[hpsdr] Troubleshooting a Hermes 5v Power issue

[Kjell Karlsen]

Hi Dave.

I believe you are right. The SMPSU has a current limiter and will
fold-back the voltage if shorted. The fuse is a PTC so it will come back
after the voltage is removed. The short can be anywhere on the PCB!

Fortunately I have an old instrument named Polar Toneohm 700 Faults
Locator. With this in use, I can pinpoint the short within a few mm. It
has been my best friend for this type of work for >30 years!

Good luck!

73, Kjell




På Thu, 03 Apr 2014 20:43:16 +0200, skrev David Carlson
<kdcarlso at gmail.com>:

> Not yet. I'm looking for a 5v supply but I checking pin 2 of j26 showed  
> .6
> ohms to ground, I'm thinking that's a bit low.. Time to go over it with  
> the
> microscope again :-(
>
> Thanks,
>
> Dave
> KA2OQZ
>
>
> -----Original Message-----
> From: hpsdr-bounces at lists.openhpsdr.org
> [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Kjell Karlsen
> Sent: Thursday, April 03, 2014 2:07 PM
> To: hpsdr at lists.openhpsdr.org
> Subject: Re: [hpsdr] Troubleshooting a Hermes 5v Power issue
>
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> Hi Dave.
>
> Have you tried with an external 5V PSU?. But first I think you must  
> measure
> if there is a short on the 5V bus after F3. If Hermes works with an  
> external
> PSU, there is something with the SMPSU. And I know it can be difficult to
> measure on the circuit!
>
> 73, Kjell
>
>
>
>
>
> I finally got my Hermes built and had no 5v. I re-soldered u24 aka u58  
> and I
> now have 5v at pi3 of J26 but as soon as I connect the jumper (pins 2-3)  
> the
> voltage drops to about .4v. I thought it might be a solder bridge  
> somewhere
> but fuse f3 is not tripping so I'm thinking it might still be a power  
> supply
> issue. Does anyone have any ideas?
>
> Thanks,
>
> Dave
> KA2OQZ
>
>
>
>
>
> På Thu, 03 Apr 2014 18:40:37 +0200, skrev Dave . <kdcarlso at gmail.com>:
>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>
>


-- 
Sendt med Operas e-postklient: http://www.opera.com/mail/

 1396556088.0