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From: T i m on 14 Oct 2009 10:39
On Wed, 14 Oct 2009 03:53:43 -0700, "William Sommerwerck"
<grizzledgeezer(a)comcast.net> wrote:

>> [1] I note the stereo indicator never comes on, even when it sounds
>> like it's tuned into a local station that I know is stereo. Would that
>> confirm my thoughts that it's a component after the front end, before
>> the stereo decoding happens?
>
>The indicator light might be burned out.

It's part of the fluorescent display so difficult to tell.

> Or, as someone else is pointed out,
>the tuner might be slightly out of alignment.

Whilst I'm sure that's not impossible I'm not sure how likely? I say
that because I've had many radios / tuners / scanners over the years
and I'm not aware of that happening, especially without some external
influence. However, I guess components can age, capacitors dry-up etc
....

I will have a quick look in there and see if the schematics I have
look correct for my unit and then see if I can follow anything through
and some of the alignment procedures that I can with my limited (for
this sort of work) service equipment. I guess even a tweak of a
pre-marked coil or pot should tell me if I'm in the right area or not
(no difference = wrong area or it's *way* off / broken)). ;-)

As I have mentioned elsewhere, a safer, quicker and potentially better
solution (as no one has come up with a specific weakness / experience
with this particular unit so far) is an external FM / DAB tuner as
then I can enjoy the DAB stuff as well.

Cheers, T i m

From: Mark Zacharias on 14 Oct 2009 21:32
"T i m" <news(a)spaced.me.uk> wrote in message
news:53obd554hbsbesei3vup43ht3lohgotst1(a)4ax.com...
> On Wed, 14 Oct 2009 03:53:43 -0700, "William Sommerwerck"
> <grizzledgeezer(a)comcast.net> wrote:
>
>>> [1] I note the stereo indicator never comes on, even when it sounds
>>> like it's tuned into a local station that I know is stereo. Would that
>>> confirm my thoughts that it's a component after the front end, before
>>> the stereo decoding happens?
>>
>>The indicator light might be burned out.
>
> It's part of the fluorescent display so difficult to tell.
>
>> Or, as someone else is pointed out,
>>the tuner might be slightly out of alignment.
>
> Whilst I'm sure that's not impossible I'm not sure how likely? I say
> that because I've had many radios / tuners / scanners over the years
> and I'm not aware of that happening, especially without some external
> influence. However, I guess components can age, capacitors dry-up etc
> ...
>
>


Extremely common.

Mark Z.

From: Mark Zacharias on 14 Oct 2009 21:48
"T i m" <news(a)spaced.me.uk> wrote in message
news:9hebd5p7jaivik88bjkshnd6jshimher8m(a)4ax.com...
> On Wed, 14 Oct 2009 05:46:17 -0500, "Mark Zacharias"
> <mark_zacharias(a)sbclobal.net> wrote:
>
>>
>>Digital tuners often exhibit a problem where the discriminator alignment
>>drifts enough that problems similar to yours occur.
>
> Ah, ok.
>>
>>Really needs to go to a shop. It's a simple alignment, but not for a DIY
>>with no service manual or training.
>
> I think I now have the service manual so potentially some test /
> alignment procedures to follow. I have a scope, DMMs and frequency
> counter etc but no signal injection kit but could probably rig
> something if need be.
>
> I would be happy to take such a thing to 'a shop' 1) I don't think we
> have many over here (UK) any more and 2) if we did I think the work
> would probably out-value the equipment?
>
> I have been an electronics service engineer for much of my life it was
> mainly on data-transmission / communications kit. I even got my Radio
> Amateur ticked to do Packet radio. ;-)
>
> I've had a look about and a DAB / FM tuner can be had for about �60
> new so I could use that instead of the tuner part (I'm not too
> bothered about 'quality' as long as it sounds ok and works).
>
> Cheers, T i m (G7ICW)
>
> p.s. I might see if I can find a local 'radio enthusiast' who might be
> interested in having a look for a beer.


Typically there are two test points physically near the discriminator
transformer. One uses a DVM to measure the DC millivolts across these two
points, while tuned to a station near 98 mHz. Adjust for zero millivolts. A
center bar-graph display, such as seen on Fluke meters, is useful - one can
adjust the moving voltage to center around zero.

Mark A.

From: T i m on 15 Oct 2009 07:16
On Wed, 14 Oct 2009 20:48:28 -0500, "Mark Zacharias"
<mark_zacharias(a)sbclobal.net> wrote:


>> p.s. I might see if I can find a local 'radio enthusiast' who might be
>> interested in having a look for a beer.
>
>
>Typically there are two test points physically near the discriminator
>transformer. One uses a DVM to measure the DC millivolts across these two
>points, while tuned to a station near 98 mHz. Adjust for zero millivolts. A
>center bar-graph display, such as seen on Fluke meters, is useful - one can
>adjust the moving voltage to center around zero.
>
Right, I think I saw mention of that on a schematic. I'll give it a
closer look. Thanks.

T i m
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