Post by dumbtechie on Nov 17, 2007 0:11:44 GMT -4
Bravo, grmcdorman!
It sure looks like you've got an intermittent open somewhere between the anode end of D2 and the left (on your schematic) end of the 2.2 ohm resistor. The most likely suspect is certainly D2. The only other thing you need to check for is a possible crack in the PC traces going to and from D2- inspecting them with a magnifying glass should show you if that's the case.
If, as I suspect, D2 turns out to be a 1N4001, any of the rectifiers in the 1N4001-1N4007 series will be fine as a replacement. The 1N4001 has the lowest peak inverse voltage rating of the lot; as all the others have a higher PIV and the same forward current ratings, they will sub for it just fine. The 1N4001 series might be the most commonly used silicon reciifier diodes in the world; they shoud be a Radio Shack, or Fry's, or whatever the Canadian equivalent is, item.
Just a few tidbits that might interest you:
Your wallblob is definitely an unregulated, filtered DC output type. The solid line over broken line symbol just means "DC"; the fact that the output voltage changes significantly between no load and loaded conditions shows that it's unregulated. I'm a bit surprised that the charger for your drill batteries is that primitive; the charger for our Makita has a bi-color LED that indicates "chargins", "charging complete", "ready to charge" and "battery fault" by either steady or flashing illumination in either red or green, so there's some charge management circuitry in there. Yours must not be a fast charger, or perhaps it relies on the thermal cutoff in the battery pack to prevent excessive overcharging.
The 48 ohms you read across D3 is the series combination of R1 (2.2 ohms) and R3 (47.0 ohms). Your ohmmeter is probably just a hair off but most likely within spec.
It sure looks like you've got an intermittent open somewhere between the anode end of D2 and the left (on your schematic) end of the 2.2 ohm resistor. The most likely suspect is certainly D2. The only other thing you need to check for is a possible crack in the PC traces going to and from D2- inspecting them with a magnifying glass should show you if that's the case.
If, as I suspect, D2 turns out to be a 1N4001, any of the rectifiers in the 1N4001-1N4007 series will be fine as a replacement. The 1N4001 has the lowest peak inverse voltage rating of the lot; as all the others have a higher PIV and the same forward current ratings, they will sub for it just fine. The 1N4001 series might be the most commonly used silicon reciifier diodes in the world; they shoud be a Radio Shack, or Fry's, or whatever the Canadian equivalent is, item.
Just a few tidbits that might interest you:
Your wallblob is definitely an unregulated, filtered DC output type. The solid line over broken line symbol just means "DC"; the fact that the output voltage changes significantly between no load and loaded conditions shows that it's unregulated. I'm a bit surprised that the charger for your drill batteries is that primitive; the charger for our Makita has a bi-color LED that indicates "chargins", "charging complete", "ready to charge" and "battery fault" by either steady or flashing illumination in either red or green, so there's some charge management circuitry in there. Yours must not be a fast charger, or perhaps it relies on the thermal cutoff in the battery pack to prevent excessive overcharging.
The 48 ohms you read across D3 is the series combination of R1 (2.2 ohms) and R3 (47.0 ohms). Your ohmmeter is probably just a hair off but most likely within spec.