did the original capacitors have shrink tube over the wires where they connect to the cap? are there any numbers or marks to look for?
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Re: 1966 fan capacitor ID
If memory serves, the factory original blower fan RF capacitors from the era did NOT have shrink tubing over the lead wires where they exit the capacitor's body. That was a running change 'improvement' that came along somewhere in Shark era designed to 'beef up' the strength of lead wire's attachment to the capacitor.
Originals I've seen have lead wires terminating in a rather large 'blob' of solder at the cap body that's easy to visually verify. Of course, the adroit use of an Exacto knife to cut & remove the shrink tubing can effect a 'fix'.... -
Re: 1966 fan capacitor ID
If memory serves, the factory original blower fan RF capacitors from the era did NOT have shrink tubing over the lead wires where they exit the capacitor's body. That was a running change 'improvement' that came along somewhere in Shark era designed to 'beef up' the strength of lead wire's attachment to the capacitor.
Originals I've seen have lead wires terminating in a rather large 'blob' of solder at the cap body that's easy to visually verify. Of course, the adroit use of an Exacto knife to cut & remove the shrink tubing can effect a 'fix'....Comment
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Here's from my late '65
There is a stamping 'C - D' in an oval cartouche, and nearer to the slot is 'NFT854-1'. Also checked my early '65 air car (hard to see when installed) and can make out the 'C - D', but not sure of the other characters. In the '65 AIM, this 'capacitor' assy is part # 3847975. Probably the same # for many model years. The ends are not shrink rap, but a tight fitting rubber tubing.
P.S. Jack -- is this not a sort of RF high by-pass filter (in spite of AIM description) ? If it was technically a capacitor, no current would flow, in my limited knowledge. Please set me straight.
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Here's from my late '65
There is a stamping 'C - D' in an oval cartouche, and nearer to the slot is 'NFT854-1'. Also checked my early '65 air car (hard to see when installed) and can make out the 'C - D', but not sure of the other characters. In the '65 AIM, this 'capacitor' assy is part # 3847975. Probably the same # for many model years. The ends are not shrink rap, but a tight fitting rubber tubing.
P.S. Jack -- is this not a sort of RF high by-pass filter (in spite of AIM description) ? If it was technically a capacitor, no current would flow, in my limited knowledge. Please set me straight.
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Re: Here's from my late '65
C-D identifies the specific supplier, Cornell-Dublier in this case. There were other qualified vendors... Sometimes you'll see caps from alternate suppliers, no big deal--GM RARELY sole-sourced purchased parts to safeguard against labor disputes at the supplier(s).
If you clean that cap up a little, Wayne, you should see the convex 'blobs' on the ends of the cap body where the lead wires attach are actually shiney solder. The later service replacement era versions of the cap had that portion of their construction TOTAL encased and hidden from view by the improved strain relief feature.
On isn't this a high pass filter vs. a capacitor, the answer is no. It's actually a single pole, low-pass filter made from one capacitor.
Do you understand how high-pass and low pass filters are constructed? You use energy storage components (inductors/chokes and or capacitors) to give frequency dependence differences to the different routes across a circuit. The complexity of the filter (1-pole, 2-pole, Etc.) and its circuit topology dictate the design realization.
Here, the dc motor of the blower fan generates unwanted high frequency noise by its natural operation. The idea is to 'hush up' that noise at the source rather than letting it 'splatter' throughout the car along the wiring harness' power lines.
The capacitor is a 2-port device (one connecting wire serves as the input, the other wire serves as the output, and the mounting leg attached to the case is the path to ground. Attach a VOM and you'll find the two lead wires have straight through continuity.
But, the capacitor connects both input and output leads to ground through the capacitor (a 'T' arrangement). DC flows straight through and the capacitor blocks the DC from going to ground.
High frequency 'trash' generated by the fan motor sees two paths to take: (1) go back out through the lead wires and travel along the car's power lines to get to ground EVERWHERE there's a path, OR (2) take the 'cowards' way out and jump straight through the capacitor to reach ground at the fan via the mounting bracket.
Electricity is basically 'lazy'. It follows the path of least resistance. Here, it's easier for the high frequency racket generated by the fan motor to 'leap' to ground through the capacitor and its mounting bracket than it is for it to travel back through the power line to reach ground through every circuit in the car...Comment
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Re: Here's from my late '65
C-D identifies the specific supplier, Cornell-Dublier in this case. There were other qualified vendors... Sometimes you'll see caps from alternate suppliers, no big deal--GM RARELY sole-sourced purchased parts to safeguard against labor disputes at the supplier(s).
If you clean that cap up a little, Wayne, you should see the convex 'blobs' on the ends of the cap body where the lead wires attach are actually shiney solder. The later service replacement era versions of the cap had that portion of their construction TOTAL encased and hidden from view by the improved strain relief feature.
On isn't this a high pass filter vs. a capacitor, the answer is no. It's actually a single pole, low-pass filter made from one capacitor.
Do you understand how high-pass and low pass filters are constructed? You use energy storage components (inductors/chokes and or capacitors) to give frequency dependence differences to the different routes across a circuit. The complexity of the filter (1-pole, 2-pole, Etc.) and its circuit topology dictate the design realization.
Here, the dc motor of the blower fan generates unwanted high frequency noise by its natural operation. The idea is to 'hush up' that noise at the source rather than letting it 'splatter' throughout the car along the wiring harness' power lines.
The capacitor is a 2-port device (one connecting wire serves as the input, the other wire serves as the output, and the mounting leg attached to the case is the path to ground. Attach a VOM and you'll find the two lead wires have straight through continuity.
But, the capacitor connects both input and output leads to ground through the capacitor (a 'T' arrangement). DC flows straight through and the capacitor blocks the DC from going to ground.
High frequency 'trash' generated by the fan motor sees two paths to take: (1) go back out through the lead wires and travel along the car's power lines to get to ground EVERWHERE there's a path, OR (2) take the 'cowards' way out and jump straight through the capacitor to reach ground at the fan via the mounting bracket.
Electricity is basically 'lazy'. It follows the path of least resistance. Here, it's easier for the high frequency racket generated by the fan motor to 'leap' to ground through the capacitor and its mounting bracket than it is for it to travel back through the power line to reach ground through every circuit in the car...Comment
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Excellent explanation -- Thanks Jack *NM*
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Excellent explanation -- Thanks Jack *NM*
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Re: Excellent explanation -- Thanks Jack
my original one was identical to the one shown. but i gather this is not the only brand used?there for caps with other markings are correct.Comment
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Re: Excellent explanation -- Thanks Jack
my original one was identical to the one shown. but i gather this is not the only brand used?there for caps with other markings are correct.Comment
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