Voltages pins 5 and 14 of IC1

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Voltages pins 5 and 14 of IC1

Postby ejet » Sat Sep 16, 2017 8:21 am

Hi all,

I've just soldered together the OTGW bought at Kiwi with the USB cable. Also I have gathered all supplies to use RS232 since I probably will use the OTGW with an USR IOT RS232 ethernet bridge. But that's only if the OTGW is operational and as for now, it is not.

I have replaced the transformator with 710564 Print transformator VB 2,0/1/15 and the DC converter with 157954 DC/DC-omvormer R-78E5.0-0.5 SIP3. I have soldered the 4 capacitors for the RS232 IC on the board already but I am focusing now on getting USB working.

When I test voltage on pins 5 and 14 of IC1 I get 3,2V, on X1 and pins 15 and 16 of IC2 as well. With power disconnected, when I check the DC converter it seems all pins are short-circuited, as well as C2. Is C2 or the DC converter broken or do I need to check elsewhere? I have moderate soldering experience and I have checked all soldering connections for short-circuits but I cannot find them. I lack the advanced electronics knowledge to troubleshoot myself. I have a multimeter that can check voltage, resistance, diodes and capacitors but not current (Fluke 110).

Thank you for your time and effort!
ejet
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Re: Voltages pins 5 and 14 of IC1

Postby hvxl » Sat Sep 23, 2017 10:31 am

Outputs of devices usually have a low impedance. When powered down that may appear like a short-circuit. C2 is connected in parallel with the IC3 output, so also there you measure the low output impedance of IC3.

I would suggest to check that the transformer and DC/DC converter are the actual type you ordered. Then check the voltage across the opposite ends of D1 and D3. You should find around 24V. If it's much lower, there could be a problem with the transformer, or there is a short-circuit somewhere. If the transformer gets warm after a while, it's producing too much current. That points to a short-circuit. In that case contact Kiwi support to help you investigate further.
Schelte
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Re: Voltages pins 5 and 14 of IC1

Postby ejet » Sat Sep 23, 2017 8:57 pm

Thank you for the reply, I wil check all your points mentioned this week and report back here.
ejet
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