This was about fifteen years ago and I had a Beckman that was good but its
resistance measurement wasn't good enough.
The dremel works great but it is a bit disconcerting to see done...
Dave
> -----Original Message-----
> From: ModularSynthPanels@yahoogroups.com
> [mailto:ModularSynthPanels@yahoogroups.com] On Behalf Of Ben Stuyts
> Sent: Monday, September 28, 2009 2:29 AM
> To: ModularSynthPanels@yahoogroups.com
> Subject: Re: [ModularSynthPanels] ChaQuo Wiring Question...
>
> Ouch, that hurts... :-)
>
> What I usually do is get a good DMM (a Fluke 45 in my case),
> and just
> measure the resistance across all the caps. Yes, we're
> talking 10's of
> milli-ohms difference here, but the lowest one(s) are easily
> found. If
> you follow a power/gnd pair of traces, you can even see if you're
> getting close because the resistance is getting lower and
> lower. Also
> works when finding a bad chip with an internal short.
>
> Ben
>
>
> On 28 sep 2009, at 07:43, Dave Halliday wrote:
>
> > The tants had a really good high frequency response IIRC -- good for
> > filtering out noise as well as 60Hz.
> >
> > My technique was to follow the power buss on the circuit board and
> > find an
> > arbitrary mid-point that was away from any critical wiring
> and use a
> > dremel
> > tool to sever it.
> >
> > Find out which half had the short and proceed until you had
> three or
> > four
> > caps to test. Unsolder one lead and lift the leg and test
> the power
> > buss
> > again.
> >
> > I could usually find a dead cap in 10-15 minutes. A good friend of
> > mine
> > nearly fainted when I dug into his Odyssey although he had
> thought the
> > problem was in the power supply and had disassembled it. Took me
> > longer to
> > put that together than to find and replace the dead tant.
> >
> > Scrape the traces on each side of the dremel cut and solder
> a bit of
> > solid
> > wire to bridge the gap.
> >
> > Dave
> >
> >> -----Original Message-----
> >> From: ModularSynthPanels@yahoogroups.com
> >> [mailto:ModularSynthPanels@yahoogroups.com] On Behalf Of
> >> Richard Brewster
> >> Sent: Sunday, September 27, 2009 6:32 AM
> >> To: ModularSynthPanels@yahoogroups.com
> >> Subject: Re: [ModularSynthPanels] ChaQuo Wiring Question...
> >>
> >> I'd not use any tantalum caps. Their main benefit is the
> >> smaller size
> >> vs electrolytic of the same specs. They also cost more. I
> >> have one of
> >> my own tales from the days of yore. I used to hand-build audio and
> >> video synthesizer circuits in the seventies. These were all
> >> prototypes
> >> and needed plenty of power line bypassing. At one point we
> >> used a bunch
> >> of 100 nf Panasonic tantalums. We might put 20-30 of them on
> >> a board.
> >> And yes, they did fail by shorting out. But unless it fried
> >> and burned,
> >> we could not tell which one failed. So, one by one, each had to be
> >> clipped out until the bad ones were found. Then all the
> "good" ones
> >> that had been removed too had to be replaced. Needless to say, we
> >> stopped using the tantalums. If you do want to use some, I'd
> >> recommend
> >> ones with at least a 35 volt rating.
> >>
> >> Richard Brewster
> >> http://www.pugix.com
> >>
> >> mcb, inc. wrote:
> >>> On Sat, 26 Sep 2009, Scott Deyo wrote:
> >>>
> >>>
> >>>> Yeah, I torched a polysty on mine too. That's probably the
> >> culprit. Polysty's
> >>>> and tantalums are bummin' me out lately...
> >>>>
> >>>
> >>> Speaking of tantalums, came across this interesting tale from
> >>> days of yore:
> >>>
> >>>
> >> http://www.designnews.com/blog/Made_by_Monkeys/23362-Do_You_Wa
> >> nt_Butter_On_Those_Capacitors_.php?nid=3073&rid=398497
> >>>
> >>> --
> >>> Monty Brandenberg
> >>>
> >>>
> >>
> >>
> >>
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