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Old 04-06-2016, 12:02 PM
Captainclock Captainclock is offline
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Sony ICF-200W Handheld Transistor Radio Issues

Hello Everyone, the other day I bought from goodwill a Sony AM/FM Pocket Transistor radio from about the late 1970s or early 1980s that runs off of 3 "AA" batteries which when I got the radio home I found that the radio had some 20+ year old Duracell batteries in it that had leaked into the battery compartment but somehow managed to spare the rest of the radio I think, but anyways I tried putting some new "AA" batteries into the radio and the radio refuses to power on. The circuit board looks like its in good shape yet there aren't any bulging capacitors in it (it uses only 3 or 4 electrolytic capacitors the rest are ceramic disc capacitors.) I'm hoping that the old batteries that leaked in the radio didn't ruin the radio beyond repair. What could be the issue with the radio?
Any help would be appreciated.
Thanks,

Levi.
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Old 04-06-2016, 01:33 PM
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Electronic M Electronic M is offline
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With the batteries in and the set open see if there is the correct battery voltage at the wires coming from the battery compartment. Odds are the terminals corroded and are now insulators (if that is the case there will be no battery voltage at the batt compartment output wires). Sanding the corrosion off the terminals should help.
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  #3  
Old 04-06-2016, 02:34 PM
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jr_tech jr_tech is offline
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On low power devices, a bad electrolytic does not necessarily bulge because there is simply not enough power to heat up a shorted one enough to bulge. You may indeed have some shorted or open capacitors in the circuit, regardless of appearance.
But the first order of business is to clean off the battery connectors and check for voltage on the board, as mentioned above. Power switches often fail on these sets, so check for voltage on either side of the switch while turning it on and off.
Do you then hear a click/pop in the speaker when you operate the switch, or any scratch noises as you operate the volume control?

jr
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Old 04-06-2016, 03:16 PM
Captainclock Captainclock is offline
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Quote:
Originally Posted by jr_tech View Post
On low power devices, a bad electrolytic does not necessarily bulge because there is simply not enough power to heat up a shorted one enough to bulge. You may indeed have some shorted or open capacitors in the circuit, regardless of appearance.
But the first order of business is to clean off the battery connectors and check for voltage on the board, as mentioned above. Power switches often fail on these sets, so check for voltage on either side of the switch while turning it on and off.
Do you then hear a click/pop in the speaker when you operate the switch, or any scratch noises as you operate the volume control?

jr
I do not hear a popping noise through the speaker or a scratching noise through the speaker as the volume is rasied it is completely dead silent regardless of what I do with the power/volume switch.

I did clean most of the corrosion off of the battery terminals that I could and I still don't get anything.

Edit: Recleaned the terminals and reflowed the solder on the terminals on the terminal boards and I tested at the terminals with batteries installed and unit powered on, and I'm still getting nothing, tested at terminals with batteries installed and unit powered on with voltmeter and I get 1.5 volts at each terminal on the back side of the terminals, but then when I test at where the wires from the terminals go on the main circuit board with the unit powered on I only get a 1/3 of a volt and when the unit is powered off and I test at the place where the battery terminals connect to the main board I get 1.5 volts (there should be 4.5 volts there because that's all 3 of the batteries combined flowing into those wires.) Do I perhaps have a bad battery or something? I bought a package of batteries brand new from the store and I would of thought that they were all good but then again I bought generic batteries so who knows.

Last edited by Captainclock; 04-06-2016 at 04:35 PM.
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Old 04-06-2016, 03:19 PM
Captainclock Captainclock is offline
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Quote:
Originally Posted by Electronic M View Post
With the batteries in and the set open see if there is the correct battery voltage at the wires coming from the battery compartment. Odds are the terminals corroded and are now insulators (if that is the case there will be no battery voltage at the batt compartment output wires). Sanding the corrosion off the terminals should help.
I could try using some sandpaper on the terminals and see if that helps, which when I did some initial cleaning on the battery terminals i just used soap and water on some q-tips and then a flat-blade screwdriver to bust loose any stubborn corrosion. By the way the terminals on this radio are all solid copper, would using some metal polish like brasso work to clean the corrosion off of these terminals as well?
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Old 04-06-2016, 06:06 PM
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jr_tech jr_tech is offline
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Quote:
Originally Posted by Captainclock View Post
I'm still getting nothing, tested at terminals with batteries installed and unit powered on with voltmeter and I get 1.5 volts at each terminal on the back side of the terminals, but then when I test at where the wires from the terminals go on the main circuit board with the unit powered on I only get a 1/3 of a volt and when the unit is powered off and I test at the place where the battery terminals connect to the main board I get 1.5 volts (there should be 4.5 volts there because that's all 3 of the batteries combined flowing into those wires.)
Sometimes the corrosive chemicals from the leaky battery "wick" into the wires connected to the battery terminals and eat away the copper conductor... the wire may look ok from the outside but may high resistance. Suggest an ohm meter check of the wires to the board (remove batteries first, of course).

