Grundig Melody Boy 500

[Cursitor Doom]

I've had this great old classic radio for the best part of 40 years and
it's always sounded great on the FM/VHF band until recently. Now I'm
finding it increasingly difficult to tune-in properly, even with strong
stations. It just sounds a bit scratchy like it's off-frequency slightly.
The usual leeway I got with tuning a station has gone; it has to be dead-
on yet it's still not quite right. Speech can often sound totally fine,
but when there's a musical interlude the problem suddenly becomes
apparent again. Is this symptomatic of it needing a re-alignment? I can't
think what else could be causing it, but since I've never experienced
such a problem before, I'm really pretty much in the dark here. Any ideas?



--
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[Foxs Mercantile]

On 12/3/2017 6:54 AM, Cursitor Doom wrote:
> I've had this great old classic radio for the best part of 40 years

Dried out aluminum electrolytic capacitors.

--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

 

[N_Cook]

On 03/12/2017 12:54, Cursitor Doom wrote:

I've had this great old classic radio for the best part of 40 years and
it's always sounded great on the FM/VHF band until recently. Now I'm
finding it increasingly difficult to tune-in properly, even with strong
stations. It just sounds a bit scratchy like it's off-frequency slightly.
The usual leeway I got with tuning a station has gone; it has to be dead-
on yet it's still not quite right. Speech can often sound totally fine,
but when there's a musical interlude the problem suddenly becomes
apparent again. Is this symptomatic of it needing a re-alignment? I can't
think what else could be causing it, but since I've never experienced
such a problem before, I'm really pretty much in the dark here. Any ideas?

If you do start twiddling IF Tx cores , mark the angle and measure the
depth of each, making up a little nut and screw "depth gauge" and only
try 1 at a time , so you can get back to where you started from.
Another consideration, any ceramic resonator filters perhaps not 40
years back, the silver inside can migrate over the resonator edges and
make them go ohmic, losing selectivity

 

On Sunday, 3 December 2017 14:41:50 UTC, N_Cook wrote:

On 03/12/2017 12:54, Cursitor Doom wrote:
I've had this great old classic radio for the best part of 40 years and
it's always sounded great on the FM/VHF band until recently. Now I'm
finding it increasingly difficult to tune-in properly, even with strong
stations. It just sounds a bit scratchy like it's off-frequency slightly.
The usual leeway I got with tuning a station has gone; it has to be dead-
on yet it's still not quite right. Speech can often sound totally fine,
but when there's a musical interlude the problem suddenly becomes
apparent again. Is this symptomatic of it needing a re-alignment? I can't
think what else could be causing it, but since I've never experienced
such a problem before, I'm really pretty much in the dark here. Any ideas?




If you do start twiddling IF Tx cores , mark the angle and measure the
depth of each, making up a little nut and screw "depth gauge" and only
try 1 at a time , so you can get back to where you started from.
Another consideration, any ceramic resonator filters perhaps not 40
years back, the silver inside can migrate over the resonator edges and
make them go ohmic, losing selectivity

SAW filters got into consumer goods in the 80s. It'll be cans with slugs.

the following is more from reading than experience...
Before doing any twiddling you really need to know the set up technique, it was not as simplistic as twiddle for best volume/clarity. AIUI the slugs were stagger tuned to get the best shaped response, fail to follow that method and you'll end up with really crap audio frequency response for AM, for FM I presume lousy signal capture & distortion.


NT

 

[Chris]

On Sun, 03 Dec 2017 07:01:42 -0600, Foxs Mercantile wrote:

On 12/3/2017 6:54 AM, Cursitor Doom wrote:
I've had this great old classic radio for the best part of 40 years

Time to buy a new one then!

> Dried out aluminum electrolytic capacitors.

???

 

[pfjw@aol.com]

On Sunday, December 3, 2017 at 8:01:47 AM UTC-5, Foxs Mercantile wrote:

On 12/3/2017 6:54 AM, Cursitor Doom wrote:
I've had this great old classic radio for the best part of 40 years

Dried out aluminum electrolytic capacitors.

--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

What he wrote - AND BEFORE screwing around with slugs filters and/or any other 'adjustables" in the radio - unless you really do want to split a slug, break something and utterly destroy it. Either the caps are bad, or they are bad after 40 years, or they are bad out of sheer cussedness. And as there are no other variables that would explain the increasing deafness of the radio, start with the obvious (and necessary) before risking anything else.

Peter Wieck
Melrose Park, PA

 

[Cursitor Doom]

On Sun, 03 Dec 2017 12:59:49 -0800, pfjw@aol.com wrote:

On Sunday, December 3, 2017 at 8:01:47 AM UTC-5, Foxs Mercantile wrote:

Dried out aluminum electrolytic capacitors.

--
Jeff-1.0 wa6fwi http://www.foxsmercantile.com

What he wrote - AND BEFORE screwing around with slugs filters and/or any
other 'adjustables" in the radio - unless you really do want to split a
slug, break something and utterly destroy it. Either the caps are bad,
or they are bad after 40 years, or they are bad out of sheer cussedness.
And as there are no other variables that would explain the increasing
deafness of the radio, start with the obvious (and necessary) before
risking anything else.

