need help getting a capacitor replacement. - Page 1
Forum section: electronics / beginners

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 05:31:59 pm
content: A Pic of the cap with all of its specsHi I'm new here, I have some limited experience with electronics and need help with a replacement capacitor that is on a pump that failed. Now I have tested the pump with power applied to it and the impeller wont spin unless you nudge it physically. I tried to get it rebuilt at the plumbing whole sale but they said they shut down there pump service department and then told me a replacement was 600$ so ya going to try a repair my self. Pumps are simple devices; windings, aniron core in the impeller and finally a capacitor and I'm pretty certain that the failure point is the cap due to my “test” so I need to get a replacement part.The pump is a Grundfos UP15-42RUC7115v 0.74A 60Hz 85watt, there is no common or power wire they are either or and I don't see any polarity markings on the cap its self. I dont need an exact replacement but do it it needing to be in a cover it needs to not be massive (6.1cm long, 2.5cm diameter is the old cap size) so if some one can help me find a replacement that can deliver in western Canada that would be very helpful.Just one last thing I measured the internal dimensions of the cover 6.9cm L x 3cm W 3cm H anything bigger wont fit.

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2023, 05:42:31 pm
content: The picture isn't working.

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 05:49:30 pm
content: this should send the img directly to the forum no link click required

author: Gyro
author_rank: Super Contributor
timestamp: April 04, 2023, 06:17:49 pm
content: The magic search term is 'MotorRunCapacitor' (not 'Start' - that's very important). After that it is simply a matter of matching the value (10uF), voltage rating (you can go higher but not lower), and physical dimensions. You want the same style, with wire terminations rather than terminals too.You will be able to find one at any of the standard electronics distributors, but electrical distributors / stores will probably also stock them.

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 07:09:06 pm
content: ok just quick question the cap has 180V~DB, what does that mean exaclty?

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 07:14:33 pm
content: https://www.mouser.ca/ProductDetail/Cornell-Dubilier-CDE/935C2W10K-F?qs=UPOXXNJhWxOnrhxZuu6FCg%3D%3Dwould this work?

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 07:22:33 pm
content: https://www.mouser.ca/ProductDetail/KEMET/C284ACR5100AL0J?qs=W0yvOO0ixfHpkQNG9oPhbQ%3D%3Dthis is the only wired with leads at 10uf

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 07:34:11 pm
content: ok this is a Motor Run cap and should be okhttps://www.mouser.ca/ProductDetail/KEMET/C284ACR5100AL0J?qs=W0yvOO0ixfHpkQNG9oPhbQ%3D%3Dits alittle big though

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2023, 08:05:22 pm
content: That's the right general type but if your measurements are correct it's not going to physically fit. If you can find one with a lower voltage rating closer to the original 180V rated part it will probably be smaller. Is there an electrical trade counter, industrial/agricultural supply, co-op or electric motor repair shop anywhere near you? You might have better luck if you can walk in with your old one and ask for a suitable replacement.I had a similarly frustrating experience a while back trying to find replacement start and run capacitors for my air compressor. The mechanical dimensions are fairly critical in order for it to actually fit in the covers and I kept finding conflicting data. Amazon is particularly terrible, a lot of searches lead there and they usually don't have the dimensions listed at all.

author: kato1144
author_rank: Contributor
timestamp: April 04, 2023, 08:16:26 pm
content: ya im finding the other run caps are just too big, im still looking on mouser but its not looking like i will find anything closer then the last one i posted there

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2023, 08:18:44 pm
content: Mouser is probably not the best place to look for those. You want an electrical, motor, pump or HVAC shop.

author: Gyro
author_rank: Super Contributor
timestamp: April 04, 2023, 08:29:05 pm
content: Quote from: kato1144 on April 04, 2023, 07:09:06 pmThe voltage rating is 180V AC RMS. I'm not sure about the DB though - it's common for these capacitors to quote a different lifetime rating according to the actual operating voltage (below the specified one often by a factor of 3:1), I assume it's a usage lifetime rating.Kemet are a good, well known brand, and with a 470V rating would most likely last for ever, I'm surprised you can't find lower voltage in a 120V mains country. Cornell Dubilier are also a good brand but the form factor makes it much more of a pain to fit, heatshrink sleeving, wire extension etc. If the others won't fit then you might be better off with one with tags at one end, use the existing wires and carefully insulate the connections.BTW, the reason that I made the Run / Start distinction is that Run capacitors are metalised film (usually Polypropylene), designed to be continuously in circuit. Start capacitors are designed to operate for no more than a few seconds at a time before being taken out of circuit by a centrifugal switch, these are often bipolar electrolytics. All of the ones you listed are PP film (MKP) so are fine.P.S. ^ What James said.

