Sir Michael:
Are we to assume that since you have had de “hood up” on that critter and that the unit is actually a TVM…vice a VTVM… that is using a FWB diode rectification scheme in the power supply with but a Zener regulator diode on the regulation aspect and that voltage then trickle charges two 18 V supply batteries…assumedly two series pairs of 9 V batteries. The “vacuum tube” aspect of the design is replaced with a tandem pair of bipolar transistors (4x) used in a differential pair configuration.
See if any of that info jives out with your unit…whose frontal appearance resembles an upgraded WV97 series of layout with two additional thumb controls and a mirrored scale…along with Japanese looking function switching knobs as compared to the older, familiar knobs.
In all “plobabrility” the “flied” resistors will be associative with a low range current or ohms functions resistors that are run around in a circle of one of the range switches wafers.
Check the associative resistors out and see if you find a series arrangement of :
.1776 ohms - .3333 ohms - 1.167 ohms - 3.353 ohms - 11.87 ohms - 35.20 ohms - 140.22 ohms and 641 ohms
Or another string would be :
9.75 ohms - 100 ohms -1k ohms -10k ohms -100k ohms -1meg ohms -10meg ohms…of course the 9.75 or 100 ohms probably being the only candidate on this series.
If you find that to be true, you are in luck, as that is the same as is used on a newer series of RCA meter.
If R2 happens to be located in another position, inform me of its electrical connections and I will see if any of the other data I have would be applicable.
Ye olde “new” Wv500B:
73's de Edd
:See if any of that info jives out with your unit…
Hi Edd:
.. only because you are such an accurate and exacting guy.. I thought you might like to know ( It surprised me too!) that "jive" is probably not the word you meant to use but in fact "jibe" is the accurate word here.
Common mis usaage... I made the same error myself for years and still have to catch myself....lol
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jibe 2 (jb)
intr.v. jibed, jib·ing, jibes Informal
To be in accord; agree: Your figures jibe with mine.
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Well….
…..Good show!
Looks like that unit will be measuring ohms properly again, after you have replaced that decade resistor.
I guess that the old carpenter’s axiom would have to equally apply in electronics, with its variant being:
Check the function and range knobs twice and measure once !
Since that solid state 500 series seems to be of the same design, should you ever have further problems in the future ….here is a large GIF of its schematic.
BTW…PBpix….the v versus b was merely an unnoticed typo from a lazy left index finger not quite reaching the b…..and that’s no jive talk!
73's de Edd
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:Dear Sir, I am in need of a schematic. your GIF schematic appears corrupted. I can only see the top 1" of it. RCA wv-500b voltohmyst. Thanks.
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Try the actual posted image:
http://img183.imageshack.us/img183/2288/rcawv500seriestvmschemasg1.png
Carl T
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::Dear Sir, I am in need of a schematic. your GIF schematic appears corrupted. I can only see the top 1" of it. RCA wv-500b voltohmyst. Thanks.
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