Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Nov Mon 29, 2021 9:04 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 57 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject: Re: HH Scott LK-60 Calibration
PostPosted: Jun Fri 21, 2013 11:01 am 
Member
User avatar

Joined: Mar Fri 14, 2008 1:40 pm
Posts: 6770
Location: SE USA
Maraakate wrote:
Is there a difference between the 85 and 105C? The amp does not get very hot and it will be in a temperature controlled room..


Yes. The 105s use a different electrolyte and are generally less prone to failure in some situations regardless of temperature.

_________________
The beatings will continue until the morale improves


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration
PostPosted: Jun Fri 21, 2013 2:24 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13473
Location: Fernandina Beach, FL
Glad to hear progress. I built the tuner that was a match to this amp back in 1967, the LT-112B-1 and still have it. At the time, I had an Allied Radio KG-870 so that was my amplifier for the system. I now have a couple LK-60 amplifiers in the queue for restoration as well to go with the tuner.

I look forward to your results. Sounds like you are making progress!

_________________
Don


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration
PostPosted: Jun Sat 22, 2013 5:15 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
All that is left is the three large caps and new 2N3053s.

Here is the pictures before the recap. Notice in the 3rd picture the foil cap for the speakers. On another picture I've seen they were replaced with some mylars. I did the same, though they seemed OK.


Attachments:
image005.jpg
image005.jpg [ 60.65 KiB | Viewed 4300 times ]
image004.jpg
image004.jpg [ 54.97 KiB | Viewed 4300 times ]
image003.jpg
image003.jpg [ 55.56 KiB | Viewed 4300 times ]
image002.jpg
image002.jpg [ 45.23 KiB | Viewed 4300 times ]
image001.jpg
image001.jpg [ 62.85 KiB | Viewed 4300 times ]
Before_Recap_1.jpg
Before_Recap_1.jpg [ 165.2 KiB | Viewed 4300 times ]
Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration
PostPosted: Jun Sat 22, 2013 5:19 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Here is the recap (sans the one preamp board and main large caps) photos.

Also attached is the leftover caps I replaced, my long string of desolder wick, and finally the inside of these paper caps just for fun!

I didn't bother using axials for the two that were under the unit since regular caps were much cheaper and quite frankly it was easy to just do point-to-point with those anyways.

Most of the unit has been cleaned up now since these pictures. Though, I would like to get the wood to get some sort of shine again. I use some orange furniture polish and it helped a bit, but not as much as I would like. Any tips on this?


Attachments:
image013.jpg
image013.jpg [ 54.17 KiB | Viewed 4299 times ]
image012.jpg
image012.jpg [ 64.23 KiB | Viewed 4299 times ]
image011.jpg
image011.jpg [ 63.42 KiB | Viewed 4299 times ]
image010.jpg
image010.jpg [ 67.57 KiB | Viewed 4299 times ]
image009.jpg
image009.jpg [ 64.98 KiB | Viewed 4299 times ]
image008.jpg
image008.jpg [ 31.99 KiB | Viewed 4299 times ]
image007.jpg
image007.jpg [ 44.25 KiB | Viewed 4299 times ]
image006.jpg
image006.jpg [ 49.87 KiB | Viewed 4299 times ]
Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration
PostPosted: Jun Sat 22, 2013 5:26 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Don Cavey wrote:
Glad to hear progress. I built the tuner that was a match to this amp back in 1967, the LT-112B-1 and still have it. At the time, I had an Allied Radio KG-870 so that was my amplifier for the system. I now have a couple LK-60 amplifiers in the queue for restoration as well to go with the tuner.

I look forward to your results. Sounds like you are making progress!


Hopefully after the main three caps are replaced and the faulty transistors are replaced it should work well. It does pass the "initial test" bulb test and everything was done slowly over a span of 8 accumulated hours. Slowly doing each cap one at a time so there'd be no mistakes.

I hope you get yours going soon too. When the amp was working it sounded great! It's a really nice amp for a small room, which is essentially my office/playroom/etc.

There is a full manual headed my way, once I get it I will see if there is some extra details I could scan.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Wed 26, 2013 4:53 pm 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Got my 2N3053s today. Amp is working great, except I did a small boo-boo on the one channel. I accidentally had the bias pot adjusted for max voltage on startup so the one output transistor got hot really faster a few minutes and heated up. Happened while I was adjusting the balance.

Still all that school of hard knocks for me! But, right channel sounds great, hah.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Wed 26, 2013 6:35 pm 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
I take that back... I put everything known good into the left channel side and the volume meter shoots really high up! I found out taking out Q3 seems to stop it but I don't see any traces touching, etc from there. How can I test if there is something funky going on with the socket?

All resistor read points on the schematic are reading properly... I am not quite sure why this is happening?


These are the right transistors as once everything is on the right side it works.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Wed 26, 2013 11:00 pm 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Bah! Ended up being the crappy plastic piece that came with the NTE had a crack in it. Now the left is working all I need is another plastic heatsink spacer and one more 2N3055 and should be smooth sailing.

