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Help with fuse resistors please to fix a tape deck

raymate

Im new to electronics and I have an old cassette tape deck that I was getting going but managed to short something and burnt out a fuse resistor.

Now we are dealing with a tape deck thats 30 years old so no one will fix it in my area so im learning to try and fix it myself.

So I checked continuity and found the resistor that has blown I also saw smoke come from it when I killed it so im pretty sure I just need to replace it.

The service manual says its a " fusible resistor 1.5 5% (1/2W) F " located at R736 but when I look at the resistor on the board it seems to be 2.2 not a 1.5  .....  if I'm reading the resistor right?

This is the help I need, is this dead one on the board 2.2 or 1.5  ,  could it be possible they used 2.2 not a 1.5 as I think its just acting as a fuse. Should I put back what the service manual says or the same as what already in place.

Attached the picture of the resistor thats dead on the board and has no continuity, i ordered online what the service manual says and what I think is the direct replacement for whats still on the board.

So I purchased three resistors types 1.5 and 2.2 (and another 2.2 from a different vendor) also the new ones are so much smaller I guess thats OK things have moved on in 30 years.

So I would like to know have I purchased the right thing. Im just confused as the new ones seems to have arrived with 5 bars.

One I purchased said its a " res 2.2 OHM 5% 1/2W AXIAL " (this is the smaller one in the picture) the other larger ones are generic from ebay.

Thanks for your help, I know this is basic stuff.

imageimage

  • It's possible someone has bodged a 2.2Ohm resistor in there in the past - have you had the cassette deck from new?  A fusible resistor should have a white band around it (maybe, see below), like your smaller middle 4 resistors - the one that's in the board doesn't but maybe there is writing on it that isn't visible?

    Anyway, it's not that basic a question really.  Doing some research, I've come across:

    • A fifth white band is fusible resistor
    • A fifth black band is a fusible resistor
    • A fifth black band could be temp coefficient
    • A fifth white band means wire-wound.
    • And others...

    If the service manual says 1.5 1/2W 5% then if it was mine, that's what I'd be replacing it with (or <5% or >1/2W, view those parameters as maximum and minimum respectively.)  You could try the 2.2 Ohm as I guess it will still work and you have them on hand, but as its job is protection it may be worth shelling out for the correct one.  In either case, I would replace with a known manufacturer with datasheet specifically indicating fusible, not something off eBay (unless that of course.)  You want to minimise any issues relating to dodgy components!

    Let us know how you get on - perhaps create a blog of your testing/diagnosis/progress as it always generates interest and help.

  • Can you post the info from the service manual, and the schematic that shows this component?

    Did it work before you caused the smoke? What did you do that generated the smoke? What components do you think you shortcut?

  • in reply to Andrew J

    Thank you, leant something new, the fifth band can mean type,, nice. the small one was from digi-key so I assume a OK quality one, the larger ones are ebay specials, so I may get the correct value from digi-key

  • in reply to Jan Cumps

    One of the motors in the deck is not spinning so I was probing the motor terminals and it did show me 11.5v going to the motor which is correct but for some reason I was checking it again to make sure and I got puff of smoke and no more 11.5v, I caught the smoke from the corner of my eye and just started checking components in that area, this time with the power off. I found this resistor had no continuity and one lead from this resistor goes to the motor. 

    Does this show you enough?

    imageimage

  • in reply to Jan Cumps

    Not sure if im allowed to upload a PDF but if you search " sony tc-k677es service manual " you can easily find the PDF service manual 

  • in reply to Jan Cumps

    Oh and its the motor M1053 capstan motor that does not get power now

  • in reply to Jan Cumps

    So I shorted the motor terminal M1053 and that caused the smoke, im almost 100% certain its just the R736 I killed. No the motor was not turning and I have another motor on order I was just checking that it was getting power. Deck is 30 years old and I got it used..... un working, doesn't look like anyone has been inside and tinkered with it.

  • in reply to raymate

    First looks, there isn't anything on that fuse but the motor and an LED.
    This is normal, because in most tape decks, the capstan always runs when the deck is powered on. Also one of the reasons why it gives up first.
    With a bit of luck, you only damaged the fuse. Can be checked by measuring if one side of the fuse still sees 12.2 V DC, compared to earth.

    Without luck, you may have damaged the 2 controller ICs next to it. You can test that by seeing if the deck tries to do at least something  when you press fwd, rev ...

    You'll have to fix the capstan motor if the deck is not dead, but first check if you only blew that fuse.

  • in reply to raymate

    on the other news, I have this one: Sony TC-K(630ES)570

    (edited because I just realised I sold the 630 in 2014 according to my mail archive, still have the 570 - I think)

  • in reply to Jan Cumps

    Think I might just got lucky and just killed the fuse, everything else on the deck seems to work, it will fast forward and rewind. It engages and moves up the heads into position when play is pressed still.

    Got the deck from a thrift store and wasn't aware the flywheels should always be spinning when I opened it all I saw was floppy belts, so change all the belts and only then worked out the tape would still not turn and only then seeing a youtube video worked out the flywheels should always spin. So then turned to the motor.

    Like you say it always should spin so maybe just worn out.

    Replacement motor is coming from Slovakia so its not with me yet, so to be honest until I install that I'm not going to probe anything else as I'm not completely sure what I'm doing and don't want to kill anything else, I can change parts and solder but thats about it. If after the motor changed still not playing I will check the voltage going to that fuse.

    In regards to the fuse/resistor do you have any idea why it says 1.5 ohm in the manual and its actually got a 2.2, in your view does it not matter that much in this circuit. If its only going to a LED and motor? or do you think I should just buy a 1.5 ohm one, the originals are rather large, the replacements are about half the physical size. I have the decent 2.2 from digital-key that I can use, they are awfully tiny in comparison to original. Guess that should not matter they are the correct spec... on the packet it says " RES 2.2 OHM 5% 1/2W AXIAL "

    Thank you so much for your time and input, you have been super helpful.