- Vintage equipment voltage measurement - 19 Updates
- Help for iPhone batteries on continuous charge? - 2 Updates
- TDA1085 - 4 Updates
| John Larkin <jjlarkin@highlandtechnology.com>: Aug 19 09:56AM -0700 On Sun, 19 Aug 2018 16:41:26 -0000 (UTC), Cursitor Doom >On Sun, 19 Aug 2018 09:24:57 -0700, John Larkin wrote: >> Why not ignore the voltage notes and just fix it? >You're obviously not a service engineer. ;-) I'm an engineer, not a service technician. This is an electronic design group. I think there is an electronic repair group. The engineering approach to fixing things is to probe around, understand how it's supposed to work, and figure out why it doesn't. -- John Larkin Highland Technology, Inc lunatic fringe electronics |
| Tom Gardner <spamjunk@blueyonder.co.uk>: Aug 19 05:59PM +0100 On 19/08/18 17:56, John Larkin wrote: >>> Why not ignore the voltage notes and just fix it? >> You're obviously not a service engineer. ;-) > I'm an engineer, not a service technician. Spot on! |
| Cursitor Doom <curd@notformail.com>: Aug 19 05:46PM On Sun, 19 Aug 2018 09:56:08 -0700, John Larkin wrote: > I'm an engineer, not a service technician. Good Lord!! I've only been reading your comments on this group for the last 20+ years and never really noticed that before! ;-) -- 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. |
| Andy Burns <usenet@andyburns.uk>: Aug 19 07:05PM +0100 John Larkin wrote: > This is an electronic design group. I think there is an electronic > repair group. This thread is cross-posted to both ... |
| mike <ham789@netzero.net>: Aug 19 11:28AM -0700 On 8/19/2018 8:17 AM, Cursitor Doom wrote: > that used by the people who wrote the service manual? > Never heard of an analogue meter with such a high Zin, but here it is: > https://tinyurl.com/ycjz9l4o What's so hard about putting a resistor in parallel with your meter? |
| bitrex <user@example.net>: Aug 19 02:40PM -0400 On 08/19/2018 12:56 PM, John Larkin wrote: > repair group. The engineering approach to fixing things is to probe > around, understand how it's supposed to work, and figure out why it > doesn't. The engineering approach to climbing Mt. Everest is to find out where it is. Learn to climb stuff. Get a bunch of money. Buy the stuff and hire the people you need to climb it. Go to where it is. And then climb it using the stuff. |
| Cursitor Doom <curd@notformail.com>: Aug 19 06:53PM On Sun, 19 Aug 2018 11:28:10 -0700, mike wrote: > What's so hard about putting a resistor in parallel with your meter? Never even occurred to me. -- 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. |
| Rob <nomail@example.com>: Aug 19 07:09PM > On Sun, 19 Aug 2018 11:28:10 -0700, mike wrote: >> What's so hard about putting a resistor in parallel with your meter? > Never even occurred to me. That's what you get when people lack basic understanding of the matter. |
| John Robertson <spam@flippers.com>: Aug 19 12:14PM -0700 On 2018/08/19 11:53 AM, Cursitor Doom wrote: >> What's so hard about putting a resistor in parallel with your meter? > Never even occurred to me. Resistance used depends on the range: https://canadianvintageradio.com/how_to/example-how-to/ better explanation: https://www.allaboutcircuits.com/textbook/direct-current/chpt-8/voltmeter-impact-measured-circuit/ John |
| Cursitor Doom <curd@notformail.com>: Aug 19 07:41PM On Sun, 19 Aug 2018 19:09:10 +0000, Rob wrote: >>> What's so hard about putting a resistor in parallel with your meter? >> Never even occurred to me. > That's what you get when people lack basic understanding of the matter. I've only recently discovered that I invariably overlook simpler solutions. Fortunately I'm only a hobbyist and don't do this for a living! -- 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. |
| Tom Gardner <spamjunk@blueyonder.co.uk>: Aug 19 10:00PM +0100 On 19/08/18 20:41, Cursitor Doom wrote: >> That's what you get when people lack basic understanding of the matter. > I've only recently discovered that I invariably overlook simpler > solutions. Fortunately I'm only a hobbyist and don't do this for a living! And that is clearly true for more than just electronics! |
| mike <ham789@netzero.net>: Aug 19 02:14PM -0700 On 8/19/2018 12:14 PM, John Robertson wrote: > better explanation: > https://www.allaboutcircuits.com/textbook/direct-current/chpt-8/voltmeter-impact-measured-circuit/ > John Or you could just read the question: I'm currently TS on a mid 70s Tek scope the manual for which states the readings given are valid for a meter with a Zin of between 100k and 200k (specifically a Triplett 630NS see link). |
