Farnell D30 2T PSU - sticky push-buttons - UK Vintage Radio Repair and Restoration Discussion Forum

Simondm · 19th Dec 2021, 11:55 am

It's a really useful PSU, but I am frustrated by the push-buttons, especially the mains switch. Whatever the BBC at Bush used to lubricate them (if anything) has gone very viscous, to the extent the mains one in particular (but also the two output switches) sometimes gets stuck.

I don't really want to remove them, and I've tried things like meths cautiously in the past to flush them a bit and it's helped.

I've tried disassembly with similar switches in the past, but it's never ended well - usually either little lugs broken off or 'hunt the ballbearing' on the floor.

So I don't want to break anything, and ideally not disassemble either, as it would be a major job too.

Is there a recommended method for dealing with them?

Thanks for any advice,

Simon.

Chrispy57 · 19th Dec 2021, 1:07 pm

Hi Simon,
in the absence of any better solution why not just leave the mains switch in the "on" position and switch the supply externally - (I also took the easy way out with my Philips PM5133 Function Generator!).

Cheers
Chris

Diabolical Artificer · 20th Dec 2021, 7:22 am

I replaced the SW on my Farnell PSU though you could try a good squirt of sw cleaner or Bog forbid WD40.

Andy,

Alistair D · 20th Dec 2021, 12:53 pm

A few years ago Harry Leeming wrote an article in Practical Wireless about cleaning switches that did not respond well to normal switch cleaner.

What he described was a 3 stage process using WD40 then Iso Propyl alcohol then normal switch cleaner. He reckoned he had complete success using this method. I strongly suspect that using WD40 first dissolved any hardened grease, then the IPA removed any remaining WD40 deposits.

Since WD40 has been used, wrongly, as a switch cleaner in the past I see no reason not to give the switch a wash in it first.

Al

19th Dec 2021, 11:55 am	#1
Simondm Pentode Join Date: Nov 2020 Location: Bristol, UK. Posts: 151	Farnell D30 2T PSU - sticky push-buttons It's a really useful PSU, but I am frustrated by the push-buttons, especially the mains switch. Whatever the BBC at Bush used to lubricate them (if anything) has gone very viscous, to the extent the mains one in particular (but also the two output switches) sometimes gets stuck. I don't really want to remove them, and I've tried things like meths cautiously in the past to flush them a bit and it's helped. I've tried disassembly with similar switches in the past, but it's never ended well - usually either little lugs broken off or 'hunt the ballbearing' on the floor. So I don't want to break anything, and ideally not disassemble either, as it would be a major job too. Is there a recommended method for dealing with them? Thanks for any advice, Simon.

19th Dec 2021, 1:07 pm	#2
Chrispy57 Hexode Join Date: Mar 2020 Location: Rochdale, Greater Manchester, UK. Posts: 452	Re: Farnell D30 2T PSU - sticky push-buttons Hi Simon, in the absence of any better solution why not just leave the mains switch in the "on" position and switch the supply externally - (I also took the easy way out with my Philips PM5133 Function Generator!). Cheers Chris

20th Dec 2021, 7:22 am	#3
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,658	Re: Farnell D30 2T PSU - sticky push-buttons I replaced the SW on my Farnell PSU though you could try a good squirt of sw cleaner or Bog forbid WD40. Andy, __________________ Curiosity hasn't killed this cat...so far.

20th Dec 2021, 12:53 pm	#4
Alistair D Nonode Join Date: Jan 2010 Location: Edinburgh, UK. Posts: 2,008	Re: Farnell D30 2T PSU - sticky push-buttons A few years ago Harry Leeming wrote an article in Practical Wireless about cleaning switches that did not respond well to normal switch cleaner. What he described was a 3 stage process using WD40 then Iso Propyl alcohol then normal switch cleaner. He reckoned he had complete success using this method. I strongly suspect that using WD40 first dissolved any hardened grease, then the IPA removed any remaining WD40 deposits. Since WD40 has been used, wrongly, as a switch cleaner in the past I see no reason not to give the switch a wash in it first. Al __________________ I won't tell you how I discovered that.