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| "jurb...@gmail.com" <jurb6006@gmail.com>: Apr 08 10:11PM -0700 >" true RMS " = DC equivalent value for the *heating* effect on a resistance. Known. but a DC meter might not be set up for that.To be, it would have to have some sort of filter and they don't really do that because they don't want the load. I think I told the guy to get a resistor and a cap, damn such uncritical values really, cana be 10K and a 47uF, or a 470 and a 10uF. It just doesn't matter if that meter has an input of 10 megs. Of course TRMS might come in handy for an incandescent or some sort of heating element, but for LED it is out of the game. I would think most LED dimmers say rated 400 watts (?) would be ready for multiple LEDs in parallel. This absolutely requires the max voltage delivered with PWM or they will not come on or dim at the same rate. So he was trying to measure PWM on a DC scale, might work on an old style meter with a real meter, but not on this. The first time TRMS did me any good was on TVs. Of all things, the filament winding of the power transformer opened up. I decided rather than change it, run the filament off the flyback. So I did and I wound the wire around the core and the meter read about 6.3 or so on TRMS and I connected it. ZAM it worked. I found out that with that half sine, 70KHz wave repeating at 15.7Khz came to the right voltage at 22 volts peak to peak off the fly. I had adventures in that. Shorted H-K ? We I got a winding for that. Panasonics seemed to be really affected by the capacitance though I tried to keep it low. So I EQed the video output circuit for it, just a cap in the emitter of one of the transistors. Short intermittent ? Fine, I just put like a 4.7 K in there to make it shorted all the time. I did all kinds of shit for that company that nobody else would do. Now this devout, religious person who is partner wants me to lie, to put in a good review on their local whatever they got. I would in exchange for a really glowing review of me but I am not looking for work. I even stopped advertising my business. I got enough now. I doubt the guy in Florida has my number, I might leave it that way. After all this starting a business to piss off the goniffs etc in this business and put them out of business with truth and nice reasonable repairs, I am going to lie ? Geez. |
| Phil Allison <pallison49@gmail.com>: Apr 09 12:19AM -0700 jurb...@gmail.com wrote: ============================ >> This blows Phil's statement out the water which is rare, there is no TRMS in DC. > >" true RMS " = DC equivalent value for the *heating* effect on a resistance. > Known. but a DC meter might not be set up for that. ** You are not paying proper attention. DC voltage and true RMS voltage are equivalent. DC meters read the average, DC value of a wave. ..... Phil |
| "jurb...@gmail.com" <jurb6006@gmail.com>: Apr 09 03:13AM -0700 >DC voltage and true RMS voltage are equivalent. >DC meters read the average, DC value of a wave. No dispute on that, just why a DVM might not read it right. Anyway, of the TRMS, I have noticed my average responding meter comes fairly close. The TRMS one is a Fluke 8050A which I keep on the top shelf, it has more than enough accuracy and the LED display (which is in perfect shape HAHA) is not as easy to read as the 8000A I use as a daily driver. The 8000A has one less digit and is fast, I like it. When I need accurate then well... But then sometimes I read DC voltages with a scope. Put it on DC in most things you get like maybe 25 volts tops ? Five volts per division. Most shit you just need to know if it is there. I don't care from 4.96 or 5.03. "Hack", say it. |
| Phil Allison <pallison49@gmail.com>: Apr 09 04:11AM -0700 jurb...@gmail.com wrote: ===================== > >DC voltage and true RMS voltage are equivalent. > >DC meters read the average, DC value of a wave. > No dispute on that, just why a DVM might not read it right. ** Cannot possibly help but do so. Analog ones do so by virtue of meter needle inertia. DVMs do so by virtue of a simple LP filter at the input. ..... Phil |
| Ralph Mowery <rmowery42@charter.net>: Apr 09 09:25AM -0400 In article <aa517822-c73a-43ed-9ecd-565b93c49f8cn@googlegroups.com>, pallison49@gmail.com says... > DC voltage and true RMS voltage are equivalent. > DC meters read the average, DC value of a wave. That really should be qualified. The way I understnd it is that the RMS voltage produces the same ammount of heat in a resistor as a DC voltage will. However RMS voltage could be a high peak value that will damage solid state devices. The meter could show 5 volts, peaks could be 50 volts. Again DC meters could read many different values depending on the meter and wave form. |
| "jurb...@gmail.com" <jurb6006@gmail.com>: Apr 08 09:28PM -0700 I got to Q4497, it is not being triggered by wither the normal trigger or the auto. I found (IIRC) Q4498 to be bad I think. With it in the end of the sweep switch is pretty much grounded all the time, I changed it and now it has voltage. Regular trig and auto, seems like two problems but as we all know it is likely just one. The only thing I can see dong it to both is the lack of detection of the end of the ramp out the switch. But where is that then ? I understand the Miller type ramp generator and I understand the switch changing the rate of charge, or I think in this case discharge. But somewhere the circle is not complete. Anyone familiar with this circuit or similar ? I am not completely stumped (yet) but I do not want this to take a year. |
| "jurb...@gmail.com" <jurb6006@gmail.com>: Apr 08 09:16PM -0700 A 0.068 reading zero is not uncommon. Most ohmmeters do not measure that low. Suffice it to say it is not open, and it is very unlikely to short. Before changing tht IC, you must find and fix any shorts on the secondary side of the transformer and identify the output pin. It will go straight to the transformers and may have either a cutout around it in the board or a coating of white shit on the board. Whichever it is, if nothing go with the ohmmeter from the top (+ probably) and find a pin that checks pretty much continuity to that gong to the transformer. Now look around, there will be a diode, resistor and a cap Make sure those components are not open and as they are voltage snubbers without them the IC is destroyed fast. |
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