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Need help with a Sony sony icf-sw7600 AM not working

sub2001zero

Dec 16, 2022
4
Joined
Dec 16, 2022
Messages
4
Hi I need help what wrong with the radio i change all the caps out and FM works great but no am all static. If someone can point me in an area to look at. Thanks for everyone help.
 

sub2001zero

Dec 16, 2022
4
Joined
Dec 16, 2022
Messages
4
i have a few fluke meter best one i have 289 and analog meters. i have signal generator but don't where it is. I can make a diy tester if i need to. that about it.
 

kellys_eye

Jun 25, 2010
6,514
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Messages
6,514
Signal injector and diode probe (home made if you have to - only three or four components!) is all you need - plus the schematic of course. You can even use a home made signal injector; basic squarewave oscillator, lots of harmonics.

I taught fault finding on marine radio equipment for years using just those two items plus an Avometer! Radio receiver fault location is a well studied and practised 'art' with many practical examples of 'the tube' but, basically, inject a signal starting at the audio section - you know that part works - then work backwards until the signal stops i.e. detector, if amp, mixer, rf amp etc..... fault found.

Another simple test is to place another receiver close to the dud one and listen for a tonal harmonic as the oscillator section of the known-good one 'interferes' with the dud one. If you can't get the harmonic then the RF oscillator is dud.
 

73's de Edd

Aug 21, 2015
3,636
Joined
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Messages
3,636
Sir sub2001zero . . . . .


Hi I need help what wrong with the radio i change all the caps out . . . . .

Hi I need help what wrong with the radio i change>>>>>(
all )<<<<<<< the caps out . . . . .
all . . . . .really ? . . . . . ALL . . . . . . . I'll bet that was one HELL of a job. . . . . . . or if it was E-caps, you don't know squat about radios AM sections.


Now, what a coincidence . . . . . I have the larger GRANDFATHER model . . .design prototype . . . . of this / your smaller unit, it only failed me in 2000 with no FM, I replaced a 74HC00 CMOS Quad nand gate, used in synth switching, and it came to life ! worked until 2 yrs later and the same chip failed again.
Replaced it again BUT, then used a ceramic cased full blown mil spec temp and reliability rated unit and added a top side small finned heat sink.
Still going great after 22 yrs and its reproduced FM sound is only being excelled by my large CD-3000 Bose Sound Wave . . . . mean machine..

Before I poke up a schematic snippet of this units related circuitry. . . . for us to work from, how about obtaining this info ?
??? Will another AM radio work in the SAME position as where this Sunny is having its problems ???
Can you at least pick up one strong AM station ? on the Sony . . . . . or is static and or interference or squeals and whistles *** being the problem.
( *** Take it up against the face of one of your operating Tee Wee's or computer monitors and you will thereby confirm / experience what I loosely describe there. )

You ALSO have short wave AM bands on the unit and they rely on a pull up rod antenna ( switched and shared with FM band ) for their reception, whereas the AM broadcast band uses a sensitive built in ferrite loop antenna . . . .inaccessible. . . .trouble free.
Pull out the antenna rod to its full extended length and try the AM short wave bands to see if reception is possible . . . . . this lets us isolate / evaluate the units two separate AM RF amplifier stages, as one is used for short wave and the other is solely for AM broadcast.

Its your info requested fulfillment time now . . . . .

ASIDE . . .
Another simple test is to place another receiver close to the dud one and listen for a tonal harmonic as the oscillator section of the known-good one 'interferes' with the dud one. If you can't get the harmonic then the RF oscillator is dud.
But . . .But . . .But . . . but . . . . but . . that was his grandfathers set, you really need to take a more IN DEPTH study of THIS receivers AM circuitry . . . . . I.F. frequency 55.8425 MEGA- hurts. . . . . .BABYCAKES ! ( No sub harmonic phantom, second image problems there ! )

Thaaaaaaaaaassit . . . . . .


73's de Edd . . . . .



Do I lose ? . . . . . . . . . . . when the police officer pulls me over and says papers and I say . . . . . . . . . . scissors?



.
 
