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Scott LK-150 rebuild/modification thread

NOSValves said:
Oh don't read anything into my Tiawan/Chinese comment those cans are decent. I don't see a 50/50uF @ 500V on Angela's website. Geezzzz I haven't been there in years. I used to buy a good bit of parts from them 10 to 12 years ago before I started buying most everything direct from the manufacturers.

I bought about 40 of the 32/32uF @ 500V Ruby Gold's directly from Ruby a few years ago and tried them out, I thought they were darn nice and my cap analyzer showed they did a nice job all around. At the time the 50/50uF they sold was too tall for the Scott integrated amps to still get a factory case on it by about a 1/4" so I complained but they never did anything about it at the time. What is the height of that 50/50uF you have?

Heck I even cut these things apart to investigate the quality....the Ruby and JJ are very similar inside....the AES cheapo not so much ;)

I never noticed the Japan markings....interesting. But really not that surprising the fluted Marshal style Scott knobs they used were made in Germany. All the vintage manufacturers were very much global shoppers...heck they almost exclusively used imported tubes.
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The 100/100 and 50/50 are each 3" tall. The 50/50 is in the third row of the electrolytic capacitor page, right under the 100/100. Their pages are not laid out very logically...or at all logically. Fortunately the offerings on that page aren't too numerous, or it would be horrible to deal with.

I actually have a set of those Marshall-style knobs. Needed something for the 130 preamp after I get around to making a new faceplate. At least they're easy to get new.

Would you happen to have a meter in your parts bin, even a dead one? I figure I could stick a new miniature movement in an old housing, but that meter housing is weird.
 
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Back panel, with the slots opened up at the ends to properly site the binding post pairs. The heat sink for the regulator MOSFET is just sitting there for now. The holes that were already drilled for the TO-3 socket when I got the amp are what started this project down the rabbit hole of modified power supplies with solid-state regulation.

I'm going to cut some spacers to fit between the pairs of binding posts, both to close the hole and to help locate the binding posts. The holes for the accessory sockets are going to be blocked off.

 
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Nice well thought project! Don't feel bad about the rabbit hole it's your amp do what you want with it. It will sound and work great. My earlier comments were not meant to disparage any part of what your doing or Dave efforts...
 
s-petersen said:
You could try something like this:

p1010023kc_zps62e7d092.jpg
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Sam,

I can't help you on the meter sorry! I'd think about doing like above! I think that would be neat as all get out! Not sure what types of voltage a meter like that would need though..
 
I used this meter from the auction site, I blacked out the decimal point.

DC 0-33V Blue 0.36" LED 4 Digit Digital Voltmeter Voltage Panel Meter

I crazy glued it to a piece of grey filter(from a dead Eico HFt94? tuner dial glass) for mounting and a better look
 
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There are power supply wires in addition to the sense wire. The power supply needs to be 4.5 v to 30v DC. The sense wire goes 0 to 33v.
I had grounded center taps for fil voltage , so I voltage doubled the 3.3v for the meter supply. It does not measure negative voltage.
 
Well that is really cool they work with a wide variation of voltage... slick as shite! I'm going to buy some of them myself.

Of coarse they could list that specification better....
 
s-petersen said:
I used this meter from the auction site, I blacked out the decimal point.

DC 0-33V Blue 0.36" LED 4 Digit Digital Voltmeter Voltage Panel Meter

I crazy glued it to a piece of grey filter(from a dead Eico HFt94? tuner dial glass) for mounting and a better look
Click to expand...

Just ordered the green LED version of that. There's no blue anywhere on the amp, but the serial number label on the top front of the chassis has a bright green HH Scott logo, so green should coordinate nicely. The four-digit display is almost exactly the same size as the existing opening. I had previously purchased a similar three-digit display, but they turned out to be quite a bit smaller.

I have a piece of brass strip that's going to be cut to size, and I hope to use the toner transfer method to re-do the Scott Stereomaster logo for the front, along with adding labels for the four bias meter push switches. I'm also considering adding a pair of test points and possibly a switch to switch the metering between the onboard meter and the test points. Haven't fully decided on that point yet. The inboard meter will probably be accurate enough, but it would be nice to be able to double-check with a good external meter.

Just had an idea - put the test points on the back, in the holes from the old accessory AC sockets.
 
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Well, the amp was built in 1961, and the Jetsons originally aired from 1962-1963, so that seems appropriate. :D

I would have made some more progress last night, but it turns out when I bought the momentary switches for the bias metering, I picked up "normal closed" instead of "normal open." D'oh! Back to Radio Shack sometime today. I can't find my big box of grommets, either, so I'll have to stop by ACE and get four grommets for 5/8" holes. As it is, I got the bias pots drilled and mounted, and bolted the T03 heatsink on the back. And, just for cleanliness, I used some acetone and cleaned off the mostly-obliterated lettering that would stick out from under the heat sink. And the second "0" from under the old speaker terminal strips.
 
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I found a closeup of the front silkscreen, until you get a better one. likely the same as another model you might already have. A small plate secured by the bias switches may work well
 

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I'll probably use contact cement to secure the plate in place, but the four bias switches will also add some mechanical clamping. I wish the previous owner had drilled the holes for the bias pots he installed to the outside of the existing switch holes instead of right in the middle of the silkscreen...
 
Chassis progress.





Now I just need to look over the transformers and decide if they really need new paint, or if I just want to polish up what's there and live with a bit of flaking. It's not like this is going to win any cosmetic awards, though it's not as deliberately ugly as the Fisher 70s.
 
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One thing that I can't figure out are the holes under the OPTs. They each had a star washer riveted into them. Nothing else, just a star washer.
 
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