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 4. GQ Hot Air Soldering Rework Station
 Lost control of heating element on hot air.
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eclipse5435

3 Posts

Posted - 06/10/2022 :  19:04:17  Show Profile  Reply with Quote
Hello,

I have an issue with my GQ 5200 w/ hot air and tweezer that I was hoping to get some assistance with.

During a soldering project while using the hot air to shrink some heat shrink tubing, a loose wire touched the heating element and shorted the device. When this happened, the device immediately shut off.

I found that a small glass fuse at the back of the device had blown, but could not see anything else obvious. I replaced the glass fuse, and the unit powered up again.

The soldering iron works just fine. I can turn it on or off, as well as control the temperature of the soldering iron.

Problem is with the hot air. If I turn the hot air on, the temperature simply skyrockets to infinity. I have no control over how much heat is coming out. I do however, have full control over the fan speed.

I can increase or decrease the air speed coming out of the nozzle, but have no control of how hot the heating element is getting. There appears to be only one setting for this, regardless of what setting I put the heater control - MAX.

The temperature readout just quickly and continuously rises as soon as the hot air is turned on.

When I try turning off the hot air from the front of the rework station, nothing happens, the internal air pump continues to run, and the heating element inside the nozzle continues to glow brighter and brighter, getting hotter and hotter.

The only way to turn it off is by pulling the plug behind the rework station. If I immediately re-insert the plug, the hot air starts to run again and rise (even though power switch has been turned off in front of the rework station). If on the other hand, I wait a minute or two before reinserting the power, the rework station stays off (until I turn things on in front).

I have successfully replaced the heating element, just to rule it out, and it is not the culprit. There appears to be something else wrong.

Any ideas?

Thanks for your time.
Reply #1

eclipse5435

3 Posts

Posted - 06/11/2022 :  00:31:01  Show Profile  Reply with Quote
Just a slight amendment to my original post - The hot air comes on as soon as the 3 prong plug is hooked up to the back of the soldering station, regardless of what position the switch is in. As mentioned above, I have command over the air speed, but no control over the heating element of the hot air wand.

So I took out my digital multimeter and started poking around for connectivity within the main switch in front of the soldering station.

Terminals 2 and 2a show continuity regardless of which position the switch is in (ON and OFF).
Terminals 1 and 1b only show continuity when the switch is at the ON position

I'm no expert when it comes to electronics, but this would seem to point at an issue with the main power switch? It would have been my impression (given the position of the white wires on 2 and 2a, and the white wires on 1 and 1b) that green pair and white pair of wires should experience a loss of continuity at opposite switch positions. As is now, the white wires on 2 and 2a on the power switch show continuity regardless of On or OFF position on the switch.

If anyone has any ideas, I'd appreciate them.
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Reply #2

EmfDev

1693 Posts

Posted - 06/14/2022 :  10:26:42  Show Profile  Reply with Quote
Hi eclipse5435, it looks like the triac transistor may be broken. Can you check the transistor T1 and T2 here to see if they are broken? The schematic is here https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=4180

If they are, we can send you the parts for free but you have to pay for shipping. You can also buy them from your local electronics store.
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Reply #3

eclipse5435

3 Posts

Posted - 06/17/2022 :  03:17:57  Show Profile  Reply with Quote
Thanks for getting back to me. I'll have to do some research to see how to test them (i'm a bit of an electrical novice, but an eager learner), and I'll get back to you. I'm still working on taking the PCB out of the device at the moment without breaking anything!
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Reply #4

EmfDev

1693 Posts

Posted - 06/23/2022 :  16:27:55  Show Profile  Reply with Quote
Let me know your results :D You can send it via email.
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