CPC 464 Tape Deck clicking/popping on playback

[jm100]

Hi all,

Long time reader, first time poster!

Looking for some validation/advice on a noise that my 464's tape deck has been making - sort of a clicking or a popping. Seems to happen on playback and on FF and is coming through the speaker, as if I turn the volume off I can no longer hear it. Also seems to happen even with no tape in the drive, so doesn't appear to be tape related.

I've serviced the following parts of the deck recently:

• New belts
• New idler tyre
• All new Rubycon capacitors on the tape PCB (apart from the non-polarised one as I didn't have any in stock)
• Cleaned pinch roller and tape heads with IPA 99

Also seems to be a bit of wobble in the tape signal but not sure why.

Concerned if the popping is happening over the tape signal it could be leading to unnecessary read errors?

I have a Mabuchi motor in stock and some replacement tape heads so could try changing those, although it's a lot of work to do for potentially no gain, and the tape head currently looks fine.

Audio recording of the sound taken whilst playing a blank tape: https://vocaroo.com/1bDQRYY2ugVy

Is this normal or something I should take action on?

Cheers
jm

[tibbs1972]

Hi,

To me, this sounds like a mechanical issue being picked up as noise.

Electrical Issues

As you've done some servicing already, I'm assuming you cleaned the Volume Control, as this itself can contribute to noise.

Another possibility is a bad ground connection between the Tape Mechanism and the Power Supply, but this is a pretty solid connection in my book.

I think the final, last resort would be replacing a faulty Audio Chip, but I don't like to go there.

Mechanical Issues

As you've covered all the usual servicing areas, it now gets more difficult to fix, maybe the Motor, Bearings or Spindles are worn from long term use causing the wobble.

I've only serviced Two 464's. Even though they had new Belts, the sound is still a bit shaky during playback, I'm putting it down to wear and tear over 40 years.

Ever tried Grok on X.com, I use it a lot for technical queries at home and during my day job, as everyone else with more electrical experience than me has retired. If you give Grok your hyperlink to the Audio recording, it will even analyze the sound and give you further clues.

Good luck.

Regards
Tibbs

[jm100]

Hi,

Thanks for coming back to me on this, I appreciate your thoughts. I'll give Grok a go, I've never heard of it but sounds interesting!

I was going to have a go at the motor next, as somebody mentioned here on an old post they managed to replace it with a modern Mabuchi motor, but needed to drill out the metal mounting bracket a bit so that it would fit the mounting holes.

I assume the plastic piece on the spindle (that holds the belt) just lifts straight off? Maybe if I got some hook-ended tweezers under it and pulled up?

Thanks
jm

[Bryce]

Hi,

Thanks for coming back to me on this, I appreciate your thoughts. I'll give Grok a go, I've never heard of it but sounds interesting!

I was going to have a go at the motor next, as somebody mentioned here on an old post they managed to replace it with a modern Mabuchi motor, but needed to drill out the metal mounting bracket a bit so that it would fit the mounting holes.

I assume the plastic piece on the spindle (that holds the belt) just lifts straight off? Maybe if I got some hook-ended tweezers under it and pulled up?

Thanks
jm

Are you sure it's not just the tension switch clicking? There's a switch (white piece of plastic between the read head (silver head) and erase head (white head)) that dis-engages the motor when the tape comes to an end. If the tape you're playing is old and has become too tight, the tension switch tends to click while the tape turns. 

Bryce.

[jm100]

Hi, sorry I've only just come back to this!

As far as I can tell it's not that because even if I press Play and run it without a tape, I can still hear the clicking.

Also, it seems to be coming through the speaker as I can no longer hear it when I turn the volume down to zero.

Thanks
jm