- Harman Kardon 930 lost channel. Hoe to trouble shoot ? - 6 Updates
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- Why is this, charging and using battery pack at the same time. - 4 Updates
| Steff <e-post.nu@gmx.com>: Oct 11 08:50PM +0200 Den 2018-10-08 kl. 22:48, skrev Ralph Mowery: > OUtside of that the 2n3771, 2n3772 and 2n3773 are all similar. They are > a much higher power than the 2n3055 and I also use them to replace the > 2n3055 in most power supply circuits. That is correct.. The smaller TO3 ones have small "collers" on them and I noticed that the aluminum coolers dont have to much contakt with the shell of the transistor. The grease have dried out and the aluminum cooler did not have much contakt with the metall casing. I think this is a think for others to have a look at in therir working units. since bad cooling can kill this NPN transistors. Cleaning and new grease would make wonders I think. |
| jurb6006@gmail.com: Oct 12 05:36AM -0700 >"The grease has dried out..." I guess now would be a good time to dispel this old husband's tale. When the union between heatsink and transistor is undisturbed, dried out grease that is like cement is perfectly fine. I have conducted a few studies on it albeit subjective. That is that the temperature difference between a transistor and the heatsink to which it is mounted is not significant, AS LONG AS IT IS NOT DISTURBED. That assumes it was installed properly in the first place. First of all you never spread the compound, you put a dab or a bead where it will be squished out as it is tightened. this eliminates air pockets. If you have a big air pocket between there you would be better off with no compound at all. Granted, the old dried out compound does not have as good thermal conductivity as nice new wet goop, but it is seated over the years and works quite well. If you doubt what I say take a meat thermometer and check the case of a TO-3 and its heatsink on one that has been there for decades and ne that you remount with new goop now. In fact to make sure there is no error, clean those surfaces with "things". Scrub pads, alcohol, maybe acetone, and finish with a coffee fitter to get the surface nice and smooth. Apply a dab or bead right where the ounting will exert the mos even force, on a TO-3 for example, that will be about in the center and it is normal for some of the goop to squeeze through the holes for the pins. then get that thermometer out after using the unit to get the heat up, like on a stereo amp, run both channels at like 1/3rd power for an hour, that'll warm er up. As soon as you detect heat, measure. It has JUST been produced so it is still conducting to the heatsink. That would be the most accurate comparative test, but not for absolutes. It is not a number except for "how much" one is better than the other. Your actual calories of heat/watts dissipation and all that shit matters not. Iti s simply better or worse. Try it. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Oct 12 06:01AM -0700 An infra-red heat gun is better at very close range. It will show variations of fractions of a degree. Also very good for pinpointing hot-spots. Within a couple of inches, the spread is 1/6" for a standard 12:1 unit. There are narrower devices, but they are comparatively pricey. Peter Wieck Melrose Park, PA |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 12 09:24AM -0400 > An infra-red heat gun is better at very close range. It will show variations of fractions of a degree. Providing that the thermal infrared emissivity of the surface is high, e.g. plastic or glass. A dab of grease or some tape will make it work a lot better. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| John-Del <ohger1s@gmail.com>: Oct 12 07:19AM -0700 > >"The grease has dried out..." > I guess now would be a good time to dispel this old husband's tale. > When the union between heatsink and transistor is undisturbed, dried out grease that is like cement is perfectly fine. You beat me to it. It's not the liquid component of heat sink compound that transfer heat, it's the solids that are suspended in the goop. The compound may get hard, but the solids are still packed between gaps doing their job. |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 12 11:27AM -0400 On 10/12/2018 10:19 AM, John-Del wrote: > compound that transfer heat, it's the solids that are suspended in > the goop. The compound may get hard, but the solids are still packed > between gaps doing their job. Provided they're really undisturbed. Thermal cycling can cause delamination problems that don't occur with the oil present. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 11 03:38PM -0400 On 10/10/2018 07:51 PM, Ralph Mowery wrote: > did learn enough to do repair work but replace like parts with like > parts except the paper capacitors with the newer tublar type. As > mentioned electrolytics do tend to dry out after 50 years. NB: the bar on Orange Drops is the side _away_ from the outside foil! CHeers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com |
