sci.electronics.repair@googlegroups.com

Google Groups

"Michael A. Terrell" <mike.terrell@earthlink.net>: Nov 17 09:32PM -0500 > Followed by the 'false premises' fallacy: "But everyone knows that....".   > Usually there is a sprinkling of "ad hominum" in the mix - such as the word Nazi and so forth.   > Sorry. But we here in the US are entirely within a "time will tell" situation. We have not had such a polarized election with two such foul candidates since Grant ran against Seymour in 1868. Grant did not rise to the occasion. One hopes that this is not an historical precedent.       It was in some of the deleted emails.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

"Michael A. Terrell" <mike.terrell@earthlink.net>: Nov 17 09:36PM -0500 > https://mail.aol.com/webmail/getPart?uid=33646633&partId=2&scope=STANDARD&saveAs=Trump.jpg   > Just an FYI.     You posted a link with your account ID. That's not very smart, and it isn't accessible by anyone else.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

"pfjw@aol.com" <pfjw@aol.com>: Nov 18 05:33AM -0800 On Thursday, November 17, 2016 at 9:36:37 PM UTC-5, Michael Terrell wrote:     > You posted a link with your account ID. That's not very smart, and > it isn't accessible by anyone else.   That is the point of DropBox - it allows one to share large and small files without risking a direct connection. My "account ID" is the sharing link. I have used it for years without incident. Nor is there anything in it that is at all actionable or confidential   Peter Wieck Melrose Park, PA

"pfjw@aol.com" <pfjw@aol.com>: Nov 18 05:35AM -0800 On Thursday, November 17, 2016 at 9:32:08 PM UTC-5, Michael Terrell wrote:   > > Usually there is a sprinkling of "ad hominum" in the mix - such as the word Nazi and so forth.   > > Sorry. But we here in the US are entirely within a "time will tell" situation. We have not had such a polarized election with two such foul candidates since Grant ran against Seymour in 1868. Grant did not rise to the occasion. One hopes that this is not an historical precedent.   > It was in some of the deleted emails.   And the independently verifiable links to that information are?   Thanks in advance!   Peter Wieck Melrose Park, PA

Cursitor Doom <curd@notformail.com>: Nov 18 11:51AM Hi all,   Has anyone had to work on one of these? If so, is it possible to probe through the transparent conformal coating of the PCB to measure voltages on traces without (more than minutely) damaging the coating? Also, has anyone had any luck injecting voltages in the same way in order to mimic signals the chips inside "expect" to see (for example to defeat the ignition coding/immobiliser system?   thanks.

"pfjw@aol.com" <pfjw@aol.com>: Nov 18 05:16AM -0800 On Friday, November 18, 2016 at 6:52:19 AM UTC-5, Cursitor Doom wrote: > to mimic signals the chips inside "expect" to see (for example to defeat > the ignition coding/immobiliser system?   > thanks.   http://www.ebay.com/bhp/ecu-programmer may be what you want right out of the box. Especially if you are going to make a habit of it.   At the same time, you are not going to be able to repair/modify at the component level without damaging the coating. So, you might just have-at then repair the coating after the fact.   Peter Wieck Melrose Park, PA

Chris Jones <lugnut808@spam.yahoo.com>: Nov 18 11:01PM +1100 > surroundings at-risk either a little bit, or perhaps quite a bit > depending on the tool. It is, in every case, under every condition, > an exceedingly bad idea.   meh. That is quite a generalisation. Sometimes upgrades and modifications make things safer, especially when starting with older equipment that, in its original condition, would not meet modern safety standards. Of course one has to apply sensible engineering, and not overstress parts, and consider any safety consequences of parts failing, but that does not necessarily preclude improving performance in some cases, as the original designers of the equipment did not have the components available to them that we do now.

"pfjw@aol.com" <pfjw@aol.com>: Nov 18 05:09AM -0800 On Friday, November 18, 2016 at 7:02:02 AM UTC-5, Chris Jones wrote:   > but that does not necessarily preclude improving performance in some > cases, as the original designers of the equipment did not have the > components available to them that we do now.   Sure. But, look at what you just stated. Sensible engineering. Not willy-nilly speculation by individuals with no or very limited basic knowledge of the design parameters of the tool/machine involved.   "more than they were designed to do" is not sensible engineering.   Better bearings, better capacitors, better lubricants, more effective switches, better snubbers (rubber parts), better insulation, better electrodes, better shielding - all of the above are perfectly valid (and sensible) improvements for about anything. One does not have to use 30w non-detergent oil in a vintage automobile, or propylene glycol antifreeze today.   But, at the same time, running a stock Model T on nitro-methane is, perhaps, inadvisable.   Peter Wieck Melrose Park, PA

"Michael A. Terrell" <mike.terrell@earthlink.net>: Nov 17 09:44PM -0500 Pat wrote: > actual power. The transmitter's actual power usage is a drop in the > bucket compared to all the other energy a TV station uses for lights, > cameras, HVAC, etc.     I was an engineer at an analog UHF station with a 5 MW EIRP, on a 1700' tower. The Comark transmitter used a pair of 65 KW EEV Klystons, for 130 KW of RF into the diplexer. A third 65 KW Klystron was used for the aural signal. That was in the late '80s, and our electric bill for the transmitter site was $45,00 a month.   Solid state transmitters are modular, with around 1KW output, per tray. Look at the Harris Broadcast website for some actual data.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

Clifford Heath <no.spam@please.net>: Nov 18 04:20PM +1100 On 18/11/16 13:44, Michael A. Terrell wrote: > Pat wrote: > Solid state transmitters are modular, with around 1KW output, per > tray. Look at the Harris Broadcast website for some actual data.   I have a half-dozen such modules here, unfortunately with the water-cooled heatsink removed, if you want photos or to ask any questions. The modules are single or dual, using a BLF278 dual FET each. A 30W input is split into six to drive three duals, which are then combined to produce about 1KW from about 6KW input at 50V. The power supply rectifies three-phase 415V mains and chopped it to produce 50V at 60A, scary.   A local ATV transmitter was using more than 50 of these to put 50KW up the spout. Pretty old-tech now though, the new lateral MOSFETs from NXP produce 1500W from a single device (two FETs), as Michael T has pointed out recently.   The really interesting bit to me is how simple the baluns are - just a couple of 8cm lengths of special hardline to match from about 12 ohms up to 50, at 225MHz. Transmission line transformers FTW! There's quite a few reference designs for this class of transmitter at http://nxp.com   Clifford Heath.

thekmanrocks@gmail.com: Nov 18 05:01AM -0800 Clifford, Michael:   So you're saying modern ATSC transmitters actually use less power then the old NTs?

Phil Allison <pallison49@gmail.com>: Nov 17 05:56PM -0800 N_Cook wrote: > cooked and melted relay case , so the contact is permanently closed, > explains the switch on and off thumps/chirps , over a few weeks, that > did not used to be there.   ** Typical scenario when an amp has been made to oscillate at a supersonic frequency. The WW resistors in the Zobel overheat, destroy whatever is next to them and then detach from the PCB. If the output devices have survived, repair is simple enough. What event caused it is not a job for a tech but requires a detective with police powers.   Had a DJ customer one who blew his power amp up twice because he did not appreciate the difference between a speaker lead and a signal lead. When he came to me the second time, trying to claim warranty on my repair work, he left very disappointed.     .... Phil

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.