(SOLVED) HOT connector on Main PCB HEATER 2

Dear all,
while printing, my printer died.
I investigated a melted + pin main connector (the green main power screwing connector).
I could not disconnect the wire of the + 15V from the connector.

Further more, I saw the HEATER2 connector (that with the wires) in a fine brown housing.
This means, the connector for heater 2 was going to melt as well.

Investigation:

  1. resistance of both heater cartridges are 8,4Ohm +/- 0,2Ohm
  2. swapping connections on main PCB from HEATER 1 to HEATER 2 and vis versa,
    the connector on the HEATER 2 getting hot.
  3. Temp sensor shows almost identically temp (+/- 0.4C)

So it is NOT a question of the heater cartridge itself, but of the connector on the main PCB.

In short:
what ever site of the nozzles are connected to the main boards HEATER2 soldered connector, will lead into a warm to hot connector (that with the wires on).

Any ideas what this can cause the problem?

the main board functions ok, as far as I can heat up any nozzle and heat bed.
Temp sensors are showing almost the same temp for the nozzles, so there is no prob

Burning connector means too much amps through a too thin connection = bad contact…

Hi,
thanks for the answer, I was assuming this, since I have an education in this kind of business.
But I could not find anything.

Since I swapped the wired connectors (labeled HEATER 1 and HEATER 2), it can only be that he soldering on the board has a problem, right?
I have to disconnect everything and check the PSB (main).

But why are this happened, since I did not change anything on the mother board?

Best
Frank

Dear all,
I went to the local electronic shop and they checked the PCB in detail.
They did not found any possible mistake on the main board, but suggested to change some connectors.
So I bought a new two pin soldering connector for the PCB and a new 15V main connector for the PCB.

I soldered everything in place and checked the wires again. even with the new on board connector, the jack got hot.
So I changed the pins of the jack as well.
So on board connector and wired jack have been replaced.

From there on, no heat up problems on the connection.

Printer is up and running again.

If I compare the strength of the connection (spring tension),
I can say, that almost every two pin connector from the original wiring are more or less slightly loose.

So I will check the heater connectors again (HEATER 1) to make sure I do not run into the same problem again.

In general, I can say it was a problem of the origin design of the board, using this kind of connectors, for such a high current.

Best 4 now
Frank