Sapphire radio repair tutorial - PART HELP NEEDED

[arthurnugen]

With all the "how to" topics on here, I am surprised that nobody has done one of these. Based on my search there are a lot of us wih non working radios and a few who repair them, but nobody has done a thread on diagnosis/repair? If there is one, I couldn't find one.

Something simple, like what to look for, common problem areas, parts sources, etc.?

So, how about it?
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[YellowSplittie]

Radio repair is a bit more involved than the average person might think.

There can be a hundred components in a set, any of which could be bad and make the radio dead. Diagnosing a set can take a couple of minutes or several hours.

Normally, a tech will try to isolate the problem:

Check for correct voltage
Check the RF stages
Check the IF Stages
Check the AF stages

You quite often need a signal generator and an oscilloscope to locate a fault.

Parts can be very hard to find and often must come from salvaged radios. I'm talking about RF coils, switches, controls and not common parts like resistors and transistors.
_________________
'78 Champagne Edition II Westfalia
'70 Squareback
'71 Squareback x 2
'65 Karmann Ghia, Arcona White
'65 Standard Bus with SO-42 installed
'64 Kombi
'62 Beetle
'61 Standard Bus, Mango

[YellowSplittie]

Some tips to start off with:

Sapphire radios are quite plagued by electrolytic capacitor failure. After 40 years or so, they just dry out and cause all kinds of problems.

Usually I just replace all of these as a matter of course because sooner or later they will give you grief.

The antenna trimmer has to be set correctly by the installer. I've come across many radios that work fine once the trimmer is set right. There is a procedure in the radio manuals you'll find on this site.
_________________
'78 Champagne Edition II Westfalia
'70 Squareback
'71 Squareback x 2
'65 Karmann Ghia, Arcona White
'65 Standard Bus with SO-42 installed
'64 Kombi
'62 Beetle
'61 Standard Bus, Mango

[arthurnugen]

Excellent. For a radio dummy, what do those look like?
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[YellowSplittie]

They are usually canister shaped. There are sometimes a dozen or more in a set, all with specific values.
_________________
'78 Champagne Edition II Westfalia
'70 Squareback
'71 Squareback x 2
'65 Karmann Ghia, Arcona White
'65 Standard Bus with SO-42 installed
'64 Kombi
'62 Beetle
'61 Standard Bus, Mango

[arthurnugen]

Thanks YellowSplittie. What are all the stages you mention? So what is the best online source for parts? I have been checking out www.tubesandmore.com.

So anyone want to walk me through how to diagnose capacitor failure? I need an Ohm meter, right? The schematics I can get here, fortunately. Any other common failure spots?


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[Major Woody]

Don't know if this helps but...

http://www.applianceaid.com/micro4.html

[///Mink]

[crofty]

[arthurnugen]

[arthurnugen]

[BarryL]

Is that for all capacitors or just those big-ass 110 vac jobbies?

[dstefun]

[Major Woody]

Good post, Dave!

[arthurnugen]

Thanks Dave and all others. I understand now that I am way out of my league on this stuff.
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[arthurnugen]

Ok, So I was cleaning off my bench and opened the radio case just for the heck of it as it was sitting right there. I think I found the problem.

The numbers on the other side are:


Mallory
Made in USA

MFD VDC PIN
1000 4 1
50 4 2

2092246-0705

235-6725A

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[YellowSplittie]

That's exactly what happens to the electrolytic capacitors. That is one of several in your set.

That particular cap is in the power supply. Actually, it is two caps in one package. You can substitute separate 1000MFD and 50 MFD caps for those. Just make sure you observe the voltage rating and polarity on installation.

If that one is bad, you can be sure others are not far behind.
_________________
'78 Champagne Edition II Westfalia
'70 Squareback
'71 Squareback x 2
'65 Karmann Ghia, Arcona White
'65 Standard Bus with SO-42 installed
'64 Kombi
'62 Beetle
'61 Standard Bus, Mango

[arthurnugen]

Thanks YellowSplittie! Any idea where I can find the parts?
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[YellowSplittie]

An electronics supply store should be able to set you up.

Even Radio Shack should be able to source something for you. They may have to special order it as they don't stock many components any longer.
_________________
'78 Champagne Edition II Westfalia
'70 Squareback
'71 Squareback x 2
'65 Karmann Ghia, Arcona White
'65 Standard Bus with SO-42 installed
'64 Kombi
'62 Beetle
'61 Standard Bus, Mango

[Culito]

Keep in mind that although the ratings (MFD, and voltage) are the same, the new ones are going to look totally different, and possibly much smaller.
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© CJ Industries, Inc.
'64 standard w/2.0L type 4
'62 bug