Restoring a Farnell E30/1 PSU...

[Nick]

Just found this in my loft - I bought it in the 1970s - was a good PSU in its day. Needs a restore and clean up - bit of noise on it - some "over heating" marks on the PCB

I'll start by re-capping it and move on from there... also needs a flexible/sprung new handle - 5 inch fixing hole centres - any ideas for a good supplier? You can see the type required in the photo below - it goes flat against the case.

Found the service manual which may be useful for others as it includes the schematic for all the Farnell E30 models...

Looking at the spec, even by today's standards, it's not half bad

HTH



Edit: Manual is available in The Archive: https://golbornevintageradio.co.uk/forum...p?tid=3770

[AlanBeckett]

That's a good Manual, better than the one I have
They're good Supplies. I use mine all the time. The only problem I've ever had is they're not protected against reverse current flow, so if you're charging a Battery and you turn the O/P down too far it blows a couple of Transitors - no big deal.
Good luck with it.

Alan

[Skywave]

Well, it may not be a "big deal" if the said PSU is fairly straight-forward to dismantle and repair. Seriously chunky jobs like the Farnell TSV70 (for example) are anything but - and they are large and extremely heavy! Then there is the inconvenience of doing a repair, of course. However, I've come across that short-coming on many a commercial bench-top PSU. But a fix is easy, of course: a diode, reverse-biassed across the voltage output terminals. A diode with a hefty current-rating would seem a good choice.

Al. / Oct. 6, '13 //

[Refugee]

There are a few difficult ones out there as I found out.
I have posted it in restoration stories as it is the one I did earlier.
http://golbornevintageradio.co.uk/forum/...p?tid=3767

[Mark Hennessy]

Old thread, but Google found it while I was searching for this one: http://www.vintage-radio.net/forum/showt...hp?t=49109

With the addition of 1 diode - neatly under the PCB - you can give these protection against "load dump". And while it's apart, add one in parallel with the output to protect against other external nasties. The scan of the diagram found in post #5 includes these (added in pencil).

A friend of mine discovered the "load dump" problem in a fairly dramatic way. He was using one to charge a small-ish lead-acid battery - fortunately this was outside in the garden. The power was interrupted, so the battery did the usual damage to these (VT5 IIRC). When the power was restored, pretty much all of the unregulated voltage was available to the poor battery. After a suitable delay, the battery exploded