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I am devastated. I can't play my B3 without the preamp on the 21H Leslie blowing its fuse. Recenly had the preamp reconditioned. Should I call that guy back? I don't think he knew what he was doing. I certainly have no clue where to start.
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Well that makes two of you. If you don't think the tech who worked on it knew what he was doing, don't call him back. The last thing you should do is put a higher value fuse, or try to override the fuse, as it is fire protection.
For a start, you could try replacing the tubes. A dead short within the elements of a tube can quickly blow fuses.
The downside here is you'll need to purchase several 1.5a fuses and use one each time it blows.
If it's not a tube problem you will most certainly need a qualified tech to look over what is going on, and don't keep trying to power it on. -
I think that amp might have a second fuse under the chassis that supplies screen power to the 6V6s and organ preamp. If that fuse blew, but not the primary 2 amp fuse, that may be why the sound died but the motors still ran. Also, that might have happened because of a shorted 6V6...Tom in Tulsa
Fooling with: 1969 E100, 1955 M3, 1963 M100, Leslie 720Comment
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The last 21H amps were built in 1957, so it's at least 62 years old. It needs to be checked out by a reasonably skilled amp tech at this point. And because the speaker field coil is part of the amp, you need a tech who understands that aspect of the design.I'm David. 'Dave' is someone else's name.Comment
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Thank you for the reply. David, I believe the amp is 1958 from the plate on the speaker. (11923) The man claims that he is the guy you describe. Said he works on Leslies all the time. I was just surprised when he removed the preamp and took it to his home. (I understood he was going to work on it here.) When he brought it back he said, "Oh, look I think some of the tubes are burnt out." When I was surprised (yes, again) by that, he told me that he had no way of checking the preamp at his place as he did not have anything to plug it into! -
I really can't evaluate your tech's work based on the information you've provided. If you can tell us where you live, perhaps we can connect you with someone else. Unless someone on here is willing to hold your hand through an amp repair, step by step, I'm not sure what other options you have.
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Thank you, David. Northern Illinois if anyone has knowledge of someone in the area.Comment
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Could the sockets be disintegrating? We are looking into that now.Comment
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The phenolic tube sockets on these Leslie amps can become brittle and crack with age and heat, especially the rectifier tube sockets. But if they are cracked or broken, it would be pretty obvious. Your initial problem is fuse-blowing, so if they are cracked enough to cause a fuse-blowing short, you should be able to see that easily from underneath the chassis.
I have one 32H amp of my own that had lots of sockets in bad shape, to the point where I replaced them all and completely rebuilt the amp, but that would be a relatively expensive repair if you had to pay someone to do it. You have to drill out all the old sockets, install new ones, and completely rewire it.
In later production of 1950s amps, Leslie themselves transitioned to using Micanol (plastic) sockets.I'm David. 'Dave' is someone else's name.Comment
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