Is it safe to open a SS amp and replace the caps?

[cheddatom]

The volume keeps going up and down in an SS amp. I've asked around before (it's been sitting around for a year while i've been lazy/busy) and it was suggested I replace the "output caps". I had a look inside and thought it might be wise to just replace all the big caps. Am I at any risk here? It's been sitting around for at least 12 months. Are there any specific "musical" caps or do I just get the matching values from Maplins?

Thanks in advance for any help

[stevie]

[quote name='cheddatom' post='711171' date='Jan 13 2010, 12:22 PM']The volume keeps going up and down in an SS amp. I've asked around before (it's been sitting around for a year while i've been lazy/busy) and it was suggested I replace the "output caps". I had a look inside and thought it might be wise to just replace all the big caps. Am I at any risk here? It's been sitting around for at least 12 months. Are there any specific "musical" caps or do I just get the matching values from Maplins?

Thanks in advance for any help [/quote]
I think you mean the power supply caps. Here you are: [url="http://www.ehow.com/how_5511786_safely-discharge-capacitor.html"]http://www.ehow.com/how_5511786_safely-dis...-capacitor.html[/url], although I'd be surprised if there was much charge left after a year.

[cheddatom]

Thanks! Now I just need to know if I can use any opld replacement caps?

[Bloodaxe]

[quote name='cheddatom' post='711412' date='Jan 13 2010, 03:29 PM']Thanks! Now I just need to know if I can use any opld replacement caps?[/quote]

By "any old Caps" I take it to mean Generic vs Branded, in which case I'd say yes.

The two key things to match are the value & the rated voltage. With power supply caps it's normally fine to exceed both - e.g if you've got a 2200μF 250V smoothing cap, there should be no problem with replacing it with a 3500μF 250V, or, say a 2200μF 500V cap. [i][b]Don't go [u]below[/u] the figures printed on the casing.[/b][/i] This applies to conventional Transformer > Rectifier > Smoothing > Regulator types - switched-mode lightweight PSUs are a whole different Ketlov Fish.

Also, don't be surprised if a modern replacement is physically considerably smaller than a "vintage" smoothing capacitor - the technology has advanced somewhat over the years.

Also also, make sure that you observe the polarity of an electrolytic cap, if you get 'em the wrong way round much unpleasantness can result.

If it's caps in the signal path, they need to be matched to the μF values otherwise you may find that the tonal response goes completely up the pictures.

Pete.

[cheddatom]

OK, i'll just get the closest matches I can from Maplins and giove it a go. Thanks!

[Mr. Foxen]

If you buy in maplins, check everything and believe nothing the staff tell you.

[Bloodaxe]

[quote name='Mr. Foxen' post='711801' date='Jan 13 2010, 07:28 PM']If you buy in maplins, check everything and believe nothing the staff tell you.[/quote]


Word.

[stevie]

I've found these people very good - much better choice and much better prices than Maplin. [url="http://www.rapidonline.com/"]http://www.rapidonline.com/[/url].

[cheddatom]

It's just I work right next to one so can take back stuff if it's wrong etc. If they don't have the right values, i'll order online from somewhere else. Thanks for all the help guys!

[Pentode]

I've always gone to this chap - excellent service and Matt knows his caps!


[url="http://www.audiocap.co.uk/high-voltage-can-capacitors-ft-31-c.asp"]http://www.audiocap.co.uk/high-voltage-can...ors-ft-31-c.asp[/url]


All the best

Grahame

[Bernmeister]

Well, i take my Caps off to him !!!!

[Pentode]

[Bloodaxe]

[quote name='Bernmeister' post='715886' date='Jan 17 2010, 06:56 PM']Well, i take my Caps off to him !!!! [/quote]

[url="http://www.instantrimshot.com/"]I see what you did there[/url]

[cheddatom]

Well, I was determined to do it this week end. I'd already ordered the replacement caps. I was seriously nervous about turning it on as it was near impossible to determine the polarity of the old caps. Anyway, it's all worked out, ta for all your help