DCC capstan howl?

Hi All,

I'm attempting to repair a high end DCC recorder (Philips DCC900), the
fault only seems to affect DCC tapes not normal cassettes...

On playback there is a high pitched howl, suprisingly load from the
transport mechanism, loading the capstan flywheel (with my finger, to
slow it down) didn't make much difference, pulling the rubber pich
roller away also made no difference.

When the transport is howling the audio level goes to zero.

For a while, the sequence of rewind, stop, play -> howl, if followed by
a stop and play then the howl went away.

This doesn't happen when the cassete is removed or using a regular
cassette, different DCC tapes also howl.

If I press the tape lightly while playing in one corner the howling stops.

All help welcome, I'm trying to sort this out for an elderly neighbour
who has a large collection of DCC tapes.

TIA!
Paul

 

First I would look for a mechanical slippage.

 

Sounds like bad bearnings.


NT

 

I had a similar howling problem. Certain tapes were worse than others,
and it depended how far through the tape you were playing.

It was caused by the slipping clutch on the take-up capstan. Instead of
slipping, it's actually oscillating between stop and go, hence the
howling sound (a bit like producing a note with a wine glass).

Many clutches have a simple torque adjustment. Changing the torque MAY
stop the howling. There are three spring fingers pressing onto a
'stepped' part of the underside of the take-up wheel. You adjust the
torque by rotating the spring fingers onto the next step.

Ian.
--

 

I'm attempting to repair a high end DCC recorder (Philips DCC900), the

Thanks to all who replied - much appreciated.

I've given the captan bearings a good lube but unfortunately there
doesn't seem to be any way to adjust the torque on the take-up clutch.

The clutch seems to consist of a disk of felt between two plastic disks,
I tried wetting the felt if only to change the characteristics of the
system but with no improvement, possibly worse - but very variable

The number of moving parts is limited so resigned myself to "toucing"
all of them in some way but the deck ony seems to dismantle "easily" to
a certain level, I can't get the take-up sprockets apart - very
disappointing
---Paul