Kind of a generic electrolytic cap question

Whidbey Island is just a day trip to Vancouver/Burnaby. I'd be happy to archive your EPROMs and burn you up a set of spares if you can't sort it out...

I think you are neighbour to my friend the ex-basketball player who loves pinball, if you know who I am speaking of, tell him I said "Hi!".

John :-#)#

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one and test them for value, ESR, and dielectric absorption. Testing ESR i n circuit on many modern circuit boards is a waste of time.

by all means replace them. But if I pull an electro during testing and it' s good, I put it back and continue working on the board. No sense changing good caps on a board that may have to be replaced, like OP is dealing with .

een intentionally defaced, and processor ICs for which there is just no dat a. Sometimes you just have to replace a board.

'lytic caps go bad eventually. After removing the caps for testing you've a lready run the risk of damaging the board. Why put the old ones back? In br oadcast gear small value caps are the most common failures. I've replaced t housands of 100uF 25 V caps. Unit price 32 cents, 1000 for $83. Buy in bulk and replace in bulk. It costs less than testing and re-installing.

less than testing and re-installing.

Right, at the small cost of the capacitors, it is foolish to put backin an old one even if the board may have other problems and not used.

Now if it was a $ 10 or even maybe a $ 5 part it may be worth putting the old part back on.

At the rate capacitors fail, the one that tested good may go bad much sooner than a new one. Then you have to do it all over again.

It takes often takes more labor time and effort to test than to just put in a new one.

Like where I work, a man from the factory came in to repair a 480 volt 3 phase 200 HP motor speed control. He found 2 bad dioides that were rated at something like 200 amps. I asked him to replace the 3 rd one. He told me those things cost arond $ 200 each. I told him that with 2 bad it may have weakened the 3 rd one. With the machinery costing the company over $ 1000 per hour for down time, and the cost of getting him back in the plant, I am willing to pay $ 200 for insurance and piece of mind. That old diode may pop in a day or 10 years, but I know that I have done my best to make sure the machine keeps on running for minimal extra cost.

On Saturday, November 16, 2019 at 5:05:47 AM UTC-5, snipped-for-privacy@yahoo.com wrote :

, by all means replace them. But if I pull an electro during testing and i t's good, I put it back and continue working on the board. No sense changi ng good caps on a board that may have to be replaced, like OP is dealing wi th.

been intentionally defaced, and processor ICs for which there is just no d ata. Sometimes you just have to replace a board.

already run the risk of damaging the board.

Anyone who would ruin a board by removing a cap isn't a professional and sh ouldn't be playing with it. There is ZERO chance of damaging even a multi- layer board.

common failures. I've replaced thousands of 100uF 25 V caps. Unit price 32 cents, 1000 for $83. Buy in bulk and replace in bulk. It costs less than t esting and re-installing.

You actually quoted my reason (thanks for not snipping it) but either didn' t read it or didn't understand it. So I've copied and pasted my previously posted reason below:

"If you know the board *will* be fixed and put back in service, then yes, b y all means replace them. But if I pull an electro during testing and it's good, I put it back and continue working on the board. No sense changing good caps on a board that may have to be replaced, like OP is dealing with. "

"Lots of these industrial boards use custom ICs, ICs and semis that have be en intentionally defaced, and processor ICs for which there is just no data . Sometimes you just have to replace a board."

So if I have to replace a board that caps won't fix, why go through the tro uble of recapping it? On low to mid percentage shots like these one-off in dustrial controls, the plan is five stages:

1)I troubleshoot and repair the board first. If it's not repairable, I go to step 5. If I get the board repaired, I go to step 2. 2)recap it 3)Clean and deflux the board, and inspect under a bright light and loop. Re flow any questionable solder and reflow all the solder on edge connectors, transformers, and high heat generating components. 4)Deflux again and spray with conformal coating if the board originally was built with it. 5)Get paid for my time.

ve already run the risk of damaging the board. Why put the old ones back? I n broadcast gear small value caps are the most common failures. I've replac ed thousands of 100uF 25 V caps. Unit price 32 cents, 1000 for $83. Buy in bulk and replace in bulk. It costs

I've read that sentence like 5 times and all I can say is that you wouldn't be working for me..

