New here and a beginer at electronics, help please

[woodworkerjb]

I am working on a board in hopes of determining what component(s) might have failed. There are 3 components that I can't identify and hope that someone might help me determine what they are. The orange component has the following printed on the cardboard sleeve:

Mallory, 12 MFD 200 VNP, 20-47446, 235-7408A

the yellow component has:

105-69, .47/10 250v it is printed on a paper type wrap around what looks to be a plastic core

The purple is a glossy looking ceramic coating on of the says 3 ohms. One of which I know is bad because it is broken and you can see what appears to be some windings around a copper core.

I am sorry for what I am sure are rookie questions but I wasn't able to definitively determine what they are after doing google searches.

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[eddwhatley]

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Woodworking man . . . .

What ? . . . . 175 views of those components . . . .and no one is coming forth.

I will admit that I did lift the photos . . .particularly the last one which just initially seemed to be your test leads and probes .
Also I did some digital enhancement on all of them, but reflected light and the limitations of that I-phones camera did not let me see the best detail of your 3rd part.
Also seems like I did make out some French on the chassis below it.

Now, hold on tight . . . here we g o o o o o o :

[b][color=#FF0000]The orange component has the following printed on the cardboard sleeve:
Mallory, 12 MFD 200 VNP, 20-47446, 235-7408A[/color][/b]

That would be a cardboard encased non polarized 12 microfarad at 200 working volt dry electrolytic capacitor.

AND . . . that cryptic 235 tells me that the electrolytic was made by Mallory . . . which we can also see additionally marked as such.
The next numbers tell me that the date of manufacture was the 8th week of 1974 . .by the day shift (A)

Sooooo your equipment proper should be a bit later than that date, if they used / stuffed it with fresh parts.


[color=#FF0000][b]the yellow component has:

105-69, .47/10 250v it is printed on a paper type wrap around what looks to be a plastic core[/b][/color]

That will be an axial leaded tubular mylar/or/teflon/or/polypropylene capacitor rated at .47 ufd at a 10% tolerance and having a 250 volt rating.


[b][color=#FF0000]The purple is a glossy looking ceramic coating on of the says 3 ohms. One of which I know is bad because it is broken and you can see what appears to be some windings around a copper core.[/color][/b]


Now that is an older generation wire wound resistor with axial lead and an outer glazed . . . almost glasslike . . . overall conformal / protective coating. "Burple" just happened to be their "color of the month" as I have seen them using many other voluntary colors . . . particularly green.

I will buy your . . . . "windings" around a copper core . . . on the windings, which should be of nichrome wire , but will pass on the copper core . . . . as it is usually having that resistance wire wound around a ceramic bisque rod or a form of hard fiberglass to tolerate the heat generation around it.

I had no related spatial referencing of adjunct components to judge its sizing, with the translucent form placed just behind it being a mystery to me . BUT it seems to be a 3 watt size at your prescribed 3 ohms of resistance, with an alternative possibility of it being up to a 5 or 7 watt unit.

Of all of your parts , the resistor typically discolors around its center if TIMELY being overloaded and may eventually open up . . .check for that with your ohmmeter.
Also no logic for it being broken (in half ? )unless someone pried up on it with a small screwdriver tip ?

The next item in suspect would be that electrolytic, with its internally normally slightly "moist" dielectric drying out with time and heat and the associated downward degradation of its capacitive value.

The last .47 capacitor is least suspect of all.

NOW:

Other considerations would be shorted power diodes on the board associated in the flow path of that 3 ohm WW resistor.


Now pray tell us what is this PCB from . . it possibly a motor speed / torque controller board for one of your woodworking equipments motors ?

It , possibly no longer available . . . or . . .if found, they want an arm and three legs for it ?


[b][size=120]73's de Edd[/size].[/b]



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