Just Picked-up My 200S From the Shop

[LPB]

 When I purchased the amp recently it still had the stock(I'm assuming)Golden Monarch and Mullard tubes, original 2-prong power chord, and all the caps were original. While it sounded it great, I wanted to get everything checked-out. I supplied a new complete set of JJ's and 20ft "extra beefy" grounded cable. The tech cleaned, tested, tightened, etc. It turned out the every component in the amp spec'd out perfect. He set the bias, charged me for 1.5 hrs and overall I'm very happy to have a bone-stock '67 200S that works just like new.

Yay Sunn.

[Greg_M]

Happy Days!

[LPB]

Yes. I've had other non-pcb tube amps and love the fact that they can almost always be rebuilt and brought back to "new" specifications, but I feel extremely fortunate that this amp has persevered in the way it has.

[george]

If those are the stock capacitors in your amp and you plan on actually using it - they will fail.

[LPB]

 Yea, everything is stock, and I most certainly plan on using it, in fact that was my main reason for bringing it in.
 So is it pretty much standard service procedure to re-cap a 40+ year old amp, if nothing else but for good measure? It seems like     I've heard this before. Now I'm kind of curious why this tech didn't suggest this work to me.

 My buzz is crushed, but I appreciate the comment/concern george. If one of the caps fail what other components am I in danger of damaging?

[Greg_M]

Some of the caps are a real bugger to find.
While searching for mine, I had to often times more than I needed to satisfy minimum and lots and so on.
They are out there, it just takes some work to find them

[CLD]

There are some pretty lengthy threads on this topic, try doing a search for them.

I beefed up the caps on a 200S I bought because I knew I wanted to gig with it. Also bought a variable voltage regulator for additional protection and reliability.

[EdBass]

There are some pretty lengthy threads on this topic, try doing a search for them.

Yeah, the filter caps have been pretty much hashed out ad infinitum. 

I beefed up the caps on a 200S I bought because I knew I wanted to gig with it. Also bought a variable voltage regulator for additional protection and reliability.

+1
I also have power supply modded 200S and 2000S’s for gigging purposes. These amps are old, the original design was for 110-115V, and even at those line voltages the original spec filter caps will see in excess of their 525VDC rating. I’ve played clubs were the wall voltage was in excess of 125V, heck my house is 122-124V. If your amp will just be used occasionally for light duty, that’s one thing, but if you need to depend on it to take a pounding for money, IMO it’s better to be safe.

I’ve sourced every part on a 200S. If you want to stay “box stock”, as Greg posts the stock values for everything are still mostly available; the 1N2070 in the bias supply can be a little elusive, but overall I really haven’t had too much trouble finding anything.
Most parts I’ve found more than one source for, if you need something specific, PM me.

[LPB]

 Thanks guys!

 

[Soundmasterg]

Pretty much if you plan to gig with the amp, then the electrolytic caps in the amp should be replaced. You can use a can cap as others have done, but these will be over their voltage maximum rating with the wall voltages today, and that shortens their expected lifespan considerably. A better approach is to use series connected individual caps inside the amp and leave the can in place for cosmetic reasons, but disconnected electrically. If you series connect caps, you end up with half the uf value but twice the voltage rating. You also need to connect a 220k 1 watt resistor in parallel with each cap so the caps will share the voltage instead of one trying to hog all the voltage and exploding as a result. You can stay close to stock values or go with larger cap values for tighter and quicker bass response and less noise. If you use the amp for bass, and decide to change to larger cap values like many here including me have done, then I would suggest to only change the first two filter sections to larger cap values. If you change the ones after that, it will directly change the sound of the amp, but changing the first two will only change the feel of the amp.

The signal caps are probably just fine and won't need replacement, though the brown blob caps that were used in many of the Sunns aren't very good caps with high ESR, and while they almost always still work ok, just about any modern cap will sound better than those. The rest of the caps are just fine sound-wise and I wouldn't replace them unless they are leaking DC to the next stage in the amp from where they are located.

Some of the carbon comp resistors may have drifted off their tolerance and should be replaced if so. Carbon comp plate resistors often get moisture in them and will crackle, especillay in the plate resistor position in the preamp. If you replace them, use the same carbon comp types. The carbon comps in the power supply and negative feedback areas should be replaced with modern metal film or metal oxide. Carbon comps are famous for bursting into flames in overload conditions, and metal film or metal oxide resistors will not do this. The resistors in these positions are not in the audio path either, so as long as the value of resistor used is the same, there will be no change in sound.

Greg

[Walt-Dogg]

Wait, so it's probably a bad thing that I've been gigging my Concert Lead regularly without ever taking it in and getting certain components such as the caps replaced in order to keep the amp from going FUBAR?

[Isaac]

I don't think it's a bad thing. Caps often live longer if they're used. If your amp is working well, and I assume that it is, as you're gigging with it, then you're not hurting anything by using it. However, you should be aware that the caps are indeed old, and could fail at any time. You'd probably be well advised to find an opportunity to get it recapped.

[Greg_M]

Think....preventive maintenance.

[Isaac]

Exactly.