Today i opened the MasterBlaster to take a look inside. I must do it at the livingroom table, because it´s too big for my working station.

Front:


Back:


It was horrible. All screws are rusted...
2 broke, but finally i could open it without damage:


There is much inside - much space


But the big body and the big speakers results a lot of bass:


Look at the main board:


The belts of the tapes seems to be OK:


The endamplifier IC´s. I hope i can get new ones:




Next to the right speaker you see the alert sensor:


At night:


Putted together with impoving 2 screws:




This is the schematic of the LA4508
Seems to be manufactured by SANYO!

And i checked the alert function!
Worked so:

Power on > pushing the alert button > box goes standby > when you come close after a short time the siren starts (up+down tone)!

Its kind of nice that all the electronics are right there on front panel and not buried in back box Looks real nice though

You cannot be suprised by the "sanyo" brand chip
Some Panasonics I have use Sanyo (LA) or even Rohm (BA) chips, even when Matsuhita Group have manufactored tons of IC's (AN) and integrated power amps. But business are business ....

Yeaaah, today i found a shop in Germany, that have the IC avaiable!
I should get it in a few days.
Wish me luck.
I hope it´s fully working after changing the end-amplifiers...

Good luck Roman! Hope you get her all fixed, it's a killer ghettoblaster!



Rock On.

What issue does this boombox have ? (curious).

Today i got the IC´s.
Best thanks to BASTLER-SHOP in Germany.
But it looks, there must be a other problem too.
After changing the IC the right speaker works, but only very weak. And the volume there is not able to regulate....
It seems, any other transistor or so must have a problem. I´m sure, it´s only a peanut, but heavy to find it.
So next days when i have more time, i must take a complete check up.
I want to get this monster fully working.

Todays working at it:




A positive thing:
The tapes works now after a good cleaning.

Could be the preamp section failed, just enough signal getting through to the main power amp chip to give a weak sound, and if the volume control is via the preamp that explains why it has no effect on the sound you can hear faintly.

Just a thought

Thanks for the tip!
I hope i have soon time to make a full check up.
But first my scooter must get clear for summer.
Will be a project for a rainy day.

there is so much space inside this boombox even if the original components cannot be replaced there is tons of possibilities for bringing it back to life.
i think you chould make it better than it was if you cannot get the parts to repair it.

It is easy to plop a car audio cd player into one of these boxes and would probably look/work the best, BUT it is about keeping the box true and vintage that is the cool part. Good luck, seems like we are in the same boat with our big BBXs....