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Why ‘soitanly …just got in a fresh shipment this morning .
And would you be wanting the X axis or Y axis model?
Your circuit is located @ :
http://octopus.freeyellow.com/octopus.html
73’s de edd
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Hee Hee…I see that the URL that I referenced was one for a rudimentary curve tracer semiconductor tester…..however, also marketed in a quite more refined state for ~$700 as a Huntron Tracker Semiconductor analyzer. Sooo, you just might find that information equally usable if you are not already in on the know.
I am currently not able to relocate my URL for the “ringer” test, I will fill you in by experience/memory.
The Old Silly Scope will need access to a sample of the sawtooth signal that is already being used to enact a hoz sweep across the screen for each recurrent lateral trace of the scopes pattern. On old general purpose service scopes, that is typically referred to / labeled as either a saw/sawtooth/sync output or on a more refined Tek or H/P lab quality unit , it is accessible as a + gate output. On Teks it is usually on back at a BNC connector designated as + gate out .
Assuming that you are wanting to test an old flyback transformer or a deflection yoke, the procedure is thus:
To enact a test, have the flyback’s collector(xstr design) / plate(tube design) connective wire removed/floating from the set circuitry and that will then be the sampling connection point for a scope probe with the scope ground wire going to the B+ supply point for the flyback. A wire routes and couples the previously referenced sawtooth sample over to that scope sampling junction via a series .001 ufd capacitor being used.
The hoz time base frequency of the scope is set to ~10 us on a lab scope, or if on an old free running recurrent sweep model, in the ~10-20 khz freq range.
What will happen now is at the start of the trace of the scope , the peak of the sawtooth waveform will be injected to the coupling cap but only its AC element will pass thru on to the flyback , with the DC component being isolated thru the coupling cap, and in reality, only a fast rising spike will be passed on to the flyback. On newer scopes, this may only be in the 5 V P/P range or on some of the older tube kluges, there may be ~ 10 V P/P available. At any rate that is adequate for that short fast rising spike to inject itself into the winding. Now if all is well in the flyback, displayed on your scopes screen, there will be the driven initial positive node rise of a sine waveform and then progressively weaker trailing + and – nodes trailing off to the right. This would represent the recurrent “ringings” recovered from the initial single spike activating the inductor.
The design and “Q” of the inductor typically will result in your counting of 7-10 “rings” off to the right on a satisfactory unit. If testing a marginal fly, the trailing off amplitude and number of rings will be diminished appreciably. With a shorted fly possibly only giving a single damped ring.
The procedure for testing the hoz winding of a deflection yoke is done in the same manner, with it also being isolated from its normal circuitry loop.
It would certainly be most informative to initially test a known good flyback to hone ones analytical skills.
Typically one tweaks the hoz time base freq to get a series of rings to display across 1/2 the screen.However, if that freq is too high, only a short partial sequence of rings will be displayed or if too low in freq , multiple ringings will be displayed.
An impressive demo, if one has access to the open flyback core, and most are, is to do this. Get a series sequential string of rings displayed across the scope and then take a length of solder and pass it thru the
core and then short it to effectively make the presence of one shorted turn being within the flyback.
You will notice a drastic change in rings and their trailing amplitude.
Overall, conveying this electronic anomaly to a mechanical analogy, its like a clapper striking a bell. If all is well, the bell will continue resonating downwards from the initial strike. However, if that bell had a crack or flaw in itself…or even ones hand touching the bell… the resonating effect would be damped proportionally.
73’s de Edd
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