- CRT question - 15 Updates
- Help hacking a laser tape measure? - 1 Update
| etpm@whidbey.com: Aug 24 10:07AM -0700 On Thu, 22 Aug 2019 09:02:25 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote: >>Eric >Well, there might be a component failure, but let's play with the >knobs a bit more first to see if things improve. Well, I got time this morning to fuss with the CRT. The astigmatism adjustment works but I cannot get the display to be as sharp on one side of the tube as the other. I did degauss the thing too but there was no change. Later today I'll swap the X axis wires and see if the out of focus swaps too. If that happens then it must be the circuit and not the CRT, right? Thanks, Eric |
| etpm@whidbey.com: Aug 24 01:25PM -0700 On Fri, 23 Aug 2019 13:30:31 -0500, Jon Elson <elson@pico-systems.com> wrote: >A scope could show that both plates are driven, but not sure a DVM would >give a definitive reading. >Jon I tried swapping the X axis connections to the CRT and the out of focus conditionn swaps too. So it is not the CRT. I'll contact the contact the kit supplier and see what he says. Thanks, Eric |
| tabbypurr@gmail.com: Aug 24 02:47PM -0700 > contact the kit supplier and see what he says. > Thanks, > Eric We already knew it's not the crt at fault. Another poster that asks and gets the correct answer, but remains entirely lost. |
| Phil Allison <pallison49@gmail.com>: Aug 24 03:17PM -0700 John Robertson wrote: > However the surrounding metal could possibly get magnetized. While I > agree it is very unlikely, it can't hurt to run a demagnetizer over the > setup. ** A demagnetiser for tools is not likely to work on a steel box. In any case the earth's magnetic field deflects the trace on a CRT screen - unless the CRT is fully mu-metal shielded. That is why most decent scopes have a "trace rotate" control that applies a correcting field. > I can't see it affecting the focus though, that does sound more like a > voltage issue, a stray magnetic field would simply deflect the beam to > some extent, but it would not make it fuzzy. ** Correct. > On our old B&W picture tube monitors when the HV at the anode (does this > 'scope have an anode connection?) drops the image gets fuzzy and the > image blooms in all directions... ** Yep, the spot on the face of the picture tube de-focusses and the ( magnetic ) deflection becomes excessive if even some EHT is lost. The simple test for a weak HV rectifier valve was to turn up the brightness, thereby increasing electron beam current and hence loading the EHT supply. OTOH colour sets and monitors usually had regulated EHT supplies. .... Phil |
| Jeff Urban <jurb6006@gmail.com>: Aug 24 06:08PM -0700 >Scope CRTs (unlike picture tubes) never become magnetised, and >even if one did somehow it would deflect the trace not de-focus >it, Nail on the head. |
| Jeff Urban <jurb6006@gmail.com>: Aug 24 06:13PM -0700 Get the print even if you have to scan it. Send it to me. If you cannot get my email here I will give it to you. You send it to me and I will post it where I can hotlink to it. Or don't you have a scanner ? Or did you build this purely from instructions ? You're not even telling us what this contraption is. |
| etpm@whidbey.com: Aug 24 06:29PM -0700 >> Thanks, >> Eric >We already knew it's not the crt at fault. Another poster that asks and gets the correct answer, but remains entirely lost. Hogwash. I went back and read all the responses to my posts about this CRT. Most likely the CRT was not at fault but this was not known for sure. Now I know for sure the CRT is OK. Your reply does nothing to enlighten anybody. You have not posted anything useful. Why is that? You posted "Presumably the electrode voltages aren't staying the same as the thing sweeps across the screen." That's all you posted. Should I take what you presume as being true in all situations? In any situation? Why? And why did you presume what you did? How do I check what you said? I'm trying to learn, what are you trying to do? If I am lost then why not show me the way? When people ask me questions about machining I try my best to help, often with several explanations because some folks don't get it as easily as I do when it comes to machining. Please, if you can't bring yourself to help then don't waste your time responding to my posts, especially since I won't be wasting any more of my time reading yours. Eric |
| Jeff Urban <jurb6006@gmail.com>: Aug 24 08:04PM -0700 How can you build an electronic circuit without having the schematic ? |
