I was operating the panel when i first got it, now the numbers do not light up, panel is unresponsive, and run light stays lit.(just describing the behavior, i will not start it back up till I work on the power supply)
On Fri, Jul 17, 2015 at 3:50 PM, devin davison <lyokob...@gmail.com> wrote: > I had to do some cap replacement on some older Motorola tube radios,I have > some basic soldering skills. I was under the impression that the capacitors > in computer equipment this big from this year would have been of better > quality and it would not be an issue. > > I have someone scheduled to come out tonight after i get off work and get > it out of the rack. > > On Fri, Jul 17, 2015 at 3:45 PM, Brent Hilpert <hilp...@cs.ubc.ca> wrote: > >> On 2015-Jul-17, at 11:42 AM, tony duell wrote: >> >>> It is generally a good idea to re-form electrolytic capacitors in >> power >> >>> supplies, and to bench check the power supplies (under some kind of >> >>> load) before actually applying power to the whole unit. >> >> >> >> It is always a good idea to replace electrolytic capacitors in power >> supplies. >> > >> > Could you, please, explain why? And how often should this be done? Every >> > week, every month, every year, or what? >> > >> > FWIW, the number PSU elecrtrolytics I have replaced can be counted on >> the fingers of >> > one hand -- in unary. Well, perhaps both hands. But it's <1% of all the >> PSU electrolytic >> > capacitors I own. >> > >> > Only 2 cases spring to mind : >> > >> > The PSU in my 11/44 had a high ESR capacitor on the +36V rail (all >> other caps in the machine >> > were fine) >> > >> > I changed the 2 mains smoothing capacitors in my HP120 not because they >> were electrically >> > defective (they tested fine) but because one was bulging a little on >> top and had it exploded it would >> > have hit the neck of the CRT with all the problems that would be likely >> to cause. >> > >> > I do find this witch-hunt against capacitors to be curious, given how >> few I've found to have >> > failed. I suspect a lot of it comes from audiophools who think this is >> the way to fix anything... >> >> This is something Tony and I are quite in agreement on. >> >> Similar to Tony, (and as mentioned in discussion on this topic a couple >> of months ago): in the solid-state category, of the many pieces of 1960s & >> 70s and later equipment I have or have serviced, the vast majority are >> running with their original capacitors. >> >> If you're dealing with a 1936 or 1952 tube radio, a knee-jerk "replace >> the capacitors" is warranted. >> If you're dealing with a 1970s computer, it isn't (IMHO). Esp. when >> they're screw-terminal 'computer-grade' caps. >> >> My own perception of the concern is that it has been perpetuated over the >> years from the vacuum tube / antique radio arena. The issue of capacitors >> "drying out" dates from the days (1920s,early 30s) when electrolytics >> actually were filled with an active liquid which actually did dry up. >> "Dry electrolytics" were developed in the 1930s, and while early dry >> electrolytics also warrant replacement, the chemistry and techniques have >> seen a few improvements in the many intervening years, and solid-state >> equipment is not placing the same stresses on caps as tube equipment. >> >> In other arenas it's a real issue, in a modern arena it is largely lore. >> >> The point of electrolytic caps is to form an oxide to be the dielectric, >> formed (in part) out of the electrolyte, and while I'm no expert on the >> chemistry, I will point out the oxidised state is 'the' or 'a' low energy >> state, and hence relatively stable. Rust doesn't normally undo itself. >> >> >
