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Old 18th December 2012, 03:19 AM   #1
AJT is offline AJT  Philippines
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Default Super Leach amp rebuild

Super Leach amp, this is a 20 year old amplifier and begging for a rebuild,

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as it look 20 years later:
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soft start and protection circuit board....
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central ground point.....
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power traffo....
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Old 18th December 2012, 03:27 AM   #2
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do you have the schematic for it ?
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Old 18th December 2012, 03:31 AM   #3
jcx is offline jcx  United States
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20 yrs isn't much, vacuum up the dust, power, preferably thru a Variac to ramp V slowly for electrolytic reforming

but many would go ahead and just replace all electros

looks like power wiring could be improved - at least some twisting

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Old 18th December 2012, 03:43 AM   #4
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I agree with jcx, I would clean it well, change all electrolytics, adjust bias/dc offset, also I would check for bad connections. That is all!!!
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Old 18th December 2012, 03:49 AM   #5
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Old 18th December 2012, 04:55 AM   #6
AJT is offline AJT  Philippines
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Quote:
Originally Posted by jcx View Post
20 yrs isn't much, vacuum up the dust, power, preferably thru a Variac to ramp V slowly for electrolytic reforming

but many would go ahead and just replace all electros

looks like power wiring could be improved - at least some twisting
the plan is to dismantle the whole thing and have the panels and chassis powder coated to make it look new...

the main filter caps will be replaced with newer Nichicon 47Kufd/100volt rated for 105*C....all ecaps will be replaced also...

the power traffo will be replaced so i can get +/-95volts dc rails at idle...
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Old 18th December 2012, 10:09 AM   #7
jaycee is offline jaycee  United Kingdom
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Most of it looks 20 years old, except the output transistors. They are branded ON which means they are from 2000 at the oldest.

Other than that, a good clean and some new electrolytics, and im sure she'll be golden
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Old 18th December 2012, 10:50 AM   #8
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The Leach SuperAMP is described here:

Leach SuperAmp Plans

Best regards - Rudi
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Old 18th December 2012, 11:46 AM   #9
AJT is offline AJT  Philippines
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Quote:
Originally Posted by jaycee View Post
Most of it looks 20 years old, except the output transistors. They are branded ON which means they are from 2000 at the oldest.

Other than that, a good clean and some new electrolytics, and im sure she'll be golden
you are correct, i have repaired the amp around 2004, before that i used MJ11032/MJ11033.....
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Old 18th December 2012, 12:07 PM   #10
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I'd retighten the star ground, but you say you're going to rewire it anyway. Also change the diff amp emitter resistors and feedback resistors at the least with metal film, 25ppm .1% or better, and any other resistors you can afford. Maybe a cermet pot for bias; better quality.

Good job on the cooling fans; that'll let it crank out all the watts your ears can stand.
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