jr
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  #7  
Old 04-06-2016, 07:56 PM
zeno zeno is offline
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1)Unhook or unplug the battery box from the radio.
If soldered in one lead is fine.
2) measure volts. If 4.5 V the batteries & holder OK.
If not then the problem is the holder or bats.
3) If the voltage drops a lot when you hook up
the radio something is loading things down. Look
at the output IC or transistors first.
The radio may have crapped out then got tossed in a drawer
& the bats leaked......

If you like working on small stuff ( I do !) get some DC
output wall warts. They used to make them with a voltage
switch ( 4.5 - 12 V ), multi connectors & polarity switch.
ADD a pair of wires with alligator clips that are color coded
& you can sub it in to any low current device without
batteries involved. As for bats I only use duracells from a
known source to avoid Chi-Com junk & counterfits.

73 Zeno
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  #8  
Old 04-06-2016, 08:55 PM
Captainclock Captainclock is offline
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Quote:
Originally Posted by zeno View Post
1)Unhook or unplug the battery box from the radio.
If soldered in one lead is fine.
2) measure volts. If 4.5 V the batteries & holder OK.
If not then the problem is the holder or bats.
3) If the voltage drops a lot when you hook up
the radio something is loading things down. Look
at the output IC or transistors first.
The radio may have crapped out then got tossed in a drawer
& the bats leaked......

If you like working on small stuff ( I do !) get some DC
output wall warts. They used to make them with a voltage
switch ( 4.5 - 12 V ), multi connectors & polarity switch.
ADD a pair of wires with alligator clips that are color coded
& you can sub it in to any low current device without
batteries involved. As for bats I only use duracells from a
known source to avoid Chi-Com junk & counterfits.

73 Zeno
The batteries I bought were the generic store brand batteries (they were almost 50% less than the Duracells price wise for the same amount of batteries, and I've bought store brand batteries in the past and never had any issues with them.) I used to have a switchable voltage AC Adaptor but it took a dump on me a while ago (it was one I had gotten from radio shack several years before they went through bankruptcy and when they still had a decent selection of electronics parts yet in store.)
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  #9  
Old 08-26-2016, 01:39 PM
YankGee YankGee is offline
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Hi..as per my knowledge you may indeed have some shorted or open capacitors in the circuit, regardless of appearance.But the first order of business is to clean off the battery connectors and check for voltage on the board, as mentioned above. Power switches often fail on these sets, so check for voltage on either side of the switch while turning it on and off.

smt assemblies

Last edited by YankGee; 09-27-2016 at 01:44 PM.
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  #10  
Old 08-26-2016, 02:06 PM
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maxhifi maxhifi is offline
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Quote:
Originally Posted by zeno View Post
1)Unhook or unplug the battery box from the radio.
If soldered in one lead is fine.
2) measure volts. If 4.5 V the batteries & holder OK.
If not then the problem is the holder or bats.
3) If the voltage drops a lot when you hook up
the radio something is loading things down. Look
at the output IC or transistors first.
The radio may have crapped out then got tossed in a drawer
& the bats leaked......

If you like working on small stuff ( I do !) get some DC
output wall warts. They used to make them with a voltage
switch ( 4.5 - 12 V ), multi connectors & polarity switch.
ADD a pair of wires with alligator clips that are color coded
& you can sub it in to any low current device without
batteries involved. As for bats I only use duracells from a
known source to avoid Chi-Com junk & counterfits.

73 Zeno
I have a couple EICO 0-30V 0-500mA variable power supplies which are awesome for this kind of work. Keep eyes open for one, they work amazingly well and aren't worth much money.
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