author: floobydust
author_rank: Super Contributor
timestamp: April 05, 2023, 01:06:53 am
content: Original made bySeika Electric Co.Taiwan, HPFMS series. Oddball 180V to keep it small- so I think it's a custom part.I could not find much with 30mm OD. These caps are commonly used in appliances washing machines etc. rated 450VAC and 35mm OD, no fit?The chinese CBB60 PP run cap series you can search for "CBB60 10uF 250V" but I only found CBB60 10uF250VAC27*48mm and it's a gamble as far as quality goes.

author: kato1144
author_rank: Contributor
timestamp: April 05, 2023, 05:44:09 pm
content: well the two caps I have linked: will fit but wrong typehttps://www.mouser.ca/ProductDetail/Cornell-Dubilier-CDE/935C2W10K-F?qs=UPOXXNJhWxOnrhxZuu6FCg%3D%3D,or exact right type but to big for the cover requiring me to mod the cover to closehttps://www.mouser.ca/ProductDetail/KEMET/C284ACR5100AL0J?qs=W0yvOO0ixfHpkQNG9oPhbQ%3D%3Dso I have to use one of these as I really can't find any electronics web sites that are not industrial or a commercial supplier only besides mouser and digi-key, they have a slighly smaller KEMET lengh wise, that helps but I will still have to defrom the case to make it fit....anyway any suggestions, this appears to be my only options

author: james_s
author_rank: Super Contributor
timestamp: April 05, 2023, 06:01:52 pm
content: That first one should work, it's a high quality part, you'll just need to solder wires to the leads and insulate them carefully with heatshrink tubing.Are you housebound or something? Even if you live out in the middle of nowhere there has got to be an electric motor shop, farm supply, electrical trade counter or co-op around somewhere. There are also loads of websites that sell parts for fountain pumps, hot tub pumps, hydraulic pumps, air compressors, HVAC and so on. Even Amazon has motor run capacitors. I did a google search for "motor run capacitors Canada" and came up with loads of hits. With the exception of most HVAC trade counters, almost all of the industrial/trade suppliers will happily sell to an individual that walks in there with cash knowing what they need.

author: kato1144
author_rank: Contributor
timestamp: April 05, 2023, 06:06:23 pm
content: ya I'm disabled and dont have a vehicle so going to store to store to see if they can help is not out of the question but would be very difficult and unfair to the ppl that I would need to lean on to bring me over, I looked at every website that was local and they either were industrial/commercial suppliers only or they did not list there stock and the ones that did list there stock only had a handful of large caps meant for equipment they soldBut ya I might go with the first one due to its size and make it work

author: james_s
author_rank: Super Contributor
timestamp: April 05, 2023, 06:08:25 pm
content: Ok well that does make things more difficult. Anyway that CDE part should work nicely, it will just take a bit more effort to install it. You can probably clip the wires off the original capacitor and solder them onto the new one.

author: kato1144
author_rank: Contributor
timestamp: April 05, 2023, 06:42:20 pm
content: ya thats exactly what im going to have to do, I took the plunge and ordered 3 caps from mouser (the shipping was almost as much as a single cap but if the total is over 100$ its free shipping so what the hell I guess) anyway I will be using heat shrink and the existing wires to make the connection, im looking in to buying some liquid electrical tape to better seal the ends but other then that this should work out good and will save me 600$ in buying a direct replacement

author: james_s
author_rank: Super Contributor
timestamp: April 05, 2023, 06:51:33 pm
content: I wouldn't bother with liquid electrical tape, just do a nice neat job with the heatshrink and call it good. Ordering a selection of heatshrink tubing from Mouser may have been a better option to get the free shipping than extra capacitors unless you have multiple pumps.

author: kato1144
author_rank: Contributor
timestamp: April 05, 2023, 10:45:02 pm
content: ya I have 3 more of these pumps and all 4 caps failing is unlikly but I wont be suprised if another fails in due time

author: james_s
author_rank: Super Contributor
timestamp: April 05, 2023, 11:41:50 pm
content: If you have more of the same kind of pump it's not actually that unlikely they will fail, I've had run capacitors fail in a handful of different things, they're essentially a consumable part.

