When to replace cap's ?

[stokes]

Shep,its been a while since I've been in a MKIV but if I remember correctly,it has 2X 220uf/300v stacked,and 3 or possibly 4 30uf/500v,pretty much the same as most MK's.You are going to have to look inside first as there are a few more lower voltage caps associated with the bias and EQ supplies.
Kdove,if your caps are original,I would say its time.I have seen posts here and elsewhere where people say"my amp was just at Mesa for a tune-up and they didnt change them".I personally dont buy into that.I had a guy ,who,happened to be the last parts supplier down in lower Manhattan in what was known as "Radio Row",he was also a designer for RCA back in the '40's and '50's,so he knows what hes talking about,tell me that manufacturers only recomend a 10 year shelf life for electrolytics.I actually saw him throw out boxes of them when he closed up in the '90's.He actually gave me a couple of boxes of fresh ones so I wouldnt think about taking the older ones out of the garbage.And believe me this guy was tighter than a bulls *** in fly season,so if he thought he could get away with selling them off he would have.That along with seeing what can happen when a cap explodes,convinced me.It is possible your caps may last,but I will never take that chance.

 

[kdove]

A particular brand you recommend?

 

[stokes]

Read the earlier post,I said F&T's and Sprague-only.All the rest are Jap or Taiwanese and in my opinion sound like crap,just arent as good,dont hold up as well.

 

[user 2126]

Shep,its been a while since I've been in a MKIV but if I remember correctly,it has 2X 220uf/300v stacked,and 3 or possibly 4 30uf/500v,pretty much the same as most MK's.

Here pics of the inside my Mark III:

 

[stokes]

I just dug up a Tech Manual I forgot I had from Mesa.Here is what the schem has.Shep your main power supply has 2X220uf/300v stacked and 3X30uf/500v.The EQ supply has 2X220uf/63v.The bias supply has 2X47uf/100v.There are some others in the 6.3v heater supply but the values are not marked on this schem,so like I said earlier you have to open it up.Also this is not the import version,so I dont know which you have,if it is the import it may be different.Darkirish,the MKIII is different,I can see from the picture that you have simul,which has 2 extra 220/300v caps in the main supply,they are under the board on the right with the other 2.I can also see that one of your caps is not stock.Depending on the age of the caps I would suggest changing them all.If one went south because of age the rest could be right behind.

 

[user 2126]

I can also see that one of your caps is not stock.Depending on the age of the caps I would suggest changing them all.If one went south because of age the rest could be right behind.

I never know about the mod (one caps is not stock) until I open it, I buy this MarkIII like it is, do you think it a cheap cap this cap can change something in the sound. All the other caps look very nice, no burst, no blistered membrane nothing rush you know. But just to know, Where I can find Mesa caps. What you think.
Thanks

 

[stokes]

Cant see what make the cap is in the picture.What does it say on the cap?Is it the right value,should be 30uf/500v.Like I said earlier a cap doesnt always show a sign of deteriation,I use the age to determine when a cap needs to be changed.Mesa uses Spragues for the 30uf's and just puts their own label on them.The 220uf's are Illinois in the amps I've seen.I have stated all my opinions on the matter of when and why to change caps in my earlier posts here.I understand there are people who dont agree with this and that is fine,everybody has a right and reasons for their own opinions,everybody draws their conclusions based on what and who they have heard from,and their own experiences.Whether or not you should change your caps is up to you.I dont think the fact that one cap has been changed is a cause for panic,but the amp is over ten years old and it raises a question as to why it was changed.You cant go wrong changing them,they wont last forever and its just good insurance against other possible problems.

 

[user 2126]

Mesa uses Spragues for the 30uf's and just puts their own label on them.The 220uf's are Illinois in the amps I've seen.

Thanks strokes, where I can buy these caps, dont forget I am in Canada.
Thanks again

 

[stokes]

I dont know of any Canadian suppliers.I get mine from a place called Newsensor, as I said earlier they are not the cheapest supplier,but I have my own personal reasons for using them.Do a web search for parts suppliers up there.I am sure there are some up there.