[chucketn]

A friend bought a KBIC-120 controller to use with a treadmill motor on his lathe. He hooked it up per the manual, but it blows the AC fuse immediatly at turn on. Loud pop. I have the controller on my bench. I have checked his hook up and it was correct. He has the correct fuse, and correct power resistor for 1 hp motor. motor is a PM type.
Anyone have experience troubleshooting KBIC SCR controllers? Help! at this point, with all connections removed except the ac in and the fuse, it still blows fuses. Help please!

Chuck in E. TN

[chalky]

Is the type of fuse as well as its rating correct? You may need a slow blow rather than a quick blow fuse.

[chucketn]

The fuse in the AC line is as recommended by KB. The fuse blows with a loud pop indicating to me that a dead short exists, w/o the motor even hooked up.
I downloaded KB's checklist for troublshooting and all resistance checks fail. I emailed KB asking for a parts diagram so I could try replacing the diodes called out by the Troubleshooting guide, and they don't supply one. They also said by my description the controller was hosed.

Chuck in E. TN

[chalky]

You could try removing MOV1 and C23 temporarily and then reconnecting the KBIC to 110Vac. If it doesn't blow the fuse when you do this then replace MOV1 ( V275LA20A ) and C23 ( 0.047uF 250Vac ) with new parts. You could also try replacing D13 and D14 with new parts ( sorry don't have type numbers for these ). Capacitors and MOVs across the ac mains live and neutral are more likely to fail in the US than in Europe because you have more thunderstorm induced surges. If your KBIC is a different revision to mine the parts numbers may be different but you should be able to locate the corresponding devices fairly easily. If you aren't confident about messing with the KBIC then junk it and buy a new one - they aren't very expensive.

[Isplat]

Hi There,

I just fixed two KBIC-120s. One had been overvoltaged to the point some traces on the back were "opened" by melting. The other one looked to me like it had been hit by lightning or a very high voltage spike.

In the later KBIC's case I found that at least one of the SCR's was blown. The MOV mentioned above was also damaged. I had to remove the MOV and both SCRs to find the one blown.

A simple check you could make is to OHM out the two AC inputs L1 and L2 -- they should not have continuity. If there is continuity the board has been damaged. In the blown board above I could use my OHM meter's continuity check (beeps) to check this.

From the symptom you described, I would guess some of the components are blown.

I haven't found a replacement SCR part number for the A69154 (Teccor) SCR on the KBIC. I believe Little-Fuse bought out Teccor. Digikey has a "case isolated" SCR that looks like a fit but I'm still trying to find an old datasheet so I can confirm the power rating needed. Don't want to put one in that has too small or too large a power rating as either can be a problem.

I'm not sure what function the MOV has in KB's circuit (over voltage?/Lightning suppression/Noise Suppresion -- I'm not positive) I haven't personnally looked up the MOV's replacement -- I trust the value above is correct. I was able to use a MOV off of another KBIC I am troubleshooting for the time being.

If I find the right datasheet I'll post an equivilent current SCR. The Diodes are also candidates for trouble (The SCRs and Diodes i'm referring to are mounted in the vertical against the metal backplate). You could use a multimeter with diode check to see if any of the were blown.

As another option, you can find them on Ebay for $20-$40 pretty regularly. So if you aren't an electronics type it might be less frustating to just try a different KBIC as your friends sounds damaged.

[chalky]

The MOVs are there to prevent spikes on the ac mains from damaging the KBIC drive circuitry and also to keep spikes generated by the KBIC from feeding back into the ac mains. The part number I gave for the MOV was for the 240Vac version of the KBIC. The 275 in the part number stands for the voltage and the 20A is related to the current rating. In the US you could use a V130LA20A. The V275LA20A wouldn't cause any problems but would let through spikes between 130 and 275V which the V130LA20A would catch. Having said all that I doubt if it matters which MOV you fit. MOVs don't last for ever and they fail short circuit.

[chalky]

Just let me clarify the statement I made in my previous post. You can use MOVs with either of the part numbers I mentioned, NOT just any old MOV .

[kwispykweems2]

I was able to locate a replacement SCR for these guys, since mine had shorted and blown a trace and the 47ohm resistors. Called up Littelfuse/Teccor they gave me great info, and ordered from Digikey this: S6010L. This replaces the special part number used between Teccor and KB Elec, A69104. The tech support guy knew exactly what I was repairing when I gave him that number! I also have speed controllers that use A69154, and since I didn't ask about these, I don't know if the replacement will work, but I assume so since the replacement, S6010L is rated at 600V 10A and has isolated tabs, well beyond the working range of either controllers.

[Al_The_Man]

What I have done in the past is to replace the bridge with high rating stud mount type on their own heatsink.
2 SCR's 3 rectifiers, one of which is the reverse emf diode.
Al.

