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Are you attempting to build one or repair one? If you are attempting to repair one, what seems to be the trouble with the one you have? If you are attempting to build one....any standard 12V ni-cad charger should do the charging job, the trouble is replicating a convenient connection scheme.
As far as a schematic goes, I would guess that it is proprietary in nature and that not even dewalt "repairs" them. I wouldn't be at all surprised if the same model had several different versions of circuit boards representing different production runs. Unless someone has reverse engineered that particular model and has then decided to publish that information I can't see finding a schematic for it, but, again, a Ni-Cad charger is pretty much a Ni-Cad charger.
Fish
As far as a schematic goes, I would guess that it is proprietary in nature and that not even dewalt "repairs" them. I wouldn't be at all surprised if the same model had several different versions of circuit boards representing different production runs. Unless someone has reverse engineered that particular model and has then decided to publish that information I can't see finding a schematic for it, but, again, a Ni-Cad charger is pretty much a Ni-Cad charger.
Fish
Thank you Fish for fun. It is repair that is needed. The problem being that there is no volts at the battery connection pins. The obvious such as transformer output and fuse are OK. No physical signs of component failure.
Fish
Thank you for your ongoing interest.
Two pictures attached.
I hope I have used the correct method to attach them.
David
Thank you for your interest Bob,
Such a charger might get by for a lead acid battery but not for a NiMH battery. All NiMH chargers have many more components in them.
Dear Fish,
Further to the pictures sent earlier I should have given to you more symptoms which I established prior to seeking a schematic.
When the charger does not have the battery pack inserter in to it, the volts available at the charger connectors is 17 V DC, (no AC present).
The battery which I wish to re charge has zero volts. When it is inserted into the charger the charger volts drop to zero and the green LED lights up to indicate that the charging cycle is completed.
If I plug in a new battery with an initial voltage from it of 11.5 V, the charger volts fall from 17 V to 11.5 V and again the green LED lights up.
Also the identification on the two solid state devices is almost faded to nothing, but appear to be LM393N 901801 and P19N0? (or may be P19NG?) 3805 for what looks like a regulator. Both of these appear to be branded ST.
David
Hey David,
Ok, first, there is nothing particularly fancy about the circuit. It is using the dual comparator (LM393) to test the charge state. There are A LOT of smd passive components on the copper side, more than I would think requisite and yet there they are....there are also what appear to be 2 smd active components on the copper side. They differ in appearance from the passive components in that they have 3 leads instead of 2. They are located near the transformer secondary on the copper side. If you can get a number off them, please do. Also, if there are any other SMD components with three or more leads, please report their location and any markings on them.
Visually the only thing I note is the 100ohm current resistor shows some small signs of over-heating. It is difficult to guess if perhaps the resistor is out of tolerance, I wouldn't guess so, but that would be the first thing I would test.
I assume you are in the UK as the charger was made for the UK market. This being the case, before we get too far into this, remember this is an option: http://www.battery-discount.com/Bat...r-compatible-with-DEWALT-ref-type-DE9103.html ; just saying......
Ok, how you proceed from here depends a lot on what equipment // skills you have. I don't see anything proprietary on the PCB, so the easiest solution is likely the "shotgun" approach; that is, start replacing components until it works....If you have a Multimeter, we can do some fairly quick testing of the resistors to ensure they are within tolerance. As previously stated, the only "tell-tale sign" I see is the slight discoloration of the 100 ohm current limit/sense resistor (brown /black/brown). Test it first, or simply replace it if you have one on hand.
The next thing to test (I assume you have a Voltage meter from post #8) is the voltage on all three pins of the "P19Nx" device with respect to ground in all three cases ===> 1) No Battery 2) Battery w/Charge 3) Dead Battery. In reporting this info, assume Pin 1 is to the left when viewing the device from the side with the writing.
Example: No Battery: Pin 1 = 17Vdc Pin 2 = 0Vdc Pin 3 = 5.1Vdc
While the part# P19N did not yield any search results, it is quite possible it is in fact a 7805 or some other voltage regulator (though it could just as easily be a transistor//mosfet).
