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. I’ve 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 don’t 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 don’t 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!!!