For kicks I mix/matched them to see if there was a different in sound and I haven't noticed any difference.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Thu 27, 2013 2:11 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Wee! Took a 2N3055 with insulator from a dual bench power supply I had sitting around and everything works awesome! The phono weak channel issue is also resolved thanks to the recapping too.

What a great amp. I'll be sure to post some pics after I'm done tidying up.

Thanks to everyone who lended a hand in some way. :D


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Thu 27, 2013 2:18 am 
Member
User avatar

Joined: Mar Thu 31, 2011 4:52 am
Posts: 2745
Location: Long Island
Mara,

I just found this thread. Nice work! I admire your tenacity. Looking forward to the pictures.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Thu 27, 2013 2:28 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
neali wrote:
Mara,

I just found this thread. Nice work! I admire your tenacity. Looking forward to the pictures.


Thanks neali,

This was my first extended diagnosing of electronic stuff. I've recapped older consoles and things of that nature. The biggest project I ever did before this was recapping a GCE Vectrex console. Took me about 8 hours to do that (did it really slow double checking as I took each one out, etc).

Now I just have to let this bad boy run for a few hours and then recheck everything here and there as it all warms up.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Thu 27, 2013 3:03 am 
Member
User avatar

Joined: Mar Thu 31, 2011 4:52 am
Posts: 2745
Location: Long Island
What I especially admire is that you kept going after making a bonehead move (we all make them) and blowing stuff up. Sometimes that derails me for weeks/months. I feel stupid, I look at the radio, I hate it, I hate the last guy that messed it up. Hopefully I can learn from your example! You just kept going. Just kept posting your progress too sometimes with little feedback. This is supposed to be fun, something I should have needle pointed and framed. :D


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Jun Thu 27, 2013 3:25 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
I won't pretend there wasn't quite a bit of swearing involved during some of it, haha.

Hopefully, you were working on a relatively simple amplifier like this. I've never worked on tuners, but from the various threads around here if you make a wrong move you can knock the alignment all out of whack.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Feb Sat 11, 2017 8:16 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Large bump to this years later. Amp was doing great for years, being used almost daily, and then the other day I went to turn it on and a loud buzz emitted from the right channel and popped the fuse. Checked resistance measurements and found a short. Followed it to the junction of wires from the middle 1000uF/65V cap. Trimmed it one by one and found it was a short with the one 2N3055. I cleaned up the insulator and the general area. Short was fixed. Resoldered the wires I cut. Still popping fuses.

Took a while to figure this out, but checked the stud mount diodes and the diode network on the heatsinks. Now, if you check the diodes on the heatsinks with a diode tester it should be reading 0.5V one way and ~1.0V the other way. One diode was reading 2.88V (open for my meter). Ended up being a cold solder joint on the diode.

This also killed the 2N3053s on the driver board. But checked by moving left channel transistors over to it and the amp works. So once the new 2N3053s arrive I can get it back in service again.

Also helped having a working "parts" amp (yeah I really like this amp!) to compare with. I do need to recap that one too at some point.

Despite that diode issue, the amp has been working great for years and I can't thank this site enough for all the help it's given me over the years.

The parts amp is interesting by itself that I got that one cheap because the shaft was stuck. I had to remove the whole input selector shaft which wasn't that easy since it leads into the preamp "cage". Heated it up with a torch and a lot of old grease came out and now it works fine. All the fooling around back there did crack one of the wafers. Had to repair that with some panel bond. When I get caps for that I'll do another thread for fun.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Feb Thu 23, 2017 6:27 am 
Member
User avatar

Joined: Mar Sun 10, 2013 7:03 pm
Posts: 192
Location: Lancaster, PA
Fixed the diode, replaced the driver transistors on the defective channel and all is well again. Love this little amp!


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Mar Wed 01, 2017 1:40 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1078
Location: Tucson AZ
I've got one of these that has been waiting to be worked over for a few years now. Maybe one day I'll get to it.


Top
 Profile  
 
 Post subject: Re: HH Scott LK-60 Calibration and Restore [56k Warning!]
PostPosted: Sep Mon 20, 2021 9:19 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13473
Location: Fernandina Beach, FL
Four years later, I finally got one of my HH Scott LK-60 amplifiers working. Without trying it first, I simply made sure that the power transformer was good. Then, I removed all 6 boards one at a time and replaced all electrolytic capacitors with new stock. I measured the two output capacitors, they were relatively good with normal leakage for a capacitor of that high value. It worked first time. Took about three days to restore. Next is the cosmetic restoration. This can be a mate to my LT-112B-1 that I built right out of high school.

_________________
Don


Top
 Profile  
 
Post New Topic Post Reply  [ 57 posts ]  Go to page Previous  1, 2, 3

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 9 guests



Search for:
Jump to:  




































Privacy Policy :: Powered by phpBB