| "jfeng@my-deja.com" <jfeng@my-deja.com>: Aug 19 02:16PM -0700 On Sunday, August 19, 2018 at 11:30:00 AM UTC-7, mike wrote: > What's so hard about putting a resistor in parallel with your meter? Even better would be to understand why they specified VOMs with 20k/V sensitivity, and the implications with modern instruments. Back in those days, the commonly-available multimeters were 1k/V and 20k/V VOMs and 11 Meg VTVMs. The cheaper 1k/V would load down the circuit and give an erroneously low voltage reading. With the 20k/V VOM and the VTVM, this error was usually smaller than the inaccuracy in the analog meter movement. Resistors had 10%-20% tolerance, and the power line voltage could easily vary by 10%, so the values in the service manuals were approximate, not a specification with a precision of 0.1V. Significant discrepancies could be a hint of the source of a problem (for example, a positive voltage on the control grid and a very low plate voltage might be due to a leaky coupling capacitor). A modern DMM without modification is fine as it is if you understand what you are doing. |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 19 04:22PM -0700 On Sun, 19 Aug 2018 19:41:48 -0000 (UTC), Cursitor Doom >I've only recently discovered that I invariably overlook simpler >solutions. Nothing is simple or stays simple. Everything becomes more complexicated. >Fortunately I'm only a hobbyist and don't do this for a living! I know the feeling. Three times in my life I've turned my hobby into a business. Now, I'm getting ready to begin to start planning to retire and I'm turning my business into a hobby with at least one of my hobbies into a potential business. Perhaps it would be better for the skools to teach hobbies instead of professions? -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 19 04:44PM -0700 On Sun, 19 Aug 2018 09:56:08 -0700, John Larkin >The engineering approach to fixing things is to probe >around, understand how it's supposed to work, and figure out why it >doesn't. Nope. The difference between engineering and repair is that the engineer assumes that the problem is due to a design error and fixes the problem by redesigning the circuit. The repair tech assumes that it was designed and built correctly, therefore something has blown. The engineers needs to make production lots of an instrument work. The repair technician usually needs to make one work. The engineer tries to determine how the circuit should work. The repair tech tries to determine what the engineer was thinking when he designed the circuit. The engineer understands how the circuit should work. The technician understands what the circuit actually does. The engineer has experience making the instrument work under laboratory conditions. The technician has experience making it work in the rather nasty "real world" environment. The engineer selects components based on availability, performance, price, and lifetime. The repair tech substitutes whatever can be found in his junk box. The engineer writes the documentation partly to demonstrate to the world the cleverness and greatness of his design. The repair tech doesn't read the documentation unless he's desperate. The engineer makes measurements in order to find problems. The repair tech looks for smoke, burned parts, bulging capacitors, broken connections, manufacturing errors, and mechanical damage. Well, maybe he does take a few measurements like the power supply voltages. All this works very nicely as long as engineers don't try to act like technicians and technicians don't try to act like engineers. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Cursitor Doom <curd@notformail.com>: Aug 20 12:14AM On Sun, 19 Aug 2018 16:22:39 -0700, Jeff Liebermann wrote: > and I'm turning my business into a hobby with at least one of my hobbies > into a potential business. Perhaps it would be better for the skools to > teach hobbies instead of professions? Not sure about the US, but schools in the UK are teaching kids *what* to think rather than how to. Very little of a typical school day is now spent learning anything genuinely useful. The kids the schools turn out into the world of work nowadays are mostly only suited to flipping burgers or delivering pizzas. -- 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. |
| "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com>: Aug 19 08:35PM -0400 Cursitor Doom wrote: >> I'm an engineer, not a service technician. > Good Lord!! I've only been reading your comments on this group for the > last 20+ years and never really noticed that before! ;-) Your nym isn't that old. What was it before? |
