Announcement

Collapse
No announcement yet.

Farfisa Compact Duo Lower manual volume

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Farfisa Compact Duo Lower manual volume

    The volume on the lower manual (With the lower manual balance pot at max) matches the upper when I have Principale selected on the lower and Flute 8 selected on the upper. Adding Dolce and ottava on the lower slightly increases the volume while adding voices to the upper greatly increases the volume. As this is the first compact duo I've worked on, what is normal?

    Model is CD/30 Compact Duo

    Jim

    #2
    No Principale is noticeably louder than flute 8 on my CD/30. Have you recapped the preamp board yet? I would say that mine only levelled up properly after replacing all of the electrolytic caps. The switch mechanisms are multi -contact in many cases and you may have dirty contacts in there too. WHen I first got the CD/30 the lower manual was quieter and I had to change one of the transistors in there. Have you found the schematic and owners manual? David Anderson is the other forum member with lots of experience of tackling these beasts. Congrats on finding one though, They are very rewarding to play one they are working properly.
    Hammond BC
    Farfisa Compact Duo MK2
    Lowrey Berkshire Deluxe TBO-1
    Leslie 147 ​and ​​​​​​Hammond PR-40

    Comment


      #3
      Thanks Dave
      I cleaned up the power to see what that would give me. I found manuals online. I'm in the process of figuring this beast out. Noticed tremolo wasn't working. Once I locate the boards and id the in's and out's I'll work through the problems.

      Jim

      Comment


        #4
        Tremolo is optical. There is a small bulb that may have failed. Mine had the incorrect spec bulb and it seemed to affect the bulb in the expression pedal, making it pulse so if you do replace that bulb, stick exactly to the one called for in the schematic. It’s different to the spec used elsewhere in the organ.
        Last edited by Drawbar Dave; 02-13-2020, 11:22 PM.
        Hammond BC
        Farfisa Compact Duo MK2
        Lowrey Berkshire Deluxe TBO-1
        Leslie 147 ​and ​​​​​​Hammond PR-40

        Comment


          #5
          I don't have the external expression pedal, but the knee lever has no effect. I'll dig into this later today and the weekend.

          Jim

          Comment


            #6
            There are two bulbs in the knee lever unit. Do you have the original F/AR power supply with it? That should send 9 vac and 24vdc. The dc gets knocked down to 9 vdc by a diode as it enters the organ and then powers all of the boards. The 9 vac powers the knee lever bulbs, the expression pedal bulb and tremolo bulb. There's also a gizmo under the bottom right end panel that boosts the dc up much higher for the neon in the repeat circuit. Give me a shout if you need any help!
            Hammond BC
            Farfisa Compact Duo MK2
            Lowrey Berkshire Deluxe TBO-1
            Leslie 147 ​and ​​​​​​Hammond PR-40

            Comment


              #7
              The knee lever will work with the expression pedal disconnected? The 125 VDC from the FA-28 bd under the right lower check block is ok. I'll start chasing the 9Vac.

              Jim

              Comment


              • Drawbar Dave
                Drawbar Dave commented
                Editing a comment
                Yes it should do. Check for the 9 vac on the tag strip bottom right when viewed from rear. Organ should work full volume without the pedal. You can make up an adapter for the expression pedal plug and use a stock single ended synth pedal if needed.

              #8
              The 9VAC is fine. The 9.8 VDC derived from the 9VAC is not. I disconnected the load to the diode and still nothing. The cap was replaced so I have a bad 2EQ5 diode. Replaced with a 1N4148. Now I have the 9.8 VDC. The volume is better and the tremolo works. The volume will vary by itself. Going to replace the electrolytic caps on the amp bd. Just a process of working through the issues.

              Thanks for the insight.

              Jim

              Comment


                #9
                The 10 & 25uf caps on the PA-31 bd looked leaky. - one tested bad which was in the lower manual input. Replaced all. Manual volume is normal. On to the the divider and knee level.

                Jim

                Comment


                  #10
                  I would use something larger than a 1N4148 for any kind of DC rectification. Those are mainly used for key switching in organs. Their forward continuous current rating is only 300mA. There are known cases in guitar amps where designers tried to use 1N4148 for low voltage supplies, and they did not survive long term.
                  I'm David. 'Dave' is someone else's name.

                  Comment


                    #11
                    Thanks David - I replaced it with a 1N4004. Fun little organ.

                    Jim

                    Comment


                    • David Anderson
                      David Anderson commented
                      Editing a comment
                      Much better.

                    • Drawbar Dave
                      Drawbar Dave commented
                      Editing a comment
                      That rings a bell I think that’s what I used in mine too.
                  Working...
                  X