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TC620C circuit trace

Posted: Wed, 08 Mar 2017, 04:04
by coulomb
Geoff O'Toole was kind enough to send me a TC620C module to find out what's in it. I haven't found any information on what these things do. I'm sure some Blade owners will need to find out in time, or at least it may save them a lot of time.

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The black and white potting material is quite soft and crumbly. It's just tedious to remove. There are two screws holding the PCB to the case (as well as the potting material, of course); they are at the end with the three cables.

After removing the potting material:


The only components are a 12 V relay, two NPN transistors, and two 510Ω resistors. I traced the schematic as shown below.

In summary: one cable (red, green, and black) is for connection to the LEDs; mine had a tag on that cable that reads "TC-621A" and "Work Led". Black is ground, red and green are for the red and green LEDs (I assume).

The other three-wire cable extends the usual +12V, GND, and Enable signals. The enable signal does nothing on CAN model chargers. Note that GND on this is green, not black. Note also that this "GND" is basically tied to the negative end of your pack: it is *NOT* isolated.

The final cable with only two wires, red and black, are the normally open contacts of a relay connected to 12V from the charger. So whenever the charger is powered (even when charging is finished, I believe), the red and black wires will conduct to each other. These contacts are isolated.

There are also pads that connect to the serial in and out (pins 6 and 7 of the 7-pin round, not necessarily in that order), and to the spare set of contacts of the relay, but these are buried under the potting compound. Should you need them, however, you should be able to figure out where to dig the potting compound from the above photos. It should be easy to solder to those pads without taking out the PCB.


The cable gland nuts were extremely tight, and when I finally got them to move, there was a sharp crack, like superglue breaking. So don't expect to get one of these out of its box without breaking something.

My guess is that TieCheng (the charger manufacturer) assumed that many users would want a box like this with isolated "charger on" signal, and external LEDs, but Blade were the only ones to ask for it, or to use them. Maybe they were a special order for Blade only.

TC620C circuit trace

Posted: Wed, 08 Mar 2017, 20:41
by Richo
coulomb wrote:I haven't found any information on what these things do.

No one asked the manufacturer?