| Phil Allison <pallison49@gmail.com>: Oct 11 09:22PM -0700 Ralph Mowery wrote: > Reason for asking is that I bought an old receiver that someone has > replaced many of the capacitors. The book says pape capacitors for some > but they have been replaced by the ceramic disk type. ** See: https://www.youtube.com/watch?v=67M7fsbLUIU The author use a 5 digit "Gen Rad" LCR meter to demonstrate differences in various types tempcos. .... Phil |
| Boris Mohar <borism_void_@sympatico.ca>: Oct 12 04:13AM -0400 On Thu, 11 Oct 2018 15:38:08 -0400, Phil Hobbs >NB: the bar on Orange Drops is the side _away_ from the outside foil! >CHeers >Phil Hobbs WAAT! Why would they want to be different? -- Boris --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 12 09:17AM -0400 On 10/12/18 4:13 AM, Boris Mohar wrote: >> CHeers >> Phil Hobbs > WAAT! Why would they want to be different? Dunno. I discovered this on Paul Carlson's YouTube channel--he made an outside-foil detector gizmo and tried it out. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| "jfeng@my-deja.com" <jfeng@my-deja.com>: Oct 12 08:06AM -0700 On Friday, October 12, 2018 at 6:17:31 AM UTC-7, Phil Hobbs wrote: > Dunno. I discovered this on Paul Carlson's YouTube channel--he made an > outside-foil detector gizmo and tried it out. It would have been a lot cheaper and more convincing to have sacrificed a capacitor and open it up. If it were important, I would pay this price before I put my faith in a claim of a non-standard marking on the part, based on the old adage that extraordinary claims require extraordinary proof. |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Oct 12 11:25AM -0400 > pay this price before I put my faith in a claim of a non-standard > marking on the part, based on the old adage that extraordinary claims > require extraordinary proof. Suit yerself, or watch the video. You probably don't believe that tantalums are marked on the positive side either. ;) Carlson wanted a test gizmo for many caps used in his antique radio and test equipment restorations. Some of them are fun, though a bit slow-paced for experts, of course. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com |
| Adrian Caspersz <email@here.invalid>: Oct 12 12:16AM +0100 On 10/10/18 20:02, micky wrote: > 3 out of 4 answers say it's bad. Why? or why not? > https://www.amazon.com/ask/questions/Tx10I7HVBTAQGV6/ref=ask_dp_dpmw_al_hza > And what is "PD capable". USB Power Delivery https://www.androidauthority.com/usb-power-delivery-806266/ -- Adrian C |
| jurb6006@gmail.com: Oct 12 05:16AM -0700 >"3 out of 4 answers say it's bad. Why? or why not?" For one because if you blow the fusible on the mobo to the USB power I will charge you fifty bucks to replace it, more if it is a laptop. The thing here that batteries charge at a much higher rate than they used to. The old NiCds would charge slowly, at a low current rate, generally you had to charge longer than you could run. But newer battery technology has them charging at a much faster rate which requires more current, making that current drain significant. Say, in the old days (yeah right) a batteryu might charge at 75 mA and the device needs 900 mA to run. The 75 is less than 10 %, not a big thing. But by the laws of physics (thermodynamics believe it or not) if the battery charges in say 2o minutes and will run an hour on that charge, the charging current must be 3 X the drain current. A battery, except for dry cells and that weirdo machine that suck magnetism out of PMs, is noting but a storage device like an electrolytic capacitor. In fact the operation is replete with similarities. Let me try to draw this; (I suck at it) Power - \ --- device ..........--- current regulator/logic --- battery The "bottom line" there used to be insignificant, but now it can actually be MORE than the device pulls to run. A USB port might not be able to handle it. |
| Stephen Wolstenholme <steve@easynn.com>: Oct 12 04:00PM +0100 On Wed, 10 Oct 2018 15:02:48 -0400, micky <NONONOmisc07@bigfoot.com> wrote: >Why is this, charging and using battery pack at the same time. >3 out of 4 answers say it's bad. Why? or why not? I have never had a problem with simultaneous charging and use any electronic device. I've worked on a variety of electronic systems all my life and I'm now 70. There are many very common devices that charge and use a battery at the same time. Cars, telephones and PCs for example. Steve -- http://www.npsnn.com |
| Look165 <look165@numericable.fr>: Oct 12 05:15PM +0200 Why is there an alternator in a car ? It is charging when the battery is on also ! This is designed for compensating power loss and power gain ; there must be a controller IC to compute everything. micky a écrit : |
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