author: floobydust
author_rank: Super Contributor
timestamp: April 06, 2023, 01:21:08 am
content: Did you measure the old run capacitor to confirm it failed low value? Or maybe mains transients are chipping away at them. All I could find is "The motor is a 2-pole, asynchronous, squirrel-cage PSC (permanent split capacitor) motor ".I notice the CDE part rated 200VDC (140VAC) 935C2W10K-F. Is that enough? If you are going with axial caps, there is alsoSolenQuebec that sells similar. (boutique audio crossover/tube amp caps are priced silly though i.e. 10uF 1,300V teflon CAD $888). Dayton is a chinese product, the others made in France.PPE1000 10uF 630V PP29x48mm $11, no stock onPB1000 10uF 400V26x38mm $9.I've worked with a few different Grundfos pumps, they are very good. Firmware on the smart pumps is not very good lol. You can't update it and very buggy. I have on occasion contactedservicein Oakville Ont. I found them helpful.I did not find a pump service manual to get the cap p/n or price. The website seems to want to railroad you into a customized service agreement, service contract, their on-site repair etc. which can be a bit overboard.

author: james_s
author_rank: Super Contributor
timestamp: April 06, 2023, 02:09:41 am
content: In my experience the caps usually fail open and in many cases you don't realize they've been slowly deteriorating until the motor either doesn't run or draws excessive current and trips the breaker. In the case of my air compressor I noticed the current was high and thought maybe I had a mechanical problem then forgot to look into it then eventually the start capacitor failed too and that's when I discovered the run capacitor was also completely open. That motor would run without the cap but it was noisier and drawing more current than it should.

author: kato1144
author_rank: Contributor
timestamp: April 08, 2023, 01:55:59 pm
content: floobydust you do make a good point, i should have tested the old CAP on the pump before determining if it was the problem, the only issue with that is I have no idea how to test a cap for failure or wear and tear, I have very nice Milwaukee multi-meter (CAT.No 2217-20) that I bought back in the early 2010s when I was still plumbing, I'm not sure if I can use that to do a proper test as I have heard in the past you need a specialist device to test caps.anyway I have ordered the replacement caps already so unless they don't work I wont be looking for alternatives atm but if something happens I will look in to the alternative you posted.(for testing I have the multi-meter, a cheap oscilloscope 25Mhz @ 100ms/s, and a inexpensive DC linear bench power supply, if I can rig something up for testing let me know what to do, if I need a piece of equipment let me know too and I will see if I can secure something, as james_s said caps are consumables and if I knew how to test them for failure that can be useful)EDIT: this is my meterhttps://www.milwaukeetool.com/Products/Instruments/Digital-Multimeters/2217-20but I dont have the TRMS lable on it, I'm not sure what that means, maybe they added the TRMS stuff on the modle after I bought mine or it does have the TRMS stuff it is just not stamped on the face of mine like the new ones, I have no idea how to tell, but the numbers on the back are the same as the TRMS ones soooo not sure

author: floobydust
author_rank: Super Contributor
timestamp: April 08, 2023, 05:17:07 pm
content: I would do a basic cap test. With it disconnected/off, measure DCV across the cap to make sure it has no stray charge, then read Ohms and then read Capacitance with your multimeter. Just to ballpark check if the part is to blame.It was something I learned as a tech, go after and find the bad part and then the repair you know with confidence is done properly. Other techs guessing the bad part, would change out a lot of stuff for no need and many call-backs pissed off customers. I was just curious what part had failed so I went after it. It made a huge difference in my repair career long ago. Sometimes I do get lazy and guess though, especially if in a hurry.Oil-filled and sealed metal-can motor run/start capacitors contain a pressure-switch which open-circuits them to stop them from blowing up if gas pressure builds inside.But this is a plastic film cap (no gas to evolve) so I would not expect it to go 0uF but who knows what's inside for safety switches.Here it sure looks like the run cap is low value so I would go after it first.

author: Jwillis
author_rank: Super Contributor
timestamp: April 08, 2023, 06:46:56 pm
content: Inductors (your motor) lag current in relation to voltage and capacitors lead current in relation to voltage. This is phase shifting of the current in relation to the voltage.To low or to high a capacitor value will shift the phase of the current to much and will cause hesitation in the motor. You described that hesitation in your opening post.It will also cause current consumption of the motor to rise because the field can't "build" properly . This creates heat in the motor and can be destructive to the motor The rise in current consumption can also trip breakers.You can test with an Ohm meter but will only tell you that its shorted or not. If the resistance rises to infinite then the cap is charging off your DMM.But it won't tell you its charging enough. All capacitors will show an open circuit when fully charged. even weak ones.Your DMM you described has a capacitor test setting. Use that but discharge capacitor before testing. The reading should be close enough to indicate if the value is within exceptable tolerance.

