- Zenith safety cap ID (22-7672-05) - 2 Updates
- Replacing Large Electrolytics - 4 Updates
| tabbypurr@gmail.com: Sep 02 11:16AM -0700 On Friday, 31 August 2018 16:10:01 UTC+1, John-Del wrote: > The solution was to use a TRMs meter (15K cycle AC from the fly) and adjust with winding count and/or a resistor to ensure the filament stayed at or even a bit smidge below 6.3TRMS AC. I did those and got many years out of those repairs. > Going back farther, we used to install hang on filament boosters in TVs with weak tubes to allow customers time to either save for a new TV or a CRT swap. Typical life of a boosted tube was two to six months. > I bought a new B&K 467 (still have it and two others from closed shops) and the life of the CRTs after boosting was 6 months to two years. The Sencore was supposed to be better but I never had one of those. In any case, we never sold a boosted tube of any type. I'm surprised to hear this. I had very good results with filament voltage boosting, the odd ones I kept lasted very well. I don't know at this point why the difference. What voltage boost % were you using? In what way did the tubes end up ruined? Tubes soon tire if _under_volted. You mention hang-on boosters, I presume you mean 10% boosting transformers. 10% isn't enough to be adequate for long. It'll tickle it up a bit, but not enough to be really worthwhile. The zero emission Sony Trinitron I experimented on got 66% heater voltage boost, it ran yellow hot rather than orange. I was surprised to find it ran happily for years like that, but it did. Obviously I never sold it. It was my main set for years, then a second for years more. I kept 2 heavily experimented on trinitrons - the other ran missing the psu board. I was familiar with Sencore boosted tubes. It didn't always work, tube life was not usually as much as a year and severe smearing always condemned them. Filament power boosting worked much better IME. And the Sencore didn't work on Sonys. There was also anode voltage boosting, not something I'd consider reputable but I've encountered it being done with lousy tubes in junker sets. It does boost the output, but I wouldn't do it outside of an experiment never for sale. NT |
| jurb6006@gmail.com: Sep 02 10:22PM -0700 Umm, we used to bump the heater and then let the thing run for about a week. I have seen them get better and better with a moderate boost and then last a very long time. We never rejuved a camera tube but someone told me and I found out that is you keep one of those old cameras running for days and days looking straight at a white surface it rejuved them somewhat. There was really no way to boost the filament, there was no room for anything. |
| Cursitor Doom <curd@notformail.com>: Sep 02 06:50PM On Sun, 02 Sep 2018 06:03:04 -0500, Fox's Mercantile wrote: > That's not how manufacturing does it. > Their installed and at the end of assembly line, full power is applied. > They either work or they don't. That's all very well for *brand new* capacitors! -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
| +++ATH0 <news@ringpiece.local>: Sep 02 12:38PM -0700 On 2018-08-28 10:47, Cursitor Doom wrote: > On Wed, 22 Aug 2018 04:03:23 -0700, tabbypurr wrote: > I've got a box full of the oil & paper caps that come in cubiod cans and > they all tested fine (I have an awful lot of vintage spares here). Enjoy your PCBs. |
| tabbypurr@gmail.com: Sep 02 01:06PM -0700 On Sunday, 2 September 2018 20:38:38 UTC+1, +++ATH0 wrote: > > I've got a box full of the oil & paper caps that come in cubiod cans and > > they all tested fine (I have an awful lot of vintage spares here). > Enjoy your PCBs. and not the good type NT |
| whit3rd <whit3rd@gmail.com>: Sep 02 07:36PM -0700 On Sunday, September 2, 2018 at 4:45:44 AM UTC-7, Stephen Wolstenholme wrote: > On Sun, 2 Sep 2018 06:03:04 -0500, Fox's Mercantile <jdangus@att.net> > wrote: [about electrolytic capacitors] > the day after. > I never found out why that happened but I assumed it was an > electrolytic so I changed the lot. Electrolytics have to be formed (kept under bias for a period) before they develop the dielectric (oxide) layer, AND that layer is continuously renewed when they're under bias. On the shelf, however, it degrades. Some switchmode power supplies (the old Apple II types) rely on timing capacitors for startup sequencing, and the power filter electrolytics are NOT the prime suspects when such a power supply doesn't work. You can often fix those power supplies by leaving 'em turned on overnight. The most plausible reason for this is that the timing capacitors (not the big filter caps) have to be re-formed. This syndrome can't be improved with new filter capacitors (I've tried). Once they work, they're reliable again. |
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