More switchmode power supply grief - Cisco IGS router

[Peter Coghlan]

"Maciej W. Rozycki" wrote:
>On Sat, 5 Feb 2022, Peter Coghlan via cctalk wrote:
>
> > >  This PSU seems to have been used across various Cisco devices and I had 
> > > one fail several years ago in a WS-C1202 Ethernet/FDDI switch, also having 
> > > suffered from leaking caps.  Back then RS still had it in stock at a hefty 
> > > price of £489.60: <https://uk.rs-online.com/web/p/products/8338173/>, so I 
> > > chose to recap the failed one and thanfully it has continued working ever 
> > > since.  You may try to enquire with the manufacturer.
> > > 
> > >  Good luck with bringing yours back to life!
> > >
> > 
> > Thanks Maciej.  I'll be surprised if the manufacturer has records of
> > what they used for the chopper in power supplies 30 years ago - who
> > knows if their design has changed between then and now.  I'll be even
> > more suprised if they will talk to me about it but I guess it's worth
> > a try.
> 
>  I've checked their web site and they continue to offer a MAP80-4000G, 
> which I suppose is just a minor update from the original, and is visually 
> the same, as it seems from the datasheet dated 2021.  So I'm fairly sure 
> they have all the data.  Those discrete semiconductor components do not 
> change much, I was able to order exact replacements for another faulty 
> device from 1990s a few years ago.
> 
>  They may offer you a paid repair or replacement service or if you're kind 
> enough and they are reasonable, they may identify the single part for you.
> 
>  NB Mouser has the MAP80-4000G in stock actually, so if all else fails and 
> you are determined to get the IGS running, you can pick a brand new one: 
> <https://www.mouser.co.uk/ProductDetail/784-MAP80-4000G>.
> 

Thanks again Maciej.

I've bit the bullet and unsoldered most of the electrolytic capacitors and
other components that seem to be in trouble.  When I got the chopper
transistor out, I found that if I hold it at exactly the right angle to
the light, I can see that there are faint markings on it after all and it
turns out to be an IRFPE50 HEXFET.  I was wrong about the cracked RIFAs
not being mains filters too, they are actually across L-E and N-E and
they seem to have between a few hundred kOhms and a few MOhms leakage too.
The driver transistor looks like it might be ok.

Regards,
Peter Coghlan.


>  Good luck!
> 
>   Maciej