• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

CT-600 fuseable resistor where do you buy these?

T

tnmorrow

Member
So I am starting to source parts and I have run across a 4 ohm, 300ma fuse resistor or three of them. What can I use in their place as I cannot find one close to these values. Any suggestions?
 

Attachments

  • DSC_0336b.jpg
    DSC_0336b.jpg
    60.2 KB · Views: 18
Register to hide this ad
Replace them with other flameproof (that's why these were used back in the day) resistors and calculate the right power rating by using Ohm's Law.

Vishay Dale RN, CMF or CPF.

So: P=I^2*R -> 0,3^2*4 = 0,36 Watt. But I don't think 360 mW does exist, so I would go for 500 mW.
 
Sure it will work. I don't like using RN in fusible applications.
 
Standard metal film should do the job. Just make sure they have max clearance from other components as they get HOT ...
 
tnmorrow said:
So I am starting to source parts and I have run across a 4 ohm, 300ma fuse resistor or three of them. What can I use in their place as I cannot find one close to these values. Any suggestions?
Click to expand...

Hello

Why do you want to replace them if they are working well ??
 
Mr. Yamaha said:
You said that before, but why? They are exactly the same as commercial version Vishay Dale CMF, only coated differently and better protected against moisture due to military specs. But still the same flame retardant epoxy coating.

See the data sheets of both:

https://www.vishay.com/docs/31027/cmfmil.pdf

https://www.vishay.com/docs/31018/cmfind.pdf
Click to expand...
jheu02 said:
I love the Dale resistors, but, for use as fuse resistors definitely compare the datasheet of the RN series to the CMF series. CMFs are the identical resistor, but labeled for industrial use, so they're not subject to the MIL-SPEC rating requirements. It can be a BIG difference. For instance, the RN60 series is rated at 1/4W @ 70C 1/8W @ 125C and max rated voltage of 300V, whereas the CMF60 series is rated 1W @ 70C, 1/2W @ 125C and max voltage of 500V (historically was rated differently, now it seems there's a combined datasheet, had to dig this one up).

RN series
http://www.mouser.com/ds/2/427/cmfmil-223788.pdf

CMF series
http://www.vishay.com/docs/31018/cmfind.pdf

So, to get a true 1/4W Dale For use as a fuse resistor, go no larger than RN55 as previously stated.
Click to expand...
John sums it up here.
 
You must log in or register to reply here.
Back
Top Bottom