Hi all, I'm working on a WM-D6 (not the D6C) and would appreciate a sanity check from anyone who knows the board. Background: the original fault was the classic motor running too fast. A few months ago I fitted a replacement CP602 servo unit, but afterwards the motor had no power, so I removed it again and shelved the job. Having gone back to it, I've found that three of the CP602 pads on the solder side have lifted/corroded away completely: pins 1, 5 and 11 (numbering with pin 13 at the Q308 end and pin 1 at the D601 end). That would explain why the new unit never powered up. What I've done so far: - Pin 1 (ground): jumper to C611's negative leg, confirmed 0 ohms to GND. - Pin 11 (supply): jumper to C611's positive leg. My two questions: 1. Pin 5: the mounting diagram shows 5.4V at CP602 pin 5 and 5.4V on Q603's base, so I'm assuming pin 5 connects directly to Q603's base. However, R604 is drawn nearby. Is there a resistor in series between pin 5 and Q603 base, or can I jumper pin 5 straight to the base? I don't want to bypass anything and end up with fast running again. 2. Pin 11: the diagram marks C611 positive as 6V, whereas pin 11 should be around 5.5V (fed via R602, 100 ohms). Should pin 11 go to the other end of R602 instead of C611 positive? I also plan to replace C607 and refit the small capacitor between pins 1 and 4 when the unit goes back in. Photos of the solder side (normal and backlit) are attached. Thanks in advance megabass
Hi and welcome to the forum. In answer to your questions: 1. Pin 5 of the CP602 connects directly to the base of Q603. 2. The positive side of C611 should be 5.5V. I think the diagram may be a bit confusing because it shows "6V" above a red arrow pointing to the pad for pin 4 of the CP602, which is the positive connection directly to the incoming power supply which supplies the motor drive system. Pin 11 of the CP602 SHOULD NOT be connected directly to the 6V since this is the direct connection to the VCC pin of the CX20024 chip. It should be connected to the +ve side of C611 (or the 5.5V side of R602). I think R602 acts as a current limiter to protect the CX20024 and is part of the reason why the CP602 module on the WM-D6 is much more robust than the CX20084 chip which replaced it in the WM-D6C. I have seen plenty of WM-D6Cs with CX20084 chips destroyed by reverse polarity power supplies or switch mode power supplies but, so far, I haven't seen a CP602 which has been permanently destroyed by reverse polarity or switch mode supplies. Where did you get your replacement CP602 module from? I have seen some replacements advertised on Superbuy but I haven't tested one yet. If you still have your old CP602, keep hold of it. It can most likely be repaired. I have attached a high definition layout and schematic for the CP602 which should help.
