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HELP! No sound on Clean Channel on Dual EQ SLO clone

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  • HELP! No sound on Clean Channel on Dual EQ SLO clone

    I'm working on a SLO clone with dual EQ stack on a ampclones SLO100 PCB. I followed the BOM list and official SLOcone schematics. I've built many regular SLO clones before so this baffles me!!

    Overdrive channel works OK, all controls work. When I switch to Clean I only get a pop and faint sound at Max gain (probably a bleed from the OD channel) The Volume and EQ controls have no effect.

    Troubleshooting
    1. I ran line from FX loop send to another amp and had same result. loud/normal overdrive signal and faint clean/bleed signal
    2. replaced V1 tube -no effect
    3. replaced C7-22nf Coupling cap - no effect
    4. replaced LDR5 and LDR4 VTL5C1 - no effect.
    5. Bypassed clean/crunch switch circuit going from board to gain pot -no effect
    6. Bypassed LDR5 with jump from R17 to R21, I got a boost in volume but still not much. still very low compared to OD
    7. Checked voltage at V1a Pin 1 & 3 to be normal range
    8. cant be heater issue since OD sound awesome
    9. Since running 7 LDR's changed switching circuit power suppply resistors R64 from 47ohm to 15ohm & R65 33ohm to 15ohm.

    I've traced the board out and this channel is to small to give me such a big headache.

    Any Ideas how to resolve this. Click image for larger version

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  • #2
    Check the voltage between the LDR LED pins. Some LDRs are in series with the signal, those should be on when the channel is enabled. Others shunt the signal to ground, they should be off when the channel is enabled. The schematics you posted are a little blury, can't read all the LDR numbers or resistor values.
    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
    REMEMBER: Everybody knows that smokin' ain't allowed in school !

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    • #3
      Did.you check the wire from the crunch switch to the normal gain pot?

      Originally posted by versital View Post
      I'm working on a SLO clone with dual EQ stack on a ampclones SLO100 PCB. I followed the BOM list and official SLOcone schematics. I've built many regular SLO clones before so this baffles me!!

      Overdrive channel works OK, all controls work. When I switch to Clean I only get a pop and faint sound at Max gain (probably a bleed from the OD channel) The Volume and EQ controls have no effect.

      Troubleshooting
      1. I ran line from FX loop send to another amp and had same result. loud/normal overdrive signal and faint clean/bleed signal
      2. replaced V1 tube -no effect
      3. replaced C7-22nf Coupling cap - no effect
      4. replaced LDR5 and LDR4 VTL5C1 - no effect.
      5. Bypassed clean/crunch switch circuit going from board to gain pot -no effect
      6. Bypassed LDR5 with jump from R17 to R21, I got a boost in volume but still not much. still very low compared to OD
      7. Checked voltage at V1a Pin 1 & 3 to be normal range
      8. cant be heater issue since OD sound awesome
      9. Since running 7 LDR's changed switching circuit power suppply resistors R64 from 47ohm to 15ohm & R65 33ohm to 15ohm.

      I've traced the board out and this channel is to small to give me such a big headache.

      Any Ideas how to resolve this. [ATTACH=CONFIG]28831[/ATTACH][ATTACH=CONFIG]28832[/ATTACH]

      Comment


      • #4
        Hello, I have also the ampclones PCBs but I dont know the values of some components. You'd know tell me that is "RY1"?. Values of C38,C39,C40 capacitors and R70, R74, R75 resistors?. R74 and R75 are in the power PCB, they look like the other two resistors where the six capacitors. Thanks and Cheers!

        Comment


        • #5
          Originally posted by Pivi View Post
          Hello, I have also the ampclones PCBs but I dont know the values of some components. You'd know tell me that is "RY1"?. Values of C38,C39,C40 capacitors and R70, R74, R75 resistors?. R74 and R75 are in the power PCB, they look like the other two resistors where the six capacitors. Thanks and Cheers!
          RY1 is for a 6V relay to switch on and off a panel mount LED for overdrive, Low Signal Relays - G5V-1-DC06 This is optional and not true to a SLO build. R70 is a resistor for the LED I believe. I bypassed these items.

