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#1
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So "b" is the correct answer to my question... agree? Now, where do you set the baseline "0 volts" before probing a DC voltage? If probing a positive voltage, I set the baseline to the lowest line on the 'scope face and count divisions up from there after the DC is applied to the probe. If unsure of polarity, I set the baseline (with no voltage applied) to the center graticule line and see which way the trace goes when probing the voltage. jr |
#2
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For the DC I put set it to GND and moved the trace to the bottom of the screen and then switched to DC. It moved up as it was positive. Since the DC was showing a waveform, I moved the baseline to the top of the first division so it would show the entire waveform.
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#3
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jr |
#4
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I just scoped all of the B+ 125V to and from each of the modules. It was consistent throughout, if I thinned out the waveform, it was roughly 1 VPP before it lost the trigger. If you count the fat wavefrom, it would be roughly 3.5 VPP. So I'm pretty sure 1 VPP of ringing isn't going to create the jail bars. That and I've pretty much ruled out the ABL. Not sure where check next. I've done the horizontal oscillator, wave generator and output on the horizontal board. I don't have the probe necessary to do anything with the FB, yoke or HOT.
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#5
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Okay, moved on the 240V boost section. I'm attaching three waveforms. Each are done at 50V/div and 20us/div.
The first is directly from the lead off the flyback where it connects to the boost diode. It's taller than my scope can display. I didn't realize it was 900V. Glad my scope didn't do something bad. I'm growing fond of it. The second is on the other side of the boost diode and is now 248V. The waveform covers just over two divisions, so it's just over 100V and there's ringing in it. The third is through a resistor and to the 10uf 300V capacitor. Again, I'm getting a really crappy waveform, but the basic form is the same as pic 2. Now I tried scoping the other 240V boost, but I couldn't get a meaningful waveform. Where I scoped for pic two, it splits off from there to another point where it's connected to a 15ohm coil. It measures at 248V, but the waveform is pretty much non-existent. Don't know if it's the coil smoothing it out, or if my settings aren't working for it.
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
Audiokarma |
#6
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I don't understand "other"... are you saying that the set actually has *two* sources of 240 Volt "boost voltage"... I suspect that there is only one source and it is distributed to other boards that may be marked "B+ or 240V", but these are boards where the 240V is used, not produced?
jr Add: same for the 125V supply... two sources would seem to be unlikely. Last edited by jr_tech; 09-30-2013 at 04:55 PM. Reason: add 125 v comment |
#7
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#8
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Yes C-1 is Zeniths term for composite video. Some sets
even have a "C-1 adjust" pot. Grounding the ABL base proves its NOT coming from there so ignore all between the ABL base & tripler. Depending on the scope I was using I almost never used DC only AC since I was looking at waveforms. On my sencore there was a built in meter to speed things up. Also be sure all your calibrations are set. The are the red knobs are set to "cal". Some have an arrow to show which direction to turn them. If the scope is dual trace you can use sync on B to stablize the waveform. Hook the B channel probe to a clean hoz signal such as the hoz drive collector, this may get rid of the multiple traces. 73 Zeno |
#9
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Yes, the red knobs are in the calibrated position. Not ready to mess with those kinds of adjustments. When I check the C1, I get a staircase type pattern. Is that what it's supposed to look like? I have the pattern generator on the color bars w/IQW and chroma off. That gives me long b&w bars on the screen. Inside the set there's a sheet glued to the wall. It has a section w/the heading of "Major Test Points". The first one is C1 (Picture Detector Output). The other two are used for calibrating the ACC and some IFAGC.
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
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