MXR - Custom Audio Electronics - Boost/Overdrive MC-402  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 20 Jul 2010, 15:29

I thought this one sounded decent for a chip
i opened the boost / dist combo box but the smt parts
are impossible for me to see and it was a little harder to
tell where each was [ horrible sounding dist. imho ]
i need glasses but i keep spending money on gear, ha !

I thought the sinle boost pedal sounded better than the combo version
but that may be my imagination as i didn't listen to them at the same time

I can post pix of the combo , or send it

whatdya say ?
Last edited by lolbou on 21 Jul 2010, 16:24, edited 2 times in total.
Reason: Topic renamed to match the unit shown and moved to "Modern..."
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR MC-401 CAE Boost / Line Driver Pedal ?

Postby Steven_M » 20 Jul 2010, 19:23

Do it! You dont need to ask, post away!
Steven_M
Resistor Ronker
 
Posts: 419
Joined: 06 Jul 2009, 20:50
Has thanked: 71 times
Have thanks: 35 times

Re: MXR MC-401 CAE Boost / Line Driver Pedal ?

Postby okgb » 21 Jul 2010, 16:12

even with macro camera doesn't seem to focus well
[ i do need glasses ] but here's a couple for interest
curoius the better OP 275 i.c. is closer to the overdrive section ??

I'd be happy to sent this to any established member , I just can't see that well
photobucket's being a dink today as well , can't see all the pix
image code isn't showing up here ??
Image
Image
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby lolbou » 21 Jul 2010, 16:37

I've read in a french guitar magazine (an article by "Dr Boost" - which I hate) that these MXR/CAE were having a steel case instead of aluminium, and the author claims that it brings a better shielding (and also more weight).

Can you confirm this?
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.
User avatar
lolbou
Old Solderhand
 
Posts: 2710
Joined: 18 Nov 2008, 22:38
Has thanked: 346 times
Have thanks: 234 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 21 Jul 2010, 17:32

It's definitely hevier than aluminum but cast metal ? or ??
Image
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby lolbou » 21 Jul 2010, 17:58

Try to attract it with a magnet... :wink:
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.
User avatar
lolbou
Old Solderhand
 
Posts: 2710
Joined: 18 Nov 2008, 22:38
Has thanked: 346 times
Have thanks: 234 times

Re: MXR MC-401 CAE Boost / Line Driver Pedal ?

Postby Steven_M » 21 Jul 2010, 18:37

okgb wrote:even with macro camera doesn't seem to focus well
[ i do need glasses ] but here's a couple for interest
curoius the better OP 275 i.c. is closer to the overdrive section ??

I'd be happy to sent this to any established member , I just can't see that well
photobucket's being a dink today as well , can't see all the pix
image code isn't showing up here ??
Image
Image


Upload the images as attachments on the forum, that way we can see them in full res, and also, if your account becomes inactive, the pictures dont disappear for all of eternity.

Any chance of getting pictures of the bottom side of the board too? Perhaps if you have a scanner, you could use that.

Any idea what the markings are on the transistors?
Steven_M
Resistor Ronker
 
Posts: 419
Joined: 06 Jul 2009, 20:50
Has thanked: 71 times
Have thanks: 35 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby relic_elite » 22 Jul 2010, 02:45

hi,

more picture (bottom side) please so i can try tracing it :mrgreen:
relic_elite
 
Posts: 7
Joined: 13 Feb 2010, 20:00
Location: Jura, France
Has thanked: 3 times
Have thanks: 0 time

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 22 Jul 2010, 05:03

transisters as seen from top of , the formatting doesn't stay
to physically represent their location once i save this but
if you think of it as 3 rows then this is the order

-----2n5088 ---------------- 5087 ---- j177
------------- 5087

5087 ------------5087 ---------- j177--- 5087 -------j177

hope that makes sense , I'll take a bottom pic tomorrow
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Jarno » 22 Jul 2010, 12:03

lolbou wrote:I've read in a french guitar magazine (an article by "Dr Boost" - which I hate) that these MXR/CAE were having a steel case instead of aluminium, and the author claims that it brings a better shielding (and also more weight).

Can you confirm this?


These enclosures are nearly always metal die-cast products, and you can't die-cast steel. There are a number of other options ranging from zinc to aluminium and brass as well. There are weight differences in that range. With regard to shielding, I would expect better shielding with brass or copper, but I don't think that's necessary/ noticeable, and it's WAAYYYY more expensive.
From the picture, looks like your average zinc die-cast.
"It crackles....., but that's ok"
User avatar
Jarno
Solder Soldier
 
Posts: 201
Joined: 12 Nov 2008, 11:18
Location: Rosmalen, NL
Has thanked: 3 times
Have thanks: 4 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Dirk_Hendrik » 22 Jul 2010, 12:54

Whatever the discussion, the MC402's cases are definitely not made of aluminum.
Now I was going to wonder why anyone would want to trace this one. Until I figuired that's the only option to invent modifications to make the distortion side sound better. Those are easy mods though since it cannot get any worse.
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
User avatar
Dirk_Hendrik
Old Solderhand
 
Posts: 4158
Joined: 03 Jul 2007, 09:44
Location: Old Amsterdam
Has thanked: 250 times
Have thanks: 997 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Nikifena » 22 Jul 2010, 14:27

before a few months, a guy bring to me the same pedal for repair. I get draw the schematics from booster's part only.
There is nothing special or "custom" in this schematics as usually...
You do not have the required permissions to view the files attached to this post.

