Maxon - CP101 Compressor  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
Post Reply
User avatar
ilcaccillo
Breadboard Brother
Information
Posts: 119
Joined: 11 Sep 2013, 00:02
Has thanked: 2 times
Been thanked: 18 times

Post by ilcaccillo »

Hi,
the Maxon CP101 Compressor is an higly regarded opto-compressor. If someone is interested in analysing the circuit here it the schematic and the PCB layout.

This Schematic is for the vintage red Maxon CP101 Compressor.
The new black Maxon CP101 Compressor has the same circuit but some added features, it has a input buffer, fet switching if I recall and uses 4558 instead of 741.

Image

Image

Image

Image

User avatar
Borderline
Information
Posts: 13
Joined: 07 Nov 2014, 12:41

Post by Borderline »

Hi there,

I was just wondering if anyone knows how to mod the attack of this pedal.

On the Maxon website there is advertised a " Subtle Squash Mod ". ( as well as a super squash mod ).

can anyone figure out what this would involve ?

Thanks in advance.

User avatar
ilcaccillo
Breadboard Brother
Information
Posts: 119
Joined: 11 Sep 2013, 00:02
Has thanked: 2 times
Been thanked: 18 times

Post by ilcaccillo »

Borderline wrote:Hi there,

I was just wondering if anyone knows how to mod the attack of this pedal.

On the Maxon website there is advertised a " Subtle Squash Mod ". ( as well as a super squash mod ).

can anyone figure out what this would involve ?

Thanks in advance.
I have no ideia,
also I dont know why do they have that in their website?

Are they offering those mods for that pedal?

User avatar
Borderline
Information
Posts: 13
Joined: 07 Nov 2014, 12:41

Post by Borderline »

The strange thing is , theres no way of contacting Maxon themselves. you have to go through godlyke the distributer. I remember asking before when only the subtle squash was advertised. They replied that they couldant contact anyone who knew how to do the mods anymore.

i went back on the site recently and they have now added super squash mod - so i dont know whats changed. Ive shot them a mail but not very hopeful for an answer to be honest.

it would be great to be able to add an attack knob.

User avatar
ilcaccillo
Breadboard Brother
Information
Posts: 119
Joined: 11 Sep 2013, 00:02
Has thanked: 2 times
Been thanked: 18 times

Post by ilcaccillo »

I've contacted Maxon directly in the past using this email:

maxon5@maxon.co.jp

There's also this one, but I got no luck:

sales@maxon.jp

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

Came here looking for a schematic of a simple optical compressor and found only broken links. Best I could find on the web was a blurry lo-res thumbnail by Yamazaki. So I've redrawn the schematic starting with the blurry thumbnail and using part values from Storyboardist layout. This schematic is the vintage red version with features added from Storyboardist's layout; input pulldown R1, reverse polarity protection D1, and power filtering C9. I also added component numbering.
Maxon_CP101_schem_GBisson.png
Last edited by G.Bisson on 16 Sep 2021, 17:37, edited 1 time in total.

User avatar
plush
Cap Cooler
Information
Posts: 640
Joined: 08 Dec 2015, 09:29
Location: Moscow, Evil Russia
Has thanked: 36 times
Been thanked: 171 times

Post by plush »

G.Bisson wrote: 16 Sep 2021, 14:55 Came here looking for a schematic of a simple optical compressor and found only broken links. Best I could find on the web was a blurry lo-res thumbnail by Yamazaki. So I've redrawn the schematic starting with the blurry thumbnail and using part values from Storyboardist layout. This schematic is the vintage red version with features added from Storyboardist's layout; input pulldown R1, reverse polarity protection D1, and power filtering C9. I also added component numbering.
Maxon_CP101_schem_GBisson.png
Ldr's anode should be connected to v+, not ground

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

plush wrote: 16 Sep 2021, 16:18
G.Bisson wrote: 16 Sep 2021, 14:55 Came here looking for a schematic of a simple optical compressor and found only broken links. Best I could find on the web was a blurry lo-res thumbnail by Yamazaki. So I've redrawn the schematic starting with the blurry thumbnail and using part values from Storyboardist layout. This schematic is the vintage red version with features added from Storyboardist's layout; input pulldown R1, reverse polarity protection D1, and power filtering C9. I also added component numbering.
Maxon_CP101_schem_GBisson.png
Ldr's anode should be connected to v+, not ground
Fixed, thanks

User avatar
george giblet
Resistor Ronker
Information
Posts: 404
Joined: 30 Dec 2008, 17:27
Has thanked: 206 times
Been thanked: 309 times

Post by george giblet »

It's likely to be the same board as the old Orange Ibanez Compressor, This one is a later version and has an LED.

viewtopic.php?f=19&t=1880

pics, pcb CO102A

https://www.tonehome.de/ibanez/narrow-b ... ompressor/


The version prior to that had no LED (and no power jack). About 1977.
It had the trimpot loaded and transistors were 2SC828Q. PCB marked MP-CO102A.
Pic attached.

