- 1/4 " phone plugs loose. - 2 Updates
- Microwave troubleshooting - 7 Updates
| David Farber <farberbear.unspam@aol.com>: Jul 18 08:28AM -0700 I was given some speaker cables to test which terminate with 1/4" phone plugs. The complaint was that the sound cuts out and can be momentarily corrected by jiggling the wire near the connector. I unscrewed the sleeves and the wiring looked fine however I noticed that on some of the plugs, if I firmly held the common terminal at the rear of the plug with one hand, I could easily rotate the plug end with the other hand. Only one of those loose plugs had issues with cutting out. Do all of these plugs need replacing? Thanks for your reply. -- David Farber Los Osos, CA |
| KenW <ken1943@invalid.net>: Jul 18 10:08AM -0600 On Sun, 18 Jul 2021 08:28:48 -0700, David Farber >one of those loose plugs had issues with cutting out. Do all of these >plugs need replacing? >Thanks for your reply. I would try to clean them first or twist them around when plugged in. Usually the 'tarnish' cannot be seen. Doing that now with 1/8" on an Intel NUC computer. KenW |
| "hondgm@yahoo.com" <hondgm@yahoo.com>: Jul 17 01:57PM -0700 I have a microwave from the mid 2000s that failed on me. It uses basic circuitry: transformer, diode, cap, magnetron....not an inverter type or anything fancy like that. One morning it seemed to mostly work, but the output rapidly dropped over a few minutes. No bang, no smoke. Just stopped heating. Everything tests ok, the transformer, diode, cap, even the magnetron resistance measurements are "good". I know there's about 10A to the filament with indirect testing, and I know the capacitor has near 2kV on it right after running the unit and unplugging it. This was determined by knowing the cap has an internal bleeder and using the RC time constant to allow the voltage to drop to a safe value to measure. Would this be indicative of a bad magnetron? Almost everything I read about magnetron troubleshooting leads me to believe there's nothing wrong with it, but then again the rest of the circuit also seems to be functioning correctly. |
| Phil Allison <pallison49@gmail.com>: Jul 17 03:35PM -0700 hon...@yahoo.com wrote: ====================== -------------------------------------------------------- ** Might not have a good vacuum any more ? Happens with power output tubes quite regularly. ..... Phil |
| John Robertson <spam@flippers.com>: Jul 17 04:10PM -0700 On 2021/07/17 3:35 p.m., Phil Allison wrote: > Happens with power output tubes quite regularly. > ..... Phil Would that not burn out the magnetron heater if it was exposed to the atmosphere? RapirFAQ may be of use to the OP: https://www.repairfaq.org/sam/micfaq.htm I bought out a distributor of electronic gear for Radio/TV/VCR/etc. repair shops and they had a couple of boxes of Microwave parts. So if the OP figures out what he needs and can't find it online I may be able to help... John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Phil Allison <pallison49@gmail.com>: Jul 17 04:30PM -0700 John Robertson wrote: ==================== > > Happens with power output tubes quite regularly. > Would that not burn out the magnetron heater if it was exposed to the > atmosphere? ** Why ? Don't happen with regular tubes. When they lose vacuum, the " getter" absorbs the oxygen ( goes white ) and leaves mainly nitrogen. Nitrogen is what incandescent light bulbs are full of. So it is like a light bulb with a very low filament temp. ..... Phil |
| John Robertson <spam@flippers.com>: Jul 17 05:21PM -0700 On 2021/07/17 4:30 p.m., Phil Allison wrote: > Nitrogen is what incandescent light bulbs are full of. > So it is like a light bulb with a very low filament temp. > ..... Phil I've seen plenty of regular tubes whose filaments burn open shortly after the tube body is cracked. The getter can only absorb X amount of oxygen after all. Of course the microwave couldn't work if the tube looses its vacuum in any case - it was just that the OP mentioned he checked the filament and it seemed OK and I thought it should have burned open if not in a vacuum any more... I have no experience with magnatrons other than heating up my food, so it is purely guesswork based on what I've seen happen with evacuated tubes after they loose integrity. One is always learning! John :-#)# |
| "hondgm@yahoo.com" <hondgm@yahoo.com>: Jul 17 05:40PM -0700 On Saturday, July 17, 2021 at 6:10:52 PM UTC-5, John Robertson wrote: > atmosphere? > RapirFAQ may be of use to the OP: > https://www.repairfaq.org/sam/micfaq.htm Oh I've read the repairfaq. Good information, but it seems nearly all (or all?) magnetron failure modes involve something more dramatic than what I'm getting. The filament could be shorted to itself, but it claims that's unlikely. The other is low output resulting from decreased cathode emission, due to wearout. Mine failed over a few minutes though. There's other issues like incorrect oscillation frequency, but water is still supposed to heat. I'm really leaning towards bad magnetron because everything else *seems* good and how it didn't fail instantly. |
| Phil Allison <pallison49@gmail.com>: Jul 17 06:07PM -0700 John Robertson wrote: =================== > > So it is like a light bulb with a very low filament temp. > I've seen plenty of regular tubes whose filaments burn open shortly > after the tube body is cracked. ** The case here is likely to be a tiny, slow leak of air. > any case - it was just that the OP mentioned he checked the filament and > it seemed OK and I thought it should have burned open if not in a vacuum > any more... ** Takes time and a lot of oxygen rich air. ..... Phil |
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