[DICKEYBIRD]

Interesting & informative thread, thanks! I have 1 KBIC-120 running the spindle motor in my little Denford Micromill and another one I got off eBay to run a treadmill motor for an add-on lathe spindle. I have a couple of questions for ye KB enlightened folks.

KB's spec sheet shows 1 hp. max for the -120 with a heatsink. I don't have their "official" heatsink but am going to add the one I got off the scrapped treadmill's dead MC-70 control and a muffin fan to cool it. My motor has "2.5 hp" on the label. I figure that's probably a very optimistic rating but am concerned about the 120 being able to handle it.

The usage and duty cycle will be pretty light. I'm going to mount a lathe toolholder on the left end of the Micromill's table and use its X/Y movements for lathe ops. I'm building an ER-32 spindle powered by the treadmill motor and will mount it on the left side of the Micromill enclosure. I will be making fairly light cuts at around 1500-2000 rpm on 3/4" aluminum rod. I figure a 2.5 or 3:1 stepdown pulley will be about right. Does the KB control care about the different motors armature winding resistance it "sees" or will it just grunt out it's designed power rating and the motor never outputs its maximum potential? I can't see me ever needing anywhere near the available power from the motor. Ya'll think the -120 will be reasonably happy given the usage I've laid out?

Last question (for Al): Could you translate this to a 6th grade level please?

"What I have done in the past is to replace the bridge with high rating stud mount type on their own heatsink.
2 SCR's 3 rectifiers, one of which is the reverse emf diode."

Are you saying you replaced the KB components with generics and installed them in a separate location with their own heatsink? I may need this someday...got any pics or a schematic?

:cheers:
Milton

[Al_The_Man]

Last question (for Al): Could you translate this to a 6th grade level please?

Are you saying you replaced the KB components with generics and installed them in a separate location with their own heatsink? I may need this someday...got any pics or a schematic?

:cheers:
Milton

Yes.
I posted some details here on an old post, I will see if I can dig it up.
Al.

[mikkojay]

Note to self, don't panic post at 2AM after not realizing your wiper lead on the speed pot is the orange wire, not the white one.
Sorry to waste bandwidth- nothing to see here folks...(chair)

[DICKEYBIRD]

Sounds like it's OK if it's humming; probably the max speed adjustment pot has been tweaked around before you got it. They usually come set to run slow at full CCW pot rotation.

Download the KB manual and have a read. They are completely adjustable to fit your needs. I think you & your motor will be happy eventually.

[Al_The_Man]

Test the motor on an automotive battery, both directions to ensure the motor appears OK.
You should not get that much of a hum at 0rpm, should be none?
The pots could be off, if this does not correct it, test it with a 120v lamp and see if you get full voltage.
If not, sounds like a dud unit?
Al.

[DICKEYBIRD]

You should not get that much of a hum at 0rpm, should be none?

Maybe we get different AC down here in the states Al? I have 2 KBIC-120's in service at the moment and the motors hum very noticeably as soon as the controller is powered up. The noise is worse if the motor is attached to anything that vibrates easily. I had to mount one motor on 4 lord mounts to quieten it down. His would probably be much quieter during the lamp test you mentioned.

[Al_The_Man]

The fact that the motor hums or vibrates indicates there is current through the motor, it could be so low that the current is not enough to operate the load at rest, the min pot should decrease this, DC motors are rated in Form Factor, this is the ability to operate successfully at something less than pure DC, the F.F. rating is based on pure DC being 1.0 and the max suggested for DC motors being SCR full wave 1ph which amounts to 1.35 and this should not normally be exceeded.
The firing angle of the SCRs also determines how "clean" the DC output voltage will be, the cleaner the DC the less power lost to heat and less brush wear at low rpm.
You can improve the F.F. to some extent by using a simple inductive filter to smooth out the ripple improving their form factor.
KB mention making sure your motor is an "SCR duty motor" which is made to handle the imperfect DC.
PWM has a F.F. nearer 1.0
Here is a couple of PDF's.
Al.

[mikkojay]

Wow, sorry I didn't see these great replies until after I went in and edited my foolish post!
You guys were on the right path with the pot issue though. Don't ask me why I was "sure" which lead was the wiper, but sure enough, my last check was to meter it out- and then oooohh man, I hung my head and felt really small.
Also, the min and max pots on this board were glued in the strangest positions. After setting them "within reason", and getting the pot hooked up properly, everything is rocking
Thanks again though, you guys are the best.
I have been spending some LATE nights working on this Emco F1 servo/SmoothStepper retrofit, and it is sometimes hard to put it down and go to bed when I should.
-Mike

[DICKEYBIRD]

...everything is rocking

Gotta love a happy ending!