SV: Re: [sdiy] repairing a BBD delay

[Karl Ekdahl]

Hmm... i figure, the MN3101 as well as the MN3005 are
using this weird scheme where VDD goes to GND and GND
goes to +15. It's as in the example schematic in the
datasheet for the MN3005 (couldn't they just have
renamed GND +15 and VDD GND?).

Anyway, how do i lift my scope from ground? do i have
to get a non-grounded power cable or something, sounds
like danger.. (?)

Karl

--- Bob Weigel <sounddoctorin at imt.net> skrev:

> Yeah the 3101 should have a clock output.  Make sure
> the ground pin is 
> good.  Sounds like maybe it's lost the ground and
> the whole chip is 
> floating.  Hmm..wait on the diagram..that's right
> pin 1 is ground and 
> pin 3 is Vdd (-15V)
> 
> Sooo.  you are not measuring from that reference
> frame I assume or it's 
> in a design where everything is cap isolated and
> they are using ground 
> on pin 3 and +15V on ground.  Anyway measure with a
> ground lifted scope 
> so you don't short anything and put the ground then
> on pin 1 and see if 
> any signal is out of 2 and 4.  First. I have some of
> those but they're 
> easy to get compared to the bbd's themselves.  -Bob
> 
> Karl Ekdahl wrote:
> 
> >Hi list, i've got an old delay that has stopped
> >working. Inside i found a MN3005 driven by a
> MN3101. 
> >
> >I'm thinking that the MN3101 might be busted as i
> >cannot see any output signals at all on the scope
> from
> >the MN3101, using a DMM all the pins but pin 3 is
> at
> >15V or 14.5V. 
> >
> >How do i debug this, should there be a "seeable"
> >signal at pin 2 & 6 that is fed to the BBD or does
> the
> >MN3005 eat the whole clock signal? Should i be able
> to
> >get a oscillator signal on pins 5,6,7 - i'm
> thinking
> >that perhaps the surrounding components on this end
> >might be busted?
> >
> >There is sound coming into the MN3005 at pin 7 as
> >should be, but there's nothing else coming in or
> out
> >of that chip.
> >
> >Any help greatly appreciated!
> >
> >Karl
> >
> >
> >	
> >	
> >		
>
>_________________________________________________________
> >Flyger tiden iväg? Fånga dagen med Yahoo! Mails
> inbyggda
> >kalender. Dessutom 250 MB gratis, virusscanning och
> antispam. Få den på: http://se.mail.yahoo.com
> >
> >
> >  
> >
> 



	
	
		
_________________________________________________________
Flyger tiden iväg? Fånga dagen med Yahoo! Mails inbyggda
kalender. Dessutom 250 MB gratis, virusscanning och antispam. Få den på: http://se.mail.yahoo.com