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How to trouble shoot fm receiver

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RETGT

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How to trouble shoot fm reciver

Hello,
I have fm receiver ic is Tea5591a it was working but after change to trimmer it is not working why??
 

Re: How to trouble shoot fm reciver

Changing which trimmer? There are at least 4 cap trimmers (2 FM, 2 AM) and multiple IF filters. Ill-considered variation of any trimmer will cause performance loss or complete failure.
 

Re: How to trouble shoot fm reciver

here is the pcb which use..
philips fm 5591


only two trimmers ..
FM not AM
 
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Re: How to trouble shoot fm reciver

here is circuit on pcb.

20161119_153031.jpg
 

Re: How to trouble shoot fm reciver

Hi,

Read the IC. Find out manufacturer and IC type.
Look for datasheets, descriptions and application notes. Learn how the IC operates.

Then test if everything is like in the descriptions:
* power supply
* inputs
* outputs
* other signals

Klaus
 
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    RETGT

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Re: How to trouble shoot fm reciver

Apparently there's no varcap besides the two trimmers. Is it a fixed channel receiver? In this case, both trimmers must be tuned to set the receiver to a different station.
 
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Re: How to trouble shoot fm reciver

The datasheet shows the oscillator variable capacitor (to tune the frequency) connects to pins 18 and 19. The RF variable capacitor (to peak the sensitivity at a frequency) connects to pins 19 and 20.
If you replace the trimmer capacitors then the replacements must have the correct capacitance value. With the detailed coils shown your trimmer capacitors should be about (20pF + 30pF=) 50pF.

It is a cheap poor quality radio circuit with high distortion and poor selectivity. Since its antenna input is not tuned (its tuning is after the RF amplifier) then it is overloaded by strong local stations, a local (attenuated) distance (direct) switch is needed.
 
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Re: How to trouble shoot fm reciver

Hi,

Read the IC. Find out manufacturer and IC type.
Look for datasheets, descriptions and application notes. Learn how the IC operates.

Then test if everything is like in the descriptions:
* power supply
* inputs
* outputs
* other signals

Klaus
Click to expand...
The all input out put power supply is working problem is high noise and low gain.



Apparently there's no varcap besides the two trimmers. Is it a fixed channel receiver? In this case, both trimmers must be tuned to set the receiver to a different station.
Click to expand...

Hello Sir,
yes it is fixed radio receiver.

The datasheet shows the oscillator variable capacitor (to tune the frequency) connects to pins 18 and 19. The RF variable capacitor (to peak the sensitivity at a frequency) connects to pins 19 and 20.
If you replace the trimmer capacitors then the replacements must have the correct capacitance value. With the detailed coils shown your trimmer capacitors should be about (20pF + 30pF=) 50pF.

It is a cheap poor quality radio circuit with high distortion and poor selectivity. Since its antenna input is not tuned (its tuning is after the RF amplifier) then it is overloaded by strong local stations, a local (attenuated) distance (direct) switch is needed.
Click to expand...

Hello AG,
I never calculated or does not know how to select trimmer calculation

thanks for help and interest.
i want to lean it designing and calculation

thanks
 

Re: How to trouble shoot fm reciver

If you didn't change anything else, you should be able to get an acceptable quality by tuning both capacitors alternatingly.
 

Re: How to trouble shoot fm reciver

If you didn't change anything else, you should be able to get an acceptable quality by tuning both capacitors alternatingly.
Click to expand...

now i want to learn it working of component working in it...

- - - Updated - - -

hello,
what is this tunable square height component used for??
 

Re: How to trouble shoot fm reciver

Did you already study the datasheet application schematic and try to find the respective functions in your device?
 

Re: How to trouble shoot fm reciver

RETGT said:
The all input out put power supply is working problem is high noise and low gain.
Click to expand...
Probably because it is a very cheap simple circuit.

Hello AG,
I never calculated or does not know how to select trimmer calculation
Click to expand...
The datasheet shows coils with a tuning core and low value tuning capacitors. My FM transmitter uses coils with no core like yours but they have 9 turns but your coils have 3 turns and 4 turns. My FM transmitter uses trimmer capacitors that are 5pF to 35pF so try your circuit with trimmer capacitors that are about 56pF maximum.

Your datasheet is for the older TEA5591 but your circuit has the newer TEA5591A that has a circuit a little different.
 

Re: How to trouble shoot fm reciver

how to get new TEA5591a DATASHEET?
 

Re: How to trouble shoot fm reciver

I get my datasheets from www.datasheetarchive.com where I can select the manufacturer/and date. The original manufacturer (Philip/NXP) also have applications notes.
Right now I entered TEA5591A into a Google search and it found a few pages full of datasheet websites that have it.
 

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