Connect with us

Cannot find this specific resistor, help!

Discussion in 'Troubleshooting and Repair' started by Diamond_ingot, Apr 30, 2022.

Scroll to continue with content
  1. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    Hello, i am looking for a axial resistor that burned out a while ago, it appears wirewound and has "1Ω SEF" on it, is solid red without any color coding, it came from a old Sony TC-260. I have found the part in the parts list, but i cannot find the resistor, hopefully someone with electrical experience can help me find this part.

    I found the resistor by looking on the schematics, but i don't know how to read part lists or resistors.(boxed in red)
    upload_2022-4-30_15-25-25.png
    if you want the full service manual, with the parts list:
    Free download Sony TC 260 Service Manual (audioservicemanuals.com)
     
  2. bertus

    bertus Moderator

    2,435
    955
    Nov 8, 2019
    Hello,

    Looking at the manual, it is a 1 Ohms 2 Watt resistor:
    Sony-TC-260-power filter.png
    Bertus
     
  3. Ylli

    Ylli

    367
    106
    Jun 19, 2018
  4. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    Hello Bertus, and yes i did see that, but does that mean any 1Ω 2W resistor would work, wirewound or not?
     
  5. Ylli

    Ylli

    367
    106
    Jun 19, 2018
    You want resistor that is advertised as "Pulse Withstanding".
     
    bertus likes this.
  6. 73's de Edd

    73's de Edd

    3,294
    1,393
    Aug 21, 2015
    Got the same units big brother de e e e e e e e cades ago . . . . . .while in Hong Kong . . . . at the China Fleet Club.
    Now . . . .? ? ? ? ? ? ? is that resistor REALLY BAD ? ? ? ? ? ? as in looking at its INVOLVED circuitry, it is merely serving as an "electrical shock absorber " in coupling the power supply's 2 full wave rectifiers into the 2 storage filter electrolytic capacitors. Therefore it only takes a minimal charging surge for just an instant after initial power up.
    (Since its only dumping into a little over 1000 ufd . . . . . . . .if it was up in the 10,000 + ufds . . . .a bit more active charge up time would evolve. )
    On mine, I would only expect to see some of its dried red paint flaking / coming off from aging /adhesion loss.
    Expecting yours to look like this . . .
    upload_2022-5-1_3-15-15.png
    Carbon film on the original . . . . . . .metal film or wire wound would just be an overkill . . .but is O.K.

    RE . . . .
    Possible meaning of the "SP": http://www.sanwatsusho-global.com/product/15/15_01_02.html
    You want resistor that is advertised as "Pulse Withstanding".


    That is being a Radio Frequency use related series of carbon film resistors with a selected slurry of coating to mate with the end resistance needed as one linear film deposition. Therefore no need of use of spiral laser trimming and resultant introduction of an inductive aspect.
    I wouldn't perceive ONE . . . . infrequent, single line surge, power up, turn on "pulse" as being significant.
     
    Last edited: May 1, 2022
    Erstwhile likes this.
  7. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    Sorry for the delay, and yea that resistor is pretty important, as when it popped, so did the speakers, and every time i turned it back on, it would start smoking, also about the resistor, they are very similar, for some reason it doesn't let me upload png or jpg
     
  8. kellys_eye

    kellys_eye

    4,658
    1,284
    Jun 25, 2010
    If the resistor keeps blowing then you have a fault elsewhere in the ciruit and the resistor is preventing even more damage occurring by doing you a favour and burning out! Resistors are cheap!
     
    davenn likes this.
  9. davenn

    davenn Moderator

    13,984
    2,015
    Sep 5, 2009
    your files are probably too big

    Use jpg and keep it to ~ 800 x 600 and less than 200kb :)
     
  10. davenn

    davenn Moderator

    13,984
    2,015
    Sep 5, 2009
    Agreed .... if you dont diagnose the fault, you are going to burn out lots of those resistors
     
  11. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    Hello kelly's eye, im looking for the resistor itself, since i havent been able to find it and i believe i know how i blew it in the first place, im pretty sure the only thing wrong with the power supply filter circuit is that resistor
     
  12. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    also thanks to davenn, this is what the resistor looks like, with the "1Ohm SEF" barely visible resistor.jpg
     
  13. 73's de Edd

    73's de Edd

    3,294
    1,393
    Aug 21, 2015
    Sir Diamond _ingot . . . . .

