Tuesday, January 19, 2010

PCB Errata

Refer to the Schematic resource link above for details on each release errata, and then scroll down to the appropriate revision below for additional details and photos of some of the corrections.  Errata is classified in the following way:

Severe Critical fault, MUST be corrected and current PCBs must have work around applied
Nominal Potential-fault causing, should be corrected and if desired worked-around 
Informational Non-fault causing, should be corrected and care should be used with current PCBs to recognize issue
Enhancement Addition to future Pub to increase reliability and/or functionality.  Often can be worked-around on current PCB with manual additions


Controller v0.3.1 + display v0.3.0 

 (Last revised 7-21-2014)
This combination was used for the 'Group Build' during the summer of 2014.  Errata for those are shown here.

(Click for larger view)

(Click for larger view)

Showing offset of Chinese CR2032 battery holder

1N5817  installed in place of R13 - - - -

And R6 moved to bottom of PCB.  Note how extra lead from the 1N5817 Diode was bend over and brought to Pin 3 of P2.  This is to carry the full current needed for the display board as the existing PCB trace was not designed for this and is too small.

Revised schematic showing addition of blocking diode (D8).
 Rework above accomplishes the same by re purposing the R13 mounting position and attaching R6 in a 'Flying Lead' fashion....

PCB V: 0.1.3 Errata

 (Last revised 2-14-2013)
The following changes are needed when assembling version 0.1.3 of the PCBs:
  • PCB Trace Width on back of PCB is too narrow from the +5V switching regulator (U5-pin 2) t to  L1 and D7.  Need to add additional wires.  (I used left over leads from the Diodes).
  •  R42 and R43 values are too small resulting in excessive leakage back through protective diode D10 and providing a 'Phantom Power' to the controller board.  Change R42/R43 to 33K and 100K respectively.  Change C21 to 2uf (or 2.2uf).
  • Phantom Power can also be supplied via ~START and D17.  If there is a chance VBat will not be connected, but the 'other side' of the external starter relay will be connected - then clip D17 to prevent this phantom power path.
  • PCB layouts for all 2N3904 transistors have E and C swapped.  Install all 2N3904 transistors 'backwards' by bending the Base pin in the opposite direction and installing the transistors so the flat side is opposite of what is shown by the silkscreen.  This is true for both the Controller board and the Remote display board.
  • Q1 on the Remote board is coupling noise via the base, resulting the SP1 buzzer emitting a small noise. Darn analog nature of Transistors - Why can't they just behave like good little switches. . .   Install a small capacitor (ala 0.1uF) between the B and E pins on Q1.  Or, you can leave it off and 'hear' what the controller is doing at the moment.  (For fun, Google "Univac computer Music" for references such as this.  I have been keeping that foot note of history in mind while listing to the pops and buzzes )
  • R29 encroaches very close to the fuse holder.  I installed R29 on the bottom side of the PCB.
  • PCB Layouts for the 78R09 regulators (Remote and Controller) have the through holes offset slightly, resulting in potential crowding of other components   If desired, bend the pins slightly to bring the regulator back into alignment with the silkscreen.
  • U3 Pins 6/7 are susceptible to bridging UNDER the IC.  Take great care when soldering U3 as one will have difficulty removing any excessive solder - even with solder wick.
  • Silk screen for Q1 and Q2 call out the incorrect part number.  Use the FQP27P06's as shown in the parts list.  (Note, the 29P08 part number shown will function, but they are not what was ordered in the BOM)
  • To-220 mounting hole finished size is slightly small for #6 screw.  Use awl to gently enlarge the hole, or use metal machine screw and cut threads in hole.  (Is very very slightly too small, no need to get out a drill...)
  • Bluetooth port does not function - you might wish to leave off Q11, R35 and P11.  As (if??) Bluetooth capability is debugged one can always gain needed access via the Service Port P1, or more likely the EXP port P10..

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