Laney Supergroup MK1 restoration - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Instruments and Amps Everything that makes music, Especially including instrument amps.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th January 2017, 10:32 AM   #1
diyAudio Member
 
Join Date: Sep 2014
Default Laney Supergroup MK1 restoration

So, yesterday I picked up an early 1970īs Laney Supergroup MK1. The dude gave it away for free because he was moving and was tired of storing it. I got the info that the amp powers up but it doesnīt make any sound. Well letīs see..

I took some photos outside that shows the amp has been stored quite well. It has a couple of really small dents in the corners but the vinyl is in very good condition. I also took the chassis out and set it up for some closer examination. Looks like this beast is pretty much original and I got some serious replacement work ahead. I will print out the schematics tomorrow and start taking some measurements. Luckily the inside are overall pretty clean so itīs not too had to follow the schematics.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.


Iīm not powering it up. Iīm thinking Iīll first go through measuring the coils of the transformers to see if there are any shorts. Also checking shorts in the tubes, couple of the power tube sockets feel a little loose.

I posted this thread because I know someone has some insight reagarding this particular amp and possibly can see the condition of this unit in a different view. Also any discussion regarding this amp is welcome.

K
  Reply With Quote
Old 8th January 2017, 11:55 AM   #2
diyAudio Member
 
Join Date: Oct 2012
does the impedance selector link have continuity?
i'd also fix the ac line (looks like someone replaced that) and take the incoming ac ground off the controls and apply it to the chassis
check the output tubes section, it looks like one of the resistors was replaced, possibly to fix a previously shorted output tube.
bias supply cap looks like a replacement also.

Last edited by turk 182; 8th January 2017 at 12:18 PM.
  Reply With Quote
Old 8th January 2017, 04:55 PM   #3
diyAudio Member
 
Join Date: Sep 2014
Quote:
Originally Posted by turk 182 View Post
does the impedance selector link have continuity
How did you know where to go first? Thereīs no continuity on the link piece.

The resistors seem to be in surprisingly good condition, very well within tolerance. Yes, the bias cap has been replaced with a 25uf? Should I go back to 10uf which is in the schematic?

K
  Reply With Quote
Old 8th January 2017, 05:10 PM   #4
diyAudio Member
 
Join Date: Oct 2012
the picture gave it away (thanks to the close up) you can see the holes at the ends of the pins have no solder, but many an old Marshall with that style connector has the wire link sheared off from the head getting wedged in somewhere in the truck pack.

the bias supply cap should be fine as long as it's not an old "leaky" cap.

speaking of things in the picture the socket with "replaced" resistor looks to have been replaced as well, no?

standby switch too!

Last edited by turk 182; 8th January 2017 at 05:14 PM.
  Reply With Quote
Old 8th January 2017, 05:16 PM   #5
diyAudio Member
 
Join Date: Oct 2012
do you have a "dim bulb tester"?

reason i'm asking is i'm also suspicious that the power transformer has been replaced too.

Last edited by turk 182; 8th January 2017 at 05:29 PM.
  Reply With Quote
Old 8th January 2017, 05:26 PM   #6
diyAudio Member
 
Join Date: Sep 2014
Quote:
Originally Posted by turk 182 View Post
the picture gave it away (thanks to the close up) you can see the holes at the ends of the pins have no solder, but many an old Marshall with that style connector has the wire link sheared off from the head getting wedged in somewhere in the truck pack.

the bias supply cap should be fine as long as it's not an old "leaky" cap.

speaking of things in the picture the socket with "replaced" resistor looks to have been replaced as well, no?

standby switch too!
I think itīs the original socket but the rivets have been taken out from the way of screws. The three remaining sockets are pretty loose. Those are attached with rivets.

I think itīs the power switch that has been replaced. Looking at all the images of other Supergroup units both the switches are those with metal toggles. The power switch toggle is plastic. I have those metal toggle switches in stock too so I might just replace that to meet the original look.

Also I have a lot of 70īs NOS resistors stored from my dad so should I see about replacing those that have drifted some?

K
  Reply With Quote
Old 8th January 2017, 05:30 PM   #7
diyAudio Member
 
Join Date: Sep 2014
Quote:
Originally Posted by turk 182 View Post
do you have a "dim bulb tester"?
I have all the necessary parts but I havenīt put one together yet since I wasnīt prepared to get a project in my hands with these kind of voltages any time soon. I mainly work with low voltages.

But Iīll first go through the very principles of this thing and surely before powering this beast up I will have one bulb tester ready.

K
  Reply With Quote
Old 8th January 2017, 05:52 PM   #8
diyAudio Member
 
Join Date: Oct 2012
certainly would not hurt to replace off tolerance resistors.

as for the tube socket it looks like it's a different color and if it's on screws and not rivets it's likely not "original"
are you giving any consideration to replacing/fixing the power cord?
  Reply With Quote
Old 8th January 2017, 06:05 PM   #9
diyAudio Member
 
Join Date: Sep 2014
Quote:
Originally Posted by turk 182 View Post
certainly would not hurt to replace off tolerance resistors.

as for the tube socket it looks like it's a different color and if it's on screws and not rivets it's likely not "original"
are you giving any consideration to replacing/fixing the power cord?
Yes, the whole "reaching accross the board" type of approach to this looks a little hazardous to me. So I was thinking replacing the rubber "reinforcement" in the entrance of the AC line and anchoring the Earth to the chassis nearby the AC entrance.

This unit has been stored for 8-10 years on a shelf a dry space and has not been used since. I think Iīm probably going to sell it in some point down the line because itīs not really my thing. It is awesome, but tīs a bit too much.
Iīm trying to keep it as original as possible, but do a clean good job on the restoration on the parts so itīs in good working condition for the next owner.
  Reply With Quote
Old 8th January 2017, 06:37 PM   #10
diyAudio Member
 
Join Date: Oct 2012
sound good to me!
best of luck, i'll follow along too.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Issue with Laney GH100L blackwhaleamp Instruments and Amps 1 25th March 2016 02:35 PM
Laney AH150 ClaudioC Solid State 0 5th January 2016 09:39 PM
Laney L20H - I'm looking for the schematic Kagliostro Instruments and Amps 0 4th December 2015 06:06 PM
Laney AH200 Carlosraj Solid State 3 7th May 2014 12:20 PM
laney VC50 tuneman Instruments and Amps 0 19th July 2004 10:49 AM


New To Site? Need Help?

All times are GMT. The time now is 05:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright Đ1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki