- CRT question - 4 Updates
- Help hacking a laser tape measure? - 1 Update
| Jon Elson <elson@pico-systems.com>: Aug 23 01:30PM -0500 On Thu, 22 Aug 2019 12:11:57 -0700, etpm wrote: > I dunno Jon. How would I tell? Measure voltage to ground and see if one > or both changes? > Eric If they have a centering pot that drives one deflection plate, and some amplifier that drives ONLY the other plate, then that is single-ended deflection drive. if they have differential amplifiers that drive both plates in opposite directions, then that would be differential. A scope could show that both plates are driven, but not sure a DVM would give a definitive reading. Jon |
| tabbypurr@gmail.com: Aug 23 12:27PM -0700 > need to be degaussed. I have a demagnetizer designed for demagnetizing > tools. I'm sure it would work to degauss a CRT. > Eric Posting us a schematic would help, but you don't have one. Stating he obvious here you should look at any variation in focus voltage at the horizontal sweep speed. Generally speaking Russian CRTs are perfectly capable. NT |
| Phil Allison <pallison49@gmail.com>: Aug 23 06:03PM -0700 Some fucking idiot called "Eric" wrote: -------------------------------------- > need to be degaussed. I have a demagnetizer designed for demagnetizing > tools. I'm sure it would work to degauss a CRT. > Eric ** Total stupidity. Scope CRTs (unlike picture tubes) never become magnetised, and even if one did somehow it would deflect the trace not de-focus it, .... Phil |
| John Robertson <spam@flippers.com>: Aug 24 08:45AM -0700 On 2019/08/23 6:03 p.m., Phil Allison wrote: > Scope CRTs (unlike picture tubes) never become magnetised, and even if one did somehow it would deflect the trace not de-focus it, > ..... Phil 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. 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. 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... John :-#)# |
| N_Cook <diverse@tcp.co.uk>: Aug 24 04:18PM +0100 On 06/08/2019 17:26, N_Cook wrote: > heights, averaging to about true presumably oe t least offsettable. A > "proper" geodometer with interface topc is far too expensive for this > sort of project. Decoding so far, for anyone else doing similar (J makes an ideal search engine term along with SZYCLCD.COM and ident YGFB178004-A1). 12MHz sampling and 20 M samples per run on the analyser with d0 line for trigger. SPI protocol with d3 as clock,d0 as MISO, d4 as MOSI, 4 bit word length so superfluous analyser 8bit zeros removed in the following. d1 and d2 only active during power-up page , not in measure mode. For clarity and reduction, repeats in the coding via the following look-up table. J= 4,F,D,8,8,D,D,4,1,E,8,C,6,0,C,2,A,0,2,0,5,0,9,2,C,B,1,1,1,1,1,1,1,1,6,0,7,C,8,0,0,0, K= 3,0,0,0,0,0,0,0,0,0,0,0,0,0, L= 2,0,0,0,4,0,7,0,8,0,0,8, N=2,0,A,0,0,8,4,0,8,0,0,4, P=0,0,0,0,0,0,0,0,8,0,0,0, Q=8,A,0,0,0,8,F,0,8,0,0,C, 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, U=0,0,0,0,0,0, Assuming J is invariant for this make and model in question, about 20 readings so far in the 1.000 to 2.000 display range ,it is invariant, L to U would contain variation for units ,hundreds and thousands, DPs and nulls and probably annunciators and other display rows data for the other 3 lines in the display. Single example of coding for the reading 1.264 in the bottom line for the frames sent on pressing "measure" , running the analyser after power-up each time and d0 line trigger occuring after pressing "measure" , second frame is repeat of the first, powering down the measurer after each reading. 1.264 J,K L,K N,K Q,K P,K 2,D,R,K 6,B,S,K C,E,T,K 8,7,U, J,K 2,D,R,K 6,B,S,K C,E,T,K 8,7,U, Preliminary decoding for readings in the range 1.0.. to 1.7.. for tenths in the rank P,K,*,x,R,K,*.y,S,K after the primary ident J, where * is don't care/ignored and x,y is the coding 2 on the LCD codes to (x,y) D,B in the SPI 3 ~ D,7 5 ~ D,5 6 ~ D,D 7~ 9,7 for hundredths, only *.*5* and *.*6* measures in the display so far in the rank T,K,*,x,U 5 ~ SPI F 6 ~ 7 will probably require 1 or 2 other elements for the full set 0 to 9 for thousandths (for eventual use thousandths [mm] would be redundent) R,K,x,*,S,K,y,*,T,K,z,*U x, y, z SPI 1~ 6, 4, 0 2~ A, C, 4 3~ 6, C, 4 4~ 6, C, 8 6~ E, 8, C 7~ 6, 4, 4 8~ E, C, C I might hookup an Arduino or a Pi , as in the intended usage , rather 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. -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm> |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 5 updates in 2 topics"
Post a Comment