want to get data sheet/ specifications of old (20 years) passive
electronic components:
Part number IRC 8903; RB-4; 30M ; 15%.
Also, part # 8533TRW PW22, 12K; 10%; 863-0135
 I do not know the name of the components. I have given the
inscrptions as they appear on the components.

---

Clarification of Question by kag5-ga on 16 Dec 2004 14:04 PST

On 10th Dec, at last I located an old electro air technician turned
distributor 20 minutes from my home and he dug up an old model used
but working pwr supply board complete with all the resistors, doides,
caps & lamp for $35. I have substituted my old defective one with this
one and the air is now being ionized like a charm. Apparently an AC
capacitor 5000V, 0.011uF was partially bad!30M resistor is new in the
board he gave me.
 Any way the problem is resolved and I learnt a few things. Thanks
very much to Guzzi-Ga for his patient follow up.

Part number IRC 8903; RB-4; 30M ; 15%.

This is a resistor manufactured by IRC (now part of the TT group).
Value 30M ohm, tolerance 15%, power rating unknown but might be 4
watts. This will be a film resistor. If you can post a full
description of the item, including size, power rating could be
determined.


part # 8533TRW PW22, 12K; 10%; 863-0135

This is a resistor manufactured by TRW (who seem to have disappeared).
Value 12k ohm, tolerance 10%, power rating possibly 22 watts but might
be 7 watts. This is likely to be wire-wound and the winding might be
visible under the coating. A full description will determine.

If you want substitutions, in addition to full details state your
county. Might be a problem with the 30M resistor but lower values can
be wired in series.

Data sheets (if available) would say little more than what you already
know. Not critical components. Only proviso is the voltage rating of
the 30M -- any idea what might be expected?

Best

These resistors were found in the power pack of old (about 20 years)
Electro Air electronic air cleaning unit model 14C12V-01000. I find
one of the resistors 2"x 0.5" x flat (IRC#... w/axial leads ) has
blackened. I am indeed trying to get replacement/ substitution/
procurement details. Original mfg is helpless. I live in allegheny
county in PA. This should not matter for procuring from elsewhere.
According to the mfg (emerson.electronicaircleaners.com) website
downloaded check-out sheet, at one end of this resistor the open ckt
voltage could be up to 8000VDC +/- 750V.
The other resistor 2" x .5" x .5" w/ axial leads bearing #TRW...is not
bad as yet but still want to have a few as handy spares.

I suspected it was an ioniser you have. Are you absolutely sure the 30
meg resistor has failed though? Sometimes they go black from
contamination, especially when there is 8kV on it. It is however a bit
dangerous if blackened because the high voltage can flash across the
contaminant. I would suggest that you clean it first with gentle
solvents -- soap and water is a good start. Contrary to popular
notion, water doesn?t usually damage electronics it gets a brief
soaking when unpowered then (completely, absolutely, totally) dried
off. Alcohol in the form of ?solvent cleaner?, meths, surgical
spirits, bourbon (NOT Scottish single malt!) often does a good job.
The last three are very impure though and after use must be wiped very
clean and then washed with damp soapy rag then clean water. White
spirits (turps) and nail varnish remover (acetone) are often good too.
In all cases, test a small part of the coating first and make sure the
solvent doesn?t soften the coating.

The reason I would suspect the 30 meg resistor is OK (apart from dirt)
is that it isn?t under any great heat stress. If you choose to clean
it you might be able to borrow a meter to test the resistance. Most
don?t go up that far though but if you can find one which measures up
to 20 megs (quite common) it should measure open circuit. Bear in mind
that your fingers will conduct far more readily so when you are
measuring it, clip the leads on and don?t hold on to it. obviously it
would be best if you could actually measure about 30 megs but if when
the unit is powered up there is a spray discharge it should be OK. A
pointed tip on the end will blow a flame and make a shishhh noise. You
might also see a slight blue discharge.

