Hello,
recently I found an old Hitachi boombox in the trash.
I turns on, but no sound is coming out, except little pops and hissing.
I assume it's amp is working because of those sounds.
So, can I just somehow wire an rca or 3.5mm input straight to the amplifier board and make it work like that?
If yes, how could I tell what wires are the right ones?
Pics of the board attached.
And please give noob-friendly explanations, my knowledge of audio stuff is pretty limited.
Thank you!
And sorry if I posted to a wrong place, I'm new here 🙂
recently I found an old Hitachi boombox in the trash.
I turns on, but no sound is coming out, except little pops and hissing.
I assume it's amp is working because of those sounds.
So, can I just somehow wire an rca or 3.5mm input straight to the amplifier board and make it work like that?
If yes, how could I tell what wires are the right ones?
Pics of the board attached.
And please give noob-friendly explanations, my knowledge of audio stuff is pretty limited.
Thank you!
And sorry if I posted to a wrong place, I'm new here 🙂
Attachments
You can probably do what you are trying to do but you will have to put some legwork in.
1/ If you can, identify the original model number and try and locate a service manual. That will show you how its all configured.
If you can't find the manual then look up the chip numbers (those two on the heatsink) and look at the data sheet for that device. That will show you the input pin/s. You can then identify where those connect to on the board.
For an experienced tech with the board in front of them its an easy task, however just looking at pictures and its pretty near impossible to make out how its all configured.
1/ If you can, identify the original model number and try and locate a service manual. That will show you how its all configured.
If you can't find the manual then look up the chip numbers (those two on the heatsink) and look at the data sheet for that device. That will show you the input pin/s. You can then identify where those connect to on the board.
For an experienced tech with the board in front of them its an easy task, however just looking at pictures and its pretty near impossible to make out how its all configured.
Well, I found the data sheet for the two chips. Each chip seems to be 2 channels. In the pic included pins 6 and 7 are in1 and in2. I tracked all 4 of them to same 6-pin cable on the board. The remaining 2 pins are the in gnd ground pins.
There are 4 woofers in the boombox, 2 small and 2 bigger. So 4 channels total.
There is probably a crossover between the smaller and bigger woofers, right? Or might they just play the same sound in pairs? How should I go about wiring the 6 wires to an input? Do I need to use a crossover?
And in case I'm wrong about the pins and I try them with an audio source, will I risk frying something?
There are 4 woofers in the boombox, 2 small and 2 bigger. So 4 channels total.
There is probably a crossover between the smaller and bigger woofers, right? Or might they just play the same sound in pairs? How should I go about wiring the 6 wires to an input? Do I need to use a crossover?
And in case I'm wrong about the pins and I try them with an audio source, will I risk frying something?
Attachments
The upc1277 is quite a common device.
Deal with one IC at a time and try and confirm that its configured as per the standard configuration for that chip. You will have to trace the speaker wiring and see what they have done.
If there is a crossover then it may well be before the chip. The speakers should connect via large electrolytic caps (C7 and C8). RL1 and RL2 in the picture are the speakers.
If you just want to make an amplifier from it all then you are probably best cutting all the wiring off that board and then starting from scratch connecting it all up so that it conforms to the standard circuit.
If you connect an audio source then remember to include a volume control. You also have two wires per input, signal and ground.
Deal with one IC at a time and try and confirm that its configured as per the standard configuration for that chip. You will have to trace the speaker wiring and see what they have done.
If there is a crossover then it may well be before the chip. The speakers should connect via large electrolytic caps (C7 and C8). RL1 and RL2 in the picture are the speakers.
If you just want to make an amplifier from it all then you are probably best cutting all the wiring off that board and then starting from scratch connecting it all up so that it conforms to the standard circuit.
If you connect an audio source then remember to include a volume control. You also have two wires per input, signal and ground.
Attachments
For vintage boomboxes, you can try the Stereo2Go forums. Someone there might be able to help out with experience or service docs for this model. I can't tell an awful lot about speaker configuration from the pictures provided, must be a mid-80s set though ('82-'87-ish).
Thanks for the help everyone. Managed to sort it out. It sounds like **** tho 😀. But got the amp working anyways and that's the main point.
and stuff like this is great for learning with.- Status
- Not open for further replies.