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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Jan 29, 2013 5:33 pm Post subject: |
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I can do that!
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Jan 29, 2013 7:17 pm Post subject: |
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even at $20. it's cheap compared to the AD834. That one was either $20. used off flea-bay China or $35. brand new from some outfit called techspec .
I opted for the new one.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Jan 29, 2013 8:14 pm Post subject: |
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OK, I'll buy at least 10 then. I need 3, and 2 for spares. I've only ever had two boards fail with these, so I don't think I'll need a pile of stock.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 29, 2013 8:48 pm Post subject: |
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| Nashou66 wrote: | At 7.50 I'll take at least 3.
What about the AD834 those are 60 bucks now.
Nashou |
I also received some quotes on the AD834 at 12.50 each for 10. But it was the same place that quoted this price on the 835's also. I can check for lower prices on these also if you wish.
I don't mind ordering a bunch of either or both numbers and then distributing them out if I can get a count.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jan 29, 2013 8:50 pm Post subject: |
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Just remember it takes 10 to 14 days to get them when ordered.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Thu Jan 31, 2013 5:09 pm Post subject: Re: What am I doing wrong here? Marquee 8500 |
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| Curt Palme wrote: | I normally don't post schematics, but here's the video output stage of a standard 2035-02 VIM. I've got two here with identical problems- very low output on red on one, green on the other. THe other two channels are fine.
I've narrowed the issue down to the AD835 video output amp. Signal is fine going in, very little coming out. I ordered two new (very expensive, I might add) amps from China, so I put one in. Same problem. I'm not putting in the other one, as I don't buy that two amps would have the same issue. Voltages in and out are fine. I've paralleled the control pins between chips, to see if the red connection will bring down the blue for example, or if paralleling them will bring the red back. Nope, not unless I parallel the chip output, then the red comes on full with the blue output working fine.
So what the heck am I missing? |
The AD835's are not likely your problem. The problem with low output from that chip is usually caused from the control voltage that drives the chips output. That voltage is on pin '8' on AD835.
The problem is almost always U21. Remove U21 and from there put jumpers on "PS1" "PS2" "PS3" right near each of the AD835's
When you jumper the PS connectors you would be bypassing U21. U21 was from the original "Edge Blending" design and was also how they were controlling the the edge blending in the video chain.
I have been removing U21 for the longest, because they seem to not only cause shunted outputs, they also cause the signals to not increase equally when using the contrast/gain controlling. Or can even cause calibration problem by their erratic or non linear performance.
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Thu Jan 31, 2013 5:12 pm Post subject: |
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everyone should use a 03p, much better low level detail.
maybe i`ll etch another board with more groundplane and just attach wires for the power supply spots.
_________________
1 answer always poses multiple questions.
marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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