          C38,C39,C40 capacitors are 4700uf 16v
          R74 and R75 are 220k 1watt to be pared with R55 and R54 as bleeders to the 220uf filter caps.

          Hope this helps

          Comment


          • #6
            Thanks!!! I thought I would never find the components. Do you know how to reduce power to 50W? I already have the transformers to this power but I still don't understand the connections. What capacitors and resistors should I connect?

            Cheers!

            Comment


            • #7
              Originally posted by Pivi View Post
              Thanks!!! I thought I would never find the components. Do you know how to reduce power to 50W? I already have the transformers to this power but I still don't understand the connections. What capacitors and resistors should I connect?

              Cheers!
              Same connections the only thing that changes is the number of tubes and adjusting the bias. I run 50w units with 100w power only to save money by having only one PT built for both. Its all the same voltages but just higher amprage and heater current for additional tubes. I also found that over wattage output transformers sound better also (18/20w<30w OT and 50w<100w OT)

              Comment


              • #8
                Originally posted by versital View Post
                Same connections the only thing that changes is the number of tubes and adjusting the bias. I run 50w units with 100w power only to save money by having only one PT built for both. Its all the same voltages but just higher amprage and heater current for additional tubes. I also found that over wattage output transformers sound better also (18/20w<30w OT and 50w<100w OT)
                Ok, Ill try to made the same circuit with 50W transformers because they were paid yet Thanks!!
                Last edited by Pivi; 07-10-2016, 09:00 PM.

                Comment


                • #9
                  Originally posted by versital View Post
                  RY1 is for a 6V relay to switch on and off a panel mount LED for overdrive, Low Signal Relays - G5V-1-DC06 This is optional and not true to a SLO build. R70 is a resistor for the LED I believe. I bypassed these items.

                  C38,C39,C40 capacitors are 4700uf 16v
                  R74 and R75 are 220k 1watt to be pared with R55 and R54 as bleeders to the 220uf filter caps.

                  Hope this helps
                  Hello, I was looking into the part list and the PCB and I found some new problems. C6 is 1nF/400V in the part list but it has a different value in the PCB (22nF). C41 isnt in the part list but its in the PCB. It looks like the C6 capacitor because they have the same value 22nF. The third problem is the C42 capacitor, it either is identified. It looks connected to clean treble potenciometer. I hope you can help me with these dudes. Thanks!

                  Cheers!

                  Comment


                  • #10
                    Originally posted by Pivi View Post
                    Hello, I was looking into the part list and the PCB and I found some new problems. C6 is 1nF/400V in the part list but it has a different value in the PCB (22nF). C41 isnt in the part list but its in the PCB. It looks like the C6 capacitor because they have the same value 22nF. The third problem is the C42 capacitor, it either is identified. It looks connected to clean treble potenciometer. I hope you can help me with these dudes. Thanks!

                    Cheers!
                    Does someone know the value of C42 capacitor?. Where can I find the two schematics of this post in big size?

                    Thanks!

                    Cheers!

                    Comment


                    • #11
                      Hello, I found this message:
                      This post is to help those of you who are using the Ampclones.com SLO-100 Rev. 1.3 with the dual EQ. This board is no longer on the ampclones website as it may have been discontinued or in process to come out with a new version. I've built many SLO clones using the Turret and C3amps boards and this ampclones version has given me nothing but pure Hell and huge losses in Time, Money, Sleep, and a wife who's upset the amps are not working and so much wasted. Ive reached out to other people on the forums having similar issues and most of them gave up and never finished the builds or switched to a different board. There is absolutely no support from Ampclones as they seem to only respond to email every couple of months and dont participate in their own forum. The slocone Forum wont help as they will only support their boards and schematics from which ampclones stole it from.

