Actions
Forum Thread Details
  • Replies 21 replies
  • Subscribers 302 subscribers
  • Views 6599 views
  • Users 0 members are here
Related
See a helpful answer?

Be sure to click 'more' and select 'suggest as answer'!

If you're the thread creator, be sure to click 'more' then 'Verify as Answer'!

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

Parents Reply
  • 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.

Children
  • 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 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.

  • in reply to raymate

    I have no experience with fusable resistors. In this scenario the 700 miliohm difference will likely not make the difference, because the motor has a speed setting screw (if I recall well).

    Anyways, it's a later addition, because the first batches also used 12.2 V with the same motor, and they didn't have this fuse.

  • in reply to Jan Cumps

    Yes it does have a speed adjuster. OK sounds good I will just use the 2.2 ohm they seems decent quality. And as a friend said to me it probably doesn't matter its only there to stop people like me doing damage.... Slight smile

  • in reply to raymate

    2.2ohms clearly works but the fusible resistor is meant to handle in-rush current.  Like Jan, I don’t know anything about fusible resistors but you may want to check the current ratings between the 2.2 and a select number of 1.5 examples to see if there’s any significant difference.  It’s not even clear from your photo that the one currently soldered into the board is a fusible one!!

    Size of the resistor shouldn’t matter as long as it meets the service manual spec.  Let us know how you get along.

  • in reply to Andrew J

    My wild guess is that Sony went from no fuse first, to 1.5 ohm at the time the service manual was released, to 2.2 ohm at the time this particular desk was built.

    It looks to be an aftertought added after this series went in production. Likely after they had defect reports from their repair service partners that there was a repeat issue in that part of the circuit.

  • in reply to Andrew J

    Thank you for the reply. This is my first time on this forum and its been a great experience. Once the motor arrives and installed I shall report back. Thanks again for the information.

  • in reply to raymate

    Sounds logical to me, thank you for your help

  • in reply to Jan Cumps

    Could well be.  You’d think Sony would update the service manual.  I wonder if there is a later revision floating around on the web.

  • in reply to Andrew J

    Philips used to send addendums to service contractors with changes. If the product lived a very long life or had significant changes, they'd sometimes release a new version. That was in the paper version days.