I have already fixed the mechanical problem with this deck (idler tyre)
now it plays, fast forwards and rewinds ok but there is no audio output
on the right channel. Also nothing registers on the right channel
bargraph display.

I have followed the general troubleshooting for tape decks in the FAQ;
when I touch the terminal (white wire) from the left head output I hear
a buzz but when I do the same with the corresponding terminal for the
right channel I hear nothing. This leads me to believe that the problem
is in the electronics rather than a defective tape head. Does anyone
have any suggestions for common failures on this deck or perhaps a
schematic diagram?

--
Tim Phipps

replace "invalid" with "uk" to reply by email

"Tim Phipps" wrote in message
...
I have already fixed the mechanical problem with this deck (idler tyre) now
it plays, fast forwards and rewinds ok but there is no audio output on the
right channel. Also nothing registers on the right channel bargraph
display.

I have followed the general troubleshooting for tape decks in the FAQ;
when I touch the terminal (white wire) from the left head output I hear a
buzz but when I do the same with the corresponding terminal for the right
channel I hear nothing. This leads me to believe that the problem is in
the electronics rather than a defective tape head. Does anyone have any
suggestions for common failures on this deck or perhaps a schematic
diagram?

--
Tim Phipps

replace "invalid" with "uk" to reply by email

It's common on all tape decks for the wires from the heads, to break, often
inside the plastic sleeving. Give each a gentle tug to make sure that this
isn't the case. The other very common thing for no playback on one channel,
is the record / playback switch going bad, particularly if you don't record
often. As a first move, locate the switch, and give it a vigourous scrub
back and forth. If that produces a fix, squirt a little switch cleaner /
lubricant in there, and repeat the scrubbing.

Arfa

Arfa Daily wrote:

It's common on all tape decks for the wires from the heads, to break, often
inside the plastic sleeving. Give each a gentle tug to make sure that this
isn't the case.

I checked for continuity on the leads from the head to the board and
they were all ok.

The other very common thing for no playback on one channel,
is the record / playback switch going bad, particularly if you don't record
often. As a first move, locate the switch, and give it a vigourous scrub
back and forth. If that produces a fix, squirt a little switch cleaner /
lubricant in there, and repeat the scrubbing.


I could not locate such a switch on this deck. For reference, it is
logic controlled. The only internal switches on the transport are the
one that stops the tape if the eject button is pressed and the one that
detects if the 'record-protect' tab has been removed.

--
Tim Phipps

replace "invalid" with "uk" to reply by email

"Tim Phipps" wrote in message
...
Arfa Daily wrote:

It's common on all tape decks for the wires from the heads, to break,
often inside the plastic sleeving. Give each a gentle tug to make sure
that this isn't the case.

I checked for continuity on the leads from the head to the board and they
were all ok.

The other very common thing for no playback on one channel,
is the record / playback switch going bad, particularly if you don't
record often. As a first move, locate the switch, and give it a vigourous
scrub back and forth. If that produces a fix, squirt a little switch
cleaner / lubricant in there, and repeat the scrubbing.


I could not locate such a switch on this deck. For reference, it is logic
controlled. The only internal switches on the transport are the one that
stops the tape if the eject button is pressed and the one that detects if
the 'record-protect' tab has been removed.

--
Tim Phipps

OK on that Tim. The record / playback switch is not usually located on the
deck itself. It is normally a slide-type multipole switch, actuated by a rod
or lever or stiff wire, from the deck.
Whether or not the deck is directly controlled or servo controlled by logic,
is not normally an issue, with regard to this mechanical scheme.

Some cassette machines, however, do employ full electronic switching, which
is sometimes part of the record / playback subsystem IC. If this is the case
with your machine, then you will probably not get much further without a set
of schematics, and a 'scope. Have you tried to see if it records
successfully on both channels ? If it does, that at least for the most part,
proves out the heads and their wiring. It's pretty unlikely, but I'm
assuming that you have not got a very badly clogged head ? Normally, you can
still hear something on the affected channel, when playing back a previously
known good tape, but just occasionally, you can get a case that's so bad,
that you get nothing at all.

Arfa

On Tue, 20 Jun 2006 21:52:06 GMT, Tim Phipps
put finger to keyboard and
composed:

I have already fixed the mechanical problem with this deck (idler tyre)
now it plays, fast forwards and rewinds ok but there is no audio output
on the right channel. Also nothing registers on the right channel
bargraph display.

I have followed the general troubleshooting for tape decks in the FAQ;
when I touch the terminal (white wire) from the left head output I hear
a buzz but when I do the same with the corresponding terminal for the
right channel I hear nothing. This leads me to believe that the problem
is in the electronics rather than a defective tape head. Does anyone
have any suggestions for common failures on this deck or perhaps a
schematic diagram?

You can eliminate the head as the source of your problem by
interchanging the L & R wires in the connector. If the problem
migrates to the other channel, then the head or cable is the culprit,
otherwise there is a problem on the board.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Arfa Daily wrote:


OK on that Tim. The record / playback switch is not usually located on the
deck itself. It is normally a slide-type multipole switch, actuated by a rod
or lever or stiff wire, from the deck.
Whether or not the deck is directly controlled or servo controlled by logic,
is not normally an issue, with regard to this mechanical scheme.

Some cassette machines, however, do employ full electronic switching, which
is sometimes part of the record / playback subsystem IC. If this is the case
with your machine, then you will probably not get much further without a set
of schematics, and a 'scope. Have you tried to see if it records
successfully on both channels ? If it does, that at least for the most part,
proves out the heads and their wiring. It's pretty unlikely, but I'm
assuming that you have not got a very badly clogged head ? Normally, you can
still hear something on the affected channel, when playing back a previously
known good tape, but just occasionally, you can get a case that's so bad,
that you get nothing at all.

Arfa



Ok I had a good look over it again today and I'm pretty sure that this
deck does not have a mechanical record/playback switch. The only
switches on the board are those for selecting the tape type and Dolby
NR. It would seem that it is done electronically although there are
very few ICs on the board - mostly discrete components. As it happens I
do have a scope that I acquired for free but I don't think I have much
chance of obtaining schematics as it is a fairly old unit - appears to
be made around 1983 going by the dates marked on the motors.

Just to check the head for sure I tried reversing the connector that
goes to the board since it is wired symmetrically. Sure enough I got
the same result - playback only on the left channel, although this time
the signal being supplied from the right output of the head. This seems
to confirm that the head is good and unfortunately it's an electronics
fault. However, I did try a test recording and it records on the left
channel only. I checked by playing back on a known good tape deck. If
I turned up the volume on my hifi amp much higher than normal listening
level with the balance control all the way to the right I was able to
hear a faint signal. So it seems that it is a fault on the board which
is affecting both playback and recording.

--
Tim Phipps

replace "invalid" with "uk" to reply by email

Franc Zabkar wrote:


You can eliminate the head as the source of your problem by
interchanging the L & R wires in the connector. If the problem
migrates to the other channel, then the head or cable is the culprit,
otherwise there is a problem on the board.

- Franc Zabkar

Thanks, I tried this by reversing the connector as it is wired
symmetrically and still got playback only on the left channel so it
seems the problem is on the board

--
Tim Phipps

replace "invalid" with "uk" to reply by email

"Tim Phipps" wrote in message
...
Arfa Daily wrote:


OK on that Tim. The record / playback switch is not usually located on
the deck itself. It is normally a slide-type multipole switch, actuated
by a rod or lever or stiff wire, from the deck.
Whether or not the deck is directly controlled or servo controlled by
logic, is not normally an issue, with regard to this mechanical scheme.

Some cassette machines, however, do employ full electronic switching,
which is sometimes part of the record / playback subsystem IC. If this is
the case with your machine, then you will probably not get much further
without a set of schematics, and a 'scope. Have you tried to see if it
records successfully on both channels ? If it does, that at least for the
most part, proves out the heads and their wiring. It's pretty unlikely,
but I'm assuming that you have not got a very badly clogged head ?
Normally, you can still hear something on the affected channel, when
playing back a previously known good tape, but just occasionally, you can
get a case that's so bad, that you get nothing at all.

Arfa

Ok I had a good look over it again today and I'm pretty sure that this
deck does not have a mechanical record/playback switch. The only switches
on the board are those for selecting the tape type and Dolby NR. It would
seem that it is done electronically although there are very few ICs on the
board - mostly discrete components. As it happens I do have a scope that
I acquired for free but I don't think I have much chance of obtaining
schematics as it is a fairly old unit - appears to be made around 1983
going by the dates marked on the motors.

Just to check the head for sure I tried reversing the connector that goes
to the board since it is wired symmetrically. Sure enough I got the same
result - playback only on the left channel, although this time the signal
being supplied from the right output of the head. This seems to confirm
that the head is good and unfortunately it's an electronics fault.
However, I did try a test recording and it records on the left channel
only. I checked by playing back on a known good tape deck. If I turned
up the volume on my hifi amp much higher than normal listening level with
the balance control all the way to the right I was able to hear a faint
signal. So it seems that it is a fault on the board which is affecting
both playback and recording.

--
Tim Phipps

It's quite unusual to have a fault which affects both record and playback of
a channel, and is not the head or its wiring. About all that's left is the
record / playback head switching, which may be done by a couple of FETs on
each channel, although is much more commonly done inside an R/P process IC -
even on a machine of that age, some kind of open circuit between the head
connecor and wherever the switching takes place, or possibly, an open
circuit cap in the path between the head and the switching. It is possible
that the same amplifier stage is used on record and playback, and just "
turned around " but this is not usually the way it's done.

One thing that you could try, is to put the unit on record, and then put the
'scope across each channel of the head in turn, and see if you can see the
high frequency bias signal on both channels. This will at least prove that
something can reach the head ok, although it doesn't tell us a lot, as the
bias injection point could be literally just south of the heads connector.
You might also try scoping at the record and playback level presets on the
board, with a tape playing, or one recording, just to see what you get.
Interesting problem that would no doubt be resolved in moments with a set of
schematics.

Arfa

On Tue, 20 Jun 2006 21:52:06 GMT, Tim Phipps
wrote:

I have already fixed the mechanical problem with this deck (idler tyre)
now it plays, fast forwards and rewinds ok but there is no audio output
on the right channel. Also nothing registers on the right channel
bargraph display.

I have followed the general troubleshooting for tape decks in the FAQ;
when I touch the terminal (white wire) from the left head output I hear
a buzz but when I do the same with the corresponding terminal for the
right channel I hear nothing. This leads me to believe that the problem
is in the electronics rather than a defective tape head. Does anyone
have any suggestions for common failures on this deck or perhaps a
schematic diagram?


The dolby chips would fail on these and occasionally an electrolytic
capacitor would short. Chuck

On Fri, 23 Jun 2006 00:27:31 GMT, Tim Phipps
put finger to keyboard and
composed:

Ok I had a good look over it again today and I'm pretty sure that this
deck does not have a mechanical record/playback switch. The only
switches on the board are those for selecting the tape type and Dolby
NR. It would seem that it is done electronically although there are
very few ICs on the board - mostly discrete components. As it happens I
do have a scope that I acquired for free but I don't think I have much
chance of obtaining schematics as it is a fairly old unit - appears to
be made around 1983 going by the dates marked on the motors.

Just to check the head for sure I tried reversing the connector that
goes to the board since it is wired symmetrically. Sure enough I got
the same result - playback only on the left channel, although this time
the signal being supplied from the right output of the head. This seems
to confirm that the head is good and unfortunately it's an electronics
fault. However, I did try a test recording and it records on the left
channel only. I checked by playing back on a known good tape deck. If
I turned up the volume on my hifi amp much higher than normal listening
level with the balance control all the way to the right I was able to
hear a faint signal. So it seems that it is a fault on the board which
is affecting both playback and recording.

If there is any obvious symmetry between the left and right channels,
I'd be playing a test tape (eg 1kHz sinusoid) and scoping the
equivalent points in both halves of the circuit. Otherwise, if the
signal disappears inside some R/P processor IC, I'd download its
datasheet and hope that Pioneer's design follows the application
circuit.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.