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Grundig Melody Boy 500

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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Reply to
Cursitor Doom
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Dried out aluminum electrolytic capacitors.

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Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com
Reply to
Foxs Mercantile

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

Reply to
N_Cook

y.

d-

't

as?

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 w ere stagger tuned to get the best shaped response, fail to follow that meth od and you'll end up with really crap audio frequency response for AM, for FM I presume lousy signal capture & distortion.

NT

Reply to
tabbypurr

Time to buy a new one then!

???

Reply to
Chris

What he wrote - AND BEFORE screwing around with slugs filters and/or any ot her '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 a re bad after 40 years, or they are bad out of sheer cussedness. And as ther e 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

Reply to
pfjw

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.

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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  
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Reply to
Cursitor Doom

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

Reply to
Tim Schwartz

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

Reply to
Tim Schwartz

obviously that does not eliminate the possibility.

Reply to
tabbypurr

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

Reply to
pfjw

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