Cap job?

[vds5000]

Greetings! Just a quick question - I have a 25 year old tube combo, and I think one of the caps is toast (literally - smoke and all). Would it be worthwhile to have all the caps replaced when having that one replaced? Would anyone have any idea what this would cost - I'm looking for an approximate range here.

As always, any help would be greatly appreciated.

[greco]

If you are going to all the trouble of pulling the chassis, you might as well replace ALL the caps while you are under the hood. It would also be a good time to check out any other possible areas of concern.

If you saw smoke, you might be looking at something other than caps (e.g., resistor[s]).

However, if the caps are original, they are possibly/probably drying out.

I can't estimate the cost, but others will be able to give rough estimates. It would be difficult for a tech to give much of an estimate without having the amp in front of them.

It will help them if you indicated the make and model of your amp.

Peace

Dave

[konasexone]

Find a tech with a good cap meter, and I don't mean one he got at Crappy Tire.
I own a Sencore which does in and out circuit analysis. That way, you don't end up changing caps that are perfectly good, and yes there are still a good number of them in your amp. You'd be surprised. If an amp is used regularly, caps last longer. You may only have a handful to change and that will save you big bucks. Techs who have no way of evaluating their caps precisely tend to want to replace them all. That's like changing all four tires because you can't figure out which one is leaking. Beware, the "cap job"!

[greco]

That's like changing all four tires because you can't figure out which one is leaking.

Beware, the "cap job"!

After 25 years, I'd strongly consider changing all 4 tires...leaking or not.

As for the "cap job"......one always has the option to ask for replacement of only the parts that must be replaced.

I have a feeling that eventually we will have to agree to disagree (to some extent) :food-smiley-004:

Peace

Dave

[shoretyus]

The caps are cheap.To have a tech in there already it makes no sense not to change them. I finally did my 72 Fender Deluxe this winter and it made quite a difference giving me lots of power.

[vds5000]

Well, there are a couple of reasons why I'm considering doing all of them:

1.) The tech will already have opened the chassis (which alone will probably cost me money).
2.) The amp is about 25 years old, so I'd think that there could be others that could go too.

Does anyone have any idea what I should expect to pay? Are we talking $200-300?

[shoretyus]

Well, there are a couple of reasons why I'm considering doing all of them:

1.) The tech will already have opened the chassis (which alone will probably cost me money).
2.) The amp is about 25 years old, so I'd think that there could be others that could go too.

Does anyone have any idea what I should expect to pay? Are we talking $200-300?

Probably close to that. You still don't say what it is.

[greco]

Does anyone have any idea what I should expect to pay?

Are we talking $200-300?

Edit: Posted at the same time as shoretyus

Is this for the Bruno Leadman 100 listed in your sig?

Knowing the make and model might help a bit.

I'm going to guess that it will be under the $200.00 mark, but you will have to wait for a tech to get better estimate

Cheers

Dave

[vds5000]

Sorry about that - it's the Mark IIC. The Bruno is only about 6 years old.

Here's a related question - is it regular practice for a tech to have a min. charge for even looking at the amp?

[Ripper]

Sorry about that - it's the Mark IIC. The Bruno is only about 6 years old.

Here's a related question - is it regular practice for a tech to have a min. charge for even looking at the amp?

alot of techs and shops will have a "bench fee" for looking at something which is a minimum charge for looking at something, not uncommon at all.

[greco]

My thoughts on what it might cost could be a bit low, as I'm fairly sure that I read in this forum that Boogies are a pain to work on. Hence, possibly more time will be needed.

Dave

[vds5000]

My thoughts on what it might cost could be a bit low, as I'm fairly sure that I read in this forum that Boogies are a pain to work on. Hence, possibly more time will be needed.

Dave

Lovely! Stupid Boogie! Argh, but I love that stupid Boogie!

[Wild Bill]

Sorry about that - it's the Mark IIC. The Bruno is only about 6 years old.

Here's a related question - is it regular practice for a tech to have a min. charge for even looking at the amp?

I do! You have to remember, it takes more time to open up the amp and find the problem than to solder in one or two new parts! There's no way I can afford to spend an hour opening and closing and amp, plus tracing the circuit with my test equipment (parts rarely look bad on the outside! Testing is the only way to track bad parts down) to give a quote.

I DO give educated guesses! Also, while I charge a minimum of one hour's labour time to look at an amp I include that in the repair bill if the customer goes for it. After all, I have to spend that time anyway. However, if he makes me put his amp back together to take it home for a month while he makes up his mind then I charge him the $50 and when he brings it back I charge up for the opening and closing time all over again!

Nobody else works for free so why should I? I've got kids to feed too!

As for replacing just one filter cap, I've said this many times before. Would you have only one brake shoe replaced on your car?

If someone asks me to change ONLY the one bad filter cap then I will charge him for the part and all the labour time involved. When the next one fails I will charge him again. And so on.

