Bert Beukema
Well-Known Member
Hi guys,
I've got this fine piece of Sharp Hi-fi; actually it's been stored for a long time. This weekend I thought to service the little beast as it is too nice to just sit in bubble wrap until armageddon. During the service exercise I have:
- Replaced the busted rubber tire around the flywheel (this is essential)
- Replaced the rubber tire on the Take-up Idler (this presses against the rubber tire)
- Cleaned all the other rubber tires & idler wheel
- Replaced the belt with a new one
- General cleaning
- Replacing the lamps on all instances
- Replaced several capacitors (dried)
- Rebuilt the LCD circuit board
- Retouched the solder on most important PCB's.
Now. As with so many 'too complicated for their own good' machines; it works. Hurrah. But there are two problems:
1. Extreme 'warble' sound output
When I play a tape, the machine produces a warbling sound, as if the tape is not spinning correctly. But as far as I can see, everything is moving at a steady pace; no odd pacing issues. I call it 'warbling' because that is what the music from the tape sounds to me. I would generally address this to a bad belt, but that one is replaced and the torque on it is fine. I even tried the old belt (not busted) and it produces the same sound. The Idler Wheel appears to be in OK shape, there are no cracks nor bumps; minimal wear and tear. The tape is fine, it does the same thing on all tapes; doesn't matter which one I use. Repairing cassettedecks isn't exactly my field of expertise. Is this a question of torque? Or take-up speed?
2. The LCD lamps
This is a really odd one. I have replaced the lamps (same fitting, same type). The lamps were dead. There is a button on the machine 'LCD lamps' with the option 'on' or 'off'. However, it doesn't matter which state the button is in, the lamps will always light up. I did not change the circuit, all wiring is original. I have attached the schema. When I test the switch for continuity pressing the switch will move continuity to the four posts on the end of the switch. When not pressed it will have continuity on the first four posts. But, this can never work because when pressed, the first two posts on either side also generate continuity. I.e. it is not strange that the lamps are always burning, they are always getting power. It is very odd for a switch to fail in this manner; I am overlooking something here? Switch was cleaned, didn't change the outcome.
The lamps are not the main issue though, the LCD is near unreadable without illumination. The warbling of the deck prevents it from active duty and i'd rather not dismantle the drive without knowing the area i'm going to work on. It's old and each time the unit is dismantled will stress the plastic where the screws are driven into ;-).
Many thanks for your help & advice!
Bert
I've got this fine piece of Sharp Hi-fi; actually it's been stored for a long time. This weekend I thought to service the little beast as it is too nice to just sit in bubble wrap until armageddon. During the service exercise I have:
- Replaced the busted rubber tire around the flywheel (this is essential)
- Replaced the rubber tire on the Take-up Idler (this presses against the rubber tire)
- Cleaned all the other rubber tires & idler wheel
- Replaced the belt with a new one
- General cleaning
- Replacing the lamps on all instances
- Replaced several capacitors (dried)
- Rebuilt the LCD circuit board
- Retouched the solder on most important PCB's.
Now. As with so many 'too complicated for their own good' machines; it works. Hurrah. But there are two problems:
1. Extreme 'warble' sound output
When I play a tape, the machine produces a warbling sound, as if the tape is not spinning correctly. But as far as I can see, everything is moving at a steady pace; no odd pacing issues. I call it 'warbling' because that is what the music from the tape sounds to me. I would generally address this to a bad belt, but that one is replaced and the torque on it is fine. I even tried the old belt (not busted) and it produces the same sound. The Idler Wheel appears to be in OK shape, there are no cracks nor bumps; minimal wear and tear. The tape is fine, it does the same thing on all tapes; doesn't matter which one I use. Repairing cassettedecks isn't exactly my field of expertise. Is this a question of torque? Or take-up speed?
2. The LCD lamps
This is a really odd one. I have replaced the lamps (same fitting, same type). The lamps were dead. There is a button on the machine 'LCD lamps' with the option 'on' or 'off'. However, it doesn't matter which state the button is in, the lamps will always light up. I did not change the circuit, all wiring is original. I have attached the schema. When I test the switch for continuity pressing the switch will move continuity to the four posts on the end of the switch. When not pressed it will have continuity on the first four posts. But, this can never work because when pressed, the first two posts on either side also generate continuity. I.e. it is not strange that the lamps are always burning, they are always getting power. It is very odd for a switch to fail in this manner; I am overlooking something here? Switch was cleaned, didn't change the outcome.
The lamps are not the main issue though, the LCD is near unreadable without illumination. The warbling of the deck prevents it from active duty and i'd rather not dismantle the drive without knowing the area i'm going to work on. It's old and each time the unit is dismantled will stress the plastic where the screws are driven into ;-).
Many thanks for your help & advice!
Bert
