Re: [N8VEM: 15616]

[Sergey <skis...@gmail.com>]

Good, now you can continue with troubleshooting :-)

Can you please test A0 and /MREQ for pulses?

Thanks,
Sergey

On Feb 17, 12:04 pm, rbruinsma <rbma...@gmail.com> wrote:
> I did removed all IC's and re-tipped the most solder point again. After
> that I have double checked all Vcc and Ground pins from all sockets and I
> get all 5V readings.
>
> After putting back the IC's I now do get a 5V reading between pin 11&29 on
> the CPU. Also I get a High on pin 24/25 &26 on the CPU. But still no
> working SBC.
>
> Op zondag 17 februari 2013 19:49:48 UTC+1 schreef Sergey het volgende:
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> > >  When I measure the voltage between pin11 and 29 on the CPU I get 1.4V
> > but
> > > when I measure between pin 11 and ground on the power supply pin I get
> > 5.0V
> > > Any Idea where to look? What could cause the 1.4V reading on the CPU?
>
> > This is not good. If you have your ICs socketed, I'd take them out
> > first, and check continuity on power lines - between power connector
> > to ICs. Note that power pin numbers differ between ICs. For most 74*
> > logic, ground is the last pin in the first row (7 for 14 pin package,
> > 8 for 16 pin, 10 for 20 pin) and Vcc is the last pin (14 for 14 pin,
> > etc). Same for flash/EPROM/SRAM - pin 16 is ground, pin 32 is Vcc.
>
> > Consult ICs datasheets to find power pins for other ICs. (I think
> > schematic omits power inputs in most cases)
>
> > Thanks,
> > Sergey