Power Amp safe to de-solder?

Fender_Punk

Fender_Punk

BerriesAndCreamologist
Hey everyone.

I got this really old stereo receiver. It doesn't work, or at least it didn't when I tried using it. It has a whole bunch of resistors and capacitors and other nifty electronic parts I'd like to de-solder from the board. I've removed the fuse and the thing isn't plugged it, is it safe for me to open up and poke around (it says do not open, but...).

By opening it while unplugged and without a fuse, is there any risk of electric shock touching the PCB and/or taking a soldering iron to it? The thing hasn't been plugged in in MONTHS, probably around half a year.
 
Re: Power Amp safe to de-solder?

I just want to salvage the resistors and capacitors, make use of a POS. Saves me money on going out and buying stuff, and I'm broke right now. So, is this safe?
 
Re: Power Amp safe to de-solder?

I've done That exact thing before. I didn't get electrocuted or anything. But YMMV. So if ya do get electrocuted or die or something I don't wanna hear about it. Especially if ya die, Ghosts/Zombies creep me the **** out.
 
Re: Power Amp safe to de-solder?

Well, I'm thinking with the fuse out, and the thing not doing anything but collecting dust for a few months, any current that was in it is definately gone right? Has anyone ever done anything like this?
 
Re: Power Amp safe to de-solder?

Caps can store electricity for a good long time. Really, I don't think you'll be saving much money- it's not like resistors are mildly expensive... if it's just for fun- stay away from the bigger caps. Read up on discharging caps and be really, really careful- especially if they're big caps.
 
Re: Power Amp safe to de-solder?

The Golden Boy said:
Caps can store electricity for a good long time. Really, I don't think you'll be saving much money- it's not like resistors are mildly expensive... if it's just for fun- stay away from the bigger caps. Read up on discharging caps and be really, really careful- especially if they're big caps.
Click to expand...

There are some pretty massive caps. How much electricity are we talking?

I need the help/opinion of a pro here. Artie? Zhang? Jeremy? Evan? Scott_F?
 
Re: Power Amp safe to de-solder?

I'm waiting for a definate answer. I believe the last time this thing was plugged in was September? No later than December, and that's an absolutely latest. Also I've modded my guitars, played them, unplugged them and opened them right up and re-soldered a joint and the cap didn't shock me. (I believe it was a .47mfd)
 
Re: Power Amp safe to de-solder?

High quality caps can hold their charge for years. You will need to discharge the large caps; don't worry about the little ones.

Read this:
http://www.repairfaq.org/sam/captest.htm#ctsdc

On second thought, if you have high-quality components, then it's likely a valuable unit, and you'd be better off selling it whole. If it's a POS, the components are probably not worth salvaging.
 
Re: Power Amp safe to de-solder?

3th3r said:
High quality caps can hold their charge for years. You will need to discharge the large caps; don't worry about the little ones.

Read this:
http://www.repairfaq.org/sam/captest.htm#ctsdc

On second thought, if you have high-quality components, then it's likely a valuable unit, and you'd be better off selling it whole. If it's a POS, the components are probably not worth salvaging.
Click to expand...

Well it had never worked for me when I plugged it in. However, there's at least 400 resistors and a hell of a lot of capacitors as well, so if I can salvage them, it saves me trips to the sotre for buying parts to mod my pedals, or make one. I don't have any volt meters or anything. The back panel says it's 120V~ 60Hz 200VA. It's a REALISTIC STA-530 AM/FM stereo receiver. I'm guessing SS, I don't see any tubes.
 
Re: Power Amp safe to de-solder?

some of the big ol' caps can hold a charge upwards of 4-500 volts, depending on the circuit, and can store that charge for a very very long time even after the thing has been unplugged. if you have a voltmeter, you can measure the voltage across the caps to see what you're working with. if you get a reading beyond 40 volts or so, you're going to want to discharge them before poking around in there. you can drain them by connecting one end of a resistor to the positive lead on the cap, and the other end to a ground point. i can't recall what value resistor is best for this, but you could do a quick google search and find out.

i wouldn't poke around too much without having a meter to verify that there isn't any dangerous voltage in there. if you don't have a meter or any way to verify that, then i would stay out of there.
 
Re: Power Amp safe to de-solder?

I know radio-shack built it, that's why I called it a POS. However, resistors and capacitors are what they are and I want them. I think it's fairly safe to say that if I want to stay alive I better get a voltmeter, a 25K resistor, and someone to help me discharge the caps so I can get them and the resistors out.

Thanks a lot everyone. If anyone else has anymore info/suggestions, feel free to share. I'm always open to new knowledge.
 
Re: Power Amp safe to de-solder?

The caps and resistors are not worth the effort. They are not that expensive to buy new and they will at least have full length leads.
How are you going to know if you cooked a cap. in the process of taking it out?
How are you going to protect (heat sink) the components, especially caps., when they are soldered so close to the board?

Get a meter (DMM) and learn how to use it...much better use of your time.

And start reading about safety...especially around 110V AC stuff, and just safety in general.

Your life might be saved by a chopstick...you tell me how/why...This is a test question for you.

Then consider building some small 9V DC circuits...like a pedal.

If you are looking for a place for components, try here:
http://www.sayal.com

Dave

Sorry if I'm coming across a bit strong. Just don't want you to get hurt 'bro.

If you want to get into electronics, send me a PM. I have a lot of extra electronics stuff and maybe we can make a deal. I'll be more than fair as I have been helped with this hobby also.
 
Last edited:
Re: Power Amp safe to de-solder?

Old fart useless trivia: most Radio Shack home electronics were made by major brand companies, and sold with the brand name attached (aka "private label" goods). Most likely made by Sanyo/Fisher, Panasonic, Sony, etc.

Don't bother. It's cheap stuff, made for Quagmire's den.
 
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