    As the " Optician " sez, DON'T find fault with that current inrush / " shock absorber " 1 ohm resistor UNLESS it has gone open circuit !
    If its too hot, you have an over current consuming fault being associated with the circuitry, on down past my RED arrow marker.


    UNITIZED SCHEMATIC MARKUP . . . . .


    https://i.ibb.co/TvWsSXr/Sony-TC260-Reel-Reel-Tape-Recorder.png
    ( Direct Hot Link . . .as long a its kept hosted )

    [​IMG]
    INITIAL EVALUATION . . . .

    Now, with your photo, that looks like "wire wound-ish" construction.

    Now I 'm Showing the FULL power supply and its BIG power hog users in the unit . . . . the AUDIO POWER OUTPUT TRANSISTORS . . . Herein I am .signifying them as RED mark ups, of their cases..
    The short RED arrowheads are locations of one . . .1 ohm . . . . resistor being associated with each transistor

    Initially refer to bottom left corner for the unit power supply and its use of two diodes in a full wave rectifier circuit , to alternatively catch phase of the AC line output at the secondary of the power transformer.
    The configuration that they are using here is what I call an upside down and backward hook up.
    Your problematic resistor is being the ORANGE flagged unit.
    Two voltage readings are being given on that SAME line, the disparity is due to the X701 transostor being series inserted in the other bottom supply line. That accounts for the voltage differences referenced.
    A touch upon that circuitry design . . . . . . . with its use of a gyrator or " capacitance multiplier" circuit.
    Positive power supply voltage from the center tap of the transformer is fed to the C702 main E-filter . . . C702 which charges up.
    Additionally + voltage is routed to C702 minor filter and with use of a supply resistor of adequately supplying enough base drive, that X701 will solidly conduct C to E , on a bit above the most current ever expected to be needed.
    If the power pull should be enough that the SMOOTH DC level drops enough such that there is a starting of ripple presence, the transistor conducts to make up and get smooth DC again.
    The end effect is that minor 200 ufd times the beta / gain of the transistor , ends up with the filtering effectivity of MUCH MORE capacitance.
    C704 sits down there end for HF filtering and any proclivity for the circuit to transition into a power ultrasonic oscillator after time induced development of ESR within C703.

    TROUBLESHOOTING . . . . .

    Have your . . . a good . . .R702 in circuit, power up just long enough to be able to take a DC voltage measurement across R702.
    Since it is being a 1 ohm unit, you automatically have yourself a current measurement shunt there . . .ergo . . . . the DC voltage reading across that resistor is also your current in milliamperes that is now passing thru it. Now if its in EXCESS of 2 volts you are abusing it. What is it ?

    Next procedure is to move to the schematic and you will find 4 RED marked up 1 ohm resistors associated with your audio power transistors circuitry.
    Do the same procedure in reading the DC voltage across each of them, on time being just enough to get a DC meter reading..
    Ideal situation, would be like readings from all 4.
    Expecting you to not find that .
    After analyzing your readings , we can then see if we have bad or leaky power transistors or quirky diodes or leaky E-caps or mis biasing of the output transistors.

    Back referencing to the power supply section again . . .CURRENT PULL . . . . .referencing suggest the unit pulling 220 ma at no volume or going upwards to 680 ma, at full volume.

    Now GODOITTOIT and do tell us your findings . . .therewith..

    73's de Edd

    In deeeeeeeeeep thought . . . . . . . If I melted dry ice, could I swim in it and not get wet?

    .
     
  14. bertus

    bertus Moderator

    2,435
    955
    Nov 8, 2019
    Hello,

    Here is a reduced color version of the picture.

    Bertus
     

    Attached Files:

  15. Diamond_ingot

    Diamond_ingot

    6
    0
    Apr 30, 2022
    Thanks, im going to try that later today, now to the more important question... dry ice is made of co2 so melting it would just turn it back into co2, and even if you melted it and cooled it so its a liquid, to have such a large amount that you could swim in it will raise some alarms...
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-