An insane SMC motor!

[Tais]

recently i got 3 of my damaged SMC motor rewinded, the 1994 model, the 1989 model and the early 90s model.. the 1994 model works just right, more like early 90s than how it used to be.. the 1989 model is ultra quiet, accelerates slowly from 0 to around 400 - 500 RPM, i tested it with 2.5, 3 and 4 uF capacitors and they were all the same, but however, they made a big mistake in the winding of the early 90s model, instead of it being 16 poles which is the standard for all small chinese made SMC K56, it was 8 pole..




the fan runs very slowly on one direction and insanely fast on the other depending on which wire is connected to where.. as for the capacitors, i've tried many and each one had different results, i tried only on the faster setting:

speed on slow setting: ~140 RPM

fast setting: some capacitors have a range between 150 - 180 RPM
for some other capacitors, the fan accelerates to around 700 RPM

results of multiple capacitor testing to find the right one:

1.5 uF: weak ( 150 - 180 RPM)
1.6 uF: almost no difference than 1.5
2.0 uF(box): accelerates to as fast as the HK-made SMCs but takes a bit more time, but heats a lot over time (~240 RPM)
2.0 uF(cylinder 1): very low acceleration and slower than the 1.5 uF (<150 RPM)
2.0 uF(cylinder 2): similar performance to box but a bit weaker and slower
2.25 uF: similar to the cylinder 1 2.0 uF capacitor
2.5 uF(box 1): powerful acceleration to a point, then it slowly increases speed to a certain point, than it accelerates to nearly 700 RPM, it heats quite a lot, however (~240 RPM initial)
2.5 uF(box 2): motor was switching directions at start.. the capacitor is probably damaged
2.5 uF(cylinder): VERY weak acceleration (< 150 RPM)
3.0 uF(cylinder (2000s SMCs cap)): more powerful than 2.5 uF box but much more heat
unknown value (it was placed when i recieved the fan): way more powerful than the 3.0 uF but with a bit less heating, i was told it was 2.5 uF.. it seems to behave like a 4 uF capacitor when i placed on my big-motor chinese made SMC fan that was rewinded

i feel the 2.0 uF is the most appropriate one for this fan

i thought for a while is it appropriate to place a higher value capacitor on one side and a low value side that originally should have a capacitor? (concept derived from KDK fans as their regulators are capacitor type)


performance of the early 90s rewound SMC fan using a 3.0 uF capacitor:


performance of the normal early 90s SMC fan with its original 3.0 uF capacitor:

[Deleted]

If you have an amp meter, you can determine the proper capacitor value.

Install the motor with the blades. Hook it to an amp meter. With the proper value capacitor, it will draw close to the amps listed on the tag in both directions. If the capacitor is too high, it will draw too much.

[Tais]

Oct 20, 2012 8:25:02 GMT -5 @spiffy said:

If you have an amp meter, you can determine the proper capacitor value.

Install the motor with the blades. Hook it to an amp meter. With the proper value capacitor, it will draw close to the amps listed on the tag in both directions. If the capacitor is too high, it will draw too much.

i will try that someday.... i checked the resistivity of the fan, it is 88/87 ohm on the outer/inner winding compared to 160s on the original outer winding..

i flipped the wires to the slow settings and everything works allright with low heating rate using the 4.0 uF capacitor but slower (as fast as HK-made motors)