author: james_s
author_rank: Super Contributor
timestamp: April 08, 2023, 06:50:54 pm
content: An ESR meter is the best way I've found to test capacitors. You could connect an AC voltage to a capacitor and measure the reactive current that it draws. Really though the easiest test is just swapping in a known good capacitor and seeing if that fixes the problem. Motor run capacitors do fail often, and in my experience by the time I noticed something was wrong, the capacitor was completely open circuit.

author: Gyro
author_rank: Super Contributor
timestamp: April 08, 2023, 09:12:02 pm
content: At the end of the day, if it isn't the cap then the pump is trashed anyway, so it becomes a little academic (especially as the OP has already ordered a replacement cap).Just a couple of warnings on the pump itself. Don't let it spin dry, it has water lubricated (chrome plated) sleeve bearings. These will get torn up very quickly if there is no water to lubricate them, causing excessive clearance and noisy running. Re-fit, fill and bleed the air out of the inner housing (rotor + bearings) through the screw cap at the far end before running it.

author: floobydust
author_rank: Super Contributor
timestamp: April 08, 2023, 10:58:46 pm
content: There will be a thermal cutoff fuse embedded in the stator windings. Hopefully OP verified resistance with an ohmmeter, that it (windings) are not open - before thinking it's the run cap...

author: james_s
author_rank: Super Contributor
timestamp: April 09, 2023, 06:56:35 pm
content: It's usually not embedded, it's at the surface on one of the ends. I've had to replace two of those recently in small motors, in both cases the thermal fuses failed around the same time with no signs of overheating, I'm wondering if there was a power glitch that popped them. Those were both shaded pole fan motors though, I don't think larger motors typically have thermal fuses.

author: floobydust
author_rank: Super Contributor
timestamp: April 10, 2023, 02:14:29 am
content: I would say it kind of depends on the fluid temperature, the Grundfos can be pumping quite hot water which leaves not much margin I think for the thermal cutoff's trip point.For hydronics water temp of say 180ºF /80ºC (typical here on cold winter nights -25ºC) and the wire's enamel varnish 250ºF/125ºC limit, as a guess. The motor's temperature rise is unknown.As long as OP did check for continuity on the windings as well as the cap's value.

author: kato1144
author_rank: Contributor
timestamp: April 10, 2023, 08:21:32 pm
content: So the replacement parts have come in and I'm going to try and do the repair now, so I read some of the post over the past days and first of all I did test that the pump still works when I pulled it out of the housing (it still had water in the space between the impeller and winding's) if I powered the pump and pushed the impeller and it spun up so I was pretty sure it was a bad capacitor. With that said I did do a resistance reading across the power wires and got a reading of 43ohms exactly, I did plop that in to a “winding's calculator” on line and it was not giving me the answers I hoped for, either my pump need 2.67amps (0.74 rated) or my resistance should be 155.4ohmshttps://calculator.academy/motor-winding-resistance-calculator/is more then possible that I'm missing something to do with this calculator so I'm going to push on with the repair, I will try and test the old cap and new, see if I can determine the failure for certain.Just want to add the pump was quite hot when I found it a failed, it was on demeaned for almost a whole day before I noticed I had no domestic hot water (at least 12hrs) of power with no active cooling, the water was turning to steam a bit in the housing but it was not extremely hot, like, it was certainly around 70oC to 90oC I think, I was able to handle the pump with my hands about 20 seconds after I cut power, so I think/hope that the water convection was enough to keep the pump from burning up by sinking that heat, I have seen these pumps have a flow failure (air lock) for days and survive to pump again so here is hoping.Lastly the replacement cap it almost 1:1 for dimensions so it's going to fit good atleast

