OT: In case your Minolta quits

I've fixed numerous consumer electronics products by just looking for the burped up electrolyte from capacitors. Clean up the board, solder in a new part and it works again. I was talking to an old-school tv repair tech and he said that it was about 60% of his repair work.

Hello Jim,

That is sad. 50+ years ago nearly all electrolytics were of decent quality. Look around at our house: Tube radios from the 50's, a 60's Hammond organ, all stuff where the caps have to stomach elevated temperatures yet none has failed.

Today we buy a fancy product and the electrolytics fail. Sometimes the leaked electrolyte takes circuit boards and other things along into the abyss.

Regards, Joerg

Just a couple interesting links:

Regards, -=Dave

The cost difference between good and bad can be substantial, and even the worst electrolytics usually outlast the warranty unless you're pushing the voltage rating.

Try to find a capacitor for a 1/2 HP VFD mains filter that is rated to last 8 or 10 years of typical 24/7 industrial operation and costs less than the wholesale price of the finished product.

Best regards, Spehro Pefhany

"Joerg" schreef in bericht news:cb5ag.76914$ snipped-for-privacy@newssvr13.news.prodigy.com...

They probably lost a good deal of their capacity. Turn up the volume, and watch the ripple increase on the HV supply.

Reliability has been traded for space. A while ago I got a TEK465, all power supply caps had dried out. Only 10% of the original capacity left. I found some new capacitors to replace them, half the size of the originals...

Hello Frank,

Not much though. Sometimes, sadly, tube gear has to be torn down because parts aren't available anymore. The old Rhode&Schwarz SMF here in the lab might await that fate. Whenever I do that I save the electrolytics, measure them and keep the good ones. The usual, charge up across a resistor and checking the slope. Lo and behold they usually still have their capacitance at 30, 40, 50 years.

I am not familiar with those but the 7704A here in the lab is still running just fine. From all the gear in the lab I had only two capacitor failures. One dried out, the other happened during a transport in a container. The guy on the crane let go and every box in it was reduced in height by about 1/3. The cap broke off.

Regards, Joerg

Hello Spehro,

Well, I'd expect caps to last a bit longer than just the warranty...

Regards, Joerg

Hello Dave,

Yes, you really have to watch it. Especially when outsourcing purchasing along with production. "But they told us these are equivalent and the data sheet looked ok ...".

Regards, Joerg

Wahay!

The QC dept at one of my old employers had a "drop test" for new products - in their freight packaging. IIRC, the first test was a drop onto concrete from a "calibrated" height (i.e. from an arm out straight in while standing on the truck loading bay in Goods Inwards). If nothing broke, great. The second test was to drop (or, if necessary, launch, with or without packaging) as far as it took for *something* to break... and then look at what it was...

I never quite got used to the idea that there was a bunch of guys, working for the same company, who were intent on breaking something I'd just spent N months putting together.

We never let them play with a crane though.

Steve

We've done something similar. In the states, UPS is the most common surface carrier. I believe their accepted drop test is from 1.2 meters onto a hard surface. Once on each face of the package and once on each corner.

Hello Steve,

One of the places where I worked did the same thing. But their gear had to be really tough so it better be tested that way. They regularly had to switch "thumping locations" because the concrete landing surface that was regularly layered up was only allowed to be stomped so many feet into the ground.

But this capacitor was in lab equipment. That's not meant to be treated this rough. Although I did not quite understand why an electrolytic that was 2" tall and heavy wasn't mechanically supported. It was on a vertically mounted board. At least they could have laid it out so that its terminals would have been above each other and not sideways. It was a recipe for failure.

Regards, Joerg

... snip ...

Back when, big electrolytics came with a clamp. You firmly attached the clamp to the chassis (or pc board later), inserted the cap and held it firmly. Then you could add the wiring or soldering or whatever. Routine.

Later they came with several extra pins just to provide a more solid "foundation". Then I guess these were falling prey to cost reduction.

Regards, Joerg

Well, if all equipment were only treated as it's meant to be, life would be boring for at least some of us: from the ordinary repair guys to those getting tasked with the ever-evasive "fool-proof" design.

Yes, but the mounting orientation had nothing do with that. That's because Murphy's law, applied to transportation accidents, reads: "If there is any direction your goods are ill-prepared to withstand mechanical shock in, that is exactly the orientation the impact will happen in."

In other words: toast _will_ land jelly-side down. Even if, knowing this, you put the jelly on the bottom side or along one of the edges. ;-)

Clever choice of orientation would help against long-time strain during normal, as-meant-to-be-used operation. The only choice that helps against random accidents to build the thing robust in *all* directions. I.e. mechanically lock down everything that's big and heavy enough or protrudes to the outside far enough to turn external shock into internal stress on solder joints: all pieces jutting out of the front panel, any and all magnetics, and all caps higher than they're wide.

Hello Hans-Bernhard,

True. I wish all engineers would think outside their box. For example by hitching a ride on a freighter plane if they are allowed to, or at least a on truck that goes from Shannon to Ballinsloe at full speed. After that they'll design more carefully.

Yes. Like that lady that was convinced that earthquakes shake things mostly in a vertical direction. Until she had half the pool water in the living room.

That caps actually wasn't taller than wide. It was just heavy.

Regards, Joerg