In addition to the info about the non-passive smd components, and the voltage on the pins of the P19Nx, it might be a good time to let me know what skills//tools/experience you have and if there is a local electronics components vendor. If you have no tools and self-describe as "little or no experience with electronics" I would urge you to consider the £ 44,90 option simply because this project could easily become a time sucking vortex that ends in failure. You should also be aware that a NiCad/NiMh battery that reads 0V is quite frequently permanently damaged. All that being said, I also need to disclose that I am NOT a trained technician, but rather a self-taught amateur with a good track-record, but PLENTY of failures to go along with the successes. I would hope that some of the professionals here would correct me if I suggest something too far out-of-bounds, but you will need to proceed with the understanding this could end in failure.
Fish
Ok, first, there is nothing particularly fancy about the circuit. It is using the dual comparator (LM393) to test the charge state. There are A LOT of smd passive components on the copper side, more than I would think requisite and yet there they are....there are also what appear to be 2 smd active components on the copper side. They differ in appearance from the passive components in that they have 3 leads instead of 2. They are located near the transformer secondary on the copper side. If you can get a number off them, please do. Also, if there are any other SMD components with three or more leads, please report their location and any markings on them.
Visually the only thing I note is the 100ohm current resistor shows some small signs of over-heating. It is difficult to guess if perhaps the resistor is out of tolerance, I wouldn't guess so, but that would be the first thing I would test.
I assume you are in the UK as the charger was made for the UK market. This being the case, before we get too far into this, remember this is an option: http://www.battery-discount.com/Bat...r-compatible-with-DEWALT-ref-type-DE9103.html ; just saying......
Ok, how you proceed from here depends a lot on what equipment // skills you have. I don't see anything proprietary on the PCB, so the easiest solution is likely the "shotgun" approach; that is, start replacing components until it works....If you have a Multimeter, we can do some fairly quick testing of the resistors to ensure they are within tolerance. As previously stated, the only "tell-tale sign" I see is the slight discoloration of the 100 ohm current limit/sense resistor (brown /black/brown). Test it first, or simply replace it if you have one on hand.
The next thing to test (I assume you have a Voltage meter from post #8) is the voltage on all three pins of the "P19Nx" device with respect to ground in all three cases ===> 1) No Battery 2) Battery w/Charge 3) Dead Battery. In reporting this info, assume Pin 1 is to the left when viewing the device from the side with the writing.
Example: No Battery: Pin 1 = 17Vdc Pin 2 = 0Vdc Pin 3 = 5.1Vdc
While the part# P19N did not yield any search results, it is quite possible it is in fact a 7805 or some other voltage regulator (though it could just as easily be a transistor//mosfet).
In addition to the info about the non-passive smd components, and the voltage on the pins of the P19Nx, it might be a good time to let me know what skills//tools/experience you have and if there is a local electronics components vendor. If you have no tools and self-describe as "little or no experience with electronics" I would urge you to consider the £ 44,90 option simply because this project could easily become a time sucking vortex that ends in failure. You should also be aware that a NiCad/NiMh battery that reads 0V is quite frequently permanently damaged. All that being said, I also need to disclose that I am NOT a trained technician, but rather a self-taught amateur with a good track-record, but PLENTY of failures to go along with the successes. I would hope that some of the professionals here would correct me if I suggest something too far out-of-bounds, but you will need to proceed with the understanding this could end in failure.
Fish
Tell that to the people who built the charger for my cordless screwdriver. I replaced it with a smart charger after it killed 2 batteries within a year.
Bob
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BobK, are you a communist terrist? Don't you realise that making the batteries last longer is STEALING from the company that sells the expensive replacements?!?!
Hello again Fish.
With great difficulty I think I have the ID of the two SMD devices J4 1B and K2 A6. The J4 and K2 are at 90 degrees to their 1B and A6. Not sure if that is relevant.
There are no other similar three pin devices on the copper side.
I have not tried to test all of the very small resistors on the copper side, however I have checked the 100 ohm and it is ok.
I am in Australia not UK and have fairly good electronic and associated work shop skills with good access to electronics parts suppliers.. My preference is to repair if possible, as I appreciate the challenge and it saves dollars.
The measurements on the P19Nx as below. Assuming that pin 1 is on the left when viewing the board with the transformer beyond the P19Nx.
Pin 1 Pin 2 Pin 3
No Battery 0 0.05 0
Bat with charge 0 4.0 0
Bat with no charge 0.2 12.0 0
They do not make very much sense to me.
You suggestion of purchasing the comparator and the P19Nx (if I can correctly identify it) and systematically checking the other components may be the only way forward.
all the best
David
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