Results 1 to 12 of 12

Thread: EHX Bass Micro Synthesizer

  1. #1
    Member
    Join Date
    Dec 2018
    Posts
    34
    Thumbs Up/Down
    Received: 2/0
    Given: 0/0
    Rep Power
    0

    EHX Bass Micro Synthesizer

    Iíve got a vintage big box EHX Bass Micro Synthesizer that isnít working right. The clean signal going through bypassed is garbled at acceptable preamp settings, meaning itís either very quiet or garbled. When the pedal is activated, thereís just some buzz and no effected signal or clean signal passing through. What should be my first course of action in determining the problem? Iím using a Harmon 9v adaptor to power it.

    0 Not allowed! Not allowed!

  2. #2
    Supporting Member The Dude's Avatar
    Join Date
    May 2010
    Location
    Sioux Falls, SD
    Posts
    6,927
    Thumbs Up/Down
    Received: 1,694/2
    Given: 1,219/1
    Rep Power
    18
    Quote Originally Posted by sunshine_bassman View Post
    ......What should be my first course of action in determining the problem?.....
    Upload or link a schematic.

    0 Not allowed! Not allowed!
    ďYeah, well, you know, thatís just, like, your opinion, man.Ē

  3. #3
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    33,480
    Thumbs Up/Down
    Received: 2,538/7
    Given: 0/0
    Rep Power
    57
    Open it up and meter the power jack, it it still 9v? Assuming it says 9v on the machine. Also check current rating.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  4. #4
    Master Destroyer nosaj's Avatar
    Join Date
    Sep 2011
    Location
    Pace, FL
    Posts
    3,639
    Thumbs Up/Down
    Received: 1,321/102
    Given: 183/36
    Rep Power
    12
    Quote Originally Posted by sunshine_bassman View Post
    Iíve got a vintage big box EHX Bass Micro Synthesizer that isnít working right. The clean signal going through bypassed is garbled at acceptable preamp settings, meaning itís either very quiet or garbled. When the pedal is activated, thereís just some buzz and no effected signal or clean signal passing through. What should be my first course of action in determining the problem? Iím using a Harmon 9v adaptor to power it.
    I have a 90's microsynth fairly big, it uses either a 24v or 18v wall wart I'll verify after while.
    nosaj

    0 Not allowed! Not allowed!
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

  5. #5
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    33,480
    Thumbs Up/Down
    Received: 2,538/7
    Given: 0/0
    Rep Power
    57
    I just went looking at photos. Some are listed on Reverb for sale. One has a nice close up of the power adaptor. It says 24v DC 100ma.

    I looked at several more listings and all said 24vDC 100ma.

    Clearly the 9v adaptor is not the correct one.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  6. #6
    Master Destroyer nosaj's Avatar
    Join Date
    Sep 2011
    Location
    Pace, FL
    Posts
    3,639
    Thumbs Up/Down
    Received: 1,321/102
    Given: 183/36
    Rep Power
    12
    Quote Originally Posted by Enzo View Post
    I just went looking at photos. Some are listed on Reverb for sale. One has a nice close up of the power adaptor. It says 24v DC 100ma.

    I looked at several more listings and all said 24vDC 100ma.

    Clearly the 9v adaptor is not the correct one.
    24v 100ma center positive is what I have.
    nosaj

    0 Not allowed! Not allowed!
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

  7. #7
    Senior Member
    Join Date
    Jul 2007
    Posts
    618
    Thumbs Up/Down
    Received: 60/0
    Given: 11/0
    Rep Power
    14
    In accordance with the scheme, it is necessary to use a 24 VAC power supply (not 24 VDC).

