JRE Productions

Melcor EQ-20 Schematics?
« on: February 17, 2006, 12:00:17 AM »
This is a cool little eq and might make a great DIY project!  Does anyone have the schematics.  just recieved one in the mail and I want to make sure I connect this right. Then I may do a DIY of it.  It has two boards, i/o transformers, two knobs and a three way switch.  So it is pretty simplistic.


Schematics please!

Joe


Melcor EQ-20 Schematics?
« Reply #1 on: February 17, 2006, 12:34:20 AM »

gang of elk

Melcor EQ-20 Schematics?
« Reply #2 on: February 17, 2006, 08:42:30 AM »
all i have is a pinout.  eq-20 uses a +24vdc supply.  

c+f = 24v com

a+d=+24v

b,k,e,h= no connect

n = 600 ohm hi out
r = 600 ohm lo out

l = 600 ohm hi in
p = 600 ohm lo in

j+m=case ground

JRE Productions

Melcor EQ-20 Schematics?
« Reply #3 on: February 17, 2006, 10:17:14 AM »
Ok thanks.  A guy on Tape op gave me the same pinouts.  (maybe that was you?).  Anyway, the connector I have did not have solder on ones you mentioned were jumpered.  So case ground was only connected to J, and power was not jumpered.  Also, my concern was that the GME-20 had +/- 15 vdc power, and you listed this as 24v.  I wanted to make sure before I F'd it up.

Will connect tonight.

I think this would make a cool project too.  A single 24vdc 2 band EQ discrete eq.   Tons of bottom, and smooth.

Joe

gang of elk

Melcor EQ-20 Schematics?
« Reply #4 on: February 17, 2006, 10:26:12 AM »
yes that was me (pscottm).  mine work perfectly w this hookup arrangement, which was passed to me by the former owner.

don't know how likely this is but it's remotely possible there's a jumper on the board for +/-15vdc powering..  i have some urei cards from the same era that run on either +/-15v or +24(up to +30), and there's a jumper on the board that needs to be added or removed depending on which power supply is used.

JRE Productions

Melcor EQ-20 Schematics?
« Reply #5 on: February 17, 2006, 11:24:05 PM »
THanks for the help!  I found that these were the right pinouts for mine too.  Some how I think there are two versions of these going around.

Anyway for future reference, the pins are internally Jumper per your list.  I think this was so you can run power from one module to the next. So you could use "A" for 24vdc in, and come out of "D" to the next module and so on.  The connector on mine did not have any solder on the jumpered pins, so it was either the end of the line, or solo.

Anyway these are Freak'n killer on Kick and Bass. Also the top end is smooth as butta.  I tried it on sax, guitar and vocals. Each time it help to set that track out in the mix.  I think the boost is way more effective than the cut is on this eq.

Re: Melcor EQ-20 Schematics?
« Reply #6 on: January 12, 2021, 11:21:00 AM »
Bumping an old thread.  Have one of these on my bench with low output and wondering if a schematic ever turned up...

Melcor EQ-20 schematic
« Reply #7 on: January 12, 2021, 12:51:08 PM »
looks simple enough, discrete parts.
draw it out and share.  thanks in advance.

mjrippe

Re: Melcor EQ-20 Schematics?
« Reply #8 on: January 12, 2021, 01:28:41 PM »
Attached are some catalog specs just for fun.  Remove ".jpg" from the end of the .zip file

Re: Melcor EQ-20 Schematics?
« Reply #9 on: January 12, 2021, 11:54:10 PM »
Thanks!

I was about to start tracing but it turned out to be a bad solder joint on on the output electrolytic that I replaced.  D'oh

Really sounds nice, I'm loving running digital synths through it
« Last Edit: January 13, 2021, 12:46:15 AM by hereforever »


mjrippe

Re: Melcor EQ-20 Schematics?
« Reply #10 on: January 13, 2021, 03:30:58 PM »
You could still trace it out  ;)

Re: Melcor EQ-20 Schematics?
« Reply #11 on: January 13, 2021, 04:37:50 PM »
I think I actually will at some point - It would be a pretty easy project to DIY and it would be fun to make a stereo version

mjrippe

Re: Melcor EQ-20 Schematics?
« Reply #12 on: January 13, 2021, 07:41:29 PM »
That would be cool.  I have never used one of these but I love the GME-20.  Totally different beast though.  The EQ-20 runs on a single voltage rail and has transformer in and out.  The GME-20 is bipolar and unbalanced.


 

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