Hello Fellow EEVblog Colleagues
As in the title I have a problem with a grinder that have a regulated rotory setings (via a potenciometer). The grinder is not working at all. The thinks I checked :
- Brusches (because it's a brush one) | Maybe a half on them is left, but the contact to the rotor is there. No cracks oraz lose wire, only normal sights of wear.
- Cable | few ohm, so its fine
- Switch | All contacts work well, no leacked or burned pins
- All components on the PCB that i know how to measure : R, C ,D show correct values. I dind't measured the ESR of the caps because I don't have the equipment for that.
- The triac have a 0.056V drop between A1(+ multimeter wire) and Gate(- multimeter wire) as well Gate to A1, the voltage drop is the same. Changed it for a BTA 12 that has 0.112V drop
The triac replacement didn't help. And there is that 501B-8P IC, I have no clue that this thing is my brain is too smooth to figure it out by it's own. I tried to check on AllDataSheet but didn't find it with the same 214DNWG0a e3 or similar ending. The rotor moves with easy so it's not blocked or jammed.
Below I inclued the worst electronic schematic in my whole history, and photos of the board front and rear.
One think that I could discover was that the R1 20k resistor heats quite quickly after some 3-4 sec of pressing the switch trying to power on the grinder.
If someone had a similar problem maybe not exacly with the same grinder, but a similar issue with a module like that. I'd be thankful for helping to solve with this problem.