Last edited:

sub2001zero

Dec 16, 2022
4
Joined
Dec 16, 2022
Messages
4
Sir sub2001zero . . . . .


Hi I need help what wrong with the radio i change all the caps out . . . . .

Hi I need help what wrong with the radio i change>>>>>(
all )<<<<<<< the caps out . . . . .
all . . . . .really ? . . . . . ALL . . . . . . . I'll bet that was one HELL of a job. . . . . . . or if it was E-caps, you don't know squat about radios AM sections.


Now, what a coincidence . . . . . I have the larger GRANDFATHER model . . .design prototype . . . . of this / your smaller unit, it only failed me in 2000 with no FM, I replaced a 74HC00 CMOS Quad nand gate, used in synth switching, and it came to life ! worked until 2 yrs later and the same chip failed again.
Replaced it again BUT, then used a ceramic cased full blown mil spec temp and reliability rated unit and added a top side small finned heat sink.
Still going great after 22 yrs and its reproduced FM sound is only being excelled by my large CD-3000 Bose Sound Wave . . . . mean machine..

Before I poke up a schematic snippet of this units related circuitry. . . . for us to work from, how about obtaining this info ?
??? Will another AM radio work in the SAME position as where this Sunny is having its problems ???
Can you at least pick up one strong AM station ? on the Sony . . . . . or is static and or interference or squeals and whistles *** being the problem.
( *** Take it up against the face of one of your operating Tee Wee's or computer monitors and you will thereby confirm / experience what I loosely describe there. )

You ALSO have short wave AM bands on the unit and they rely on a pull up rod ( switched and shared with FM band ) for their reception, whereas the AM broadcast band uses a sensitive built in ferrite loop antenna . . . .inaccessible. . . .trouble free.
Pull out the antenna rod to its full extended length and try the AM short wave bands to see if reception is possible . . . . . this lets us isolate / evaluate the units two separate AM RF amplifier stages, as one is used for short wave and the other is solely for AM broadcast.

Its your info requested fulfillment time now . . . . .
antenna
ASIDE . . .
Another simple test is to place another receiver close to the dud one and listen for a tonal harmonic as the oscillator section of the known-good one 'interferes' with the dud one. If you can't get the harmonic then the RF oscillator is dud.
But . . .But . . .But . . . but . . . . but . . that was his grandfathers set, you really need to take a more IN DEPTH study of THIS receivers AM circuitry . . . . . I.F. frequency 55.8425 MEGA- hurts. . . . . .BABYCAKES ! ( No sub harmonic phantom, second image problems there ! )

Thaaaaaaaaaassit . . . . . .


73's de Edd . . . . .



Do I lose ? . . . . . . . . . . . when the police officer pulls me over and says papers and I say . . . . . . . . . . scissors?



.

Hi the recaping was not bad i used Tantalum tiny but manageable. The am doesn't do any just static with antenna all the way out. I am new to working on radio. I most fix old vintage game systems. Another board said I would need to use a SIGNAL INJECTOR and diode probe to see what the problem is.
 

sub2001zero

Dec 16, 2022
4
Joined
Dec 16, 2022
Messages
4
Signal injector and diode probe (home made if you have to - only three or four components!) is all you need - plus the schematic of course. You can even use a home made signal injector; basic squarewave oscillator, lots of harmonics.

I taught fault finding on marine radio equipment for years using just those two items plus an Avometer! Radio receiver fault location is a well studied and practised 'art' with many practical examples of 'the tube' but, basically, inject a signal starting at the audio section - you know that part works - then work backwards until the signal stops i.e. detector, if amp, mixer, rf amp etc..... fault found.

Another simple test is to place another receiver close to the dud one and listen for a tonal harmonic as the oscillator section of the known-good one 'interferes' with the dud one. If you can't get the harmonic then the RF oscillator is dud.
diode probe Or is it RF probe. If it a diode probe do you a a schematic for one thanks.
 

bertus

Moderator
Nov 8, 2019
3,378
Joined
Nov 8, 2019
Messages
3,378
Hello,

Perhaps the following page might give you an idea for an RF probe:

Bertus
 
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