The 30 meg resistor would dissipate a maximum of about 2.5 watts if it
was shorted to ground, though it might be considerably less depending
upon the rest of the circuitry. High value, high voltage resistors are
not common, and usually quite expensive. Lower voltage (a few kV
rating units are more readily available and could be perfectly safely
wired in series to near enough 30 megs. I could search out suppliers
in the States, or do you ever buy stuff from a company? Try the
cleaning and testing first though.

The 12k resistor is no problem. The size suggests that it is about 12
watts but I can?t say what the actual dissipation is without knowing
the rest of the circuit. If there is no transformer and it is running
from 120 volts, the dissipation should be less than 2 watts. Again
though, try to measure the resistance first. Just because it has
surface contamination doesn?t render it faulty. Even though the
voltage across it will be relatively low, best to clean it too though.
If everything works after cleaning, that resistor could get quite
warm, but it?s unlikely to get so hot that it burns your finger unless
there is a fault somewhere. Running at warm temperature, one can
expect a lifetime of tens of years as long as there is no corrosion.
If faulty though I could search out suitable replacements.

I?ll watch out for further communication.

Best

How did you get on? Do you still think you need new resistors?

Best

I thank Guzzi-ga for for his lucid clarifications on resistor/ their
characteristics etc. and also for his continued interest to follow up
my problem. His comments were helpful to  also look for trouble
elsewhere. I was able to measure the resistors with a Radio Shack
digital multimeter and all the resistors check out for the respective
M-ohm values. Unfortunately,I could not borrow HV probe nor afford to
buy the least priced probe (Tenma) for ~$90.00 for one time use to
electrically check the various obsolete parts involved in the power
supply system. I have traced the circuit and put in a dwg format. By
the way how does one send attachments to the comments? I could e-mail
the .pdf document if Guzzi-ga is willing to offer any helpful
suggestions. I could perhaps buy a new (approx. $125) substitute
complete power supply unit with lot of electronics as seen in a
picture in Bel-aire electronic air cleaners web site and save all the
hassels with old / obsolete parts. But I am leery of its durability. I
feel I should be able to invest about $25 worth of few new components
in the present unit and have the whole system going for quite a few
years more. I think this makes economical/"scrooge(?)" sense. Indeed I
have procured a few parts from Allied electronics and wish to replace
the 2- diodes one by one and also 2- 5KV DC capacitors. I know this a
crude method of trouble shooting! I am still stymied for a substitute
for .11uF, 4KV AC capacitor. Yes, the whole process of researching for
equivalent components, procure and try them out is frustrating and
time consuming but I have not yet  given up. I think, I will now
measure with decent/ ordinary multimeter current (mA) in some HV
portions of circuit just to examine if the components are good at all.
I wonder if this a good idea?
 By the way the 30M resistor is encapsulated in a thin flat blue
sleeving and the discoloration is from inside, translucently visible
from outside. All components have axial leads and are soldered. I have
so far hesitated to de-solder and 'play' with the components.

Hi kag5. Thanks for the thanks. We are of a mind with saving things
from the bin. Scrooge is my hero, especially at this time of year ;-)

I?ve seen HV resistors in a blue sleeve before, not tight. It would be
best to remove the contaminant but (gentle) solvents can?t really be
introduced. You could possibly heat the sleeve to soften it so it can
be eased off. Either that or carefully snip it off it and replace with
heat shrink of similar thickness -- bearing in mind that the substrate
is likely to be ceramic so mustn?t be allowed to scrape metal off any
tools.

Are you sure the 4kV capacitor is 0.11uF? That would be a heck of a
beast. Definitely not 0.11nF? Is it disk ceramic or plastic?

I do wish Goog had a mechanism for document transference but most
questions are word nature. Tough for techies. If you?d like to post an
email address (encrypted a bit to avoid crawlers) I?ll link up with
you and I can have a gander at your circuit. Alternatively, do you
know anyone with a web page you could post it on? No rush, but you
expire on the 16th, if you see what I mean.

Best