For this message the author Nikifena has received thanks:
Wiseblood (06 Mar 2015, 06:57)
Nikifena
Solder Soldier
 
Posts: 186
Joined: 04 Oct 2007, 07:12
Location: Bulgaria
Has thanked: 4 times
Have thanks: 33 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 22 Jul 2010, 14:43

It's the boost which i liked and wanted to know what
made it so [ just happened to get this combo ]
Totally agree with you about the overdrive , don't know how it
made it to market or why CAE put their name on it
[ just a not very interesting buzzsaw sound , is it just
a Dist+ or variation ]
I'm assuming a couple of mosfets in place of the clipping
diodes may help ala ocd , anyone know who was the first to use mosfets this way ?
sell pix 001.jpg
sell pix 002.jpg
You do not have the required permissions to view the files attached to this post.

For this message the author okgb has received thanks:
modman (16 Apr 2018, 18:44)
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 22 Jul 2010, 14:46

Hey thanks for posting the circuit , I'm still fine to send the pedal out
if someone wants to delve further , As Dirk mentions , I would'nt
use the Dist. side but wonder if it can be made usable enough ?

Anything that gives the boost a slight hf lift ?
and is that 220 uf on the input ?
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 22 Jul 2010, 17:19

On the boost schematic the 100k by itself off the second 1Meg
has a different symbal than ground ? where is it going ?
tia regards Greg
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 23 Jul 2010, 14:53

Since the boost schemo got posted [ thanks ]
maybe i'll look at " fixing " the dist side, but
any suggestions [ Dirk ? ] where to start ?
typical Dist+ mods ?
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Nikifena » 23 Jul 2010, 15:47

okgb, the input cap is 220nF. the bias resistors 2x100k are connected to +V and GND. This resistors give 1/2V to the 1meg resistor.
Sorry I'm left handed bass player and I write very ugly with hand ;)


EDIT: about modification, first you need to know how and where in the schem this pedal make distortion effect. Then use your favorite clipping method for modification. If you like to modify the tone ( AFC - amplitude frequency characteristic), than you need to get all the schematics with all component values.

As I remember this pedal use a lot of FET's for switching the signal path. All they are at the bottom of the pcb near the switches.
Nikifena
Solder Soldier
 
Posts: 186
Joined: 04 Oct 2007, 07:12
Location: Bulgaria
Has thanked: 4 times
Have thanks: 33 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Dirk_Hendrik » 23 Jul 2010, 17:32

okgb wrote:Since the boost schemo got posted [ thanks ]
maybe i'll look at " fixing " the dist side, but
any suggestions [ Dirk ? ] where to start ?
typical Dist+ mods ?


The first start is having a schematic so we can wonder why the thing has such a crappy drive section.
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
User avatar
Dirk_Hendrik
Old Solderhand
 
Posts: 4158
Joined: 03 Jul 2007, 09:44
Location: Old Amsterdam
Has thanked: 250 times
Have thanks: 997 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby Gila_Crisis » 27 Jul 2010, 10:28

this is another schem of the boost section, it comes from an italian forum.
the guy who traced it, reverse-engineered it from the MC401 Boost-Linedriver and it's verified!
oh well forget the flip-flop bypass section an build it with a normal true-bypass
the boost pot is a 100k lin, and R12 100k
You do not have the required permissions to view the files attached to this post.
Zwischen Ordnung und Chaos fangt die Musik an

For this message the author Gila_Crisis has received thanks:
modman (16 Apr 2018, 18:44)
User avatar
Gila_Crisis
Resistor Ronker
 
Posts: 349
Joined: 01 Jul 2007, 09:37
Has thanked: 1 time
Have thanks: 63 times

Re: MXR - Custom Audio Electronics - Boost/Overdrive MC-402

Postby okgb » 27 Jul 2010, 15:05

Thanks for posting that
it looked like the list said 1k for r 12
but 100k makes sense with the other schematic showing 47k
for the gain pot , dispointing that they went with the fet switching
That's bradshaw selling out ? must be by the sound of the dist+ side
Anyone seen the circuit for the Dist ? see if it's fixable
Any comments on the i.c. used for boost ? why they choose it ?
was it used out of cheapness or sound , why not paralell the halves if you're
going to use a dual ?

can anyone deny / verify my opinions earlier that the stand alone one seem to sound better
[ or that it seemed to have a slight hf lift ] of course maybe there was some bad loading
going on with my pedal chain or i had too much coffee that day
okgb
Diode Debunker
 
Posts: 758
Joined: 16 Mar 2010, 04:58
Has thanked: 185 times
Have thanks: 41 times

Next

Return to Modern Stompbox Effects (1975 - ...)

Who is online

Users browsing this forum: Blend and 10 guests