Honestly, sometimes I wonder if people just post because they want to say * something*.

I doubt that I would work for a tightwad like you. If those capacitors are less than one dollar, it will take more time to test and replace them than the labor would pay.

Lets say I just make $ 20 per hour. It may take me 5 minuits to setup the capacitor checker and test it. That would be about 33 cents. If the capacitor was a dollar, you have saved 77 cents.

However if the board is good, I have to pull that capacitor and replace it anyway. How long would that take and what would it cost ?

You have just lost money on that capacitor you thought you were saving.

There is when *I'm* around! Here's how I got an inaccessible cap out of this network analyser a couple of days ago:

But as you will probably gather, I'm no professional. :-D

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I'm worried about cheap Chinese crap getting into the supply chain and that's why I'd rather leave things be. I might end up replacing a perfectly serviceable 40 year old cap made by a prime manufacturer with something nasty from China that's going to go *phut* long before the original one would have.

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It's a good plan to avoid knock-off parts of any type. Many of old timers have seen counterfeit parts going back 40 years or more.

You just need to be careful about where you source your parts. Here in the states, I use DigiKey mostly. I can buy cheaper caps but I prefer to buy from a trusted supplier. Plus, companies like DigiKey and Mouser have a hu ge selection of caps. So one can select not only value, voltage rating, an d lead configuration, but also have the option of selecting manufacturer, E SR, and lifetime hours ratings.

I generally only buy Panasonic capacitors because I've grown to trust them. In industrial controls where they are all on the time in a wide variety o f temperature extremes, I don't want a cap with a 1000 or 2000 hour rating.

I also know that with DigiKey and Mouser, I'll get a genuine Panasonic or N ichicon capacitor if I order one. They cost more than I can get them elsew here, but I'd rather pay more to know I'm not getting a knock-off.

I also know that a new Panasonic cap (like the EEU-TA series) *will* last l onger than the original ten year old capacitor with many thousands of hours on it. Even a top quality capacitor is still on borrowed time after 40 ye ars.

Where did those fakes come from 40 years ago?? I'm guessing certainly not from China. China joined the game *much* later AFAIK.

It's kind of baffling when one first sees the range of choice available from those two suppliers, though. I find it takes me *so* much longer to find the part I want than when I was with Farnell/CPC which had a much more limited range. Sometimes you can have too much choice and it becomes a PITA to sort through it all, even with all those filters. Perhaps I'll feel differently once I eventually get used to it.

Amen to that. Same here!

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Japan mostly, but that is supposition on my part. I believe some of those fakes were simply relabeled parts and not necessarily purposely built as co unterfeits. Back in the CRT TV days, we'd buy horizontal/line output trans istors a hundred at a shot (like the Toshiba 2SC1172B or Sanyo 1308K). The n we started getting counterfeits that would last minutes to days, then blo w. We used to buy Sony SG613s in bulk and never had a problem. Suddenly th e next shipment would blow up on plug in.

We also saw TONS of Motorola and Toshiba audio outputs for stereo equipment that were relabeled. Vertical ICs, SMPS regulators etc.. There was virtu ally no category untouched. I even remember the counterfeit Sony "jungle" ICs that would work for a few days, weeks, or months, then cause shutdowns or other odd symptoms. The Sony jungle ICs were complicated devices and th ese were either line rejects or purposely built to counterfeit. I don't re ally know nor does it really matter at my end. All I know is that they cau sed costly callbacks.

My guess is that a lot of the early counterfeits were just the lower power/ current/voltage versions of the series that were cleaned and reprinted.

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** Back in 1980, on open sale in Australia were counterfeit Motorola power transistors. Thousands of them, either included in amplifier kits or across the counter. The devices were branded "TIC" for " Transistor Instrument Company" operati ng from, Florida. They did not in fact manufacture anything but had a catal ogue with hundreds of types.

