Help identifying a capacitor

[Al Strachan]

Morning all. recently refurbed a clarke ranger 50 (there's another thread knocking around) and after the refurb its struggling to start when cold.

I've replaced the oil to spec. Manual states SAE 40 and thats what i've used, but suspect it had thinner oil in previously that has now highlighted another issue.

Checking the start capacitor and there been some overheating. not sure if it's been from the capacitor itself, or the motor has had a cooking (i suspect the latter since the cap isnt deformed)

Was going to try a new cap, but unfortunately the overheating is where i hoped it wasnt - see pic!

This cap measures 19uF (could be ok, could be duff?) and dimensions are 90x40mm.

Motor is 1.5hp, and assume this a start/run cap and these motors dont have centrifugal switches in them?


Also it's been honed with new rings, so a little tighter than previous, but still turns over with ease, and the unloader is working fine. Same issue with the outlet disconnected.

Probably being an older unit i might drop the oil down to SAE 30, but for all the cost would like to replace the capacitor.

Any assistance identifying a suitable replacement cap ?

Al

 

[carbon]

Would have thought 20uf was low but manual only lists capacitor rather than the value so can’t really tell

 

[Alan Reynolds]

I might have a Ranger in my trailer. If you're not in a hurry I could strip it and have a look in the week

 

[Al Strachan]

I might have a Ranger in my trailer. If you're not in a hurry I could strip it and have a look in the week

Alan, that would really be appreciated. 8mm socket for the 6x cover bolts and you are in

 

[Alan Reynolds]

Alan, that would really be appreciated. 8mm socket for the 6x cover bolts and you are in

I'll do it Tuesday.

 

[R Kraft]

!9uf would be about right, does the motor plate happen to have the spec.

 

[carbon]

If capacitance is lower than it should be the motor will pull more current to run. This extra current will make the motor run hot. If capacitance is low the fuse usually blows at start if the motor is loaded. For a compressor it may start if there is no air pressure in the tank and the struggle when pressure increases. Don't work on compressors much

 

[dan treg]

mines says on it 30uf cbb50 50/60 hz any help

 

[carbon]

I think the same capacitor is also in the TIGER 8/35 & 8/65. If it should be a 30uf then 19uf is well outside the value suitable

 

[Al Strachan]

!9uf would be about right, does the motor plate happen to have the spec.

Posted a pic off the end of the crankcase. only remnants of a spec there is, and the manual doesn't give too much away either. 1100w/240v

If capacitance is lower than it should be the motor will pull more current to run. This extra current will make the motor run hot. If capacitance is low the fuse usually blows at start if the motor is loaded. For a compressor it may start if there is no air pressure in the tank and the struggle when pressure increases. Don't work on compressors much

had a play earlier. To check the main winding i disconnected the cap and gave it a quick fire up. As expected i got the static "humm". Put the cap back in and it gets around half a turn (assume until it finds resistance in the compressor and bounces back half a turn. almost looks as if it's trying to turn the opposite direction. If my memory is correct this points to the start winding not working (motor can drive in either direction), but the cap is having an effect but i think it's very weak. Thats my take anyway. It just doesn't seem to have any torque. Plugged in directly to a 32a ring main, where 2 other 2hp compressors start no problem. Also tried the opposite polarity on the cap, but dont think these are polarity sensitive. When i refurbed the compressor i swapped the mains lead out also and upgraded it to 1.5 from either 0.75 or 1.0mm. Haven't tried to measure current, but it doesn't seem to be running hot and its not blowing any fuses etc.

mines says on it 30uf cbb50 50/60 hz any help

Thanks for looking, is this a Clarke ranger or a 1.5hp other brand?

 

[dan treg]

its a clarke ranger looks like yours cant guarantee its the original but looks undisturbed so dont see why not all i can say is it works edit just says clarke ranger not clarke ranger 50. not sure what the 50 stands for

 

[carbon]

Ive found this in one of the ranger manuals, capacitor 35uf for a 1.5 hp motor https://www.clarkeservice.co.uk/manuals/compressors/ranger_45-65.pdf

But does have a different part no

 

[Al Strachan]

Thats great Dan, thanks

 

[carbon]

not sure what the 50 stands for

Think it just identifies the tank capacity looking at some manuals

 

[Al Strachan]

Ive found this in one of the ranger manuals, capacitor 35uf for a 1.5 hp motor https://www.clarkeservice.co.uk/manuals/compressors/ranger_45-65.pdf

But does have a different part no

The pic in that brochure is identical to my sealey 2hp/50ltr in every way except for the livery!!

I think if Alan has a peek at his, and Dan's peek also, i might be onto a winner

 

[Alan Reynolds]

Hi Al. 35uF. I checked the Ranger, the Hunter, and a Hokey Cokey Chinesium One and they all have 35uf caps. I founr an ancient Broomfade in there too. And I found three generators. So much stuff, so little time

 

[Al Strachan]

really appreciated Alan, thanks

 

[carbon]

19uf is definitely to low then, no wonder why it got a bit hot

 

[Al Strachan]

Guess what arrived in the post . First a try with the old cap and it fired up but very slowly. replaced with new and boom, instant start. Stood there with that smug satisfied grin for 20 seconds as the pressure built up and the motor just stalls instantly and hums!

Stripped down the motor and compared the winding resistances between my other 2hp compressor . Good compressor - 4ohm run winding 10 ohm start winding. the duff one had 3ohm start, 3 ohm run?

Now i'm in deep with this compressor. I've shelled out about 50 quid, not to mention the time and care in cleaning/painting, so i stripped down the motor and started poking around the connections and giving it a damned good looking at. The windings have been hot at some point i knew that from the cap, and for the 20 seconds it was running the motor was pretty hot too. Keeping the meter connected to each winding in turn, i had a good poke around and could see the meter flicking between 3 ohms and 12 ohms as i poked in a specific spot.

Being (a Jock and) so deep financially into the now titled "POS" i just had to give it one last shot. I carefully picked my way through this particular areas of the start winding until i found the spot deep inside. broken and shorting against the main winding.

now reading 4 ohms and 12 ohms, I've bodged her up as you can see from the earth wire in there, and she's now running cool, starting well and been through a good few cycles. Who knows how long it will last, but this POS wont beat me!! (although the rear motor bearing is on its way out so i'm soon to be another £2.50 deeper in!!)

 

[carbon]

It's worth a try, may pack up tomorrow or could keep going for a long time. But if you don't try you don't know