Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Micky Asat on June 17, 2013, 07:00:58 PM

Title: Lab series L5 Amp
Post by: Micky Asat on June 17, 2013, 07:00:58 PM
I have a Lab series L5 amp and would like to recap it. Anyone know where i can get the caps from,as no one in the uk seems to stock them. The two large 75v 3000mf are the ones i am haveing difficulty getting.
Title: Re: Lab series L5 Amp
Post by: Enzo on June 17, 2013, 07:13:51 PM
They are just filter caps, and those are not standard values.  When a company makes thousands of amps, they can have any caps they want made to order.  But in the general parts market caps come in standard values  So instead of looking for 3000uf, try 3300uf or even 4700uf.

And 75v is not common either, so look for 80v or 100v caps.

Dimensions tend to be in common sizes as well, but not all are alike.  And the space between the leads may matter on a circuit board.  Fortunately on the search screens at places like Mouser, the dimensions usually are listed.  SO verify the lead spacing works for you, and make sure the caps are not too tall or too wide for the space.  You don't want overly wide caps not fitting side by side, nor do you want a cap too tall so it stick out of the chassis.
Title: Re: Lab series L5 Amp
Post by: Micky Asat on June 19, 2013, 06:37:02 AM
Hi just checked with Mouser,
                                          They stock a 75v 3000 mf cap Cat no 598DCM302U75AB2B I think they should fit ok as they are quite big. What do you think.  The rest of the caps i can get over here in the UK.
Title: Re: Lab series L5 Amp
Post by: Enzo on June 19, 2013, 07:07:57 PM
I don't know, you have the amp, do the dimensions of their part fit your amp?

If Mouser ships to your area at reasonable cost, then go ahead, otherwise I'd still be looking at those alternative values.
Title: Re: Lab series L5 Amp
Post by: g1 on June 20, 2013, 12:39:38 AM
  The one you mentioned from Mouser is a screw terminal type, so I'll assume the cap does not mount on the circuit board, but has wires going to the screw terminals.
  Most modern caps are smaller than older ones, so the physical size shouldn't be a problem.
But like Enzo said, you don't need to use their odd values, and may end up paying more for them.
3300 is easily close enough, and 80 or 100 volts should be fine.  Also you can use caps with lugs rather than screw terminals and solder the wires to the lugs.
  Here are some UK offerings for 3000 and 3300uf at 80 or 100 volts, both screw and lug terminal types:
http://uk.farnell.com/jsp/search/browse.jsp?N=215573+110020382+110029824+110152057+110202702&No=0&getResults=true&appliedparametrics=true&locale=en_UK&divisionLocale=en_UK&catalogId=&skipManufacturer=false&skipParametricAttributeId=&prevNValues=215573+110020382+110029824&mm=1000002

http://uk.rs-online.com/web/c/passive-components/capacitors/aluminium-capacitors/?sort-by=default&sort-order=default&applied-dimensions=4294463072,%204294465770,4294461468,4294466587&lastAttributeSelectedBlock=4294955811
Title: Re: Lab series L5 Amp
Post by: Roly on June 20, 2013, 04:25:43 AM
Possibly worth mentioning that the value tolerance on electrolytic caps is very wide, something like +25%/-50% (or is it the other way around?), and that the difference between "3000uF" and "3300uF" is a mere ten percent and not going to make any functional difference at all.

So specially importing "3000uF" from Mouser when 3300uF is almost certainly available locally, (and even 4700uF would do if it will physically fit) is quite unwarranted.

Me, if I still lived in London I'd be heading down Tottenham Court Rd.
Title: Re: Lab series L5 Amp
Post by: J M Fahey on June 20, 2013, 12:39:01 PM
QuoteMe, if I still lived in London I'd be heading down Tottenham Court Rd.
Man, that sure brings memories !!!
I remember hunting the huge "surplus stuff" parts bins just at the door of many of them for weird curious parts.

Back to the thread: please remember that
1) electrolytics have *big* tolerance.
In the old days, as much as -50%/+100% , later improved to -30%/+60%
As you see, it's more likely to have "more" than "less".

2) Norlin/Moog/Gibson/Lab specified the best parts, so I'm certain that if those caps had tolerance (which they certainly did), they sure had *more* capacitance than specified, and supported *more* voltage also.
Way back then parts were sold on *quality*.

While a modern generic capacitor , although it will meet specs, if from a reputable manufacturer, it will "just" meet them, with not much "extra", if any, because today Market is *price* driven, like it or not.

What do I mean?: I'm certain a 3300uF x 80V will be closer to the actual cap Lab used, than a nominal "3000x75"

Plus a "standard" one will be fresher (sells faster  ;) ) than a non standard one, which may be sitting in that shelf for years.
Title: Re: Lab series L5 Amp
Post by: Roly on June 21, 2013, 10:49:26 AM
So you'd remember Proops, Relda Radio & Eagle (where I worked for a time as a tech); Nixies were all the rage when I was there.

This one's for you JM...

(http://i1341.photobucket.com/albums/o743/Roly49/Australian%20Guitar%20Gear%20Heads/reboot_zps119666f3.jpg) (http://s1341.photobucket.com/user/Roly49/media/Australian%20Guitar%20Gear%20Heads/reboot_zps119666f3.jpg.html)

We're not having riots here at the moment, just ravening mobs of 'roos and clouds of Yellow-Tail Black Cockatoos - I feel a bit left out and underprivileged.
Title: Re: Lab series L5 Amp
Post by: Micky Asat on July 12, 2013, 04:11:24 PM
Finally recapped my L5  Got the large caps from Mouser and the rest from Maplins here in the UK. I had to modify the large can caps as the screw contacts were out of line with the circuit board holes. I drilled two more holes in the board and carefully extended original holes with solder. Amp hopefully good for another 30 years. Big difference in sound quality,particulary the reverb. A big thanks for everyone who has given their opinions.