No LED light

[RDHailey]

So, second verse same as the first. Another newbie building his first kit and running into issues.  Thanks in advance for any help/advice.

Symptoms:

LED dark.

Voltage at bottom left to 4th pin of 18 pin header 5.9v

Left side of D2 and D3  25VAC

U1 gets firecracker hot within 20 seconds of applying power.

Actions so far:

Resolder transformer joints. Jumpered pin 2 to ground and LED lit. Resoldered 4 pin header.

[bdwillie]

Check to make sure U1 is not in backwards!  I haven't built a LOR kit, but many others and usually all the chip orientation goes the same direction....  USUALLY but not always.  Looks like the chip under the connectors, it looks as if it has it's dot toward the right, while all the other chips have thier dot to the left.  This could be normal, but something to check.  Usually a chip gets hot of it is overloaded or put in backwards.  If it is backwards ya might have toasted it.  Just my two cents!  Good luck!

 

 

[TheDucks]

Check the pins on the RJ45 jacks

U1  is a RS485 driver

IIRC there is a AUX 9V also on the 8 pin jacks.  Solder Bridge? Bent feeler wires inside?

[Dennis Cherry]

On 5/11/2018 at 8:36 PM, RDHailey said:

So, second verse same as the first. Another newbie building his first kit and running into issues.  Thanks in advance for any help/advice.

Symptoms:

LED dark.

Voltage at bottom left to 4th pin of 18 pin header 5.9v

Left side of D2 and D3  25VAC

U1 gets firecracker hot within 20 seconds of applying power.

Actions so far:

Resolder transformer joints. Jumpered pin 2 to ground and LED lit. Resoldered 4 pin header.

What part of Tennessee do you live? I have built many years ago and maybe could spot what is happening.

[Say watt??]

Not sure if you have solved this yet, but the same thing happened to me on a controller I built two years ago. I had the two voltage regulators swapped. One is 5V and the other is 10V if I'm not mistaken. That little mix up most definitely fried U1. LOR was kind enough to send me two 485 driver chips in short order. Free of charge as well, even though I totally admitted it was my mistake. Great service.