Well, I can't argue with that philosophy; I'm all for trying the simple
things first. I can't remember the last time I ran this radio off a
battery, but I'll get one in the morning and try powering it up with
that. I'm not sure how dried electrolytics could explain the symptoms I'm
getting but am happy to at least eliminate that possibility first and
this is the easiest way of going about it.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[Tim Schwartz]

On 12/3/2017 3:59 PM, pfjw@aol.com wrote:

On Sunday, December 3, 2017 at 8:01:47 AM UTC-5, Foxs Mercantile wrote:
On 12/3/2017 6:54 AM, Cursitor Doom wrote:
I've had this great old classic radio for the best part of 40 years

Dried out aluminum electrolytic capacitors.

--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

What he wrote - AND BEFORE screwing around with slugs filters and/or any other 'adjustables" in the radio - unless you really do want to split a slug, break something and utterly destroy it. Either the caps are bad, or they are bad after 40 years, or they are bad out of sheer cussedness. And as there are no other variables that would explain the increasing deafness of the radio, start with the obvious (and necessary) before risking anything else.

Peter Wieck
Melrose Park, PA

I have to disagree about always blaming caps. 90 % of the electrolytic
caps that I remove when a customer wants them all replaced are just
fine, unless they are near a heat source. SOME brands and series of
caps are suspect, but many are just fine. Another possibility for this
radio is a bad RF amp transistor or something similar elsewhere. For
example, in many old tuners you are more likely to find bad LM703 IF
IC's than a bad cap, especially if the IC is the dome-topped variety,
the metal cans are much better. Bad soldering or dirty tuning cap
grounds are also common issues.

Regards,
Tim

 

[Tim Schwartz]

On 12/3/2017 3:59 PM, pfjw@aol.com wrote:

On Sunday, December 3, 2017 at 8:01:47 AM UTC-5, Foxs Mercantile wrote:
On 12/3/2017 6:54 AM, Cursitor Doom wrote:
I've had this great old classic radio for the best part of 40 years

Dried out aluminum electrolytic capacitors.

--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

What he wrote - AND BEFORE screwing around with slugs filters and/or any other 'adjustables" in the radio - unless you really do want to split a slug, break something and utterly destroy it. Either the caps are bad, or they are bad after 40 years, or they are bad out of sheer cussedness. And as there are no other variables that would explain the increasing deafness of the radio, start with the obvious (and necessary) before risking anything else.

Peter Wieck
Melrose Park, PA

I have to disagree about always blaming caps. 90 % of the electrolytic
caps that I remove when a customer wants them all replaced are just
fine, unless they are near a heat source. SOME brands and series of
caps are suspect, but many are just fine. Another possibility for this
radio is a bad RF amp transistor or something similar elsewhere. For
example, in many old tuners you are more likely to find bad LM703 IF
IC's than a bad cap, especially if the IC is the dome-topped variety,
the metal cans are much better. Bad soldering or dirty tuning cap
grounds are also common issues.

Regards,
Tim

 

On Sunday, 3 December 2017 23:50:37 UTC, Cursitor Doom wrote:

On Sun, 03 Dec 2017 12:59:49 -0800, pfjw@aol.com wrote:
On Sunday, December 3, 2017 at 8:01:47 AM UTC-5, Foxs Mercantile wrote:

Dried out aluminum electrolytic capacitors.

What he wrote - AND BEFORE screwing around with slugs filters and/or any
other 'adjustables" in the radio - unless you really do want to split a
slug, break something and utterly destroy it. Either the caps are bad,
or they are bad after 40 years, or they are bad out of sheer cussedness.
And as there are no other variables that would explain the increasing
deafness of the radio, start with the obvious (and necessary) before
risking anything else.

Well, I can't argue with that philosophy; I'm all for trying the simple
things first. I can't remember the last time I ran this radio off a
battery, but I'll get one in the morning and try powering it up with
that. I'm not sure how dried electrolytics could explain the symptoms I'm
getting but am happy to at least eliminate that possibility first and

obviously that does not eliminate the possibility.

 

[pfjw@aol.com]

On Sunday, December 3, 2017 at 10:10:47 PM UTC-5, Tim Schwartz wrote:

I have to disagree about always blaming caps. 90 % of the electrolytic
caps that I remove when a customer wants them all replaced are just
fine, unless they are near a heat source. SOME brands and series of
caps are suspect, but many are just fine.

Tim

Tim:

Likely the caps in this beast are Frako, even if re-branded. May as well write FlakO. So, at the very least they are suspect as you suggest. And if he has been running it off mains power, there may well be some heat involved.

Furthermore, this is a German Radio - meaning that Grundig never used one part where three-or-more would do better. Dealing with the caps - a necessary exercise in any case - may cure the problem. At worst, the effort is not wasted.

Peter Wieck
Melrose Park, P