Recapping channel strips

[chris p]

I'm about to embark on such an exercise. Any tips / war stories (like, note down polarity BEFORE you take the electro off the board)? Thoughts on upping the voltage rating or cap value, or replacing the electro with another type of cap?

Strips are 70's console. Should I also replace the greencap / ceramic caps, or will the electros do the trick?

Any recommendations for sourcing replacement caps? Yes, besides DSE/Altronics/Farnell etc etc

Finally , most of the caps look like bog standard electros, but one looks different from the rest, and has (M) after the cap value (as in "16V 47uf(M)"). Can anyone tells me what the M means? Is it a tolerance marking?

Thanks for any assistance.

[rick]

an old one but a good one- the snip

snip the electro out BEFORE you try to desolder and remove it

it is much easier to remove a few milimetres of left over cap leg that doesnt want to act like a heatsink then it is to pull on a cap that IS acting like a heatsink (stopping the solder from giving up its grip)

this will help you from giving the tracks too much heat and burning or pulling them of the board
the snip cannot be done with some caps but if you can , try the snip first

file this advice under "dumb things i have done so you dont have to...."

[Andrew]

just finished recapping my desk...really big time consuming job. Will certainly think long & hard before I attempt this again but the knowledge I gained was invaluable.

Leave a channel or two that work as originals so that you have something to compare to. You may change the sound of the desk entirely and sometimes the old sound is better for some applications.

If you don't have a desoldering gun go and buy one. I was hesitant at first but picked one up on sale and it was the best thing for desoldering.

If you have any channels that don't work then I would replace more than just the electro's on those channels.

Thats just my 2cents. Rick wrote a fantastic article about recapping that I recomend you read then reread then reread again....anyone gotta link to that?

Oh and take photo's with your digital camera as much as possible so you have some sort of reference (as well as your own notes)

[rick]

there would be no need to go searching if mark would finish post the articles
i have already paid him to post up:)

[astrovic]

Chris - re: sourcing, would you go offshore to say Mouser or Digikey? Obviously it's only worth the effort if you're ordering a reasonable amount of stuff (which it sounds like you will be), their range is monstrous and their prices per unit are generally cheaper.

Last time I ordered from them, Mouser would send by snail mail if you asked them to (it's not an option on the website) - gets postage costs down to a reasonable level, and delivery time was still about 1 1/2 weeks.

[chris p]

Ok, I'm most of the way through recapping my first channel, having first connected it all up and powered on to make sure its basically working, which it is.

All the electro's are now replaced - thanks for the tip, Rick. Works a treat, doesn't it? And thanks, Andrew, yes I do have a desoldering gun. I love it so much I'd take it on the plane with me, except its a GUN.

My question is now on bipolar electros. To those who are strained so I don't have to, should I just replace them with a modern version of a bipolar electro, or should I substitute a more modern cap altogether, like a MKT or metal film poly? If substituting, do I use the same capacitance or is there a conversion factor?

Hey, this is actually fun. I love the smell of solder in the morning. Its the smell of ..... victory.

[Andrew]

Link not yet up so I'm repeating some stuff and its also what I go by as well now:

Electro's are usually to block DC and are quite big values so trying to do the same with poly means a massive cap which probably won't fit on the board designed to take a small electro.

I'd personally just replace old electro's with newer good quality electro's...panasonic xyf? or rubycon's. Maybe you could put sockets in a single channel for all the electro's and experiment with different types to get the best sound you like before you recapp the rest: If you've got the time and patience - I don't

Have you cleaned it with caig's de-oxit & pro-gold yet? Do this first...that will make a big difference. I had two old eq's, same age, model etc. Cleaned one with these and left the other one then plugged them both in and the noise level had dropped hugely on the cleaned one. Its amazing stuff and helps the equipment.

Recapp your power supply if you know what your doing and/or have a tech to check it or do it for you. Go the 105 degrees caps if possible.

All of this is a suggestion only (my disclaimer) and is all at your own risk so consider the 240v stuff seriously, as in 'will I seriously electrocute myself if I do this' so please don't sue me :cry: I'm not a qualified electrician btw.

[otto ruiter]

If you can physically fit bipolar electros then do so. If you can get 105 degree bipolars then so much the better, they'll last longer. The bipolar caps WILL sound better than stock polarised electros in this application. Your other choice is solid polarised electrolytics, which aren't available in all values and cost more. Using a small film bypass cap can also improve the sound of electros.

regards,

Otto Ruiter
Technician
Sony DADC

[chris p]

Thanks Otto - bipolars it is. They values are all pretty common - in fact, they're 1uf and 10uf, so getting them shouldn't be an issue. You comments are greatly appreciated.

Andrew, thanks for the De-Oxit tip. I'll give it a whirl.