Electrolytic filter caps are NOT supposed to last forever! Read any data sheet and you will see how the manufacturer might make a guarantee anywhere from 1-5 years. He might publish typical lifetime hours graphs for engineers to look at. If you told him you expected his cap to last 20 years he would first look at you like you were crazy and then flatly refuse to make any guarantees!

I know. It was my job to sell such caps to design engineers for over 25 years.

I would agree replacing only those resistors and other parts that might fail. Electrolytics are a wearable part and fall into a different category. They have a tiny vent hole in them to release any gas under pressure that might build up inside. This means they are not perfectly sealed and the wet paste inside will slowly dry up inside even if the amp is being stored. Heat makes it dry faster, which means running the amp burns up the lifetime hours even faster.

So you can test that cap today and see that it's still ok but your meter is not going to tell you how much life left you can expect. You'd need a psychic for that!

What's more, if I'm dealing with a player who only wants me to replace ONE filter cap I refuse to guarantee my work! How can I? What if another cap failed a few weeks later? He's going to bring his amp back and expect me to fix it for free!

I figure I'm being fair. If someone disagrees he's welcome to take his amp to a competitor!

I WANT my competitors to have those kinds of problems!:smile:

BTW, most filter cap jobs run about $100 for parts and labour. Some huge amps are more but that seems to be the typical charge.

:food-smiley-004:

[Paul]

I do! You have to remember, it takes more time to open up the amp and find the problem than to solder in one or two new parts! There's no way I can afford to spend an hour opening and closing and amp, plus tracing the circuit with my test equipment (parts rarely look bad on the outside! Testing is the only way to track bad parts down) to give a quote.

< big snip>

I WANT my competitors to have those kinds of problems!:smile:

:food-smiley-004:

Hey WB!

Are you fixing amps again, or still in recovery mode????

[Wild Bill]

Lovely! Stupid Boogie! Argh, but I love that stupid Boogie!

The older Boogers aren't too bad. It's the Dual Rectifiers and that type that are the real PITA service jobs.

:food-smiley-004:

[Wild Bill]

Hey WB!

Are fixing amps again, or still in recovery mode????

Hi Paul!

Yeah, I'm moving again! Not super fast but I'm moving!

It's been 3 months and while I'm not bench pressing Twins I have started builds and repairs again. Working a drill to mount transformers and controls kinda hurts a bit but lifting my soldering gun is no problem.

I opened my door to a couple of light jobs and that was it! The word was out and now you can hardly get in past a backlog of amps! I told everyone that things might take a while but no one seems to care.

Still, just working on amps again seems to be speeding my recovery. It must be the lead in the solder fumes!:smile:

:food-smiley-004:

[greco]

Thanks for your detailed (as usual) response Wild Bill.

I didn't know that electrolytic caps had vent holes....thanks for mentioning that.

All the best.

Dave

[Wild Bill]

Find a tech with a good cap meter, and I don't mean one he got at Crappy Tire.
I own a Sencore which does in and out circuit analysis. That way, you don't end up changing caps that are perfectly good, and yes there are still a good number of them in your amp. You'd be surprised. If an amp is used regularly, caps last longer. You may only have a handful to change and that will save you big bucks. Techs who have no way of evaluating their caps precisely tend to want to replace them all. That's like changing all four tires because you can't figure out which one is leaking. Beware, the "cap job"!

I would agree with you on pretty well any part like resistors, trannies/inductors, most caps or whatever. Where we part company is with electrolytics. These are the only caps that should be replaced in what's called a "cap job".

As I pointed out in my longer post, electrolytics are a wearable part like tires or brake shoes. When you drag out your Sencore you are testing a part that is maybe 4-5 times past its usual life expectancy. When the first one blows the odds are VERY good that the others aren't far behind!

Your meter says that the cap is good TODAY! It can't tell you anything about tomorrow. How do you know how much life is left in such an old part? Just how long do you expect it to last?

I can test a 60 year old resistor and if it reads reasonably true then I wouldn't bother replacing it. Or a mica cap. Or ceramics, film and even wax paper or oil for that matter. However, electrolytic caps are entirely different.

Unless you can give me a good reason to trust a filter cap that is 4-5 times past it's typical life expectancy, especially when another installed at the same time has already failed, then we'll have to agree to disagree.

:food-smiley-004:

[vds5000]

This was exactly the kind of information I was looking for...Bill, PM has been sent.

[konasexone]

You know what, buy a new amp. By the time your done with all the expertise and experience in here, it'll be cheaper. Anyway, amps sound just as good today as they did in the sixties.:zzz:

[vds5000]

You know what, buy a new amp. By the time your done with all the expertise and experience in here, it'll be cheaper. Anyway, amps sound just as good today as they did in the sixties.:zzz:

I agree that many amps sound just as good today as they did in the sixties, however, the Mesa Mark IIC is not really the easiest amp to replace.