Weller WRS1000 soldering station repair manual or tips

[neazoi]

Hello my WRS1000 does not heat up the soldering iron, everything else works fine.
Also I see no activity on the front green LED, no matter what the temperature is set to.
Could you please provide a service manual or any other advice?
I really appreciate.
Thanks

 

[D.A.(Tony)Stewart]

The heating element appears to be open circuit, is it time to repair? Too much voltage applied? Remember 2x Vac results in 4x power.

 

[neazoi]

The heating element appears to be open circuit, is it time to repair? Too much voltage applied? Remember 2x Vac results in 4x power.

The soldering iron is the weller HAP1 with heater voltage 24VAC (100w max). It has a switch for the air on it. It also has 5 pins, I cannot find the heating element pins, what short of ohms should I read?
I have just receiver the station and it is in perfect visual condition, not even any kind of dust inside and outside. The seller has 100% positive feedback out of hundreds and he had infirmed me that the unit was tested by him prior to shipping and it heated up fine.
There is no visual damage inside or outside the unit as far as I can see.
The only thing that worries me is that the back says 120v 1.6A and I am feeding this from a 220v to 110v isolated transformer of 500VA. Can these 10v difference (from 110v to 120v) really make the iron not heat up at all and the led not to switch on at all?
The air push and sucktion work ok.

 

[D.A.(Tony)Stewart]

I imagine 5 pins on wand are ;

thermal sensor (2) kOhm? ,

heater (2) <1 Ohm range

& (1) shield or ESD ground

+/-20 % Vac no problem I think.

 

[neazoi]

I imagine 5 pins on wand are ;

thermal sensor (2) kOhm? ,

heater (2) <1 Ohm range

& (1) shield or ESD ground

+/-20 % Vac no problem I think.

Yes, the thermistor was about 600R and the heater almost shows short. I applied 15vdc to the heater and heated ok. so I guess it is not a problem of the iron but something with the station.
At the same heater pins at the station I read about 2vac and when switched to dc I read 0vdc.

Could this be this 10v difference in the mains power that causes this behaviour?

 

[betwixt]

The 10V is of no importance at all. That kind of variation could occur in normal use as loads are turned on and off the mains supply.

Sounds like you have an internal power supply problem in the base unit. I would guess it should still give some signs of life even with the iron unplugged.

Brian.

 

[D.A.(Tony)Stewart]

As I recall, Weller used relay to activate heater , listen for sound or check internally.

 

[neazoi]

The 10V is of no importance at all. That kind of variation could occur in normal use as loads are turned on and off the mains supply.

Sounds like you have an internal power supply problem in the base unit. I would guess it should still give some signs of life even with the iron unplugged.

Brian.

What signs?
It has two transformers inside, one 120 to 24 and the other 120 to 12 and 24. Both measured ok. In fact as you mentioned the 10v difference seemed to play no role as I measure 11.8 and 24v which thould be ok.

It seems that this uses separate transformers for the iron and the pump. I guess so, because thease are the more power hungry parts.

One thing that worries me, there is a little 250v 200mA fuse onboard, near the transformer output, that is soldered onto the pcb and looks like an electrolytic capacitor in shape.
I cannot test this since there are no pads there.
I have to flip over the pcb, which on the top side has standard components and at the bottom side smd ones. but all smd ships are 8 pin types, I do not think there is a micro there.

- - - Updated - - -

As I recall, Weller used relay to activate heater , listen for sound or check internally.

No there is no relay in that unit, I have checked it. Swithing must be done electronically somehow.
I can see a BT138 triac connected directly with it's one pin to one of the thickest cables that go to the iron connector. Switching must be done this way.

 

[D.A.(Tony)Stewart]

It may be a glass enclosed reed relay

 

[neazoi]

It may be a glass enclosed reed relay

No there is no sich thing. I think the BT138 does the switching as I found both of it's terminals are connected to the heater. It must be in series connected with the heater. I measured it's gate voltage to be 0.2v At that low voltage I believe the triac cannot switch, unless I am reading the datasheet wrong. From these observations I see two things happening.

1. The heater PSU is functioning, since 0.2v present on the gate.
2. Maybe is it an iron thermistor error? If the thermistor gives false resistance the station may "think" that the temperature is always too high and automatically switch off the heater? (assumming temperature is maintained by switching the heater completely on/off)

What do you think?

 

[D.A.(Tony)Stewart]

Could be. If there is a 1Nxxx opto isolator or some other driver, it may use a zero crossing pulse to drive gate above 1.3V.

this model is different but may have same PCB . Check all cap voltages and chip supply on corner pins and then trace probe voltage.

 

[neazoi]

Could be. If there is a 1Nxxx opto isolator or some other driver, it may use a zero crossing pulse to drive gate above 1.3V.

Exactly!
Really near by, there is a K3020, which is a Optocoupler, Phototriac Output, Non-Zero Crossing .
Do you think it is a good idea to "fool the station" by unplugging the iron and connecting a resistor in the thermistor pins? Then I could see how the LED behaves, to determine if the thermistor is the problem.
What value of resistor should I try?

 

[D.A.(Tony)Stewart]

I think you can manage this.

 

[neazoi]

I think you can manage this.

The "cold" thermistor shows 600R, what value range should I try?

- - - Updated - - -

I think you can manage this.

I tried 330R and 2.2k, no luck.
I also manually heated the iron with an external PSU and instantly measured the thermistor. It seems the resistance goes up as it heats. So it muct be working I think.

 

[neazoi]

Hello all,
I finally spotted the problem.
It was the triac. it's power pins were cut-off brom the pcb, at a point where it was impossible to notice! This was due to the severe vibration during postage. The pins were looking as they were severely bent.
The discussion in this board led to good reverse engineering practices, and saved 300$ worth of equipment! It also lead to receiving the manual from Weller.
Thanks once again!

 

[betwixt]

Well done Neazoi, it's good to hear a story with a happy ending!

Brian.