Hi,
Recently I got A boombox which has nice tda7293 (Singapore) ICs. I want to trouble shoot it.
Details :
(1) board is from 3 v/cd player with tuner boombox.
(2) All PS, Contol, Signal connections, ribbon connections are cut.
(3) there is no visual indication of TDA ICs blown or burnt.
(4) I tested ICs on board as shown in picture.
There is no sound, no hum, nothing to indicate both ICs are working.
My query is...
1) If my connections are right can I assume ICs are dead ?
2) Is there anything related to standby and mute function for no sound ?
3) Since this boombox has multiplexer Ics and I have bypassed it giving signal directly to the TDA IC, shuld I presuem multiplexer IC plays no role in this ?
4) Any other things to check ?
Thanks,
Recently I got A boombox which has nice tda7293 (Singapore) ICs. I want to trouble shoot it.
Details :
(1) board is from 3 v/cd player with tuner boombox.
(2) All PS, Contol, Signal connections, ribbon connections are cut.
(3) there is no visual indication of TDA ICs blown or burnt.
(4) I tested ICs on board as shown in picture.
a) with nothing connected and no power supply and IC stilll soldered on board there is NO short on
supply pin (13+15) and supply and output pins 4
b) With connections made as point (5) I am getting +/-15v at pin 13 and pin 15.
(5) With series bulb tester and 12-0-12ac transformer I connected as follows. (Refer image)a) Three Parrot Green dots are 12-0-12 AC volts
b) two red dots to speaker +ve and -ve
c) two blue dots Music signal in from Mobile phone headphone output.
(6) I have bypassed speaker relay and signal selection detecting multiplexer IC.There is no sound, no hum, nothing to indicate both ICs are working.
My query is...
1) If my connections are right can I assume ICs are dead ?
2) Is there anything related to standby and mute function for no sound ?
3) Since this boombox has multiplexer Ics and I have bypassed it giving signal directly to the TDA IC, shuld I presuem multiplexer IC plays no role in this ?
4) Any other things to check ?
Thanks,
Check supply, are the voltages in line with specification?
The capacitors and voltage regulation circuit must also be checked.
You want to use this board in another unit?
Give input signal from a cheap FM module, vary the volume with its remote control.
7293 is famous for blowing up like STK chip amps, I would use a transistor amp board, those are quite reasonably priced.
The capacitors and voltage regulation circuit must also be checked.
You want to use this board in another unit?
Give input signal from a cheap FM module, vary the volume with its remote control.
7293 is famous for blowing up like STK chip amps, I would use a transistor amp board, those are quite reasonably priced.
TDA7442 is a mux and surround processor controlled via I2C bus : by a microcontroller. you should try to inject sound after the tda7442.
Try to remove C728 & C729 and inject audio on their negative side.
if it doesn’t work you should ensure to disable the 2 mute circuits :
First : with a wire connect collector of q702 to ground
Second : set anode of d791 to a voltage of let’s say 12v (r798 value is missing exact minimum value could not be calculated ). To enable tda7293 you should have a minimum of 3,5v on mute and std by pin.
Try to remove C728 & C729 and inject audio on their negative side.
if it doesn’t work you should ensure to disable the 2 mute circuits :
First : with a wire connect collector of q702 to ground
Second : set anode of d791 to a voltage of let’s say 12v (r798 value is missing exact minimum value could not be calculated ). To enable tda7293 you should have a minimum of 3,5v on mute and std by pin.
Hi,
Your current board is fine to test the TDA...no need for another. In addition TDA7293 and 94 are not pin compatible.
After the accident, did you power cycle the board and checked if the light build lit up? you could have removed only the TDA on which you made an short, then tested again.
I suggest you reinstall the tda on which you didn't make the short and resume the tests on post #3
Your current board is fine to test the TDA...no need for another. In addition TDA7293 and 94 are not pin compatible.
After the accident, did you power cycle the board and checked if the light build lit up? you could have removed only the TDA on which you made an short, then tested again.
I suggest you reinstall the tda on which you didn't make the short and resume the tests on post #3
Tda7293 fits 7294 pcb but 93 has some extra features which you may need or may not ;-)
Anyway, don't forget to unmute the chip. You should connect mute/st-by pin to +VCC rail in series with resistors(see datasheet schematic) to disable those function. You don't need extra PCBs just to check if it is working or not.
Anyway, don't forget to unmute the chip. You should connect mute/st-by pin to +VCC rail in series with resistors(see datasheet schematic) to disable those function. You don't need extra PCBs just to check if it is working or not.