[Jukebox-list] AMI TI-1 amp rebuild

[Don]

Further to Jay's technical comment I would add that if you are willling..... 
you can pop the TOP off the cans, drill and scrape out the contents, remove 
the 3 or 4 terminals at the bottom, clean up the inside walls of the 
can..... then install as many new electrolytics inside the can as will fit. 
Run their leads out the bottom thru the holes left after removing the old 
terminals. Leave the lead wire for each cap long enough to reach new tie 
points that you'll have to make. Of course you must remove the can to do 
this. Before putting back you mix some two part epoxy spread a puddle of  it 
on flat wax paper and set the rebuild electro can upside down in the puddle. 
Next evening come back trim off excess. Spray paint can top silver....  et 
voila, as you can see in the following picture.... its is hard to tell a cap 
craniectomy was performed... :-)   These two caps only have one electro 
apiece, inside as you can tell from only a black (NEG) and red (POS) wire 
protruding.

http://www.donsradiomuseum.com/images/TonyRogers6R631-02.jpg

PS. If the can has a little groove part way down the side, from the top, I 
use a copper pipe cutter as a "can" opener.  Almost impossible to tell 
anything was done when I finish...... also, I lay a little fiberglass mesh 
cloth in the epoxy resin for extra strength.

Cheers,
Don


----- Original Message ----- 
From: "Jay Hennigan" <jay at west.net>
To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
Sent: Friday, January 26, 2007 12:06 PM
Subject: Re: [Jukebox-list] AMI TI-1 amp rebuild


> bakerrj2 wrote:
>> I am in the process of rebuilding the amp of my TI-1.  All bad resistors 
>> and diodes have been replaced and am currently replacing the caps from a 
>> kit that I got from Vern Tisdale.  (Thanks Vern for lableing each cap per 
>> the schematic.)  Replacing the caps is pretty straight forward except 
>> when it comes to the "can" type filter caps.  I would like to leave the 
>> old "cans" in place for appearance purposes and install the new caps 
>> below the chassis.  The problem is that there are other terminals besides 
>> the caps pos. and neg. leads attached to the existing caps that I am 
>> unsure what to do with.  They don't seem to appear on the schematic.
>>   Can I attach the new caps to the existing terminals or should I install 
>> new terminal strips and move the pos. and neg. leads to these strips?  If 
>> so will the other attachment points have to be moved as well?
>>
>> As you can tell from the above question,  I am a rank rookie in this 
>> endeavor.  Any help offered will be greatly appreciated.
>
> The can style capacitors often contain several capacitors within the one 
> can assembly.  The negative for all the caps is the can itself, connected 
> to the four (three for the smaller cans) twisted lugs around the outer 
> diameter that hold the can in place.  This is *USUALLY* chassis ground, 
> unless the can is mounted on a fiber insulating baseplate.
>
> The positive terminal(s) are in the center.  The capacitors within the can 
> may have different values, so it is important to match the replacement 
> caps to the correct section.  You can do this by tracing the wires and 
> matching to the schematic, and also by carefully examining the base of the 
> can and the markings on the can itself.
>
> The positive terminals protrude from a fiber insulator at the bottom of 
> the can.  There will be a shape punched out of the insulator for some of 
> the terminals, either no punch, a triangle, a square, or a "D" shape. The 
> printed markings on the can will indicate the value associated with each 
> symbol.
>
> On a multi-section capacitor, the schematic will use a letter suffix to 
> denote the sections.  So a single can may have four capacitor symbols on 
> the schematic, like C401A, C401B, C401C, C401D.  This means that you may 
> use up to four individual replacement capacitors to replace one can. 
> Vern's parts are probably labeled with the complete schematic designator 
> including the suffix letter.
>
> You will need to remove all of the wiring from each non-grounded terminal 
> on the existing can and relocate it to a terminal strip. Leaving the old 
> capacitor connected to the circuit is asking for trouble.  It's certainly 
> OK to leave it in place physically for cosmetics.
>
> --
> Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
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