| Tom Gardner <spamjunk@blueyonder.co.uk>: Aug 20 07:59AM +0100 On 20/08/18 01:14, Cursitor Doom wrote: > Not sure about the US, but schools in the UK are teaching kids *what* to > think rather than how to. Very little of a typical school day is now > spent learning anything genuinely useful. And if the ex Secretary of State for Education (and poisonous brexiteer) Michael Gove got his way, they won't be taught to think at all, only to regurgitate "useful" facts such as when King Henry II reigned. But then he also wanted more madrassahs, under the guise of wanting more religion in education. He even approved the creation of three Creationist schools. But of course the success and failure is far more nuanced than CD states. > The kids the schools turn out > into the world of work nowadays are mostly only suited to flipping > burgers or delivering pizzas. Old farts have always said that, and always will. When doing A-level pure maths, homework often consisted of doing questions from past exams. The older ones were more difficult than the recent ones, with those from the early 50s being bloody hard. |
| Jasen Betts <jasen@xnet.co.nz>: Aug 20 06:47AM > Anyone come up with a solution to the problem of making voltage readings > on high impedance parts of a circuit with a meter of a different Zin to > that used by the people who wrote the service manual? if too high add parallell resistance. if too low select a higer voltage range. > https://tinyurl.com/ycjz9l4o unreal 5uA full scale. -- ت |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 19 05:49PM -0700 On Wed, 15 Aug 2018 19:35:51 +0100, Mike Coon >The replacement battery is OK so far, but I don't leave it on charge for >long periods... >Mike. The answer to overnight charging and bulging batteries is complicated. Charging Your Phone Overnight: Battery Myths Debunked <https://www.pcmag.com/news/357987/charging-your-phone-overnight-battery-myths-debunked> I could question the explanations and suggestions in the article because battery chemistry, construction, chargers, charge controllers, BMS (battery management system), and phones vary over the years. The only advice I could add is to forget everything you know about older battery chemistries (NiMH, NiCd, Alkaline) because the various LiIon chemistries are quite different. What would cause a phone battery to bulge in the middle? <https://www.quora.com/What-would-cause-a-phone-battery-to-bulge-in-the-middle> Over-simplification: Overcharging produces gases. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| bruce2bowser@gmail.com: Aug 19 07:11PM -0700 On Sunday, August 19, 2018 at 8:49:06 PM UTC-4, Jeff Liebermann wrote: > What would cause a phone battery to bulge in the middle? > <https://www.quora.com/What-would-cause-a-phone-battery-to-bulge-in-the-middle> > Over-simplification: Overcharging produces gases. As many apps as possible should all be off when charging, too. That way, the phone is using less energy while charging. |
| Baron <baron@linuxmaniac.net>: Aug 19 08:26PM +0100 Hi Guys, I'm trying to find either a reliable source for a TDA1085 Ic or a direct replacement. Failing that a functionally equivalent device. Thanks in advance. -- Best Regards: Baron. |
| tabbypurr@gmail.com: Aug 19 04:48PM -0700 On Sunday, 19 August 2018 20:26:52 UTC+1, Baron wrote: > I'm trying to find either a reliable source for a TDA1085 Ic or a > direct replacement. Failing that a functionally equivalent device. > Thanks in advance. surely ebay & google can do that better than anyone else. |
| dansabrservices@yahoo.com: Aug 19 05:10PM -0700 On Sunday, August 19, 2018 at 3:26:52 PM UTC-4, Baron wrote: > -- > Best Regards: > Baron. These are available from China and can be seen on listings on Ebay. One example: https://www.ebay.com/itm/10PCS-TDA1085-Encapsulation-SOP/382490565191?hash=item590e36da47:g:kygAAOSwnvVbImF8 |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 19 05:15PM -0700 On Sun, 19 Aug 2018 20:26:49 +0100, Baron <baron@linuxmaniac.net> wrote: >I'm trying to find either a reliable source for a TDA1085 Ic or a >direct replacement. Failing that a functionally equivalent device. See: <https://www.ebay.com/sch/i.html?_nkw=TDA1085> That shows 59 vendors, mostly in China, that have some level of inventory. Buy a few samples from a few of these vendors and ask them for a quote on supplying your unspecified required amount. You'll be surprised that many of them have literally thousands of parts in inventory. Be prepared to haggle over the price. Also, don't believe most of what they say and promise. Cover your posterior by ordering from at least 2 vendors at the same time. Even the largest US vendors are not 100% reliable, so you might find it useful to disclose which aspect of reliability (price, delivery, quality, support, credit, shipping time, inventory, etc) you find important. I couldn't find an exact replacement or equivalent. However, you might skim the data sheets for "related" parts found near the bottom of the page: <http://elcodis.com/parts/703553/TDA1085C.html> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 25 updates in 3 topics"
Post a Comment