/diy/ - Do It Yourself

>>388836
That isn't an electrolytic. It'll probably fail on DC after a while. The cheapest I can find are in the $10.00 range. Don't use bi-polar caps. Much like your first selection, bi-polar caps might fail under DC.

>>388825
500V is fine. The voltage rating is the maximum voltage it can take before it lets the magic smoke out.

>>388823
...Just get the polarity correct. Electrolytics have a "plus" and a "minus". The common connection (found as the connection that surprisingly enough goes to the speaker wire named "common") is the "minus" side.

>>388823
Yes. The highest voltage is 450V, and the highest capacitance is 30uf. You'll do fine.

>>388811
I'm glad you didn't go ahead with my "400V" suggestion. That would have been messy. If you want you can use the symbols on the can to figure pinout, but since you're replacing it with 4 separate caps I wouldn't even bother trying to decode it. You can replace all caps with a 30uf. It'll just filter out ripple on the power better. The schematic I posted had the symbols.

>>388795
..."the voltage ratings or aren't able to measure..."
Sorry for the typo.

>>388792
Yep. Four caps in one package. A 30uf and three 20uf. I forgot you still had the manual. If the manual doesn't list the voltages, it probably has a troubleshooting section that tells you what voltages you should get while testing. Also, look at the imprint on the can. If you can't find the voltage ratings or are able to measure the voltage under test, I'm quite certain a 400V part will be more than adequate. It's only a 12W tube amp. It shouldn't have any of the real high voltages needed to push the higher currents. I worked on a 1kw amp that had 1.5kv as a plate voltage. Yours is probably around 150v to 300v. Using a higher voltage than needed cap is safe. The uf rating can also be higher, just don't go past 100uf. The inrush current could possible blow the rectifier tube.

>>388771
Yep. The main filter capacitor is the tall metal can. Inside that can are the guts to 4 other capacitors. The most common thing to do is to replace the single can with multiple capacitors (like they did on YouTube). Previously I posted a schematic, but the schematic doesn't have the voltages. The thing you'll probably want to do is to hook up a voltmeter to the cap, turn on the power, and measure the voltage. Get a similar cap with a higher voltage rating and maybe higher capacitance. Actual capacitance values aren't needed for filter caps. Bigger is better.

>>388741
The cap you've chosen will replace that one nicely. Have you gotten replacements for the main filter cap?

>>388727
I'm sorry, but I didn't see any 25V capacitors in the schematic. The cap should have the info printed on it, and those tall tube capacitors actually have more than one capacitor inside. Those are normally replaced with individual capacitors.

>>387885
Pic related. Have fun.
http://www.vintage-radio.info/heathkit/

>>386026
Just giving a friendly bump for this guy
>>386483

Radio Shack has some kits and a few books by Forrest M. Mims III, although the RS crap is way overpriced, plus you'll have to bring a machete in just to hack through all the sales associates trying to sell you a cell phone. Adafruit and Sparkfun has some decent kits. Do a google for "electronic kits" for plenty of more hits. If you're just starting out, I suggest the kiddie rated stuff at Elenco to start out on.

First: Make sure the wiring in the house is proper. Make sure the hot, neutral, and ground in the plug are in the correct place.
Second: If the amp came with a three prong plug, double check the amp to make sure it's grounded correctly to the chassis. If not, attach it somewhere solid to the metal chassis.
Third: If the hum is still present, have the amp checked out for bad/old electrolytics, out of tolerance resistors, and gassy tubes (if it's a tube amp).

>>382152
When I want to build something from a schematic, I make a new schematic but make all the parts look like they really do, with all the pins in the correct place. I then try and draw lines (wires) from one pin to the other in a way that doesn't cross other wires, or cause confusion with multiple connections or funny angles. After checking my new schematic, I try and build it.

>>373662
Double argh.
Instead of masonry bits, you can also use a power actuated hammer. It basically uses something like a .22 round to explosively fire a nail into concrete. You should be able to rent those cheaply.

>>373662
Argh. I meant masonry bit without a hammer drill.

>>373662
You need more than a masonry bit. The bit will just scrape around in a regular drill. The hammer drill will "peck" out a dent in the concrete, and the masonry bit will scrape it.
>>373661
Some adhesives are designed for outdoor use.

If links to TPB aren't allowed, I apologize in advance:
https://thepiratebay.se/torrent/7687986/Electronics_All-In-One_For_Dummies_%5B2012%5D__BBS

https://thepiratebay.se/torrent/7783879/Complete_Electronics_Self-Teaching_Guide_with_Projects_%28gnv64%29

>>373650
I've got 2 cents burning a hole in my pocket, so I'd thought I'd give them to you.
Build a pressure treated wood frame around the concrete. Screw frame together well. Use outdoor rated silicon glue for attaching the frame to the concrete. Affix door to frame. This should prevent the alkalinity of the concrete from "eating" the door, and allow easy repair/re-gluing/replacement of the frame when needed. When you get a chance, you could even use concrete anchors at a later date.

Teh google shopping found this:
http://www.taydaelectronics.com/1k-ohm-linear-taper-potentiometer.html
$0.50 each. You may want to pad the order with some good stuff to make it worthwhile.

Lots of shims. Lots of poking and prying. Lots of praying to the Flying Spaghetti Monster. That's the best I have to offer.

>>369782
USB requires 5V. Too little won't work, and anything over 5V is out of spec and not guaranteed to work. USB is supposed to be able to provide 500ma, but some special chargers designed for special items can put out more current, but the same voltage. The iPad is one example. Plugged into a computer the iPad draws 500ma max at 5V. Plugged into its special iPad charger and it draws 2 amps at 5V.

>>369774
Before stores energy. The voltage coming out of the bridge rectifiers is pulsating DC. The capacitor after the regulator helps with sudden loads causing the output to droop, and it prevents the regulator from oscillating.