There was an earlier version which didn't have the trimpot.
Off-hand the trimpot wasn't even on the board and the board was CO102 without the A.
These might go back to 1974/1975.

And yes these units had 100 ohm emitter resistors and no diodes on the two rectifier transistor.
Attachments
Ibanez Compressor before 1977 and perhaps a bit after.jpeg
Ibanez Compressor before 1977 and perhaps a bit after.jpeg (25.66 KiB) Viewed 3388 times

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

Bought a modern 2010's black label version to dissect.
Maxon_CP101_pcb_top.jpg
Maxon_CP101_pcb_bot.jpg
I traced the entire circuit and drafted this schematic:
Maxon_CP101-2010_schem_GBisson.png
Few extra notes:
All capacitors 1uF and above are electrolytic type. C9 is a bi-polar electrolytic. All 1uF caps are 50v. All 10uF & 100uF caps are 16v. C4 is 10v. C18 is 6.3v.
I was unable to read any markings on D1 and guessing it's a 1N4001, 1N5817, or similar.
Diodes D2 & D3 appear to be small signal diodes similar to 1N914. They have a very short glass drop casing, shorter than a typical 1N914.
I've included most of the jumpers (JP#) on the schematic, except JP1 and JP9 are not shown. They are both part of the Vb pathway.
Last edited by G.Bisson on 01 Oct 2021, 14:01, edited 3 times in total.

User avatar
Manfred
Tube Twister
Information
Posts: 1937
Joined: 04 Apr 2009, 23:42
Has thanked: 1671 times
Been thanked: 1344 times

Post by Manfred »

The control of the gates of Q1 and Q2 is missing in the schematic, there is no connection to the circuit around the toggle switch.

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

Manfred wrote: 30 Sep 2021, 02:42 The control of the gates of Q1 and Q2 is missing in the schematic, there is no connection to the circuit around the toggle switch.
Opened up the pedal again to confirm there's a trace between C14 & R29 that's faintly visible in the photo. Schematic has been updated.

User avatar
ppluis0
Diode Debunker
Information
Posts: 915
Joined: 14 Jul 2010, 18:33
Location: Argentina
Has thanked: 127 times
Been thanked: 299 times

Post by ppluis0 »

This is the link for the optocoupler:

https://www.datasheetarchive.com/pdf/do ... P873G35687

User avatar
bmxguitarsbmx
Cap Cooler
Information
Posts: 510
Joined: 25 Mar 2010, 21:15
Has thanked: 704 times
Been thanked: 216 times

Post by bmxguitarsbmx »

check the connections around R12 and TR3 collector. They don't functionally make sense ( in my mind at least).

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

bmxguitarsbmx wrote: 30 Sep 2021, 17:13 check the connections around R12 and TR3 collector. They don't functionally make sense ( in my mind at least).
Misread my own fat marker tracings! Updated the schematic again. Detector circuit now looks identical to the older pedal version.
Thanks to all the extra eyes checking this.

User avatar
george giblet
Resistor Ronker
Information
Posts: 404
Joined: 30 Dec 2008, 17:27
Has thanked: 206 times
Been thanked: 309 times

Post by george giblet »

I traced the entire circuit and drafted this schematic:
For the 2010 version the Trimpot is 500 ohm like the other versions.
(The marking is 501 not 105.)

User avatar
G.Bisson
Information
Posts: 39
Joined: 29 Apr 2021, 13:42
Has thanked: 17 times
Been thanked: 73 times

Post by G.Bisson »

george giblet wrote: 01 Oct 2021, 05:11
I traced the entire circuit and drafted this schematic:
For the 2010 version the Trimpot is 500 ohm like the other versions.
(The marking is 501 not 105.)
Fixed. Schematic has been updated.

Post Reply