                      First off, I've traced every section of this board and I can testify that there is no errors in its layout, just extra things not included on the original design so dont waist any more time looking at this unless you just need to draw a mental reference. All the problems with this board is due to incorrect values and discrepancies between the ampclones provided schematics, notes, and xls part-list compared to the official sloclone schematic and layout.

                      Bias issues There is no Bias range resistor. Depending on your power transformer bias voltage you will need to wire a resistor in series with your bias supply wire (shrink-wrapped) to provide the correct range. My PT has a 100v tap so I used a 39k to set the range.

                      DC Heater issue R67 is listed as a 220k 1W for bias supply input but as stated above there is no Bias supply/range resistor on this board. R67 is actually part of the DC heater Mod and the correct value is 1ohm 3w. This error would have caused your pre-amp tubes 1 & 2 to not light up at all.

                      R69 is listed to be 1/3W to be interpreted as 1ohm 3w, This is incorrect as this is the Tone stack input or mid range slope resistor for the clean channel and this needs to be chosen by your flavor 39k-Marshall, 47k-Soldano, up-to 100k-Fender.

                      R68 also is listed to be 1/3W to be interpreted as 1ohm 3w. Based on the actual trace this is listed on the modified ampclones drawing to be a Input reference to LDR 5 & 6 to split to dual tone stack EQ sections. If this was needed the correct value should be 1M. Other wise you would be almost grounding out the signal and have no sound from the amp. Based on the original sloclone schematic OMIT this resistor and leave slot empty on board.

                      C41 is a 22nf coupling cap leading into R68 above. It is also listed as a 47nf on the part list for dual EQ not sure the reason for this mistake but Please OMIT this and run a JUMPER in the slot to pass the signal to the tone stack section.

                      C21 & C22 is labeled on the board to be 100nf. It may have been corrected on some boards but this is your PI Coupling cap and the correct value is 47nf 630v (600v+) Don't use Sozo Premium caps @ 400V for this for I had one fail.

                      R64 & R65 Switching Circuit issue !!!!! Ampclones Dual-EQ notes say to change R64 listed as 47R to 15R and R65 listed as 33R also to 15R. I guess to compensate voltage for additional 3 LDR's not included on original SLO added to reduce bleed and Dual tone stack switching. Using a 6.3VAC tap do not make this change. Keep the original values because even though the voltage will be a little lower than whats shown on the Schematic, the circuit will still work OK!!!! If you have changed both to 15R as stated either your amp will change channels but have a very low volume almost to a bleed volume as some of the LDR's will block or ground the signal ----OR---- you will have good volume on only one channel such as the lead and almost Zero sound on the other. You may or may not have the same results on the FX loop out while troubleshooting to another amp as this will depend on which LDR's are still open or closed. This is caused because the voltage is to high feeding the LDR's and when you switch channels the voltage is not actually cut but reduced to the opposing channel paths thus turning off the LDR but if the voltage is to high the LDR will not close because the voltage is over the threshold to deactivate. This was my biggest head ache trying to figure out even to the point of swapping LDR's and mounting a few of them upside down/reversed as shown on the Original Sloclone schematic. After tracing the LDR circuit I found the routing was done correctly to allow all the LDR's to be mounted facing the same direction. ........(Note if you did solder and unsolder the LDR's multiple times it will be almost impossible to remount these directly to the board plus you will have a ugly mess and burnt board. Trick- take a few of your thinner leads cut from your other components and cut them 1/2 long and drop them down into the LDR mounting holes with heat from solder iron and make 4 equal solder studs. Test for connectivity to the next component down the line. Then cut your LDR leads short enough to wrap around each of your new mounting studs and solder and trim off excess.)

                      I hope this will help everyone. I only wished someone would have done this for me 3 weeks ago!!!
                      I hope help you. Now I need to know some values to finish my sloclone dual stack. R70, C42 and also if you finish your projects

                      Thanks and I hope you can help me.

                      Cheers
                      Last edited by Boss; 08-06-2018, 09:22 AM.

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