Hi,
There is some problem with the “Sleep” mode on the K8048 board: on some pins of the processor a voltage of nearly 5V stays present in “sleep” mode (SW5 in middle position).
The reason for this is that the PC interface circuitry (T1, T2 and T3) stays powered in the “sleep” mode, resulting in almost 5V on PIC pins PGC and PGD. This interface circuitry should have been fed out of “Vdd” in stead of out of the +5V: the latter is always on, while the first is switched off in “sleep”.
This problem can also be the reason why some users complain about LD9 faintly blinking in the “sleep” mode: via pins “PGC” and “PGD” some current flows to Vdd if a PIC is inserted, making Vdd not zero any more. If this voltage is high enough (depending on the characteristics of the PIC inserted), then LD9 will blink.
[i]I do not know if
- the PICs can be harmed by being in this “sleep” state[/i] (having +5V on some pins while Vdd is almost 0) [i]or
- if the PICs can be harmed by removing it from the board while being in this “sleep” state[/i].
Anyway, the problem can be solved (only by electronics engineers) by:
- Cutting the track at R16 (not the side of LD7, the other side of R16), make the cut close to R16.
- Cutting the track between emitter T3 and the feed trough connected to it (make the close to the feed through).
- Cutting the track between R7 and VR2
- Soldering a wire between R16 (not the side of Ld7, the other side of R16) and C4 (not the ground side).
- Soldering a wire between emitter T3 and LD9 (not ground side)
- Soldering a wire between R7 (loose side) and LD9 (not ground side)
After the change, please test first without PIC if all voltages are Ok now:
- all PIC pins zero Volt in “sleep” mode (and LD8 and LD9 are black),
- Vdd = 5V in any of the two other modes (and LD9 is blinking),
- Vpp = 5V in “Run” mode and 13V in “Prog” mode.
- LD8 = black in the “run” mode, on in the “prog” mode.
Warning from VEL456 (see post below):
[color=red]Attention: The warranty will be void if units are modified ![/color]