- Maybe I need another 'scope? - 2 Updates
- Samsung TV problem - 6 Updates
- speaker refoam - 1 Update
| jurb6006@gmail.com: Nov 26 05:29AM -0800 >"I have a TEK 465B oscilloscope and it has served me well until now diagnosing my CNC equipment. All the voltages I have needed to measure have been below 50 volts. But looking at the 'scope it seems like at the 10x setting on the probes the highest voltage I can measure is 200 volts. That's 4 divisions at 50 volts per division. And that's peak to peak, not RMS. I do have one 20x TEK probe, a P5120, that I used for measuring the mains power, but the voltages inside tube equipment go much higher. " Get a 100:1 probe. They have them on eBay for less than $20. If you don't like eBay there are alternatives. that will igve you 500V/div. at the highest setting. Don't use it on AC coupling though it takes 10 times as long to settle. Well you can buti t takes 10 times as long to settle. >"If you all think another 'scope should be in my future I would love some advice. " The only way a scope would help is if you get an older one that goes up to 20V/div. which would be 200V/div. at 10:1. I keep at least one around just for that. A probe is cheaper unless you want to trade me that 465B for an older Tenma or B&K or something with the higher voltage ranges, but only 15 or 20 MHz bandwidth. >"Now before everybody starts giving me advice about high voltages and all that I need everybody to know that I am expert and know all there is to know about working with high voltages." Famous last words, right up there with "y'all watch this" but I am not your Mommy. I can tell you this, you ain't been shocked until you been shocked by tube equipment. If you really want some thrills try the cathode of a damper tube in a color TV from the 1960s. >"Don't waste my time telling me to put down my drink before I start working around high voltages." That is a very foolhardy attitude, you could spill it ! >"I always use plastic cups for my drinks when working with high voltages." Pussy. >"Oh, and I don't put any salt on the rims of my Bloody Marys either." That's a tokillya sunrise you sot. >"They keep my hands from shaking too much in the morning." The shakes is not from alcohol withdrawal, it is from mineral deficiencies. Get a comprehensive colloidal supplement and take a shot of that before your eye opener every morning. >"I just watched a video about isolation transformers, how to build one in a proper enclosure and how to use it properly." Don't bother with tube equipment unless it is blowing the line fuse. It doesn't like variacs much especially if it has a tube rectifier. Actually if you have selenium rectifiers use a DBT with all the tubes pulled. Also - https://www.youtube.com/watch?v=P9UjxG8sN1c >"And if anybody here thinks I could use some more advice about working around high voltages..." If we don't hear from you anymore we'll figure yes. Update your will. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Nov 26 06:42AM -0800 A proper Bloody Mary has a salted rim. Low potassium will cause cramps and shakes. Oranges, orange Juice, a banana, and so forth will address that issue nicely. V8 juice as well, tomato juice, more so. Peter Wieck Melrose Park, PA |
| Ivan Vegvary <ivanvegvary@gmail.com>: Nov 25 05:47PM -0800 Model LN52A650A1FX2A A section on the lower right side becomes blurry and ghosty. Intermittent on startup and goes away in about 5-7 minutes. Know something about electronics, old tube guy, and have equipment. Any suggestions would be greatly appreciated. |
| John-Del <ohger1s@gmail.com>: Nov 25 06:38PM -0800 On Sunday, November 25, 2018 at 8:47:41 PM UTC-5, Ivan Vegvary wrote: > A section on the lower right side becomes blurry and ghosty. Intermittent on startup and goes away in about 5-7 minutes. > Know something about electronics, old tube guy, and have equipment. > Any suggestions would be greatly appreciated. Easy. Bad display. Could be a bad IC on one of the ribbons or bad ribbon bonding between the address board and display. If it's bonding, you can sometimes stuff some soft foam between the offending ribbon and the display frame, but anything you do is a temporary solution. You can live with it or replace the TV. |
| jurb6006@gmail.com: Nov 26 01:02AM -0800 Flex it. If it clears up try a shim, like card stock or something to keep the pressure on it. Sometime it is hard to discern if a fault is in the panel or the Tcon, but in this case it is in the panel. you might have to loosen a screw or two and stick something under the panel to stress it and keep the connections alive. Also flex all those little ribbons, they might be hard to get at but most of them have COB (chip on board) and sometimes that is what you need to stress. It is is all you can do other than sell parts. You might be able to get Shopjimmy to buy them, or you can put them on eBay. At least you can say you know they're good. |
| Look165 <look165@numericable.fr>: Nov 26 01:09PM +0100 It seems to be a problem of magnetic field (magnets, loudspeaker... nearby) In those old TV there was a demagnetizing bobin for demagnetizing the screen. It was generally fed with mains through a PTC and a PTN or two PTC. after some minutes, this circuit is off. I suppose you get a prblem with this system (Bobin open-circuit ? ). This bobin is generally in a plstic tube which is rectangular formed and placed near the edge of the CRT (take care of the VHV, THT in French). After some minutes, the CRT is demagnetized even if this bobin doesn't work ; this is due to te electrons sweeping, but it is "a long time" for the viewer. You should check the wiring of this bobin Sometimes the PTC(s) and/or PTN (in a plastic "box" with 3 pins) are cracked because of their age. you should look for the common pin and then check each resistor. Heating this part should increase one and decrease the other or increase both of them. Send me a message with your E-mail, I will send you the classic system. Ivan Vegvary a écrit : |
| jurb6006@gmail.com: Nov 26 04:38AM -0800 The model umber indicates it is an LCD TV. |
| Look165 <look165@numericable.fr>: Nov 26 02:01PM +0100 You talked about gaz tube. If it is a LCD, no issue, the mosaic or the back-light is dying. It could be a miscontact in the flat ribbon cable, but I don't think (check it). The back-light is generally fed apart with its plug. If you open, you can check the back-light. But I think you have problems with the data cable. You will need a microscope or a viewer for that check. The question : did it come suddenly or gradually ? |
| Look165 <look165@numericable.fr>: Nov 26 01:49PM +0100 I did refoam speakers (mainly woofers) 5 years ago for my mother and me ; they work pretty fine (8Ohms 45W and 100W peak). The only specific check is the centering BEFORE glueing. The best is to put a cylinder of paper or plastic (about 1 or 0,5mm) around the bobin for centering (take care not to damage the wiring). Then glue the foam ring to the cone and the circular skeleton of the speaker ; NO FORCE TO APPLY ; let everything must rest where it is. After 2 days, take the cylinder off, clean and glue the diaphram. Then let rest for at least 2 days. Goodhifi is a very nice supplier, when you provide the right informations (manufacturer, exact type - written on the magnet...). They also provide tutos for operations (see Youtube). You can get new diaphragms, new cones and the appropriate glue. Before that, check the wiring is OK ; no enammelled wire damaged. Forgive my lack of English. John-Del a écrit : |
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