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From: Arfa Daily on 28 Jul 2010 20:50


"b" <reverend_rogers(a)yahoo.com> wrote in message
news:82a129f8-f25c-4c76-80d1-185ebaaf929f(a)l14g2000yql.googlegroups.com...
> On Jul 28, 3:10 am, "Arfa Daily" <arfa.da...(a)ntlworld.com> wrote:
>> "b" <reverend_rog...(a)yahoo.com> wrote in message
>>
>> news:7d34ed60-55eb-4174-bf68-80ec0af85389(a)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

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