Electronics > Repair
Bathroom timer fan repair faulty Vent-axia VASF100T pulses or runs slow
Kav1187:
Thank you for your reply.
I assume measuring voltage across the new capacitor is done by having the probes on each leg of the capacitor while it's running. If so, then it reads 5.9v.
Doing the same reading on my working fan in the other bathroom reads 4.8v
I checked the triac on the diode setting when the power was off. I got 0.66 between gate and t1.
On the working fan, I got a reading of 0.64.
I've noticed a slight browning on the plastic behind the motherboard, roughly where the triac sits. There are 4 resistors on the back of the board there. Please see the pictures attached.
floobydust:
For the triac TR1, ST Z0103 it's between MT1 and MT2 to look for a short which would keep the fan stuck on.
I don't know the ZD1 zener diode's part number or voltage. Post #1 says it's 3.3V but it needs to be in line with what IC1 the microcontroller needs... which is 2.2-5.5V so 5.9V seems high?
That 220uF 10V capacitor Chong_X is not a long life part. I thought you'd already replaced it?
The resistors normally sit there and run hot, as part of the power supply.
Kav1187:
Hi. Thanks for your reply.
The 10v capacitor was a cheap part I got off amazon to try and get the fan working. I've just soldered on the 16v one that arrived today.
Checking continuity between t1 and t2 on the triac doesn't show a short. I get the same result as I do with my working fan.
I'm seeing the same 5.9v across the new capacitor. Could it be that one of the resistors is faulty?
4262mikeb:
I've a fan with part # F100TS1 with the pulsing problem. I've changed the 220microF cap but after working fine the first time the fan was repowered the pulsing has returned. With the fan powered I put a meter (set AC V) accross the big yellow rectangule 0.33microF cap .. measured mains voltage .. but surprisingly the pulsing stopped. I can 100% consistently turn the pulsing on and off by touching the yellow cap legs with my meter.. is the cap my problem ?
Thanks
Mike
Gyro:
Almost certainly. Capacitive droppers (the Yellow cap) are subject to losing value due to self-healing as a result of the inevitable spikes on the mains.
Strictly speaking, the replacement doesn't need to be an Class X capacitor as it isn't in a direct-across-the-mains application. A 630V DC rated one would do, but to stay as close to the original design as possible, it would best to fit one. If space permits, fit an X1 cap rather than an X2 as it will give more voltage headroom and hopefully last longer before replacement is required again. [Edit: I see the capacitor is inserted in a cutout in the PCB so specific dimensions and space are probably tighter than they look]
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