Deconstructed Karaoke Machine

[jphunter]

First off, let me say that I am very beginner when it comes to electrical circuitry and whatnot. While I do know a lot about computers, I get a bit lost when it comes to the actual design of the components I use. Anyway, this is about a karaoke machine that I found out near the dumpster at my apartments. I hooked my PS3 up to it just for kicks and it worked! It showed up on the little B&W, 5" CRT and it sounded great. I played for about 10 minutes before deciding that I wanted to gut it. So I spent the next 2 hours carefully disassembling the machine, separating all of the wires and eliminating all of the components that were nonessential (CD player, buttons and knobs, etc.). What I was left with was the main board, the monitor (still connected and soldered to the main board), and the power supply. After the long and arduous task of taking the machine apart, I plugged it in and it still worked - sorta. After about 30-40 seconds, the monitor turns off. Now remember, it had worked for about 10 minutes before. I'm not 100% sure, but from the research that I did, it seems that there may be a bad capacitor on the board that is related to the power supply. Does that sound right? If so, how do I find out which capacitor is the bad one? I have the tools to replace it, I just need to know which one to replace.

**broken link removed**
**broken link removed**

Memorex MKS5627 CD+G Karaoke System w/ Monitor
PSU: 120V~60Hz AC
Power Consumption: 40W
Manufactured in 2004

 

[gabeNC]

Nice advertisement for that site, I would mark that as spam.

Anyway, you can't really tell that it's a bad capacitor without some kind of test equipment (o-scope), some voltage readings etc, unless of course it show obvious physical damage. Could be a dying voltage regulator, a resistor that is way out of spec, a flaky trace etc etc.

Be careful with the monitor and they are really dangerous. Personally I would just use this as a source for spare parts as it is very difficult to fix it without a schematic.

 

[Mr RB]

I think the engineer who designed that PCB had a brother who owned a blue capacitor company!

More seriously, regardign the shutdown it's probably;
A. Not getting a control signal now it's decapitated, so it shuts down, or
B. Has a high voltage or power fault

I agree with gabeNC the best thing is probably to strip it for parts AFTER leaving it unplugged for a couple of days to discharge fully.

 

[jphunter]

Hmm, well I thought it'd just be a fun little project taking it apart and building a new little enclosure for it, but if the two of you think that I'm better off stripping it for parts, what would I do with them? Remember, this is still very new to me.

 

[gabeNC]

Do you have a multi-meter? Any kind of test equipment? It's going to be very difficult to fix without that. If you really want to play with it, keep it and safely store it. when you have your skills developed come back to it. Remember that CRT can kill you so it's really not a good first project.

Buy some 555 timers that is a very practical, easy project. You can do all kinds of things with them.

555 and 556 Timer Circuits