Hey, I'm fairly new to repairing old electronics, I have this old Sanyo boombox that i thought to repair. I changed the belts and everything seemed to be working. After a closer listen the music seems to be getting messier and messier towards to the end of the cassette. Does anyone have any clue why this happens? I would need some diagnosing help! Here is a link to a demonstration of the problem: I would be really happy if someone could help me on this matter, kind regards.
Seems like it doesn't have enough torque to pull the tape when the takeup reel is full. Does this happen with any cassette or just with the one you're showing ? Try to rotate the cassette with you finger/a pencil. Does it rotate freely or there is significant resistance ? What belt did you use ? It is one specifically designed for this unit ? A belt that's too tight can put a higher load on motor, potentially decreasing the torque. How does the supply reel rotate by hand when unit is in play with no cassette ? There should be some slight resistance for backtension, but not much.
Hey! Thank you for the reply! It's on every cassette i tried, i bought a specialised belt kit to install for this specific unit. You can see from the video I've linked that the supply real rotates. The supply real rotates when rotated by hand but has not any tension/resistance of what i notice...
I don't know what to recommend specifically other than make sure everything is rotating smoothly in the mechanism, including the motor. Dried grease can be a problem on older devices, but I can't confirm if this is related to your problem, you must check for yourself. Let us know what you find.
Hi starting with basics did you clean all the pulleys that the belts touch? Isopropyl alcohol on a pad or small cotton tip is the best thing. Have you checked to see if there is any lubricant contamination on any belt? Also, some machines use idler wheels - with rubber tires - instead of belts to transfer the drive for some functions. Even if you bought a specialized kit for this job, it might not include idler tires. Check this because glazed or hard tires won't work well under load. It would also be worth checking the condition of the pinch roller - this *shouldn't* be a factor in change of speed towards the end of the tape as its load is less, but the pinch roller should be at least inspected as part of any work on old tape machines. Good luck!
Thank you for all the help here. I did some cleaning and testing with the cassette player; the problem seems to be that the cassettes seem to be "phasing" more or less. I think I found what is doing this, the tape inside of the cassette seems to be skidding off the capstan wheel between the capstan and the wheel and moving around and therefore not staying in position over the head. Sometimes the tapes are even skidding to the side of the capstan wheel to the side (That is absolutely not good). I found that when pressing the capstan wheel further toward the mechanism keeps the tape in place and stabilizes the problem, now it's just needed to find a permanent fix for this.
You probably need a new pinch roller - that’s what presses the tape against the metal capstan shaft. If it hardens or gets distorted it won’t control the tape path or speed properly. Measure the diameter of the whole roller and the width of the hub and the tire, and the axle. Personal recommendation is, head over to Fix Your Audio and browse Marian’s stock for what you need. Don’t worry if the nearest diameter is a quarter of a millimeter bigger. It’s important to match the hub width so the pinch roller won’t move sideways on its axle. Use nylon washers symmetrically to make up the width if you need to.
Pinch roller is more than likely the typical 13 x 8 x 2 mm one (found in most boomboxes, decks and recorders). It is this one here: https://fixyouraudio.com/product/pinch-roller-13x8x2mm/
Yes, thank you! I took some measurements from it and it seems to be the right size. Also, as I'm fairly need to repairing cassette players, i have had a hard time figuring out how to get the pinch roller out of the holder, could anyone point me in the right direction of what should be done? Kind regards
If I had to guess,there's a little E-clip or circlip on the back side of the axle post. I use a small flat-bladed screwdriver to push it off but they can fly away, some tape or plastic around it will keep it from getting lost.
Alright, i got the pinch roller changed yesterday, the unit seems to be working well now. Thanks for all the help here! ❤️