    0 Not allowed! Not allowed!

  8. #8
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    33,480
    Thumbs Up/Down
    Received: 2,538/7
    Given: 0/0
    Rep Power
    57
    I don't see a schematic. The various machines I saw had DC adaptors.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  9. #9
    Senior Member
    Join Date
    Jul 2007
    Posts
    618
    Thumbs Up/Down
    Received: 60/0
    Given: 11/0
    Rep Power
    14
    Here is the schematic.
    DC power supply can be used, but operation may be unstable when output voltage is 24VDC.
    30-32VDC is preferable.
    Attached Files Attached Files

    0 Not allowed! Not allowed!

  10. #10
    Master Destroyer nosaj's Avatar
    Join Date
    Sep 2011
    Location
    Pace, FL
    Posts
    3,639
    Thumbs Up/Down
    Received: 1,321/102
    Given: 183/36
    Rep Power
    12
    Quote Originally Posted by doctor View Post
    Here is the schematic.
    DC power supply can be used, but operation may be unstable when output voltage is 24VDC.
    30-32VDC is preferable.
    78 model is ac.
    90s model is dc
    Nosaj

    0 Not allowed! Not allowed!
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

  11. #11
    Senior Member
    Join Date
    May 2006
    Posts
    3,964
    Thumbs Up/Down
    Received: 252/3
    Given: 31/0
    Rep Power
    19
    I've been "repairing" one for the last year and a bit. I had it running properly about February last year, but when I went to reassemble the unit, something either shorted or fractured (damn you with your solid-core wire, EHX!!!). Exasperated, I needed time away from it.

    That said, the initial repair would not have been in any way possible with this drawing from my good buddy Stephen Giles, in England, who used to work as an accountant for EHX there, and seems to always have arcane pieces of technical info about their products. The schematic can be gotten in many places. Knowing which chip is which is a whole other kettle of fish, though. This drawing sorts that out. It is for the big-box guitar microsynth, but it only differs from the bass unit in terms of a few component values; e.g., for the filter.

    Click image for larger version. 

Name:	9YJyR7j.jpg 
Views:	16 
Size:	111.8 KB 
ID:	57762

    0 Not allowed! Not allowed!

  12. #12
    Master Destroyer nosaj's Avatar
    Join Date
    Sep 2011
    Location
    Pace, FL
    Posts
    3,639
    Thumbs Up/Down
    Received: 1,321/102
    Given: 183/36
    Rep Power
    12
    Quote Originally Posted by Mark Hammer View Post
    I've been "repairing" one for the last year and a bit. I had it running properly about February last year, but when I went to reassemble the unit, something either shorted or fractured (damn you with your solid-core wire, EHX!!!). Exasperated, I needed time away from it.

    That said, the initial repair would not have been in any way possible with this drawing from my good buddy Stephen Giles, in England, who used to work as an accountant for EHX there, and seems to always have arcane pieces of technical info about their products. The schematic can be gotten in many places. Knowing which chip is which is a whole other kettle of fish, though. This drawing sorts that out. It is for the big-box guitar microsynth, but it only differs from the bass unit in terms of a few component values; e.g., for the filter.

    Click image for larger version. 

Name:	9YJyR7j.jpg 
Views:	16 
Size:	111.8 KB 
ID:	57762
    The multiple versions of the microsynth https://encyclotronic.com/synthesize...theszer-r1227/ The first one is the 78 model, second on is the 90s model I have and the others are newer,

    nosaj

    0 Not allowed! Not allowed!
    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. BOSS SYB-3 Bass Synthesizer No dry signal in Mono out
    By pickups_cba in forum Guitar Effects
    Replies: 14
    Last Post: 05-07-2018, 11:09 PM
  2. advice on more bass and treble from "Micro Champ"
    By dmartn149 in forum Mods & Tweaks
    Replies: 12
    Last Post: 10-08-2016, 06:44 PM
  3. Carvin BX250 micro bass capacitor voltage rating question
    By DrGonz78 in forum Maintenance, Troubleshooting & Repair
    Replies: 18
    Last Post: 03-05-2016, 10:20 PM
  4. Carvin BX micro Bass MB210
    By nosaj in forum Maintenance, Troubleshooting & Repair
    Replies: 16
    Last Post: 11-22-2015, 09:09 PM
  5. Wanted: Behringer BSY600 Bass Synthesizer schematic
    By beerbunny in forum Music Electronics
    Replies: 22
    Last Post: 10-06-2013, 06:21 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •