The sunn Forum
Sunn Musical Equipment => Q & A => Topic started by: kupervaser on March 14, 2011, 05:49:10 pm
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I bought a Sunn Solarus amplifier from ebay.
The seller said it was all original and he also sent me the tubes. The tubes are 6550. However the transformers do not look that big to me.
Can you check the pictures and give me some ideas on what tubes should be there?
Here are the pictures:
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFh0wBGkKGrHqUOKiEE0m975qUlBNWLjbCeQ_3.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFgpB2kKGrHqYOKkQE0ZCMWsf5BNWLjRu9g_31.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFfZw2kKGrHqIOKjE0Zvgio7wBNWLjJujT_31.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFf6wWkKGrHqUOKoYE0gKMDpUBNWLjMvbUg_31.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFf6wWkKGrHqUOKoYE0gKMDpUBNWLjMvbUg_31.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFe-Q2kKGrHqEOKo4E0Wp3rQb8BNWLjHGKjw_31.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/CFzFefwCWkKGrHqYOKjgE0dTfBV5BNWLjEOKQ_31.jpg)
And another thing. I am in Europe. What is the best way to handle, convert this heat to 240 volts with a built in step down transformer, or get a portable transformer?
Is the convertion with a built in transformer difficult? Are there any partsto be changed or just adding a transformer?
Thanx
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Hi there,I think it's an older one,look on the front under the name to see where the amp is made.If it says Portland Oregon,it's the older version,should have a pair of EL 34's,(6CA7's) for outputs.Check the phase inverter tube,older models have a 7199,newer ones have a 6AN8 (A).The older ones have the 16 and 8 ohm stickers on the back,where the newer ones had 8 and 4 ohm stickers.As far as the AC goes,I would get an external AC step down transformer rather than try to mount one in the amp itself.Good luck,Mel.
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I think so too, those definitely look like the 40 watt trannies.
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Hi,
I live in Germany (with 230V/50Hz :wink:) and use the step down transformators as well, no problem.
Sorry with the tubes, I`ve Sorados and 2000S, they all take the 6550/KT 88.
Greetings
Oli
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Thanx,
It is made in Oregon:
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/DSCF1416.jpg)
Just asked the seller again and he told me KT88 are the right tubes. He got them out of the amp and stored in it.
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Ask the seller where the reverb tank is.
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Hi there,the mains fuse is 2 amps,I believe on the KT88/6550 model it is a 4 amp circuit breaker,plus like Ed says,the tranny's are too small,I really think it's a 40 watt model that has the wrong output tubes in it,Mel.
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do el34 en kt88 have the same pinout than? thanx
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Hi there,the mains fuse is 2 amps,I believe on the KT88/6550 model it is a 4 amp circuit breaker,plus like Ed says,the tranny's are too small,I really think it's a 40 watt model that has the wrong output tubes in it,Mel.
All of my 6550 models have a 3 amp slo-blo fuse. I agree that the transformers look too small.
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do el34 en kt88 have the same pinout than? thanx
Not really the same, pin 1 is the suppressor grid in the EL34, but in your amp you can plug in a KT88; the pinout isn't the issue IMO.
I think the issue is the current draw requirements for a KT88, 100ma more for the heater, more plate current, etc. vs. an EL34 taxing that little power transformer, the one everyone keeps mentioning as being "too small".
The entire power supply would be working a lot harder, and it's already working it's little butt off with EL34's installed. I doubt (but don't know for sure) if you could even get the bias close enough to spec with a pair of KT88's installed.
Here's another indicator as to it being a less than good idea; those fuses that also keep getting mentioned, why do you imagine that they are only 2 amp while the KT88/6550 amps require a 3-4 amp fuse?
Also, why you would want to use the KT88's? You know you wouldn't get more power using KT88's in that amp, right?
