Scott LK-150 restoration thread

James Cox

James Cox

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Hey everyone! Ive finally decided to do a full restoration thread from start to finish after scoring a good deal on a Scott LK-150. I've ordered the parts and have most of them on hand but still waiting for some stuff from Jim Mcshane. The amp came without any tubes but I've got some lined up for after the restoration.

This piece is going to need a decent bit of work but I think it's going to be a really nice piece when I'm done. The fuse holder is broken so I'll need to replace that and the input voltage switch is cracked but I'm thinking I may be able to epoxy it back together. Otherwise I'll have to find a replacement somewhere. The transformers are pretty rusty so those are going to get painted after I finish the majority of the work. I have a brown face LC_21 preamp it's going to paired with so I'm debating painting the trannies a chocolate brown to match instead of the original black. What do you guys think? Also theres some spots on the chassis that need cleaned up but I'm not sure how to do that without removing the gold color. Check out the pics and see what you think.
I'll be starting some of the work tomorrow with a cleaning of the chassis and replacing the 2 4uf caps under the chassis and I will also be replacing the rectifier bridge with a diode. When I start on the work tomorrow I'll be posting my parts list for anyone else who may be working on one in the future.
I'm on the fence about restuffing the can caps since it's such a nice piece and my restuff jobs usually don't look very pretty. Thinking I want to go with Hayseed caps since they look so nice but they will probably cost me double than just restuffing. Just something to ponder. Going to really take my time with this one and be as thorough as possible. I know there some modifications while this piece was in production so I need to verify how much has been done but I believe some of the service bulletins where already performed on this unit. Pics incoming!
 
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The white stuff on the third to last pic is what I'm talking about on the chassis. Also one of my knobs is missing the chrome trim. Any idea where I could source the trim from or possibly a replacement knob?
 
James Cox said:
The white stuff on the third to last pic is what I'm talking about on the chassis. Also one of my knobs is missing the chrome trim. Any idea where I could source the trim from or possibly a replacement knob?
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I had a similar problem with one of my Scott amps, had to wait almost a year before seeing a knob pop up on Ebay.

By the way, nice socks! :rolleyes: :rflmao:
 
Haha thanks, my friend made me a few pairs awhile back. And yeah on he knob I figured that be the only way I could fix the missing trim. I do have a smaller one I may put on there to see how it looks but probably end up leaving it as it is
 
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Hey James, it’s good to see you diving into a restoration. That’s a fine amp.

For stuff like whatever that white stuff is, I use a scrungee with some beeswax on it. Then throw out whatever it picks up. When done, wipe again with paper towels. I would actually do that to the trannies, too, and see how they look.
It’s not too abrasive, and it picks up whatever comes loose, which is good in case its toxic or generally unfriendly stuff.

Here’s what it did on an old speaker:

Looking forward to your progress.

Dick
 
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Ok cool, I didn't think about beeswax! Shouldn't cause any problems with the lettering right? And thanks I just got my caps in from Jim Mcshane so going to get started tomorrow!
 
Be very careful extremely cautious.

IIRC the right front can capacitor looking at the knobs. The outer can is positive, something like 360 volt or so forget. They when new had cardboard sleeves over them to protect the user

On mine I got Hayseed to make them in cardboard.
 
That's the main reason I was thinking about avoiding restuffing myself. I don't know a source for the cardboard covers but figured I could have them made by hayseed with the covers
 
So I'm starting on this thing today and hopefully by the end of the day or early tomorrow I'll be ready to power it on for the first time and see how it sounds!

My parts I plan on changing today are as follows:
Replace the broken fuse holder
Attempt to epoxy the cracked input voltage switch
Replace all of the under chassis caps with
2x .1/630v k40's
2x .047/400v K40s
4x .22/630v Nichicon poly caps
2x 4uf/250v Sprague Atoms Electrolytics
1x UF4007 diode to replace the rectifier bridge
After replacing these components I'm going to borrow some tubes from my other amps for testing. Assuming I get sound from both channels and there's no smoke or anything like that I will then replace the can caps and order the tubes I need. I think I've decided to go with the hayseed hamfest replacement kit on the cans. I've also worked out a deal through Bartertown for a quad of EI KT90s and a pair of mullards rectifiers but want to wait until after I test it out to order the tubes. I'll post updates as I get through the work today
 
The fuse holder, diode, and switch have all been changed and repaired without and issues. The epoxy seems to have held surprisingly well.
I have also installed all of the K40 caps and the Electrolytics. Only thing left is the coupling caps and a good cleaning of all of the switches, sockets, and pots. Going to go pick up some beeswax now so I can work on the chassis this evening.
 

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Alright so I'm done for the day and feel like I made some pretty good progress! I managed to get all of the caps changed, and painted the transformers. I couldn't find the original chocolate brown so I went with a hammered dark amber color that I'm pretty happy with. Still need to order the can caps but I think it's good for a test run and voltage check tomorrow morning!
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I own a small record store and it was a slow day today so I had plenty of time to work on it. Probably took around 5hrs total. Still need to figure out if the service bulletin has already been performed or not. I know it has the 20/20/20/20 cap already installed but I don't think the second part has been done yet. Has anyone done this mod yet and if so is there anything I need to remove before doing it? I haven't really studied it yet, just glanced through it but it seems pretty simple.
 
James Cox said:
So I'm starting on this thing today and hopefully by the end of the day or early tomorrow I'll be ready to power it on for the first time and see how it sounds!

My parts I plan on changing today are as follows:
Replace the broken fuse holder
Attempt to epoxy the cracked input voltage switch
Replace all of the under chassis caps with
2x .1/630v k40's
2x .047/400v K40s
4x .22/630v Nichicon poly caps
2x 4uf/250v Sprague Atoms Electrolytics
1x UF4007 diode to replace the rectifier bridge
After replacing these components I'm going to borrow some tubes from my other amps for testing. Assuming I get sound from both channels and there's no smoke or anything like that I will then replace the can caps and order the tubes I need. I think I've decided to go with the hayseed hamfest replacement kit on the cans. I've also worked out a deal through Bartertown for a quad of EI KT90s and a pair of mullards rectifiers but want to wait until after I test it out to order the tubes. I'll post updates as I get through the work today
Click to expand...

Wouldn't you be better off using four uf4007 diodes to replace the selenium rectifier bridge with a silicon bridge and an appropriate sized dropping resistor ?
 
In this case I don't believe so. The rectifier in this case only has 2 connections instead of the usual 4 that I'm used to. When putting together my parts list it confused me a bit but I figured since there are 2 rectifier tubes it must not be being used to power much. Before settling on the single UF4007 diode I did a bunch of research and on the restoration threads I came across it seems that a single UF4007 diode works just fine.
 
Nice work.

Post the Service Bulletin here and maybe someone can help you with the question.
 
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