| Phil Allison <pallison49@gmail.com>: Aug 24 11:17PM -0700 et...@whidbey.com wrote: -------------------------- ** Wot a tedious wanker.. > >We already knew it's not the crt at fault. Another poster that > > asks and gets the correct answer, but remains entirely lost. > Hogwash. ** Nope - those hogs are not in need of any washing . > enlighten anybody. You have not posted anything useful. Why is that? > You posted "Presumably the electrode voltages aren't staying the same > as the thing sweeps across the screen." That's all you posted. ** That is VERY good answer. Every half decent CRT scope made uses balanced drive to the deflection plates - vertical and horizontal. There is a reason for doing so - it keeps the spot on the screen focussed. YOU have the darn thing in front of you but are so dopey you cannot say if that is or is not the case with your simple kit scope. FYI: When I was 17 and at high school, I saved my pennies and bought all the parts to to make a basic, 2MHz, 5 tube, 3 inch CRT scope. My brother in law fabricated the steel case as an 18th birthday present - I still have it and it works fine - hence my affection for analogue scopes. It uses balanced drive for deflection. The focus is quite good. .... Phil |
| tabbypurr@gmail.com: Aug 25 12:31AM -0700 > waste your time responding to my posts, especially since I won't be > wasting any more of my time reading yours. > Eric Then I won't spend any further time clarifying either. Fool. |
| Jeff Urban <jurb6006@gmail.com>: Aug 25 12:54AM -0700 >We already knew it's not the crt at fault. How ? How can he know that, does he have a spare that acts exactly the same ? If so out with it. I put it 50/50 between the CRT and the deflection drive. And what the hell is this thing ? A dental scale ? A DVD rewinder ? What ? Knows the CRT is not at fault, well then every voltage and waveform should be known to him. Is the plate drive balanced ? Can we at least know that ? |
| Trevor Wilson <trevor@rageaudio.com.au>: Aug 25 07:11PM +1000 On 25/08/2019 4:17 pm, Phil Allison wrote: > My brother in law fabricated the steel case as an 18th birthday present - I still have it and it works fine - hence my affection for analogue scopes. **Try a Rigol DS1054z. A very impressive 'scope for not too much cash and way better than the preceding Rigol (which, if I recall correctly you own/ed). My old Tek analogue 'scope has sat idle for a long time. Like you, I love my old analogue 'scopes (put a bid in for a Tek 7704 last week and lost the auction), but for daily use, the Rigol is unbeatable. -- Trevor Wilson www.rageaudio.com.au --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Fox's Mercantile <jdangus@att.net>: Aug 25 06:42AM -0500 > We already knew it's not the crt at fault. Another poster > that asks and gets the correct answer, but remains entirely > lost. You just have to act like a cunt don't you? -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| tabbypurr@gmail.com: Aug 25 08:47AM -0700 On Sunday, 25 August 2019 12:42:46 UTC+1, Fox's Mercantile wrote: > > that asks and gets the correct answer, but remains entirely > > lost. > You just have to act like a cunt don't you? Let's see. I explained what the problem almost certainly was and how to find it. The OP ignored it. I pointed out that I'd already explained it, the op was then simply rude. So I declined to assist further. Shrug, what more do you want? NT |
| Andy Burns <usenet@andyburns.uk>: Aug 25 04:57PM +0100 Trevor Wilson wrote: > Try a Rigol DS1054z. A very impressive 'scope for not too much cash And easily hackable to add extra bandwidth and features. |
| N_Cook <diverse@tcp.co.uk>: Aug 25 02:17PM +0100 On 24/08/2019 16:18, N_Cook wrote: > than analyser ,for easier taking of pairs of readings/ LCD display > decoding look-up table determination , for the full set. There may be > transcription errors in the above of course. For units decodng From the previous, for unit=1 eg 1.264 R=0,0,4,0,5,0,8,0,0,8, S=1,0,0,8,4,0,8,0,0,4, T=1,0,0,8,F,0,8,0,0,C, unit is more simply represented by the first term of each of R,S and T string and so preliminary look-up table unit ~ SPI R(1) , S (1) , T(1) 1~ 0,1,1 2~ 3,2,1 5~ 1,3,2 6~ 3,3,2 8~ 3,3,3 9~ 1,3,3 10~ 3,5,7 (or maybe 0) , (plus 3,4 and 7 also unknown so far) and the remaining 9 terms of R,S and T are invariant for the readings taken so far. When the sun goes down a bit, I'll try some pairings in the range 10 to 50 metres, for 10s decoding -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm> |
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