author: kato1144
author_rank: Contributor
timestamp: April 10, 2023, 10:27:30 pm
content: well bad news, tried the pump back in to the housing, purged the air, applied power and nothing, the pump became warm that's it, pulled apart I could still spin it up with my finger pushing it in the right direction, it does feel weak until it get up to speed then it spins normally. When I was re-installing the backup pump I checked the resistance across the power leads and got a reading of 44.5ish ohms so the winding's on the problem pump are ok by comparison. Finally I found a capacitance tester on my multi-meter, im not sure how accurate it is but I did a test on the new cap and got a reading of 10uf and on the old cap was a result of 10.5uf so not sure if that mean the old cap is good or there is more to testing these caps then a uf reading, also I took a resistance reading of the wires that the cap attaches too and got wild reading from 2.223m ohms to 0.667m ohms. The ohms reduced over time so not sure if any of that is right, let me know what you think, should I dig in to the pump further let me know.BTW the impeller spins freely, not greased bearing freely but certainly on par with any hydronic pump impeller I have come across

author: floobydust
author_rank: Super Contributor
timestamp: April 11, 2023, 01:03:34 am
content: That's a bummer, hoped it would be a straightforward fix. If you can post pictures, I can't find any wiring diagrams for the pump.The motor has two windings, I would check both with an ohmmeter and compare, and it has a thermal fuse and the cap. Perhaps like this drawing. It's pretty low power motor.BUT I did see a UPS15 (different model, 3-speed) with a starter module. A diode+starter heater switch (or PTC?) that goes across the cap wires as the black thing. Do you have one?The lead's resistance varying 2.223m ohms to 0.667m ohms is that milli or mega.

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2023, 01:03:52 am
content: The multimeter will test the capacitance but that only tells you part of the story, it can't test ESR or leakage at the working voltage and that is a much better indication of the health of the capacitor.The fact that the pump still doesn't run is not a good sign though. Are you sure the new capacitor is wired properly?

author: kato1144
author_rank: Contributor
timestamp: April 12, 2023, 02:22:50 pm
content: Thanks floobydust, my pump is a single speed and there is no thermal fuse as far as I can tell, and i do belive it was Mega ohms, i will re-check when I dig back in to it.james_s maybe i should look in to a cheap ESR tester, but ya the old cap and new cap did not have polarity as far as I could tell, maybe I did wire it in wrong but I have also wondered if maybe there is an issue with the connections internally where the cap wiring is connected, if that reading was 2mega ohms that might indicate extreme resistance, maybe there is a component like a resistor that is damaged or just a faulty connections. The issue is there is no clear way to get to the connections due to the water resistant design for the internal connections, I fear to get to them would be destructive.I have some pics of my repair, take a look tell if you see a glaring issue with anything, maybe I made a mistake and fail to see it.

author: Gyro
author_rank: Super Contributor
timestamp: April 12, 2023, 06:11:03 pm
content: I'm sorry to hear that this hasn't been a successful repair. I was thinking that another wire (insulated) ended capacitor would be the preferred solution but, looking at the photos, it's not obvious how the existing capacitor wires are terminated, so joining to the existing ones actually looks easier.The method of attachment to the existing wires looks good, however in the 3rd photo, do I see exposed wire poking throught the heatshrink (right hand end)? I can't work out whether it's chewed insulationor whether it is the metal bracket behind, maybe contacting the cover.As previously mention by floobydust, the 200V DC rating (140V AC) sticks out in sharp focus. I must admit that I didn't spot it when you listed all of the Mouser part numbers. Even so, these film capacitors have a fair amount of contingency factor (tested at 200% voltage), so I wouldn't have expected it not to work at all, even if life might be shortened.I don't know if it is possible to check the original capacitor lead connections to the motor? They just seem to disappear down into the rubber / plastic block on the motor.

author: floobydust
author_rank: Super Contributor
timestamp: April 12, 2023, 07:15:35 pm
content: The motor has two windings, MAIN and AUX. I would check resistance across each- the white pair, and the brown pair. To see if a winding went open-circuit- which it looks like if you're getting megaohm readings. The winding or a thermal fuse popped maybe. A winding should be below a few hundred ohms I'd guess.I can't find detailed info on the Grundfos pump wiringUP 15documents show nothing but the usual marketing and install blurbs.Sometimes Grundfos hides stuff in the connector to the motor. So it looks like 4 wires going in but pump motors have in the black moulding a white connector with many more pins (6-8) on the other side.Careful the cap can hold a stray charge and bite hard, so always measure DCV across it when power is off to ensure it's discharged.Grundfos replacement capacitor "terminal strip and capacitor" UP 15 is 595424. Some pics of 595426 show a starter across the cap. It looks like they added the motor start switch to newer UP 15 designs?If it's the motor winding, I'd phone Grundfos and ask what the repair options are.