Strange problems with Denon DN720R cassette deck

[Shpalman]

Greets,

I currently have a Denon DN720R cassette deck, nice machine and all, but in
the last few weeks I'm having a little trouble with the speed drifting
(speeds up/slows down completely at random). This deck has a variable speed
control on the front panel - at the time of the speed drifting, the control
wasn't engaged so I've ruled that out as the problem, as well as the
cassettes themselves as it happens on all tapes tried (the same tapes play
fine in another machine, a technics). Is it as simple as replacing a motor
or some belts or would I have to look elsewhere in the unit?

This deck also seems to have a problem playing back a tape recorded onto it
in the form of the left channel being way down in level - again, a mixture
of tapes tried, same problem on each tape. Listening to it back reveals a
sound like something isn't quite plugged in to the input jacks properly,
however this has been ruled out as in record/pause mode I can get signal on
both channels equally - when playing back tapes recorded on other units it
also gives me normal levels on both channels. So basically:

1. Signal going into the unit is okay
2. Signal coming off tapes recorded on other machines is okay
3. Signal coming off tapes recorded on the denon not okay - right channel's
fine, left channel way down (around -10db or so with a very cut-out type
noise)

Does anyone have any suggestions of what to do here at all? Many thanks in
advance.

 

[Mark D. Zacharias]

I think a really good cleaning is in order first of all. Secondly, I would
examine the head very closely for signs of wear, especially if the machine
has lots of use. This is a common symptom, playback OK, but muffled
recording, and it seems the left channel often goes first, since it's on the
edge of the tape itself. Denon often sells the complete deck assemblies for
these, if you're in the U.S. try Pacific Coast Parts at 800-421-5080 and
check the cost.

Mark Z.