EQ Pedal build from an old boombox. help!! :)

Started by Demonikz, March 02, 2021, 12:01:48 AM

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Demonikz

Hello everyone! so i found an old boombox in the garbage and took it home cause i like recycling, it has a 5 Band EQ with volume knob wich id like to turn into a guitar pedal but i dont know much about electronics (i barealy know how basic electronics work) and i tried to search the code thats printed on the pcb on google but couldnt find anything, it seems to be in pretty good condition except that it has some kind of boxy led that seems to be corroted other than that is pretty good! :)its a RJBX0005AB



:o

antonis

What is the item code printed on IC3..??

I suspect it's some kind of BA3812L but with 6 additional pins..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Radical CJ

I don't see enough components on that board for a 5 band eq. I assume the leads go to a second board?

Demonikz

Quote from: antonis on March 02, 2021, 05:30:34 AM
What is the item code printed on IC3..??

I suspect it's some kind of BA3812L but with 6 additional pins..
its an BA3822LS i thought i edited the post with this info but seems like i didnt do it lol
its a 5 band stereo graphic eq made for cassete players car sounds systems etc
https://www.alldatasheet.com/datasheet-pdf/pdf/35975/ROHM/BA3822LS.html
hope this helps replies are apreciated :)

Demonikz

Quote from: Radical CJ on March 02, 2021, 07:27:40 AM
I don't see enough components on that board for a 5 band eq. I assume the leads go to a second board?

yes it goes back to a secondary board i also have it and its in good condition if its needed i can provide some photos if it helps :)

antonis

So, you just have to box it and feed it with +9V (max..!!) power supply..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Demonikz

Quote from: antonis on March 03, 2021, 05:24:04 AM
So, you just have to box it and feed it with +9V (max..!!) power supply..

cool! but how do i do that what do i solder where? i really dont know much... wheres the input, the output?? :S or is there any way of figuring it out myself? im getting a multimeter soon and im learning how to use it so it guess it helps in figuring out... any tips apreciated!  ;D

Rob Strand

In the original circuit all the connections are on that strip of wires.

Open up the datasheet PDF you will see 6 connections:
- input 1, to pin 21 via capacitor
- input 2, to pin 22 via capacitor
- output 1, to pin 19 via capacitor
- output 2, to pin 20 via capacitor
- ground to pin 24
- +9V power to pin 23 maybe via a resistor

Try to follow the tracks on the PCB from IC pin numbers back to the 8 pin connector.

There are 6 pins on the IC and 8 on the connector so that leave two wires unidentified.
You might find there is more than one connection to ground.
Send:     . .- .-. - .... / - --- / --. --- .-. -
According to the water analogy of electricity, transistor leakage is caused by holes.