What TIC did was buy up surplus TO3 stock and remove the original labelling - then re-ink the parts according to your order. So a 10 cent item became worth several dollars each. Just about the only similarity was the TO3 pak. The ones I saw and tried to use were Motorola numbers MJ1003 & MJ15004. The exact same scam was done by fake wholesalers in places like Hong Kong.

Another fake wholesaler in the same state was called "Aero" and dealt mostl y in relabelled and used vacuum tubes - again with a large catalogue.

On offer were "new" transmitting tubes from them for hundreds of dollars a piece that had already seen thousands of hours of use. Or tubes from famous US maker Sylvania that were re-labelled stock from places like East German y or Yugoslavia - for double the going price.

When surplus stocks ran out, shiny new fakes were created in India or China that only resembled the real things in appearance.

Manufacturers well knew to keep away, so sales normally only went to variou s retail operations and for spare parts.

..... Phil

Japan was a 'problem' back in the 50s and 60s - a friend of mine who lived in Japan in the 60s told me how they literally copied slot machines - they would buy one US slot, take it apart, and build exact replicas...

But, then again, the US was a problem back in the 1700 and 1800s!

Copyright laws did not exist in the US way back when and lots of publications that were protected in Europe were freely reprinted on the other side of the pond..

Currency:

Roman times:

Counterfeit stuff has always been around, that is why "bricks & mortar" places like Digikey, Mouser, Element 14, are trusted - unlike parts you buy off eBay or Amazon. Lots of Russian renumbered parts there...

John :-#)#

I had no idea it was so universal. I mean, until recently I thought the problem was confined pretty much solely to voltage regulators, but clearly it goes way beyond that. I find it all (the 'infection' of the supply chain) deeply concerning. :(

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** The second time ( a few years later) I found myself with fake MJ15003/4 I made an effort to track down the source.

My supplier assured me it was "Motorola Australia" in Sydney - so I rang them and explained the situation. The sales guy checked the company database and found NO sales of those types had been made to the supplier in several years.

Further investigation tracked the importing to a dealer in Melbourne who had offered them to likely customers all over the place. The stock same from a fake warehouse in Hong Kong.

The official line from Motorola here was that one should ONLY deal with authorised suppliers of the brand who offered traceability.

One such dealer told me the problem was rife, claiming hardly a day went by when nobody rang offering to sell them fake semis. The most common back then were memory chips, all nicely packed in bulk containers and all relabelled as to the rated speed.

..... Phil

If this is a consistent response, you may be able to locate the problem by heating/cooling the board. The easiest way is to have the board warmed and working. Buy yourself a can or two of 'Freeze Mist' spray half the board to cool it down, while checking operation. If it still works, let it warm up completely so you don't confuse the issue. Now cool of the other half of the PCB and check operation. If it malfunctions, you know which end to continue troubleshooting. Warm it up until proper operation, then start cooling individual parts on the bad

1/2 of the pcb, one at a time until the problem occurs. You can often isolate the problem part this way.

Or you can do just the opposite, cool the pcb in the fridge, then use isolated heat until the machine works. It is harder to isolate the heat than to cool an individual part. So, I recommend the first procedure. If you decide to use heat on the pcb, use a hair dryer, not a heat gun.

Mikek

Freeze Mist, pick the best price with shipping.

Skip the CRC automotive product, I suspect it has other chemicals in it.

Not even with $5-10 parts. My time is worth more than that.

Exactly, and then you KNOW they aren't the problem.

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Apparently some people still haven't learned, "Pay shit, get shit."

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WA6FWi 
http:foxsmercantile.com

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** Those who have not learned are dealers in components.

Counterfeiters know their best market and approach firms acting as wholesalers for many brands with "bulk surplus stock" of the same brand at an appealing price. The items then get sold as regular stock the normal rate.

Sometimes, fake items are put into stock by rogue staffers who take away the genuine stuff and sell it off elsewhere. Happened to Farnell a few years back with On Semi power transistors.

Best way to hide a fake semi is to make them look good and sell at standard going prices.

.... Phil