buzzing sound from vintage JBL amp?

[pyonc]

Hi

I purchased a vintage JBL SE400S "Energizer Power Amplifier", produced in the mid-1960s, in excellent condition the other day.
I heard a sharp electrical buzzing sound when I plugged in the power cord. (You don't hear it when you plug out the cord, though. )
Is this the usual sound from such a vingage amp or something wrong?
I apprecaite your feedback or comment or insight.

[hjames]

Hi

I purchased a vintage JBL SE400S "Energizer Power Amplifier", produced in the mid-1960s, in excellent condition the other day.
I heard a sharp electrical buzzing sound when I plugged in the power cord. (You don't hear it when you plug out the cord, though. )
Is this the usual sound from such a vingage amp or something wrong?
I apprecaite your feedback or comment or insight.

Is the buzz an electronic sound through the speakers, or is it a physical sound you heard in the room?
Find out, turn the volume down and put your ear against the amp and see if its a physical buzzing ...

Sometimes transformers will delaminate and you hear the transformer plates buzz,
but don't hear it through the speakers ...

One of my older Adcom amps did that sometimes

[Fort Knox]

Is the buzz an electronic sound through the speakers, or is it a physical sound you heard in the room?
Find out, turn the volume down and put your ear against the amp and see if its a physical buzzing ...

Sometimes transformers will delaminate and you hear the transformer plates buzz,
but don't hear it through the speakers ...

One of my older Adcom amps did that sometimes

If your amp is that OLD ..I'd drop it off at the shop for a onceover...

[hjames]

If your amp is that OLD ..I'd drop it off at the shop for a onceover...

JBL Energizer Modules ARE "that old" ... but again, is it a physical buzz, or a buzz in the speakers?

[NickH]

The power supply filter cap need to be replaced. If its never been rebuilt since it was bought, all electrolytic capacitors need to be replaced. You lucky you didn't have a fire when you plugged it in.

Never just plug in equipment that's old and has the original electrolytic capacitors in it. They dry out and become a dead short across the power transformer. When you turn it on they can explode. More then likely the ones in your amp are need to be replaced with new ones. Capacitors have came a long way over the years. New ones will be quarter the size of the old ones, or even smaller. Plus esr values on electrolytic have came down a lot. Esr is an acronym for equivalent series resistance. The lower that value the better.

If you know basic electronic trouble shooting this fix can be rather easy. If you don't then you need to send it to a shop that can do the work for you.

Nick

[Mannermusic]

The power supply filter cap need to be replaced. If its never been rebuilt since it was bought, all electrolytic capacitors need to be replaced. You lucky you didn't have a fire when you plugged it in.

Never just plug in equipment that's old and has the original electrolytic capacitors in it. They dry out and become a dead short across the power transformer. When you turn it on they can explode. More then likely the ones in your amp are need to be replaced with new ones. Capacitors have came a long way over the years. New ones will be quarter the size of the old ones, or even smaller. Plus esr values on electrolytic have came down a lot. Esr is an acronym for equivalent series resistance. The lower that value the better.

If you know basic electronic trouble shooting this fix can be rather easy. If you don't then you need to send it to a shop that can do the work for you.

Nick

Great post Nick. Those were the early Germanium transistor units - nasty, grainy sounding. Had one. A little recent personal experience: I took your advice re the last sentence with an old SAE amp. Top notch shop, they replaced all the caps and used the best stuff they could find - the original stuff is long gone. As a result, it sounds good, but not like the original . . . which was outstanding, in terms of hi fi / musicality (is that a word?). I'm with 'Dome. There comes a time when it's better to replace old gear - money, effort down a rat hole.

[pyonc]

Thanks for your comments! After some reading of its manual, it's come to my attention that I should have plugged the cord to the AC switch on the back of an preamp rather than directly plugging it in the wall outlet or surge protector outlet strip... I guess the sharp electrical bang sound was caused by this wrong plugging. Just my own thought.

[NickH]

Thanks for your comments! After some reading of its manual, it's come to my attention that I should have plugged the cord to the AC switch on the back of an preamp rather than directly plugging it in the wall outlet or surge protector outlet strip... I guess the sharp electrical bang sound was caused by this wrong plugging. Just my own thought.

I could be wrong, but I highly doubt this. The are a few issues that can cause a loud pop in the speakers at turn on. That's if your talking about that.

Nick

[pyonc]

Thanks for your comment. The instant bang (just one time when turned on) sound comes from this vintage amp, not from the speaker.
And the manual of its pre-amp match JBL SG520 says its matching amp, namely this particular SE400S, should be plugged in the AC switch on its rear panel. So, I feel that might be the start of this whole issue...of course, I may be wrong.

I could be wrong, but I highly doubt this. The are a few issues that can cause a loud pop in the speakers at turn on. That's if your talking about that.

Nick

[hjames]

First it was a buzzing in the amp, now a loud bang on power up ...

Unless you have some proof (like a receipt) that a knowledgeable service technician has gone through
and checked out your amp in the last few years, you may be in line for a bad surprise.

But I wish only the best for you ...

Thanks for your comment. The instant bang (just one time when turned on) sound comes from this vintage amp, not from the speaker.
And the manual of its pre-amp match JBL SG520 says its matching amp, namely this particular SE400S, should be plugged in the AC switch on its rear panel. So, I feel that might be the start of this whole issue...of course, I may be wrong.

[NickH]

Thanks for your comment. The instant bang (just one time when turned on) sound comes from this vintage amp, not from the speaker.
And the manual of its pre-amp match JBL SG520 says its matching amp, namely this particular SE400S, should be plugged in the AC switch on its rear panel. So, I feel that might be the start of this whole issue...of course, I may be wrong.

That could be quite a few things, some quite bad. Or it could be a loose transformer too. When there are multiple issues it makes it a bit tricky to trouble shoot.

I'd bet on it being something has loose mounting hardware. So do you have any electronics knowledge? Can you read a schematic?

If not you need not even open up the unit. Just take it to a shop and have it fixed.

Sounds like you bought a can of worms.

Nick

[script56]

I took my SE400S into a local shop for repairs. They said they could not fix it because they could not find correct capacitors. I believe they are the large can caps. They said the ones installed (not sure if theyre the original ones) leaked on other stuff on the board. I looked over the 400S schematic, but am needing info on where to find good replacement caps. Also I can use a soldering iron and am good with electronics, should I give it a try myself? I usually dont work on anything with a power cord due to shock risk.

[audiomagnate]

I took my SE400S into a local shop for repairs. They said they could not fix it because they could not find correct capacitors. I believe they are the large can caps. They said the ones installed (not sure if theyre the original ones) leaked on other stuff on the board. I looked over the 400S schematic, but am needing info on where to find good replacement caps. Also I can use a soldering iron and am good with electronics, should I give it a try myself? I usually dont work on anything with a power cord due to shock risk.

As long as you're not worried about matching the cosmetics of the originals, replacements are readily available. Just make sure everything is unplugged first.

[pyonc]

I took my SE400S into a local shop for repairs. They said they could not fix it because they could not find correct capacitors. I believe they are the large can caps. They said the ones installed (not sure if theyre the original ones) leaked on other stuff on the board. I looked over the 400S schematic, but am needing info on where to find good replacement caps. Also I can use a soldering iron and am good with electronics, should I give it a try myself? I usually dont work on anything with a power cord due to shock risk.

Have you heard the same thump or sharp bang noise from the amp, too, when you plug in?

[script56]

No. Have not heard that. Each time I plugged it in the fuse blew. So I took it into shop. I don't understand why they would say they couldn't find caps if they're readily available. They said something about the originals being 4 pin or something.