Leaky Caps & Other /\/\otorola Radios

[Batman]

We always hear about spectra's leaky cap issues, but what about other motorola radios?

is this something unique to the spectra? and if so why? why wouldn't the designers use caps not prone to leaking?

just some thoughts i have over the past few days

[Terry_Glover]

Some input here;

http://batboard.batlabs.com/viewtopic.php?f=1&t=77218

[OCSD117]

Personally I think the issue comes down to money!

A. if you build it cheap you can sell it cheap

&

B. If you use parts that will fail they will need to be replaced...hence more money!

I like the spectras, but am leary of them due to the cap issue!

I have two i am trying to get rid of but that issue is bringing down the price!

Just my 2 cents

[Mike B]

I talked to an old time Motorola engineer that worked on the Spectra project. He explained that Spectra was Motorola's first significant venture into almost total use of surface mount in high end mobile radios and they learned allot from their mistakes (learning curve). The leaky electrolytic caps were one of those mistakes.

The Syntor X 9000 control heads suffer from leaky caps. These are not surface mount, but it appears to me they compromised by using lower grade (i.e. not industrial temperature rated) electrolytic caps in order to get physically smaller caps that would fit in the cramped space of the control head. At least these are very easy to fix/replace if you get to them before they eat any copper traces and smaller industrial temperature rated caps are now available. I haven't ever seen a leaky electrolytic cap inside an X9k radio drawer.

Many computer motherboards suffer and die from leaky caps. Certain vintages of Mac power supplies are know for leaky axial lead caps (these are the big caps). This problem is allot bigger than just radios.

[jackhackett]

Many computer motherboards suffer and die from leaky caps. Certain vintages of Mac
power supplies are know for leaky axial lead caps (these are the big
caps). This problem is allot bigger than just radios.

This is known as "capacitor plague", and was the result of industrial espionage gone wrong.

http://en.wikipedia.org/wiki/Capacitor_plague

The Spectra cap problem pre-dates the cap plague problem seen in motherboards by 5 years or so. I would say the likely cause is that the caps used weren't adequately rated for the application, and being used near their design limits for 10-15 years causes them to fail.

[wx4cbh]

Many, many of the programmable logic controllers and instrumentation devices built in the same era that use the same type of capacitor as the Spectras and Syntors suffer the same cap problems. There's probably no element of the electronics industry in that era that hasn't seen the effects from the failure of this type of capacitor. I guess it doesn't help that we are still using these products well past their "market technology" lives.

[Mike B]

I'm no longer sure the industrial espionage gone wrong is anything more than a myth. Maybe it has been fostered by capacitor manufactures looking for a scape goat for defective products that are really their own fault.

Wasn't the Spectra earlier than than the 1999 date in the Wikipedia article. The time span for products with bad caps doesn't make sense for a single espionage event, even if you take the time to discover the problem and stocks of bad inventory into account (assuming bad inventory was knowingly sold). After all, Wikipedia information isn't really vetted or anything. I know, give it to the Mythbusters on TV to test !

[Terry_Glover]

...I'm no longer sure the industrial espionage gone wrong is anything more than a myth... ...After all, Wikipedia information isn't really vetted or anything...)!

Ya know, I gotta agree with that statement. Everybody online these days wants to link to a "wiki" to back their statements as if said "wiki" were the final word, or Holy Grail...

Lots of bullshite in "wiki" in my opinion. All it takes to post info in a "wiki" is a password just like anywhere else... Experience and testing on a personal level is what it takes to seperate grain from chaff.

[wavetar]

As has been said, leaky caps is not a new issue, nor is it an issue from just the mid to late '90's. Although there are cases of inferior capacitor manufacture (as can be said of almost anything), it's primarily a case of design. Stick a 16-volt rated cap in a 12 volt circuit & it'll eventually fail. Stick a 25-volt or higher rated capacitor in the same circuit, it'll run damn near forever...or in the case of electrolytic caps, until it dries out...which does eventually happen regardless of rating. Unless it's a diode based varicap, it's not a solid state component & is subsequently prone to a higher failure rate.

[Andreas]

In the time between 88~95 many equipment manufacturers had problems with leaking
high temp caps!
Those bad caps came from Rubycon(black),Elna(brown and red),Nichicon(brown).

The leaky cap problems can be found in:
All the Sony Handycams and pocket radios (88~95)
Power supply and stereo prozessor PCB in Sony VCR´s (88-95)
All NEC 4 monitors
Some Mithsubishi TV´s (91~93)

Andreas

[WB6NVH]

Going back up a few messages, regarding the X9000 heads, I have a bucket full of them with bad caps, and all of those caps are indeed surface mount. Some of them have simply rotted away and fallen off the boards. These are in 1060 and 1070 series heads.

I haven't taken every X9000 series head apart to look, but just wanted to point out that the later versions do indeed have surface mount electrolytics in them.