I'm not trying to be obnoxious, I'm just curious as to why you would want to. If I'm missing something I'd like to know... :-D
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It is not that I really want to use the KT88 tubes. It is that the seller sold me this amplifier in none working condition and he included a pair of KT88 tubes as original tubes. Already twice he assured me that those are the tubes which has been used in this amplifier before it broke down. I am just trying to find out which tubes I need to use when I will start repairing (or at least search for a problem) this amplifier. I really don;t care which tubes to use as long as the amp starts working. I like the sound of EL34. ALl the amps I own have EL34 in them.
Thanx
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It is not that I really want to use the KT88 tubes. It is that the seller sold me this amplifier in none working condition and he included a pair of KT88 tubes as original tubes. Already twice he assured me that those are the tubes which has been used in this amplifier before it broke down. I am just trying to find out which tubes I need to use when I will start repairing (or at least search for a problem) this amplifier. I really don;t care which tubes to use as long as the amp starts working. I like the sound of EL34. ALl the amps I own have EL34 in them.
Thanx
I think the seller was "confused", however if you got a pair of KT88's that are period correct for that amp as part of the deal, and they are healthy, I'd say you probably did OK.
What is the amp doing/not doing?
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I am not sure yet. I haven't plugged it in yet. I need a step down transformer first.
This was the description:
SUNN SOLARUS TUBE AMP
1968 vintage tube sound!
This amp worked great for years.
Sounded amazing!
1 day it just would not turn on.
I never got into it to look.
It has been sitting for a couple years now. Stored in a climate controlled room.
This is a good chance to get a great deal.
Could be a simple fix. I have no idea. I am tired of it just sitting.
These are not easy to come by.
If I did not have too many amps as it is, I would get this running again!
The tubes were yanked out and stored. I could use the tubes in other amps, but if the amp breaks 300, I will include them.
THIS IS SOLD AS IS!
I got it for $435 which is nog bad if you are in Europe.
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As you look at the back of the amp, the far left tube should be GZ-34 and the two in the right-center-front should be an EL34 pair.
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I am not sure yet. I haven't plugged it in yet. I need a step down transformer first.
Oh yeah, I forgot about that part. I'd check the filter capacitors first, you can do that without needing 115 VAC. Once you get the voltage sorted out, I'd see what the PT is doing.
Good luck with your project!
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he assured me that those are the tubes which has been used in this amplifier before it broke down. [/quote
I'm no techi like these other guys, but it occured to me that
maybe there's a connection between the KT88 tubes being used and the amplifier breaking down ?
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I am not sure yet. I haven't plugged it in yet. I need a step down transformer first.
Oh yeah, I forgot about that part. I'd check the filter capacitors first, you can do that without needing 115 VAC. Once you get the voltage sorted out, I'd see what the PT is doing.
Good luck with your project!
Ed is right on here. The filter caps (don't forget the bias circuit cap) and rectifier tube and fuse are good places to start. After that, the power transformer should be checked. Do all checks without tubes (except rectifier tube) first before you add tubes. If it blows a fuse with the rectifier tube in, then take it out and try to power on again once the fuse is replaced...if it still blows the fuse, then the PT could be bad, or bad filter caps. Get your voltage supply sorted first and then you can check into it, but realistically, if the filter caps are original, they all need to be replaced at this point.
greg
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Yeah, I will probably change all the electrolitycs anyway. But thanx guys. But does the KT88 has the same pinout as El34? You can't just swap them right? Basically someone have rewired this amp for KT88 on purpose but didn't think off wrong transformers?
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Yeah, I will probably change all the electrolitycs anyway. But thanx guys. But does the KT88 has the same pinout as El34? You can't just swap them right? Basically someone have rewired this amp for KT88 on purpose but didn't think off wrong transformers?
do el34 en kt88 have the same pinout than? thanx
Not really the same, pin 1 is the suppressor grid in the EL34, but in your amp you can plug in a KT88; the pinout isn't the issue IMO.
