Can I sub a wire wound resistor for a cement?

[[email protected]]

I cannot get a 180 ohms,20 watt cement resistor locally so I have two
questions:

1)Can I use a 25 watt (180 ohms) wire wound resistor in place of a 20
watt cement (180 ohms)?
2)Does anyone have other OEM part #'s for a 180 ohms,20 watt cement
standup resitor?

To know why I need one you can read below:

We in the past several years have noticed alot of those cheap 25" Orion
chassis tv's come into our repair shops with a domino effect of failed
parts due to a high ESR C446=1 Uf,160v=horizontal driver transformer
cap.The value of R506 and a part # seems to be a popular issue well the
value is 180 ohm,20 watt cement and I finally found a part #:

Panasonic # ERF20ZJ181
Orion # R5W2CH181J

Or you can try using:

150 ohm,20w=Sony # 1-205-938-11

For more info on what I am talking about read below:

25" Durabrand stereo tv modelBTV2500,chassis:M3I05,year:Oct
2000,UL:289X=Orion.Howard W.Sams # 4430.The customer turned it on one
day and it shut off.Upon inspection I discovered the following to be
defective:

C446=1 uf,160v=horizontal driver transformer cap=high ESR
Q401=2SD2499=HOT transistor (shorted)
R506=180 ohm,20 watt (open)= Orion # R5W2CH181J (cement)= 25W power
wirewound resistor NTE # 25W118
=Panasonic # ERF20ZJ181 or you can try using a 150 ohm,20w Sony #
1-205-938-11
R515=1.5 ohm,3 watt (metal)=Orion # R3X28B1R5J NTE # 3W1D5 (feedback
from pin 3=input & pin 4=output of IC501=STR30110) (open)=Orion #
R3X28B1R5J (metal)
IC501=STR30110=pins 3 (input) & pins 4 (output) are shorted

This tv uses the following parts:

FB401=Flyback # FCM-25C001 (Samsung) or 3225010 (Emerson)
Yoke # 7M062505
RCA crt # 63AHC26X

This set is the same as a Memorex MT2251,so you can go to the Memorex
site and download the Service Manual.This set is similar to
Orion/Sansui TV2520 and TVM2515 and the service manuals can be download
free at:

http://www.schematicsforfree.mattsoft.net
http://www.memorex.com
http://ads.hopperinc.com/form/product_search/search.asp?t=1
http://www.memorexelectronics.com

search on Google using those models I discovered that some of the
brands listed below also use that Orion chassis:

Orion
Admiral
Memorex
Sansui
Citizen

Sidney
Dartmouth,Nova Scotia
Canada

 

[Jim Adney]

1)Can I use a 25 watt (180 ohms) wire wound resistor in place of a 20
watt cement (180 ohms)?

I'm guessing that what you're calling a "cement" resistor is what some
people refer to as a "sandbox" resistor. It looks like a little cast
hollow box into which someone dropped some kind of resistor and them
cemented it in place with some sort of ceramic-like material.

If this is what you are trying to replace then you should know that
most of these are just another form of wire wound resistor, and
replacing it with a different form of wirewound should be fine as long
as the wattage is as high or higher than the original.

-

 

[[email protected]]

sidneybek:
With almost no exceptions.... high wattage "cement" resistors are
wirewound.... sometimes they are called sand filled resistors with a
visible sand filling and sometimes they are just cement or ceramic
cases and/or also porcelain glaze covered resistance wire windings on a
ceramic core.
Lower wattage power resistors of a couple of watts or less can be what
is called "flameproof" metal oxide resistors... good for some critical
high frequency circuits because they do not display the inductance
inherent in wirewound resistors.
I would have not problem subbing different kinds of wirewound resistors
for one another. The big considerations are wattage and ohm value
which you seem to have covered by subbing a 25 watt for a 20 watt of
the same 180 ohm value.
electricitym
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