Re: Hot Air Station - Air Pump Failing
If it's low or full-blast only, then I think most likely the pot has failed, or its soldering connections. It could be a low quality lazy BT137 triac, I did see that once.
I would check the (hot air) potentiometer with an ohmmeter and see if the wiper might be going open or it's noisy. Halfway should be around half value etc. but in-circuit it will read lower and non-linear and I would lift one end pin of the pot to take readings.
Part of the problem is the crappy design - a (hot air) 500k pot is best for 220VAC, and 250k for 120VAC, to give a good range of control (with 0.1uF gate cap). So a 500k pot on 120VAC has a huge dead zone, nothing really happens until you are past 3/4 rotation. The minimum-air trimpot is to help cover that up but it just keeps things at a minimum until the pot is way past that.
I'm not sure if you are running 120V or 220V.
If it's low or full-blast only, then I think most likely the pot has failed, or its soldering connections. It could be a low quality lazy BT137 triac, I did see that once.
I would check the (hot air) potentiometer with an ohmmeter and see if the wiper might be going open or it's noisy. Halfway should be around half value etc. but in-circuit it will read lower and non-linear and I would lift one end pin of the pot to take readings.
Part of the problem is the crappy design - a (hot air) 500k pot is best for 220VAC, and 250k for 120VAC, to give a good range of control (with 0.1uF gate cap). So a 500k pot on 120VAC has a huge dead zone, nothing really happens until you are past 3/4 rotation. The minimum-air trimpot is to help cover that up but it just keeps things at a minimum until the pot is way past that.
I'm not sure if you are running 120V or 220V.
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