micronta multimeter resistor

[aleeeeaaa]

I have a Micronta multimeter model 22-204a. There is a burned resistor rated at 0.48 ohms. What can i substitute that resistor with. I don't know what wattage resistor to use. Looking on Mouser and Digikey i noticed it does not list resistors as 0.48 ohms or even 0.50 ohms. Not sure what to order. I need help on this. Thanks, Randy

[BreakingOhmsLaw]

Providing an image or at least the Information whether its SMT or THT or the dimensions would help. That's why you are not getting responses. We're not mind readers, you need to put in put in some effort.

Anyway:
https://www.digikey.com/short/j8hfvpcn
https://www.digikey.com/short/8drqn0b9

[BrokenYugo]

You make odd values with series or parallel combinations of common values e.g.  1+1+12 in parallel comes out to .480. Wattage you need to eyeball it (post pictures, ideally with ruler in frame for scale), find a schematic/parts list that mentions it, or reverse engineer and calculate the dissipation. Guessing this is one of the current shunt resistors?

[floobydust]

Yes I think 0.5Ω with 12Ω in parallel will work, for the 500mA range shunt to get R8 0.48Ω and wattage... at least 1/2W but perhaps higher say 1W to tolerate some overload.
Not sure of the original part's rating.
edit: The original 1970's resistors are made by KOA and metal film, OP's shunt looks wire-wound though. Standard EIA values are 0.47 and 0.481 (but no stock of that could I find).
Going to 0.47Ω would be around 2.1% low on 500mA range DC current measurements, others less lower compared to the original 0.48Ω

[aleeeeaaa]

Thanks, i'll give it a try. Looking at the circuit board picture you sent, it is the black resistor that burned up. Thanks to all of you for the help. Randy

[Wallace Gasiewicz]

.47 Ohm Resistor on ebay

https://www.ebay.com/itm/144955764019?hash=item21c0096d33:g:TFYAAOSww~Rj9PDR&amdata=enc%3AAQAIAAAA4Iph7JrltgFUYL%2BrJJgf0FUxnX%2BAjV8c2trU8uzsQoAA6f6OytGZ6r6ENaioYjZN3iYBCseD2XdsG20zjgyXwxt3KvLPrjlNpzv71%2FLP7sXLfNK15a8E49uZkdzujIC0tqeJwIdL%2Ft1HbFbFKBY%2FUYQ2d6Mj6OO5eaiMqKeKovUEdxha0mU4vzQrvHYrLcIQHb7L3%2BFDH6LniQpiipWuoOZBWaDMzNy8wD2imPJOlh7sa4oSXB1%2BAQ0hfQb4pJEdCltN%2FeTRgeTgRSUBHoLzA53XP0upm%2BWG6BdXIFwKZnkQ%7Ctkp%3ABk9SR8rQv-OEYw

[Kleinstein]

Some manganin wire could be an option. I got some from Ebay that performs quite well:  TC < 10 ppm/K and essentially no thermal EMF against copper, though a little higher resistance than in the tables.
With the 0.2 mm wire this are some 3 cm of wire, so likely better 3-5 parallel strands.

https://www.ebay.de/itm/264311798887?hash=item3d8a35fc67:g:FFcAAOSwocli2oM4&amdata=enc%3AAQAIAAAA4K0DtFlArvnUKBFVakL3W%2FvzAi5V8Krwghrl8xQvjy%2FRWOO6%2BFNaQ%2BOK%2By%2BRBa8ySGxhoXB1m0UY5gVJtJ3PaQjLjpczVtgc6pWy2FKgoxQTV4EDOkZoy6SMkwpbpbouuMS9%2FEEMIIW2IgcPpPgbrd6i2NNkNcKOGeFuzijXUSRsT%2B7AoCl4r5004aO%2FXfxoIeFBVZEJ%2Fh%2F2N%2BaE9uuWy0tbaUy1obNWhshKS6zCjd5XEP0LkPo1aQjmI9dPJwiUYvX8QzI7ju0H8HjkJ%2Bk%2FOuVlwo9CZFhxjxYUaIvhZKkk%7Ctkp%3ABFBMxI-P8oRj

The resistor could anyway get a bit larger form factor for more power handling. 2 x 1 ohm + some 100 ohm to trim may also be an option.

[Wallace Gasiewicz]

Also lots of .24 ohm resistors on ebay.

[BradC]

There are 9 different 470mΩ 1W resistors listed on digikey for between $0.42 and $1.52 USD. That's within the tolerance of a 480mΩ 5% resistor. Grab the 1% 470 for $1.52 and you're golden.

Edit :
If my calcs are correct, using 470mΩ vs 480mΩ will make your low current ranges read low by :
50u   : 0.4 PPM
5m    : 198 PPM
50m  : 2,008 PPM (0.2%)
500m: 20,833 PPM (2.8%)

I'd wager the meter movement isn't that accurate.

[aleeeeaaa]

Ordered the 470 mohm resistor. Thanks for all the help everyone