Electrolytics!

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sallen
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Electrolytics!

Post by sallen » Wed Dec 02, 2015 1:38 pm

I'm in the process of replacing some electrolytic capacitors in a Gates 5, DX-50 and Nautel ND50. Gotten wonderful life out of them and have not caused any off air time and a few friends think I'm lucky they have not acted up more.

One thing I notice is the life expressed in hours on the replacement capacitor data sheets. Most are 1000 or 2000 hours. Does this mean after 4 years you should budget to replace them? I chose 4 years because it seemed more resinable than 6 months. They all have life expressed in hours. Also if your replacement electrolytic has been sitting on the shelf for 10 years is it still fresh. If not how fresh would you think it is?

I'm looking at over 30 caps for the ND50. Which leads me to the first question. What's a good Digi-key or Mouser part number for a replacement, it's a 21000uf at 100vdc. The gates stuff I have a good idea what to get.

I already had to swap out one of four 5100uf 350vdc caps with the shelf spare for the Gates 5. But I think I will just replace it along with the other three in the group once the new ones show up.

What are the common electrolytics to replace in the DX50.

Thanks for your thoughts and suggestions.

dbuckley
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Re: Electrolytics!

Post by dbuckley » Wed Dec 02, 2015 5:01 pm

That 1000 or 2000 hours is at the rated temperature, which is usually quite hot, like 85C. Keep them cooler, they last longer.

sallen
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Re: Electrolytics!

Post by sallen » Wed Dec 02, 2015 6:52 pm

I guess that's why caps last so long up here in the Puget Sound, does not get hot like Arizona or Texas. Since 4 of the transmitters are 23-25 years I'm gearing up to replace a few electrolytic caps in the next year just for good meaure. The DX50 and ND50 are in great shape and clean and so far have ran very well.

Any one else have a 20 year plus solid state with minimal electrolytics replaced?

sallen
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Re: Electrolytics!

Post by sallen » Wed Dec 02, 2015 8:39 pm

I'm getting my capacitor list together and looking through Mouser and Digi-key. Capacitors from United Chemi-Con show up on the list as an option. Has any one used capacitors made by United Chemi-Con. Is there a better place to buy them? Walt at Gates-Air has been great in answering questions but I don't even want to ask what the cost is for replacement through Gates-Air or for that matter Nautel for the ND50 caps.

I would like to know the difference between DCM, CGS and 36DX. Not finding a good link that explains it on line.

Thanks

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kkiddkkidd
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Re: Electrolytics!

Post by kkiddkkidd » Wed Dec 02, 2015 9:14 pm

Something to keep in mind is the cap mounting & contact position of generic vs OEM parts.

If the caps are connected to a PWB, the connections to that rigid PWB will determine generic replacement cap suitability. I have always used cap replacement kits from the OEM but have heard stories of good deals on caps where the caps "almost" fit without modification to the mounting or connection PWB.

YMMV, etc.
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davek
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Re: Electrolytics!

Post by davek » Thu Dec 03, 2015 2:50 am

I have been repairing some old Tek 'scopes recently. Rather than replace the original Mallory electros with NOS ones I elected to use modern equivalents. Most (if not all) modern electros are snap-in PCB mounting using 10mm spaced leads. The original caps had 4 leads around the perimeter with a 5th leg in the middle. Over lunch one day I came up with a neat answer to the square peg/round hole dilemma of fitting modern caps into older gear.
IMG_7284.JPG
IMG_7295.png
IMG_7298.png
The boards were made in China for US$1 a piece.

The original caps were used to link PCB tracks together (to allow other tracks to pass underneath the cap). I have seen other repairs where wire links had to be installed along with bodging in the replacement cap. This adapter board neatly solves that problem. :)

kcbooboo
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Re: Electrolytics!

Post by kcbooboo » Thu Dec 03, 2015 4:14 am

That's a GREAT idea! The snap-in caps are so much smaller, it makes you wonder why the older ones had to be as big as they were.

