Here are some Issues from the first batch TTSH pcbs (delivered around March 2014)
(page links/anchors)
- pcb silkscreen failure for powersupply
- Hum issue on Speaker and more
- Noise "distorted"
- Clock bleed on VCO pitch
- wrong Silkscreen for matched pairs
- wrong Silkscreen or polarity for Capaciator C20
- VCO Bleed Fix with Volatage Regulator
Resolution:
= tested
= untested
FIX for pcb silkscreen failure for powersupply
cross one Ferrite on top pcb side - the ferrite on other pcb site (not shown here)
other way:
FIX for Hum issue on Speaker:
This Issue occurs by using the internal DC-DC Adapter,
FIX: short out the 10Ω resistor and the 100p capacitor in the PSU section. E.g. just make a small bridge between the pad close to 10Ω and 100p as in the attached picture.
further use RG174 cables or shielded microphone cable for offboard wiring.
FIX for distorted Noise.
leave out the 2n5172 - use a bc337, - bend right leg to top, solder a 10K resistor in series to the 1uF cap.
Option A (from nordcore)
Option B: (from me and confirmed)
other working solution to connect a 10K resistor to the cap (after soldering, use shrinktube for cap and resistor housing )
FIX for Clock bleed on VCO pitch
at the moment 2 steps to fix the Issue - (both together must used to fix the Issue)
First Step - tested solution : leave out the 2n5172 in clock section (led driver for blinken lights), bridge 2 solder holes..
FIX for wrong Silkscreen for matched pairs Transistors in Filter section
the top 2n3906 is unmatched, you have to take 3 matched transistors if you´re not really sure about it.
FIX for wrong silkscreen or polarity for capaciator C20 in RINGMOD section (untested by me)
change the polarity of C20 10µF elecrolytics (its the right hand capaciator)
VCO Regulator:
due to VCO Bleed issues, Nordcore from muffwiggler sales VCO Regulator pcbs, this fix this issue. approved