Bridgeport Power Feed 6f Motor Mount Question

Electrolytic capacitors have a finite life span (usually 7-10 years), even if not used. The live span is decreased with both heat and operating them near their maximum voltage ratings. The specification (measured capacitance) on electrolytic capacitors can be very wide, so something like -20 to +50% of their rated uF value. Using the standard multi-meter to check capacitor value is of minimal value, unless the capacitor is completely dead. Replacing an electrolytic you do not need the exact same uF value, anything close is fine and getting something rated for the same or higher voltage is fine, they should be 105C or higher temperature rated. Newer capacitors are significantly better than those used in past years, so given the age of the drive you are best replacing them. Most electrolytics are polar as others have indicated, there ia a + and - end, the - is connected to the shell, the plus you can see some insulation between it and the outer shell. There are also non-polar electrolytic capacitorss, that do not have a polarity orientation. Newer diodes usually work or fail, so if they check OK I would just leave them.

You might consider buying the replacements parts through an online vendor like Mouser Electronics, a wider selection, fresh stock and probably cheaper even with shipping.
 
I will certainly buy from that vendor for what I can. Today I took all four of the pots off of the board. I found one that was all over the place while being tested. The cheapest I can find is $25.00 for that one. I have no idea how to cross the part number over to another one that will fit. There are only 4 of the electrolytics so I'll replace all of them. It's pretty easy. Trolling around on the internet it seems the general consensus is to leave all of the "red" (polyester?) capacitors alone.

Are the lugs on the circuit board resistors?

Do I need to test the two transformers on the board?

I'm going to replace the limit switches on the forward and reverse.
 
The pots sometimes get dirty and that causes them to be erratic, but it can also get worn out or the wiper tension has gone. There are some electronic spray cleaner lubricants for pots, you could try that first. Only use a cleaner specific for electronics. The pots are pretty standard, so you need the same value, wattage needs to be the same or higher, you need to know if the pot is linear or log, linear will show 1/2 the total resistance at 50%. Standard through hole mounting pots can be purchased on eBay or Mouser at around $10-12. Leave the polyester caps alone, they rarely go. Transformers should either work or not work in this type of application, I would leave them alone. If powering up you have no power, then check the voltages. If you are looking for a specific component, take a picture and indicate any number on the part and we can point you to a source.

Resistors are usually leaded wires, no ferules. Older boards used ferules to through connect or as standoffs. I normally do not pull everything off a board to check values unless there is a problem or something appears burnt. Unless you have a desoldering device or station, you can damage the traces on the board. I do replace the electrolytics with older equipment. Resistors can vary a bit, they usually do not need to be exact values in this application. Some equipment give voltage checks at different points on a board.
 
I tested the speed control pot on the front and it only varies between 605 and 608 ohm. It's rated at 500 ohm.
I took it apart and it has a wiper that is made up of several tines that are bent at a 90 degree angle. Almost like a claw dragging. Doesn't look that dirty.

It's a Clarostat made in the usa. Numbers on the back are: CM41655 and 19-8015 with 500 ohms. Shaft diameter of .247 length is .477 past the threads. (lol) Supposed to measure pot shafts to the thousands right?

One thing I didn't mention is I did get contact cleaner from home depot that seems to work great.
 
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You are very inquisitive! That can be a good thing or a bad thing. I applaud your dive in attitude! But a little caution can save you money. That pot that you just opened up was probably OK. And it was a “sealed” type potentiometer. Radio Shack will not have that replacement.
 
It is OK to open these types of pots, they are not hermetically sealed or molded. I assume it is a 500 Ohm linear pot, they are often +/-10% unless it is a precision pot. Manufactures often use their own model numbers and often have custom values/specifications built. Depending on the application, you can often parallel or serially add a fixed resistor to adjust the pot value (pad), this is not an issue if it is set to a fixed value as part of the calibration setup as opposed to a panel speed range dial. The pot is fairly common, in harsh environments I do look for sealed pots (often military surplus) or sometimes wire wound, the latter usually work even if contaminate with oil.
http://www.ebay.com/itm/Clarostat-potentiometer-500-Ohm-model-53C3-500-S-/322365816902
http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey53C3500
http://www.ebay.com/itm/2PCS-ALLEN-BRADLEY-500-OHM-LINEAR-2WATT-AB-POTS-/262751775766
 
chips&more said:
You are very inquisitive! That can be a good thing or a bad thing. I applaud your dive in attitude! But a little caution can save you money. That pot that you just opened up was probably OK. And it was a “sealed” type potentiometer. Radio Shack will not have that replacement.
Click to expand...

Thank you that's a wonderful complement. I can get OCD in some odd ways.
Interestingly enough I took the one off of the circuit board... the one that was going all over the place on the resistance. That one I also carefully pried up the tabs and it was filthy inside. I believe it had gotten soaked in oil like most of the components. I cleaned it up put it back together and viola! That one is back to being nice and balanced between contacts. As well as adjustable like it's meant to be. So all the pots on the board are functioning and remounted.

Last night I placed an order through mouser for the bad resistors and 4 replacement caps for the old electrolytics.

What readings should I get ohm wise on that 500 ohm pot for controlling speed?
 
mksj said:
It is OK to open these types of pots, they are not hermetically sealed or molded. I assume it is a 500 Ohm linear pot, they are often +/-10% unless it is a precision pot. Manufactures often use their own model numbers and often have custom values/specifications built. Depending on the application, you can often parallel or serially add a fixed resistor to adjust the pot value (pad), this is not an issue if it is set to a fixed value as part of the calibration setup as opposed to a panel speed range dial. The pot is fairly common, in harsh environments I do look for sealed pots (often military surplus) or sometimes wire wound, the latter usually work even if contaminate with oil.
http://www.ebay.com/itm/Clarostat-potentiometer-500-Ohm-model-53C3-500-S-/322365816902
http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey53C3500
http://www.ebay.com/itm/2PCS-ALLEN-BRADLEY-500-OHM-LINEAR-2WATT-AB-POTS-/262751775766
Click to expand...

I also added to my order last night this one:
http://www.mouser.com/Search/ProductDetail.aspx?R=380C1500virtualkey67810000virtualkey785-380C1500

Will that work?
 
If you are changing the resistors that I’m thinking about? Then they went bad/smoked because your forward-reverse switches are bad. You will need two new micro switches. Don’t bother trying to clean them, BER, just buy new ones. And the trimers on the board only get turned when you tune the board to the motor, after that, they are torque sealed. And it really doesn’t mean that much in your end result of the whole shebang working. If you think that was the problem with the feed not working, it was not. And I’m not saying it wasn’t a problem, just not the one that killed your Power Feed.
 
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