good oscilloscope for vector rescanning?

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TV-OD
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Post by TV-OD » Mon Aug 19, 2013 5:04 am

Well I checked inputs against the chart and found an issue.

Verticle ramp into verticle - as it should be
Horizontal ramp into horizontal - it sits at a 45 degree angle.

I have read and re-read the manual for the scope and, as far as I can tell I have everything setup correctly for XY. Plug an audio synth in and I can make nice figures.

Stumped.

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Revok
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Post by Revok » Mon Aug 19, 2013 5:13 am

Is there is a little screw labeled rotation or something along those lines on the scope?

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Post by daverj » Mon Aug 19, 2013 12:06 pm

Are you saying that if you feed a V ramp into the vertical input with nothing into the horizontal input you get a straight up and down line. But if you feed an H ramp into the horizontal input and nothing to the vertical input you get a diagonal line?

If so, that is odd. With only one input used you should get a straight line up and down or left and right, but not diagonally. It also doesn't matter if you are feeding a V ramp into the vertical or horizontal input, or feeding an H ramp into either the vertical or horizontal input. With only one input used you shouldn't have a diagonal line. If that happens it sounds like there is some kind of internal connection and mixing from the horizontal input to the vertical.

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TV-OD
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Post by TV-OD » Mon Aug 19, 2013 7:44 pm

Revok wrote:Is there is a little screw labeled rotation or something along those lines on the scope?
There is something on the back but I feat that would simply rotate the entire image.

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Post by Revok » Mon Aug 19, 2013 7:49 pm

What scope are you using?

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TV-OD
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Post by TV-OD » Mon Aug 19, 2013 7:50 pm

That is exactly what is happening.
I have plugged in and unplugged many times and everytime that is what I see.
So - yes - something strange inside the scope.
I think I will lay this scope to rest for vector rescanning. In the end the output was not very clear, no matter how much focusing I did.
Given this odd problem, time to look for another scope.
I can still get nice enough Lissajous figures and such on it - yet to try it as a video waveform monitor - so it will not go to waste.

Many thankyous for all the advice !
daverj wrote:Are you saying that if you feed a V ramp into the vertical input with nothing into the horizontal input you get a straight up and down line. But if you feed an H ramp into the horizontal input and nothing to the vertical input you get a diagonal line?

If so, that is odd. With only one input used you should get a straight line up and down or left and right, but not diagonally. It also doesn't matter if you are feeding a V ramp into the vertical or horizontal input, or feeding an H ramp into either the vertical or horizontal input. With only one input used you shouldn't have a diagonal line. If that happens it sounds like there is some kind of internal connection and mixing from the horizontal input to the vertical.

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Post by TV-OD » Mon Aug 19, 2013 7:53 pm

Revok wrote:What scope are you using?
It's a BWD 820 - old Australian scope.
Very vintage looking.

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Post by Arturo00 » Thu Oct 03, 2013 10:03 pm

Hi guys, I just got my Leader LBO-51MA. It looks very nice, only problem is there seems to be burn in marks of some sort smack dab in the middle of the screen. Bummer. :sadbanana: I assume there's isn't much I can do about the blotches aside from changing the CRT?

I'm waiting to hear back from both the seller and Sphere.bc.ca about replacement CRTs. Anyone happen to know the part number off hand? :despair:

Any other suggestions?...other than to just live with it :(


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Post by daverj » Fri Oct 04, 2013 6:19 pm

Burns in CRTs are basically where the phosphor has been eaten away by a repeated strong beam hitting it. The best fix is to replace the CRT and then be careful about bright spots remaining in one area too long.

Some displays have burn protection that reduces the beam strength when it is concentrated in one area. That can help reduce how easily a CRT burns, though never completely prevents it.

One trick that we used to use for tube cameras that got burns was to point them at a bright white card for a long time to burn the rest of the tube, which somewhat reduced how noticeable the burn spots were. The equivalent with a CRT would be to fill the screen with a strong signal covering the whole screen and let it slowly burn the phosphor away to try and make the difference between the spots and the rest of the screen less distinct. But chances are it won't work very well, if at all. A new CRT would be better.

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Post by Arturo00 » Tue Oct 08, 2013 2:28 pm

Thanks daverj. I don't think replacing the CRT is really within my realm of capabilities. I was informed that calibrating the CRT can be pretty intensive. I guess I'll just try to find another scope and hope the screen is ok on that one.

Oh well. :bang:
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Post by daverj » Tue Oct 08, 2013 4:40 pm

Replacing a CRT is fairly basic. It's all mechanical. Getting a replacement CRT on the other hand is getting more difficult.

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Post by Arturo00 » Tue Oct 08, 2013 9:15 pm

I believe Sphere has one, or she thinks she has one but I can't find the CRT part number to varify. I'd have to take my CRT out completely to get the number and I'm not sure I want to do that at the moment.
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Post by xart » Fri Oct 11, 2013 5:28 am

Arturo00 wrote:Hi guys, I just got my Leader LBO-51MA. It looks very nice, only problem is there seems to be burn in marks of some sort smack dab in the middle of the screen.

This seems to be very common on the Leaders...

