Sharp HiFi Stereo CD issue and touch buttons going mad

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Hi guys,

here again with couple of new queries and hope to get understanding of it. Have a Sharp XL-12x(y) HiFi system from almost 20 years and it was just sitting in packing for almost 5-7 years. Now brought back to life and works perfect in audio department but has some issues.

  1. Major issue is CD Players has stopped reading audio CDs. It just says “No Disc” to every audio cd.
  2. Second Major issue is its all buttons have gone mad, like when I press volume up then volume actually starts slowing down most of the time and sometimes it works fine. Similarly pressing power button changes mod and so on. (noticed this issue on TV boxes I used when they get old) Wondering why they acquire this issue. Remote controlled operations are fine though.
  3. Its CD tray open/close started giving some issues even before it was abandoned. It sometimes needed a slight push or pull during open/close operation.
  4. Its cassette (yes its that good old cassette thing :slight_smile:) players has loose belts…

Hoping to learn from senior Techs of this group.

Cheers!

1 Like

1 - Clean the head.
2 - Get button’s carbon pads (rear) cleaned.
3 - Lubricate the belts/cogs. Enure the motor is ok.
4 - Replace belts.

Thanks Asad bhai for quick reply.

  1. Already cleaned. Even tried to increased lens power a little by moving variable.
  2. Should clean with CTC with syringe ? as I think it has micro switches like shown in image.
  3. Yes motor is ok as sometimes it works fine and sometimes gets slow/jammed.
  4. I hope I can find these belts in these days as this technology is almost obsolete now. Hall road probably?

Cheers!

1 - If head is malfunctioning, replace it with same or equivalent part.
2 - If switches are used, no cleaning required. However, if buttons are malfunctioning or jittering on contact due to corrosion or any other issue, switch replacement might be needed.
3 - Extract and test motor externally to ensure it is not the culprit. Belts do have some slack deliberately. Do not overtighten which can potentially jam motor too. It might also be that a certain portion of the belt has hardened over time due to lack of use/movement. Please check for it.
4 - Yes, there or old audio/electronics repair shops.

Plan was to try to revive it without major parts change. Will try locating belts for cassette part as this gives feel of good old days. I still have a new untouched box of TDK cassettes laying in home :slight_smile:

Yes probably belts are bit damaged because they haven’t been used in 5-6 rainy seasons and they were bit sticky to touch so replacement is the cure.

Thinking to adjust internal bluetooth module inside also :slight_smile:

Ok. Keep us updated as and when recovered.

Nice to see an old equipment being brought back to life. I love to save the earth from electronic junk :slight_smile:

  1. Out of alignment/Weake Laser head or just needs replacement.

  2. If there are tact switches on a PCB, then the issue might be with the ribbon cable (Attaching the buttons PCB to some other board). Over long period of time, the inside contacts of these tact switches get carbon deposit / oxidation. You can check them with a multimeter, every switch should give almost zero resistance. Change the defective ones.

  3. Tray eject has a separate small motor whose belt is usually the culprit. It is about One inch diameter belt. Check this belt.

  4. You should change the belt and maybe pinch rollers too.

Good luck

Sure Asad bhai, Although always short of time but still will try to work on it step by step.

Nice to see you Ijaz bhai :slight_smile:

  1. From my last disassembly years ago, I can see the red laser light and head moving up and down trying to read the disk. At that time i cleaned it and also tried to adjust its focus, tracking, vco etc but didn’t worked. Hope I haven’t fried it by giving too much power :frowning:
    Yes replacement will be last resort.

  2. I still wonder how ribbon damage or carbon in button force it to work as another button :blush: Like volume down button causes volume to raise 50% of time and works fine other 50% or time. and so on with other buttons.

  3. Sure bhai, I was just thinking I wouldn’t be able to find belts but will give it a shot again.

  4. Aah the pinch rollers… I just recalled the pinch rollers were broken and I used elfy to fixed them almost 5 years ago. probably they will need a change along belts. Don’t know if I can find those for this model easily :slight_smile:

Thank you both for your valuable feedback. I keep learning and experimenting.

Cheers

Keypads are usually (electrically) configured / wired as a matrix. This gives advantage of scanning more keys with less number of input pins. For example, if you want to implement 16 switches in a system and you use “One” pin of IC for one button, you need to use “16” pins.

If you arrange 16 buttons in a 4x4 matrix, you can use 4 IC Pins on Rows and 4 IC Pins on Columns of your 4x4 matrix, thus saving 8 pins.

When any two rows / columns are shorted, the scanning circuit will mis-interpret the keys.

Ahan, Thanks, I recalled Its similar how a cell phone’s keypad is wired. So where exactly the problem exists and how to correct it? need to clean board or switches with ctc?