Rat Question concerning diodes in old vs. new rats

[sevenisthenumber]

I have a couple older 80's rats here that Im about to mod. Why do they have 4 1n4148's..?? Ive only seen 2 in all other models??   

[Electron Tornado]

Is it possible someone else modified them previously? Was the PCB layout done for two diodes or four?

[sevenisthenumber]

There both built that way.. no mods...
One is a turbo... Same era

[Brymus]

I bought a Rat brand new in 88 after the guy at the music store convinced me it would do Metallica sound once I learned to play
Freakin always disliked that pedal except for annoying the neighbors...
Now I wished I had held on to it

[Zzagar]

I have a couple older 80's rats here that Im about to mod. Why do they have 4 1n4148's..?? Ive only seen 2 in all other models??   

To answer your question, the switching found in a Rat uses a small circuit comprised of 2 1n4148's, a transistor, a 10M resistor, a 2.2k resistor and an led. This whole circuit is used to light the LED as well as provide true bypass for the circuit.  If there is a DPDT switch in the pedal you can count on one of those sets of 2 1n4148's to be used for this function.  I hope this helps.  Contact me via PM and i can provide you a schematic to clarify.

[WGTP]

I had a rat with 4 SI diodes like that and the layout certainly suggested that they were all involved in the clipping process (I didn't trace it to check for sure).  I don't recall if there were other diodes for the switching or not.  Check and see if the 4 diodes are conected (2 pairs) and end up with one end connected to the signal path and the other at ground.   

[sevenisthenumber]

It turns out that one of mine for sure was Mellinium bypass..

[arawn]

None of the factory rats ever had 4 diodes for clipping some had extra diodes for an input buffer. Most of them even use the 914/4148 diode for the clipping, with the obvious exception of the turbo rat, which used 2 red 5mm leds for clipping. Can't remember what the brat used but i never got to mess with one.

Check the following for more info
http://freestompboxes.org/viewtopic.php?f=19&t=2060
http://wapedia.mobi/en/ProCo_Rat

[manson]

Two are used for bypassing the pedal, and two for clipping.

[WGTP]

Thanks for the clarification.   

[WGTP]

IIRC the newer ProCo "SOLO" has diode switching.   

[WGTP]

The Solo is supposed to have asymmetrical clipping Tones, plus a different tone control.
http://procosound.com/products/catalog/show/57
http://ratdistortion.com/products/solo/