Technics dv-280 stereo system -cassette dead

[b]

Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.

This is a 'pseudo-separates' affair, where each box is connected by
means of a flat ribbon cable. The main trafo. is in the amp which then
feeds a 'sound processor'/input selector box, from whence the dvd and
cassette decks are fed. The dvd, which is downstream from the
cassette, powers up fine. I'm assuming they use the same power rail,
so will concentrate on the cassette unit first.
Going to take some measurements on the cassette pcb, but I'd like the
service data to speed things up, as this is quite a complex unit and
it would save me the hassle of having to unscrew and open all the
boxes to trace the basic voltage lines.

Anyone suggest a source for a schematic? Tried eserviceinfo to no
avail....
cheers,
B

 

[b]

On Jul 27, 5:48 pm, b <reverend_rog...@yahoo.com> wrote:

Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.

Also forgot to mention: no audio through speakers, and through
headphones nothing either -well, I get a low hiss (vol. at full) when
in tuner mode, despite the search mode working and stations appearing
as 'tuned' in the display....
-B

 

[Meat Plow]

On Tue, 27 Jul 2010 09:35:17 -0700, b wrote:

On Jul 27, 5:48 pm, b <reverend_rog...@yahoo.com> wrote:
Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.


Also forgot to mention: no audio through speakers, and through
headphones nothing either -well, I get a low hiss (vol. at full) when in
tuner mode, despite the search mode working and stations appearing as
'tuned' in the display....
-B

My educated and experienced guess is a missing voltage.

 

[Arfa Daily]

"b" <reverend_rogers@yahoo.com> wrote in message
news:7d34ed60-55eb-4174-bf68-80ec0af85389@f15g2000vbq.googlegroups.com...

Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.

This is a 'pseudo-separates' affair, where each box is connected by
means of a flat ribbon cable. The main trafo. is in the amp which then
feeds a 'sound processor'/input selector box, from whence the dvd and
cassette decks are fed. The dvd, which is downstream from the
cassette, powers up fine. I'm assuming they use the same power rail,
so will concentrate on the cassette unit first.
Going to take some measurements on the cassette pcb, but I'd like the
service data to speed things up, as this is quite a complex unit and
it would save me the hassle of having to unscrew and open all the
boxes to trace the basic voltage lines.

Anyone suggest a source for a schematic? Tried eserviceinfo to no
avail....
cheers,
B

I've sent you a set of schematics direct off-group. Let me know that you get
them ok

Arfa

 

[b]

On Jul 28, 3:10 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

"b" <reverend_rog...@yahoo.com> wrote in message

news:7d34ed60-55eb-4174-bf68-80ec0af85389@f15g2000vbq.googlegroups.com...



Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.

This is a 'pseudo-separates' affair, where each box is connected by
means of a flat ribbon cable. The main trafo. is in the amp which then
feeds a 'sound processor'/input selector box, from whence the dvd and
cassette decks are fed. The dvd, which is downstream from the
cassette, powers up fine. I'm assuming they use the same power rail,
so will concentrate on the cassette unit first.
Going to take some measurements on the cassette pcb, but I'd like the
service data to speed things up, as this is quite a complex unit and
it would save me the hassle of having to unscrew and open all the
boxes to trace the basic voltage lines.

Anyone suggest a source for a schematic? Tried eserviceinfo to no
avail....
cheers,
B

I've sent you a set of schematics direct off-group. Let me know that you get
them ok

Arfa

Quick update.
Took a few measurements - all 3 entry safety resistors in the cassette
main pcb 'psu' are fine with the correct voltages present.
Checked Q604, which drops the 10v to 5v and that has 5v on its
emittter. This 5v is also present on pin 5 of main pcb connector 901
which goes to the LED/button panel.
Checked Q602 the 9.6v regulator. Voltage present and correct there
too.
hmmm...
could this be something amiss on the button /LED panel? Will do this
next.
As an aside, whilst I had the thing on, I noticed there is a sub pcb
in the amp module with 3x B1548 power transistors mounted on a small
heatsink - getting red hot, not a good sign. may or may not be
related.
-B

 

[Arfa Daily]

"b" <reverend_rogers@yahoo.com> wrote in message
news:82a129f8-f25c-4c76-80d1-185ebaaf929f@l14g2000yql.googlegroups.com...

On Jul 28, 3:10 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
"b" <reverend_rog...@yahoo.com> wrote in message

news:7d34ed60-55eb-4174-bf68-80ec0af85389@f15g2000vbq.googlegroups.com...



Picked this up a few months back and just hauled it out. The units
power up, and lights come on but the cassette deck stubbornly remains
dead.

This is a 'pseudo-separates' affair, where each box is connected by
means of a flat ribbon cable. The main trafo. is in the amp which then
feeds a 'sound processor'/input selector box, from whence the dvd and
cassette decks are fed. The dvd, which is downstream from the
cassette, powers up fine. I'm assuming they use the same power rail,
so will concentrate on the cassette unit first.
Going to take some measurements on the cassette pcb, but I'd like the
service data to speed things up, as this is quite a complex unit and
it would save me the hassle of having to unscrew and open all the
boxes to trace the basic voltage lines.

Anyone suggest a source for a schematic? Tried eserviceinfo to no
avail....
cheers,
B

I've sent you a set of schematics direct off-group. Let me know that you
get
them ok

Arfa

Quick update.
Took a few measurements - all 3 entry safety resistors in the cassette
main pcb 'psu' are fine with the correct voltages present.
Checked Q604, which drops the 10v to 5v and that has 5v on its
emittter. This 5v is also present on pin 5 of main pcb connector 901
which goes to the LED/button panel.
Checked Q602 the 9.6v regulator. Voltage present and correct there
too.
hmmm...
could this be something amiss on the button /LED panel? Will do this
next.
As an aside, whilst I had the thing on, I noticed there is a sub pcb
in the amp module with 3x B1548 power transistors mounted on a small
heatsink - getting red hot, not a good sign. may or may not be
related.
-B

These units are known for bad joints on any heatsink-attached transistors.

Arfa