Maxons and Ibanez Types.
I looked inside my RI Maxon 808, because I wondered about the huge Sound difference.
Reaheard with my Fender Prosonic Amp ( Pure little dark Clean Channel).
compared with my: RI TS9, Bad Monkey, MEK Tubedrive TD1, Behringer TO800 and my DIYs:
Torchy TS 808 & Torchy SRV TS808, UK Electrinic TS808.
It was fun to test OPs too. Now I know much more about great, little, or subtile differences for myself.
Buffer circuits, OP Types, Diodes, In and Output R´s, C´s or not....ALL this, and much more bring,
every Stompbox to Its own "Creature"...the DIYs are my best ones.
In the End... what I really dont like are the "Fet Swichting Bypass Circuits" :slap: (Tonesuckers)
and I will not buy more of the Tubescreamers I have Paid my Tribute looooooool .... :lol:
Less is More...but... If you know what to choose :mrgreen:
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby joebob213 » 28 May 2008, 12:45

Noob question here. :)

I have true bypassed several TS9's and TS808's but never a Maxon pedal. What do I need to remove to true bypass this? Anything? Can I just connect the in/out in the traditional true bypass configuration?
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby smanq » 29 May 2008, 08:26

joebob213 wrote:Noob question here. :)

I have true bypassed several TS9's and TS808's but never a Maxon pedal. What do I need to remove to true bypass this? Anything? Can I just connect the in/out in the traditional true bypass configuration?

I've done it removing R17, Q1 (you need to link drain and source with a small wire) and Q2; but I removed TR3, C10, R18, R19, Q2, D3 and D4 too.
I removed all the switching circuit components, but you can leave them on place without problems.
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Re: Maxon - OD-808 (RI) 6 Transistors?

Postby ryanuk » 18 Feb 2009, 23:22

Hi guys.

I was considering building a Maxon OD-808 - but the early dual op amp version on Matsumin's webpage.

I know that he has a layout but I thought it would be a challenge to reverse the board from the pics on his web page.

Well, the pics were a little grainy but I managed it - see attached pdf. :thumbsup

Can anybody take a look and see if this is accurate?? I noted that the switching circuit (paticularly components around the LED transistor) are a little different to the other ibanez schems on the internet (TS808, TS9, OD-850, OD-855 etc). I assume that this circuit is just an earlier design?? Will it work??

ANy thoughts??

Ry
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