I just picked up 2 of them on eBay that look very nice but have 'marks' on the screen....presumably burn marks? They are on the inside of the crt - not on the glass. When you get them at auction on eBay there is no way you can tell with photos because of the graticule...and people selling them have no idea what your talking about when you ask questions...

I get our lzx back next week and will be able to do some tests...but I am guessing these are burns. :hmm:

Do you have to amplify the LBO-51MA is is it plug and play with the lzx?

Thanks video wizards! :tu:


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Post by Cat-A-Tonic » Fri Oct 11, 2013 9:41 am

The voltage levels on that Leader LBO-51MA are delightfully plug and play with LZX. :tu:
No amplification required. Just use the Video Blending Matrix & Ramps.

I've got the same one with burn spots in the middle too. :mad:
I brought mine from the states to Japan in carry on luggage.

I wonder what the chances are of scoring a clean one in Akihabara... :hmm:

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Post by Arturo00 » Fri Oct 11, 2013 10:22 am

xart wrote:
Arturo00 wrote:Hi guys, I just got my Leader LBO-51MA. It looks very nice, only problem is there seems to be burn in marks of some sort smack dab in the middle of the screen.

This seems to be very common on the Leaders...

I just picked up 2 of them on eBay that look very nice but have 'marks' on the screen....presumably burn marks? They are on the inside of the crt - not on the glass. When you get them at auction on eBay there is no way you can tell with photos because of the graticule...and people selling them have no idea what your talking about when you ask questions...

I get our lzx back next week and will be able to do some tests...but I am guessing these are burns. :hmm:

Do you have to amplify the LBO-51MA is is it plug and play with the lzx?

Thanks video wizards! :tu:


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That was you eh? Hahaha. You won the first two and won the last one. Did both of yours have burn in marks? I certainly hope the one I get doesn't have them as well or I'l be pissssssssed!
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Post by xart » Fri Oct 11, 2013 10:35 am

Arturo00 wrote: That was you eh? Hahaha. You won the first two and won the last one. Did both of yours have burn in marks? I certainly hope the one I get doesn't have them as well or I'l be pissssssssed!

ok. new rule video assholes....lets tell each other when we are bidding on this junk.....I would have NEVER bid up the price to $80 if I knew it was a forum member.... :tu: sorry about that.

yes..both of them are super clean but with burn marks - I'm returning them if they don't test out well (thanks ebay :tu: ) and will just keep ordering until I find a good one...unless all of them have burn marks...this is what I am beginning to suspect...

Ill know more when I get my lzx back next week.

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Post by Arturo00 » Fri Oct 11, 2013 10:43 am

I figured it was someone from here. Not sure why I didn't say anything...coulda saved me a few bucks. Oh well...

This seller has tons of these for sale and has been selling them consistently since at least early July, if not longer. But the problem with returning them and repurchasing is that you'repossibly going to end up with the same units again. That would be my fear. The issue for me is that these guys don't ship to Canada, so I have to travel to Ogdensburg, NY (about an hour and an international border away) to pick it up.

Anyway, I'm pretty much accepting that this new one I bought has marks. Does ANYONE have an LBO-51MA that DOESN'T have burn marks on the CRT?
Last edited by Arturo00 on Fri Oct 11, 2013 10:51 am, edited 1 time in total.
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Post by Arturo00 » Fri Oct 11, 2013 10:44 am

DP :bang:
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Post by johnnywoods » Fri Oct 11, 2013 1:49 pm

Arturo00 wrote: Anyway, I'm pretty much accepting that this new one I bought has marks. Does ANYONE have an LBO-51MA that DOESN'T have burn marks on the CRT?
Mine is clean. I think I lucked out. It looks like it was barely used.

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Post by Arturo00 » Fri Oct 11, 2013 2:51 pm

The one I have now still had the plastic wrap on when I first got it, like it was brand new. Aside from a little gash on the top of the case, it looked brand new. I would say that one of the only signs of wear on mine are the blotches on the CRT...and the gash of course.
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Post by nickciontea » Sat Oct 12, 2013 1:37 pm

ask for refund from the ebay seller.. explain that you use these for documenting/photographing/filming. and that these units are subpar.

ive gotten plenty of units for free that way

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Post by Arturo00 » Sun Oct 13, 2013 12:37 pm

nickciontea wrote:ask for refund from the ebay seller.. explain that you use these for documenting/photographing/filming. and that these units are subpar.

ive gotten plenty of units for free that way
Oh wow. So they don't ask you to send it back? I'll only do that if the display is actually defective, but it's good to know this has worked for you in the past. Have you dealt with this particular seller before? Esssurplus. Their auctions only have a 14 day DOA warranty.
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Post by wcfields » Sun Oct 13, 2013 2:28 pm

Ballin' hard with Tektronix 608. Found some surplus seller on eBay that was selling them for $70 shipped each!

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Post by nickciontea » Sun Oct 13, 2013 2:53 pm

nice! I have two 608s, one with a white phosphor trace and it's fantastic.

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Post by abzmuff » Tue Oct 15, 2013 12:23 pm

hey guys, just getting started on vector rescanning. wondering if there's a waveform monitor on the smaller size for flying around, or, if any of you have one i could borrow in Berlin. doing some visuals throughout europe.

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