- Too new to repair? - 2 Updates
- Japan S.Korea Feud - 1 Update
- Thermal Faults - 10 Updates
| legg <legg@nospam.magma.ca>: Sep 27 08:47AM -0400 Somebody brought in an RCA RLDED5098-D-UHD widescreen TV the other day. Damned if I could find service info or any spares on offer. Though it looked like a small post-regulator wasn't running, to prevent operation, there was no way to find out if it was supposed to be off during a protective fault, or what the replacement parts were, from smd coding alone. It looked like the only alternative to the owner, for repair, was a box distributor in the sticks of the greater Toronto area. This would be complicated by a apparent lack of a serial number on the thing. This is the first time I've run into this situation. From a service manual information, I can generally do something. RL |
| John-Del <ohger1s@gmail.com>: Sep 27 06:55AM -0700 On Friday, September 27, 2019 at 8:44:05 AM UTC-4, legg wrote: > This is the first time I've run into this situation. From a service > manual information, I can generally do something. > RL You won't get any help from "RCA".. Try disconnecting the TCON, the LED harness, and any remote and wifi boards and see if it responds differently. Many of these use a particular start (ping-pong) sequence: On plug in, the power supply standby supply turns on which feeds the standby voltage to the main board. The main board starts loading its software - this usually takes about 5 seconds on newer TVs. When the software is loaded, the main board then turns on the "run" supply of the power supply. The power supply turns on and feeds the run supply (typically about 12V) back to the main. The main detects the run voltage, shuts off the power supply and goes into standby to wait for a remote signal or the power contact to be pushed. So if you see the "ps-on" line high and no 12V (just the standby 3.3V or 5V), the power supply is the problem, not the main. If the power supply ps-on line never goes high at any point, the main is bad or being locked up by a peripheral board. It seems that there are two versions of that model; one has a separate power supply and main, and the other has them on one board. So if yours is a really low end toilet, the power supply is combined with the main board, so identifying control lines is a real problem. If you have an all in one it's best to troll the internet and look for a donor. |
| mogulah@hotmail.com: Sep 27 05:16AM -0700 "One of those chemicals, known as photoresist, is critical for top-of-the-line products produced by Samsung Electronics, the giant South Korean maker of chips and gadgets, among others. Japan controls around 90 percent of the world's supply." Japan and South Korea Feud, but Breaking Up Is Hard New York Times - August 28, 2019 -- https://www.nytimes.com/2019/08/28/business/japan-south-korea-trade.html |
| tabbypurr@gmail.com: Sep 26 01:17PM -0700 > > We use carbon film aplenty. The reasons are low cost & good availability. > > Carbon comp is used on occasion for its pulse power tolerance. > In other words, kick the can down the road.... it's not clear what issue you're referring to there. NT |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Sep 26 01:45PM -0700 The fact that carbon resistors have a pretty wretched service life and heat tolerance. Peter Wieck Melrose Park, PA |
| Trevor Wilson <trevor@rageaudio.com.au>: Sep 27 07:24AM +1000 On 22/09/2019 8:46 pm, Cursitor Doom wrote: > is/are the most likely suspects to be considered blameworthy? I'm > guessing dry joints has to be on the list somewhere, but what components > can also give rise to this issue? **All of them, but semiconductors are the most likely culprits. The worst I've seen was a varistor used in the Marantz 2325 receiver from the 1970s. When cold, the varistor was fine. As it warmed up, the amp shut down, due to huge DC shifts. As it warmed further, the amp returned to normal operation. I found that the critical temperature range was fairly narrow. Around 5 degrees C, at around 35 degrees C. It was a bugger to fault find, because the usual freezer spray would transition the component from hot to cold too quickly for the fault to appear. -- Trevor Wilson www.rageaudio.com.au --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| tabbypurr@gmail.com: Sep 26 02:44PM -0700 > The fact that carbon resistors have a pretty wretched service life and heat tolerance. > Peter Wieck > Melrose Park, PA you're clearly misinformed |
| Fox's Mercantile <jdangus@att.net>: Sep 26 05:42PM -0500 >> Peter Wieck >> Melrose Park, PA > you're clearly misinformed 30 years of servicing vintage radios tells me you're the one misinformed. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| tabbypurr@gmail.com: Sep 27 02:08AM -0700 On Thursday, 26 September 2019 23:42:18 UTC+1, Fox's Mercantile wrote: > > you're clearly misinformed > 30 years of servicing vintage radios tells me you're the one > misinformed. Vintage is the key word there. Ancient carbon composition are indeed prone to rising in value & going oc. However carbon film Rs have an excellent reliability record. I've repaired lots of stuff over however many years, and carbon film Rs are almost never a problem. I've no doubt your ego will not permit you to get real, so I see little point continuing this. Others who read this will make up their own minds. NT |
| Fox's Mercantile <jdangus@att.net>: Sep 27 05:42AM -0500 > I see little point continuing this. Others who read this > will make up their own minds. > NT Do you even pay attention to what you write? "Carbon comp is used on occasion for its pulse power tolerance." Which is the worst possible way of using a carbon composition type of resistor. Peter told you that. I told you that. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arie de Muynck <no.spam@no.spam.org>: Sep 27 01:25PM +0200 On 2019-09-27 12:42, Fox's Mercantile wrote: > "Carbon comp is used on occasion for its pulse power tolerance." > Which is the worst possible way of using a carbon composition > type of resistor. Why is that? This is IMHO not about the carbon film type but about modern massive carbon composition. I've used them for > 40 years in e.g. triac snubber networks and they never failed. All kinds of (same wattage rating) film types did fail. Wirewound is also OK but too expensive. Arie |
| Fox's Mercantile <jdangus@att.net>: Sep 27 06:38AM -0500 On 9/27/19 6:25 AM, Arie de Muynck wrote: > triac snubber networks and they never failed. All kinds of (same wattage > rating) film types did fail. Wirewound is also OK but too expensive. > Arie Obviously, you're using the film types incorrectly and not specifying specifying the correct rating for the application. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Sep 27 04:39AM -0700 http://carlscustomamps.com/do-carbon-composition-and-carbon-film-resistors-sound-better https://www.aikenamps.com/index.php/resistor-types-does-it-matter And so on. What it comes down to is cost. And, in my experience, those who wish to believe that cost is not the issue will throw up all sorts of smoke and mirrors around audiophoolery. Peter Wieck Melrose Park, PA |
| 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 - 13 updates in 3 topics"
Post a Comment