mark III Black dot blown cap.

[robvoyles]

Hi, i have a Mark III Black dot question, anyone had a cap blow and replace with a bit higher voltage value.
I have a little silver 50uf 75volt cap blow, there are two side by side exact same, i heard a pop and a smell
and one of them blew out the side. i cant seem to find a 50uf 75 volt but found a 50uf 100 volt.
Any info would be helpful, thank you in advance.

 

[woodbutcher65]

If the amp has never been serviced it's well time for a service and full recap job. The 50/75 cap is the bias cap. VERY important.,

Get that 40 year old amp recapped before other caps fail and cause damage that is more expensive to fix than the cost of a cap job!

Yes, it's OK to go up on voltage value. Replace the 75/50 with a 100/50.

 

[robvoyles]

If the amp has never been serviced it's well time for a service and full recap job. The 50/75 cap is the bias cap. VERY important.,

Get that 40 year old amp recapped before other caps fail and cause damage that is more expensive to fix than the cost of a cap job!

Yes, it's OK to go up on voltage value. Replace the 75/50 with a 100/50.

Thanks for quick reply, any idea what a full cap job with mike is these days, i haven't had to send one back in over 20 years.

 

[user 41014]

I have a little silver 50uf 75volt cap blow, there are two side by side exact same, i heard a pop and a smell
and one of them blew out the side. i cant seem to find a 50uf 75 volt but found a 50uf 100 volt.

It is always ok and even better to go higher voltage. It doesn't change the circuit at all and the component will last longer and give better protection.

The 50uF/75V caps are the bias caps so make sure your power tubes are acting right when you get it changed. It's possible a tube checked out.

Since this is the grid voltage circuit it would be a good time to make sure your two .1uF coupling caps (orange drops) at the phase inverter tube socket are upgraded from 400V to 630V. The mesa store has replacements if you still have the 400V ones which are known to cause problems.

You can find 50uF caps but it is not a standard size. Back in the day non-standard sizes were common but not anymore. The factory is currently using Illinois Capacitor 47uF / 100V for these specific caps as of a couple months ago.

If you send it to Mike he will do much more than just the filters. I would expect $300-500 range for total service. You can get it done cheaper but not more thorough.

 

[woodbutcher65]

A basic cap job is not that expensive. But yes, if you can get MB to do the work, get him to do it. He is going to retire sooner or later and he'll give the amp a clean bill of health good for another 40 years. But do us ALL a big favor and intensively photo document all the amp internals BEFORE shipping it off. And again after it returns. Having documentation of what Mike does to it will help others to follow his lead after he retires.

 

[robvoyles]

Thanks for the info, yea the amp was sitting idle on standby when it popped, it has the old Sylavania power tubes, i have a tube tester i can check them with. hopefully they are still good and the cap was just tired, the amp sounded really sweet as i was recording a bit with it. I've reached out to mike 3 times in the last 2 months trying to talk to him about my green stripe but Chris is the only one i get at boogie and he says to just email him and he will pass it to mike but so far i haven't heard back.
I've known mike since 85, i was the guitar manager at strings and things back then and i ordered my first mark amp from him. i called he picked up the phone and he said great we'll get started you should see it in about 9 months, i got it in 7 months, wow how times have changed. we've talked quite a few times over the years but lately he may just be slammed with work. i could probably re-cap it myself but know where as good a job as mike. he's talked to me over the phone and told me how to do certain mods, nothing major but it's been years and I've forgot most of them. I've got a local guy ( Tim Gibbs @ Toy Box Audio ) if i cant reach mike, he's really good but i would rather mike go through if im gonna re-cap the whole thing.

 

[robvoyles]

Will Do!!

 

[robvoyles]

A basic cap job is not that expensive. But yes, if you can get MB to do the work, get him to do it. He is going to retire sooner or later and he'll give the amp a clean bill of health good for another 40 years. But do us ALL a big favor and intensively photo document all the amp internals BEFORE shipping it off. And again after it returns. Having documentation of what Mike does to it will help others to follow his lead after he retires.

I would much rather get mike to do it but ive tried to reached out to him through Chris at boogie several times in the past few months but i haven't heard back yet. I hoped he was ok, it's not like mike to not get back with you, he may just be slammed right now.

 

[user 41014]

Thanks for the info, yea the amp was sitting idle on standby when it popped, it has the old Sylavania power tubes, i have a tube tester i can check them with. hopefully they are still good and the cap was just tired, the amp sounded really sweet as i was recording a bit with it. I've reached out to mike 3 times in the last 2 months trying to talk to him about my green stripe but Chris is the only one i get at boogie and he says to just email him and he will pass it to mike but so far i haven't heard back.

If it was on stand by your tubes only had heaters on, no juice, so your Sylvania's are hopefully good.

Just submit the RMA with the work you want done with your contact info and Mike will reach out to you I'm sure. Or reach out to them once you have the RMA #.

https://mesaboogie.zendesk.com/hc/en-us/articles/217878928-Request-a-RMA

 

[robvoyles]

If it was on stand by your tubes only had heaters on, no juice, so your Sylvania's are hopefully good.

Just submit the RMA with the work you want done with your contact info and Mike will reach out to you I'm sure. Or reach out to them once you have the RMA #.

https://mesaboogie.zendesk.com/hc/en-us/articles/217878928-Request-a-RMA

Thanks for the reply and link to form, just sent it out, use to just be able to call him and he picked up, really miss those days, all you guys help and info is greatly appreciated, Thank you. Rob

 

[woodbutcher65]

I've got Mike's email address. PM me and I'll give it to you.

 

[Fastforded]

It is always ok and even better to go higher voltage. It doesn't change the circuit at all and the component will last longer and give better protection.

The 50uF/75V caps are the bias caps so make sure your power tubes are acting right when you get it changed. It's possible a tube checked out.

Since this is the grid voltage circuit it would be a good time to make sure your two .1uF coupling caps (orange drops) at the phase inverter tube socket are upgraded from 400V to 630V. The mesa store has replacements if you still have the 400V ones which are known to cause problems.

You can find 50uF caps but it is not a standard size. Back in the day non-standard sizes were common but not anymore. The factory is currently using Illinois Capacitor 47uF / 100V for these specific caps as of a couple months ago.

If you send it to Mike he will do much more than just the filters. I would expect $300-500 range for total service. You can get it done cheaper but not more thorough.

Cost me 400 including shipping from Mike