Somewhat O/T: Identifying power supply coils?

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Somewhat O/T: Identifying power supply coils?

Justin-2
Sorry for the slightly out of Commodore lane on this as I am actually trying to repair a GRiD 1520, but I was hoping someone here would know a good way to figure out correct replacements for old coils.  The GRiD power supply had hot glue gooped throughout it and while removing a leaking paper film filter cap assembly from the glue, I broke the wire leg on one side of one of the coils that was hidden inside the glue next to the cap.  It was sandwiched between two filter cap assemblies next to the AC cord connector so I assume it is acting as a bandpass to go with the caps. It has a donut shaped ferrite core with two windings on it, a red lacquer insulated wire is wrapped on the left half and green lacquered on the right, with two black leads coming off the back.  I’ve never had to figure out a replacement for a coil before and I don’t see any obvious markings on it so I’m not sure how to figure out values/equivalent current production parts.

Thanks,

Justin

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Re: Somewhat O/T: Identifying power supply coils?

Mike Stein
Sounds like a common mode power-line choke, but they usually have four wires, not two:

http://www.digikey.ca/en/product-highlight/w/wurth-electronics/common-mode-power-line-chokes

m

----- Original Message -----
From: "Justin" <[hidden email]>
To: <[hidden email]>
Sent: Monday, December 05, 2016 8:57 AM
Subject: Somewhat O/T: Identifying power supply coils?


Sorry for the slightly out of Commodore lane on this as I am actually trying to repair a GRiD 1520, but I was hoping someone here would know a good way to figure out correct replacements for old coils.  The GRiD power supply had hot glue gooped throughout it and while removing a leaking paper film filter cap assembly from the glue, I broke the wire leg on one side of one of the coils that was hidden inside the glue next to the cap.  It was sandwiched between two filter cap assemblies next to the AC cord connector so I assume it is acting as a bandpass to go with the caps. It has a donut shaped ferrite core with two windings on it, a red lacquer insulated wire is wrapped on the left half and green lacquered on the right, with two black leads coming off the back.  Iâ?Tve never had to figure out a replacement for a coil before and I donâ?Tt see any obvious markings on it so Iâ?Tm not sure how to figure out values/equivalent current production parts.

Thanks,

Justin

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Re: Somewhat O/T: Identifying power supply coils?

Justin-2
My description needed more work. It does have four wires, there is a black insulated lead coming off the tail end of each of the two lacquered windings, so yeah, a common mode choke coil.  I didn’t have much luck with my Google-fu in finding a way to figure out what the values were for an existing coil.

I don't think there is enough wire left for me to scrape off lacquer and bridge the break with solder as-is, but since it is near the very end of the winding I was given the suggestion on another list that I can undo one loop or so and solder it from there, and it’ll probably be good enough.  This sounds reasonable to me since there is a lot of additional filtering in this power supply, and the 1990 vintage coil does not on visual inspection appear to be a masterwork of winding symmetry.  In retrospect this is an obvious approach to the problem.  The replacement caps show up from Digikey in a couple days so with any luck I’ll know sooner rather than later if this mild hack works, and either way at least the thing won’t smell like hell from burnt leaking caps and re-heated hot glue anymore.

Justin

> On Dec 5, 2016, at 11:37, Mike Stein <[hidden email]> wrote:
>
> Sounds like a common mode power-line choke, but they usually have four wires, not two:
>
> http://www.digikey.ca/en/product-highlight/w/wurth-electronics/common-mode-power-line-chokes
>
> m
>
> ----- Original Message -----
> From: "Justin" <[hidden email]>
> To: <[hidden email]>
> Sent: Monday, December 05, 2016 8:57 AM
> Subject: Somewhat O/T: Identifying power supply coils?
>
>
> Sorry for the slightly out of Commodore lane on this as I am actually trying to repair a GRiD 1520, but I was hoping someone here would know a good way to figure out correct replacements for old coils.  The GRiD power supply had hot glue gooped throughout it and while removing a leaking paper film filter cap assembly from the glue, I broke the wire leg on one side of one of the coils that was hidden inside the glue next to the cap.  It was sandwiched between two filter cap assemblies next to the AC cord connector so I assume it is acting as a bandpass to go with the caps. It has a donut shaped ferrite core with two windings on it, a red lacquer insulated wire is wrapped on the left half and green lacquered on the right, with two black leads coming off the back.  Iâ?Tve never had to figure out a replacement for a coil before and I donâ?Tt see any obvious markings on it so Iâ?Tm not sure how to figure out values/equivalent current production parts.
>
> Thanks,
>
> Justin
>
>       Message was sent through the cbm-hackers mailing list
>


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Re: Somewhat O/T: Identifying power supply coils?

Justin-2
In reply to this post by Mike Stein
Hey unwinding the damaged coil a little bit to create a new leg did the trick.  I wanted to take a minute to thank everyone who emailed me with ideas.

Justin

> On Dec 5, 2016, at 11:37, Mike Stein <[hidden email]> wrote:
>
> Sounds like a common mode power-line choke, but they usually have four wires, not two:
>
> http://www.digikey.ca/en/product-highlight/w/wurth-electronics/common-mode-power-line-chokes
>
> m
>
> ----- Original Message -----
> From: "Justin" <[hidden email]>
> To: <[hidden email]>
> Sent: Monday, December 05, 2016 8:57 AM
> Subject: Somewhat O/T: Identifying power supply coils?
>
>
> Sorry for the slightly out of Commodore lane on this as I am actually trying to repair a GRiD 1520, but I was hoping someone here would know a good way to figure out correct replacements for old coils.  The GRiD power supply had hot glue gooped throughout it and while removing a leaking paper film filter cap assembly from the glue, I broke the wire leg on one side of one of the coils that was hidden inside the glue next to the cap.  It was sandwiched between two filter cap assemblies next to the AC cord connector so I assume it is acting as a bandpass to go with the caps. It has a donut shaped ferrite core with two windings on it, a red lacquer insulated wire is wrapped on the left half and green lacquered on the right, with two black leads coming off the back.  Iâ?Tve never had to figure out a replacement for a coil before and I donâ?Tt see any obvious markings on it so Iâ?Tm not sure how to figure out values/equivalent current production parts.
>
> Thanks,
>
> Justin
>
>       Message was sent through the cbm-hackers mailing list
>


smime.p7s (4K) Download Attachment