Could a multi-section cap adapter be built that way too?

A similar adapter could probably be made for caps that have screw terminals, which are also found in a lot of equipment from 20-30 years ago.

Bob M.

sallen
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Re: Electrolytics!

Post by sallen » Thu Dec 03, 2015 7:00 pm

Just got a Memo from Gates-Air that recommends 7-8 year replacement cycle on capacitors. So 20+ years is doing good. All of the caps used in the DX and Gates 5 are compatible with whats in the transmitter according the spec sheet, terminal spacing is correct as well as size. Most are Type DCM or 36DX which I can get.

Would still be curious if any one has used the United Chemi-Con caps with any luck, the replacement that would work in the ND50 is $24.64 each, great if they will last 10 years or longer otherwise it's Sprague $95.08 ($100 cheaper than OEM). CDE and Vishay Sprague also make caps that would work for the DX and ND.

ChuckG
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Re: Electrolytics!

Post by ChuckG » Thu Dec 03, 2015 11:51 pm

United chemi-con is a Japanese made cap and seems to be regarded as good quality. Seasonic puts them in their PSU's, I regard them as the best computer PSU made...for whatever that's worth. I"ve purchased UCC caps for refurb projects from DigiKey and don't recall any issues.

Your question about a 10 year cap that's sat on the shelf- if it's an electrolytic, personally I'd trashcan it.
<><><><><><><><><>
Chuck Gennaro
Central Wisconsin

sallen
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Re: Electrolytics!

Post by sallen » Tue Dec 29, 2015 10:26 pm

Called GatesAir and got a 20% discount on the caps I needed just by asking if they could work on the price. Great Service! I have more to get and it's good to know they will work with you in the price.

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Bill DeFelice
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Re: Electrolytics!

Post by Bill DeFelice » Wed Dec 30, 2015 6:28 am

davek wrote:I have been repairing some old Tek 'scopes recently. Rather than replace the original Mallory electros with NOS ones I elected to use modern equivalents. Most (if not all) modern electros are snap-in PCB mounting using 10mm spaced leads. The original caps had 4 leads around the perimeter with a 5th leg in the middle. Over lunch one day I came up with a neat answer to the square peg/round hole dilemma of fitting modern caps into older gear.

The boards were made in China for US$1 a piece.
Did you roll your own on these or was it something that already existed? Could you share the source either way, please?
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davek
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Re: Electrolytics!

Post by davek » Mon Jan 04, 2016 12:32 am

I designed these boards over lunch one day. The mounting pins are from Harwin (p/n H2101-01) available through DigiKey.

Here are the gerber files...
Attachments
Capboard_S.zip
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CapBoard_L.zip
(6.17 KiB) Downloaded 61 times

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Bill DeFelice
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Re: Electrolytics!

Post by Bill DeFelice » Mon Jan 04, 2016 11:17 am

@davek: Thanks for the info. Did you have to do a large quantity to get them for $1 a pop? I could see a few applications to having some boards made at that sort of price point.
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dbuckley
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Re: Electrolytics!

Post by dbuckley » Tue Jan 05, 2016 1:42 pm

Bill DeFelice wrote:Did you have to do a large quantity to get them for $1 a pop?
PCB manufacture costs have come down a lot over the last few years, due to competition from you-know-where.

Start here: http://pcbshopper.com/

kcbooboo
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Re: Electrolytics!

Post by kcbooboo » Tue Jan 05, 2016 2:26 pm

A friend has had success with a company in China of all places. They have free design software. You design it, they pop out multiples of 10 circuit boards at up to about 2x2 inches, double-sided, drilled, silk-screened, etc, then ship them back, for around $15 for everything. The more you make, the cheaper they are.

Those adapter plates are something I bet a lot of vintage audio amp repair guys would love to use. Aluminum can caps are getting expensive and hard to find, and what you do find is often 30 year old NOS.

Bob M.

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