Sanyo m9990 Begginer Problems - Plz Help

[Samth3sanyo]

Growing up my grandpa always had this boom box in his boat garage and all he told me was that it didn't work. After a couple years he finally just gave it to me and I was so happy once I kinda cleaned it and the radios white light came on. But sadly since then I have taken the boombox apart and tried my best to figure out why it wouldn't turn on. When I say only that one light comes on I mean it... NOTHING WORKS! I became so desperate to fix it that when one of the belts broke I just super glued it and yes it stayed together and for a while it all worked together to spin it but it clearly needs new belts. At this point tho I would even just be happy with the radio to turn on.

Like I've said before I have taken it apart but with that a couple wires have been pulled off on accident that went to the biggest board those wires being the red and yellow wire. Also the blue wire coming from the smallest board on the left side of the box that goes to the antenna is now broken. Any help or advice would be gratefully appreciated thank u.

 

[caution]

Welcome to the site!

 

[Tinman]

If no one chimes in, I'd suggest getting a service manual if you're serious about repairing it.
You can purchase and download one or there's an original for sale on ebay (it's a little pricey but it's OBO).
I've never had a 9990 so I can't help you with where the yellow and red wires go but the antenna wire should be a fairly easy fix.
It just needs a solid way to mount to the antenna base.
Obviously you learned the hard way, you have to crack these open and separate them slowly.
Taking lots of detailed pictures is important before you start removing wires, boards, the cassette player, etc.

 

[caution]

Service manual is here

 

[Superduper]

This boombox uses a unique power setup where the entire boombox relies on a solid state switch comprising of a pair of transistors (2SD612E). The reason for this setup is because it has a special timer and sleep function that is not really found on any other boombox. The small clock has a built in control that has to have the ability to switch the entire boombox on and off. For it's time, it was quite sophisticated and more than just a plain clock. It obviously cannot switch the current requirements of the entire boombox on it's own hence the transistors. Therefore, I have found out that a common failure is this transistor pair.

In addition to eBay, you can buy the service manual (in pdf format) for about 1/2 the cost of the eBay one here: SANYO M9990 service manual.

If you pick up a service manual, the first step I would take is to determine if these transistors are working properly. I am referring to Q704 and Q705. I don't have those in stock for the example that I did work on, so I used some NPN power transistors that I did have in stock, worked fine although I did have to tweak the leads because the pin assignments are different. Any power NPN transistor with the same or better current rating will suffice in this application. Again, compare datasheets to make sure that the BCE assignments are the same; if not, then you'll have to adjust the leads to fit.

 

[Samth3sanyo]

Thank u all (Tinman, caution, and superduper) I'm gonna quickly decode all that and if anything happens I'll tell u guys. Any further help from more people would be gratefully appreciated.

 

[Samth3sanyo]

This boombox uses a unique power setup where the entire boombox relies on a solid state switch comprising of a pair of transistors (2SD612E). The reason for this setup is because it has a special timer and sleep function that is not really found on any other boombox. The small clock has a built in control that has to have the ability to switch the entire boombox on and off. For it's time, it was quite sophisticated and more than just a plain clock. It obviously cannot switch the current requirements of the entire boombox on it's own hence the transistors. Therefore, I have found out that a common failure is this transistor pair.

In addition to eBay, you can buy the service manual (in pdf format) for about 1/2 the cost of the eBay one here: SANYO M9990 service manual.

If you pick up a service manual, the first step I would take is to determine if these transistors are working properly. I am referring to Q704 and Q705. I don't have those in stock for the example that I did work on, so I used some NPN power transistors that I did have in stock, worked fine although I did have to tweak the leads because the pin assignments are different. Any power NPN transistor with the same or better current rating will suffice in this application. Again, compare datasheets to make sure that the BCE assignments are the same; if not, then you'll have to adjust the leads to fit.

So I did end up getting a manual a pdf version of it that is the same and I found Q704 and 705 but to be totally honest I have no clue what I am looking at or doing I've never worked on this stuff but I'm really trying to learn. So my questions to u are 1st where are the transistors on the box / board? 2nd what do I do when I find said transitors? And if there is a test involved how do I do said test? Lastly do I have to get the clock to work in order to get the rest of it to turn on? By the way I'm incredibly grateful for u help this is the farthest I've ever gotten and I just need a lot of explanation I'm sorry if I ask to much.

 

[Samth3sanyo]

I think one of these may be what I was looking for from what I see in the diagram I'm thinking the top one if not both. Can someone clarify? Or tell me how to test these?

 

[Tinman]

Those big barrels are capacitors.
The transistors that super is talking about are smaller black things with three legs usually roundish or flat squares (it looks like there's one of each shape on the right of the red circle you drew).
In the service manual, there should be a layout of each board, you'll have to search for the location of q704 and q705.
You can find gobs of information about testing them online and watch videos on youtube.
Being that this was free, it's a great box to work and learn on.