Thrift store find - vintage Baldwin amp

Amps, Cabs, Speakers, etc
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laurie
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Re: Thrift store find - vintage Baldwin amp

Post by laurie » Sat Sep 18, 2021 7:59 pm

The more I tinker with it the happier I become.

I really is a unique piece of gear. Once it has been rebuilt I think it will easily replace the Fender FM212R SS amp I picked up a few months ago.

More pics to follow when I have time...

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Re: Thrift store find - vintage Baldwin amp

Post by Pepe » Sat Sep 18, 2021 9:08 pm

I just see it in the second picture ... is the back cover missing? All the electronic parts are so exposed. :?
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laurie
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Re: Thrift store find - vintage Baldwin amp

Post by laurie » Sat Sep 18, 2021 9:53 pm

Pepe wrote:
Sat Sep 18, 2021 9:08 pm
I just see it in the second picture ... is the back cover missing? All the electronic parts are so exposed. :?
Back cover removed for pic.

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Re: Thrift store find - vintage Baldwin amp

Post by Pepe » Sat Sep 18, 2021 9:55 pm

Ah, I hoped so! But seeing the instrument cable was a bit irritating.
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Re: Thrift store find - vintage Baldwin amp

Post by sclitheroe » Sun Sep 19, 2021 2:20 pm

So when you say it needs a recap - obviously at 50+ years old, everyone would agree. But I am curious - can you tell from the sound of the amp, if you've fired it up, that it's required? Beyond simple calendar age, how does one know when caps are in need of replacement audibly?

Awesome looking unit, I bet it will roar when its all tuned up.

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Re: Thrift store find - vintage Baldwin amp

Post by Pepe » Sun Sep 19, 2021 2:55 pm

I think it's useful and necessary to replace all the electrolytic capacitors of a >50 year-old unit. Especially since the capacitors of that decade are working with other chemical fluids. Maybe Laurie can tell us if there will be a significant change in sound, or if all the values should be equal to the vintage parts.

Here is something about the lifetime of electrolytic capacitors. The answer to that is not too simple, but logical:
https://en.wikipedia.org/wiki/Electroly ... r#Lifetime
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laurie
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Re: Thrift store find - vintage Baldwin amp

Post by laurie » Sun Sep 19, 2021 6:51 pm

After 56 years they caps will be dry. The leaked electrolyte is actually visible on some of them. And it is nasty stuff...

Audibly? Channel 2 is distorting. Clearly something wrong with the gain structure, almost guarantee because of dead cap(s). Channel 1 works, but is not sounding "good". Again, experience tells me it is almost certainly because of the caps.

Plus there is more hum than there should be. A smoking-gun for power supply caps.

I'll show some pics of the old and the replacement caps on the meter when I start the changes. You will see massive drift in capacitance and ESR on some of them at least.

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Re: Thrift store find - vintage Baldwin amp

Post by laurie » Mon Sep 20, 2021 2:00 am

Capacitors... 2021 versus 1965.

This is the first one I've replaced. Value is still in spec (just). ESR is an order of magnitude worse.

This cap is the voltage stabilization cap for the initial amplification on Channel #1, so it was probably working OK.
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Re: Thrift store find - vintage Baldwin amp

Post by laurie » Mon Sep 20, 2021 2:18 am

This is the voltage stabiliser cap for the tremolo. If you look closely, you can see the end-caps of the device bulging.
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This is the sort of thing you can expect with caps this old. Rated 50uF. Now measuring 92uF. Who knows why? This just happens to be the failure mode for this cap.
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Re: Thrift store find - vintage Baldwin amp

Post by Dirk » Mon Sep 20, 2021 5:41 pm

That looks like an 80's transistor radio, but I bet you don't want to carry these on your shoulder around town blasting the Beastie boys or Run DMC! :lol:

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