[TechAssist] Re: Akai cassette deck model CS-M4 no audio out, schematic required

Neal and all, thanks for the replies. I was able to solve this one. FR4,
a 6.8 ohm 1/4 W fusible resistor was open. This resistor is located on
the collector of TR 10, 2SD794 in the power supply area. I didn't find
it at first because I was measuring voltage drop across all the low
value resistors and this one did have an approximate voltage drop that I
would expect to see across it, so I didn't suspect it to be open. Only
later when I had an ohm meter in the area did I notice it to be open.
Whats worse and I don't know if I should even admit this to the list, is
that the customer brought in the instruction book with the unit and I
had shelved it with the top cover so I forgot about it. When I went to
install the top cover, guess what I found inside the instruction manual?
The schematic. Figures. So if anyone ever gets paperwork come in with a
repair, look through it for a schematic.

The collector of the TR-1's now measure 3.0V rather than the 1.6V when
it wasn't working.



 Gary McCartney

 McCartney Electronics
 7134 Fife Rd, RR 7
 Guelph Ontario Canada N1H 6J4
 Fax: (519)821-1530
 email: number63@xxxxxxxxxxxxx




Neal Hartley wrote:
> 
> Hello I once had one with the same problem and it turned out to be the
> actual play/rec head had moved back in it's plastic mounting bracket so not
> in complete contact with the tape.
> Regards Neal
> ----- Original Message -----
> From: "Gary McCartney" <number63@xxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Monday, May 27, 2002 4:59 PM
> Subject: [TechAssist] Akai cassette deck model CS-M4 no audio out, schematic
> required
> 
> >
> > This Akai cassette deck model CS-M4 has no audio output. With a signal
> > tracer, I only get audio into the emitter of the first transistor after
> > the tape head, which is TR-1 (one TR-1 transistor for each channel). The
> > B+ on the TR-1 transistors collectors is only 1.6V so I am suspecting my
> > B+ is being pulled down somewhere. I've replaced the TR-1 transistors.
> > I've cleaned the internal rec/ play switch and tested the continuity of
> > it's contacts which all checks ok. The circuit is too hard to follow on
> > the pcb so I need a schematic to fix this one.
> >
> > Thanks for any help.
> >
> >
> >
> > Gary McCartney
> >
> > McCartney Electronics
> > 7134 Fife Rd, RR 7
> > Guelph Ontario Canada N1H 6J4
> > Fax: (519)821-1530
> > email: number63@xxxxxxxxxxxxx
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