Hi Guys,

Just received my Turnigy T-20Pro powersupply. http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=13765

Connected it and just noticed that Iam getting an electric shock of it.

The grounding wire is all correct. here are the readings.

1)Voltage between phase and neutral - 240 V
2)Voltage between phase and ground - 240 V
3)Voltage between neutral and ground - 1.5 V

4)Voltage between ground of the AC mains and the powersupply output ports (either + or -) - 94 volts.
5)Voltage between ground of the AC mains and the powersupply output ports (either + or -) without connecting the Ground pin to the powersupply input - 96 volts. - This means that the connection inside the charger may still be intact.

I havent yet opened the unit. What might be the issue? 

Is the power supply crappy? 

Welcome to the club,i too noticed that i i get shock when touching the balance charger,while the DC voltage is 13.84V ,the AC voltage which i measured by just placing the + terminal of multimeter to the body of the balance charger or the positve terminal of turnigy T-20 i get around 40v or more.
placing one end of a wire on the body of the balance charger and the other to the earth,solves this problem.

edit
after measuring the turning + output and the ground i get more then 100v ,the AC input voltage was 249v.

So I Use 2 chargers, that means I have to connect both the bodies to the ground right? 

Hope this is not dangerous to the lipo. 

Just check the phase is in the right side pin of the power outlet or not.

Step-1
=====
Put on the switch. Check with a live line tester. If its OK (Phase in right side) then go step2. Else just call electrician and ask to correct it.

Step-2
======
During charging, connect the cell pack terminal with the test lamp one terminal and other terminal to power outlet earth. then put a live line tester on any of the battery terminal (Charging).

a) If the lamp glows, & Tester too, the charger is defective.
b) If both are not glowing, Charger internal earth continuity wire/PCB track ( Internal) not connected. Just add an earth wire and connect it from earth pin of socket outlet to any of the battery charging terminal and your problem will be solved.

c) If the Lamp is not glowing but tester is glowing, your socket outlet earth point cuts anywhere. Just call electrical technician and correct it.

That's enough.
Thanks

Hi Kalyan, thanks for the reply.

1)The phase is on the right, I had corrected this before installing computers in my room. No issues there.

2)The earthing of the house seems to be fine. My 2 computers, microwave, aquaguard, water heater, tv etc, none gives a shock! Thats why I posted the voltages between terminals. I even tried all the wall socket in the house and everywhere I connect I used to get the shock. The POWER supply body is not giving a shock (including the screws which are not painted), its the output terminals.

Can you please explain with a simple mspaint diagram? Iam not able to understand the circuit u are explaining. Also what lamp are u suggesting? the 220V bulbs?

BTW its a Powersupply and not a charger.

Looks like the power supply is not grounded at the correct point of the PCB,since grounding the negative terminal of the output solves this issue.
A SMPS power supply like this needs to be grounded somewhere near the AC part of the circuit.
In the inside where the 3 pin AC input connector is soldered to the PCB .the ground pin is soldered to a wire which connects to the body,so it appears to be isolated from rest of the circuit,unlike most computer SMPS which has many parts of the PCB grounded.

Further more a guy in HK forums had a slightly more expensive A20 power supply which had the same problem,he went to repair shop and they grounded it which solved the problem.

Its just designed to be that way I guess. I think one of the heat sinks - that does NOT have a tape wrapped around it should be touching the body of the charger I guess. But it was not.

I just soldered a wire between the mains ground to the -ve of the smps o/p. problem solved.

1)The internal top view. you can see the yellow wire (ground). this is basically connected to the body of the charger.

2)One of the solder had come loose I connected it. But was not the issue.

3)If u see the ground. Its not connected any where. except that in PIC 1 above its connected to the body of the smps.

4)I soldered a wire in blue to the ground and the negative terminal of the output, which in turn is the ground of the output FETs.

Hope what I did was correct   I never do R&D by myself. Its working as of now. Hope it keeps working. 

Just another glaring QC issue with Hobby King products. HK has to get really careful now when they have opened store in US. Their little whinny disclaimer "We sell cheap, so dont crib if ain't work' wont work. Some body can really take HC on its toes if HC ships such product to the mainland.

Finally what u pay is what u get!  

Remember that ur great planes ESC or the Align ESC that comes with the kit are more crappier than the price u pay for HK Plush!

Charged 6 3s 2200 cells today morning with 2 charger and it works like a charm. Voltage dropped from 13.97 (no load) to 13.70(at 100 watts). Hope it lasts long.

No shock what so ever now.

Hey Viney,
Connecting the GND of the 'DC' output to the Natural Ground from your mains is not a recommended thing in power electronics. You should have had a course in your Engg.  This is much more critical in SMPS power supply.

I would still recommend you to take this supply to a good Electronic repair guy. I bet there is an issue of some leaky capacitor in the final Filter stage/

If not, at least instead of directly connecting the Natural Ground to DC out GND, connect a 100nf polyester capacitor between the +ve and -ve out put line and see if this 90V/50Hz AC is chopped off.

When ever u are free take my smps do all possible operations and give back. 

Well i did the same tests with a computer SMPS ,by disconnecting the computer SMPS ground connection and wala the same problem occurs ,one gets exactly half of the AC input voltage in both the DC output terminals.

Looks like all cheap SMPS charges have this issue and the same solution is recommended http://www.aplomb.nl/SMPS_leakage/Doc_ie.html#August_7_scoped

Quote from: vinay on November 21, 2010, 10:04:01 PM
Its just designed to be that way I guess. I think one of the heat sinks - that does NOT have a tape wrapped around it should be touching the body of the charger I guess. But it was not.

The reason why they have wrapped it in tape is that when you connect the 2 banana plugs and by accident if you touch the other end of the positive output terminal to the body you will shorting it.
What i did was i disconnected the ground wire connected to the body,since there are high chances you could accidently touch the positive output cable to the body.
so i suggest you do the same.

Ya good idea. Anyway none of the internal parts are touching the body.

Quote from: vinay on November 22, 2010, 01:57:29 PM
Ya good idea. Anyway none of the internal parts are touching the body.

Which is why grounding the body serves no purpose