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General Discussion / ANSWER TOPIC MissColorado
« Last post by Ivannxk on Today at 02:51:31 pm »
 Can't respond to an available issue, what should I do ??
What am I doing incorrectly?
 Please inform me.
Thank you.
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General Discussion / ??????????? ??????? ??? ????
« Last post by LFTLaw on Today at 01:30:48 pm »
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by Soundmasterg on April 10, 2024, 11:39:19 pm »
That's in the earlier range of the completely self contained in one chassis 200S. The grille cloth is the early style. Dynaco transformers most likely, with slightly lower voltages than the later Schumacher transformers. I personally like the Dynaco transformer amps better. That is probably from around 1967.

The 5U4 rectifier lowers the voltages in the amp below stock, which is probably why the 6L6's haven't blown out yet. 6L6GC are robust tubes, but getting above 500V and unless top notch vintage quality they will struggle to survive, especially in a UL circuit like the Sunn, and will certainly give less power than the 6550 or KT88 with the proper 5AR4/GZ34 rectifier.

It looks like a decent amp though. I'd replace all electrolytic caps in the amp, and in the first two filter stages, you should use series connected caps with parallel resistors to give it 700V capability for each stage. Something like two 60uF and 350V connected in series with 220k resistors in parallel with each cap to share voltage load will give the equivalent of 30uF and 700V. Then the second stage set up the same way could be two 47uF caps at 350V for the equivalent of 23.5uF and 700V. Mouser sells some in those values. You may be tempted to use the CE Distribution can cap that is like the originals, but it is overvoltaged with today's wall voltages, and doesn't have the best reliablity as a result, and it will also be more expensive than the solution I mentioned. Drill a couple holes in the chassis and mount some terminal strips and secure the series connected caps and parallel resistors to those. Ground in the same place as stock. Replace any 2 wire power cords with a 3 wire setup and get rid of the 'death' cap. Replace the tubes and set the bias properly, and you should be good for many years.

Greg
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by Pacafeliz on April 09, 2024, 10:02:41 am »
For an amp this old, there might be other issues that pop up. Read through this thread over on the MEF board.

Link: https://music-electronics-forum.com/forum/amplification/guitar-amps/sunn/994060-200s-sunn

Thanks, will check it out.
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by loudthud on April 08, 2024, 08:46:04 pm »
For an amp this old, there might be other issues that pop up. Read through this thread over on the MEF board.

Link: https://music-electronics-forum.com/forum/amplification/guitar-amps/sunn/994060-200s-sunn
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by Pacafeliz on April 08, 2024, 08:37:09 pm »
Those tubes are OK if that's all you can get, but output power is probably only 45 to 50 Watts. Probably needs to be checked out by a good tech.

Note: A 4 Ohm cabinet should be plugged into the "External Speaker" jack. The internal wiring should be checked to see if the amp is wired for 4 or 8 Ohm cabinets or 8 and 16 Ohm cabinets. There are pictures on this web site to check.

Link: https://forum.sunnstillshines.online/index.php?topic=4844.msg18880#msg18880

Oh wow, thanks man, that's great info!
I'll open the amp up and check (take pics) next weekend.
In the meantime I've ordered some KT88s.
I'll also try to get the correct rectifier tube, since this one's wrong, too.

Stay tuned!

PS: any idea on its age/year, by looking at the pics?
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by loudthud on April 08, 2024, 03:16:02 pm »
Those tubes are OK if that's all you can get, but output power is probably only 45 to 50 Watts. Probably needs to be checked out by a good tech.

Note: A 4 Ohm cabinet should be plugged into the "External Speaker" jack. The internal wiring should be checked to see if the amp is wired for 4 or 8 Ohm cabinets or 8 and 16 Ohm cabinets. There are pictures on this web site to check.

Link: https://forum.sunnstillshines.online/index.php?topic=4844.msg18880#msg18880
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Q & A / Re: Sunn 200s running on 6L6 tubes?!
« Last post by Pacafeliz on April 07, 2024, 09:08:14 am »
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Q & A / Sunn 200s running on 6L6 tubes?!
« Last post by Pacafeliz on April 07, 2024, 08:16:31 am »
Hey folks, nice to be back after many years of absence!
I'm back here in Mexico and happened to pick up an old 200s, and it's working. But i did realize it has a pair of 6L6 tubes instead of KT88s - that can't be right, right? The rectifier is a 5U4.
Original owner says he's been running it like that for the last 20-30 years!
The outputs on the back are not marked what impedance they take, so i guess it's 8 and 4, right?
So my brother has a big Fender Dual Showman cab here, which should be 4 ohms, so I connected that one.
No nasty noises, good sound, but one of the power tubes was massively redplating,  so i shut it off.
Will take it back to Germany with me and get some KT88 first,  then have my tech guy check it out.

Any thoughts?

Cheers,
Pat.
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