Old electros...safe?

[surfsup]

I picked up an old signal gen, a heathkit ag10.

There are three large can caps and three dry electros in circuit.

I don't have the parts handy. With tubes out, what could happen if i plug it in?

[Phil_S]

They could blow up and make a mess. Don't do it.

[surfsup]

Ok, i'll wait or try reforming. I haven't done anything with old electronics before, this is my first restoration project...

[surfsup]

The other caps are film caps. These are fine, correct?

[Structo]

I always like to post this picture when talking about old electrolytic caps.

Marshall JTM45

[img:640:480]https://lh4.googleusercontent.com/-njd9 ... C01890.jpg[/img]

[surfsup]

I ordered electros to replace all the e caps in the amp. I couldn't find a reasonably priced 40/40/40/40 can cap though. Having done this stuff for less than two yrs i dont know all the sources yet i guess. Mouser didnt seem to carry any multi section can caps at all. aES had one for $36 ouch...but i was able to get everything there at one price for shipping so that helped.

I got it anyway but for the future can one reform can caps with good success? Is there a good source for multi section electro can caps? This 36 dollar cap really kind of kills the validity of the restoration...i'm considering a lesson in electronics.

[Cliff Schecht]

Yes can caps tend to last significantly longer than standard e-caps because they are sealed well (and in general made really well). They were the higher dollar option back in the day too, but also an economical space saver, so they are relatively common in old equipment.

With regards to reforming them, I have had a great success rate with bringing old can caps back to life. Because they are sealed, the electrolyte gel tends to not dry out as it does in axial caps and so once the aluminum oxide insulation layer is properly reformed, the caps are usually good to go (if they were properly stored).

FWIW I don't usually bother recycling used can caps. They have a life expectancy that diminishes with use over time (as does any e-cap). The heat (both self generated from ESR and from external sources) does dry out the gel inside eventually and makes the caps useless.

[wyatt]

I ordered electros to replace all the e caps in the amp. I couldn't find a reasonably priced 40/40/40/40 can cap though. Having done this stuff for less than two yrs i dont know all the sources yet i guess. Mouser didnt seem to carry any multi section can caps at all. aES had one for $36 ouch...but i was able to get everything there at one price for shipping so that helped.

I got it anyway but for the future can one reform can caps with good success? Is there a good source for multi section electro can caps? This 36 dollar cap really kind of kills the validity of the restoration...i'm considering a lesson in electronics.

Well, it is FOUR 40uF caps. If you look at the target market, which is catering to vintage guitar and hi-fi repair, the competition is...

4xSpague Atoms=$44.
4xF&T=$28
4xTAD=$28

So, unless you go to Nichicon, you are falling somewhere in the middle there. It is also $36 capitalized over 15+ years. Otherwise, despite their durability, cap cans are considered obsolete, most sold today actually just regular caps loaded into the can to create a product that will fit.