They are not the same, but in your amp KT88’s can be used without rewiring the tube sockets. Pin 1 in a KT88 is connected to the metal tube base, and the beam forming plates; sort of the KT88’s version of the suppresser grid, is internally connected to the cathode. Your Solarus uses pin 1 to connect the suppressor grid to the cathode.
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Allright thanx a lot. I will start working on this amp as soon as I have my step down transformer. I bought this one:
http://www.tubeampdoctor.com/product_info.php?cPath=27_47&products_id=146
Is that ok?
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I'd say the bigger the better. That one looks pretty beefy to me!
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Hi there,at a 1000VA rating you'll be able to draw around 8A of current at 115VAC,lots of headroom,you can run 2-3 amplifiers off of that and not worry.Good luck,Mel.
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Thanx. Yes I need a bigger one to power my Model T as well.
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Hi,
I use this one for my Ampeg V4B and Sunn350B (not at the same time):
http://www.yatego.com/multimediastore/p,49ae620e902e2,430dbd8940f3d2_4,spannungswandler-vorschalttrafo-230-110v-300-watt?sid=06Y1300803796Y01f6c250f6da4bcd6f
300 VA is more than enough, I think the 2000S used app. 250W (VA) Peak when I did some measurements with the troubleshooting.
Though I paid app. 50€ for a 500 VA step down transformator at Westfalia, but they are not in stock any more.
Anyway, TAD is a great place - I bought all my tubes there, they repaired my Ampeg and the service is A +++! They really love tube amps ! :-D
Greetings
Oli
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Thanx Oli, I bought 1000VA on ebay for 60 euros. However won;t need that much power.
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I jused compared the 200S with the Solarus. Ed hind is really the best way to check it as you ll see the PIN 1 connected/not connected. You ll find the SUNN Schematics here: http://sunn.ampage.org/site/schematics/
As far as I can tell all the big caps 600V tend to bad - I had the main trouble with theses and with the chokes.
Good luck with your amp!
Greetings
Oliver
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For the record, VA and watts are not the same thing, though, in this case, they're close enough for the difference not to matter.
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Hi, shure , you are right. The idle power of the whole system woundn`t be that high, so I set VA and W equal....(I think it should not be necessary to attach a star-delta connection.... :-D.... ).
Thanks & Greetings
Oli
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Will this head work without the reverb tank or should I put that in first?
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It will work fine without the reverb tank installed. You just won't get working reverb without the tank. :)
Greg
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I looked on the inside of the amp and noticed that two of the 1000uf capasitors (the yellow once) had broken leads.
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/DSCF0505.jpg)
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/DSCF0503.jpg)
That could be the source of the problem. Still haven't got my step down transformer to test it. I'll replace the capacitors and measure some voltages.
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Soldered the caps yesterday and put in the EL34 tubes. The amplifier started working instantly.
Sounds good, only there is some hum, probably 50hz from the wall outlet hum. Or is there a chance the step down transformer can deliver such hum?
Also, what are the big capasitors on the left for? I can;t seem to find them on the schematic:
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/DSCF0501.jpg)
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Or is there a chance the step down transformer can deliver such hum?
Hi,
I had no trouble with my Step down concerter (so far.... :-P). Do you use a "grounded" cable? Otherwise you can use the polarity switch (you should change it to a "grounded" cable as soon as possible!!!!).
I would also check the 600V caps, my amps produces "neary" no hum with new caps. They are not that expensice.
Greetings
Oli
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I do not see those big capasitors on the left on the schematic. Do you have any idea what they are for?
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Kupervaser,
The silver Mallory capacitor is the original filter cap for the first pre-amp tube V1 (12AX7A / ECC83) and should be connected to pins 1 and 6. On some Sunn amps, one of the stages of the 4-section can capacitor was not used (or was used in parallel with another section) and a discrete capacitor was used locally next to the tube it served (in this case V1). It appears that the silver Mallory was left in place and bridged with a new gold-colored capacitor.
Ryan
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Kupervaser,
The silver Mallory capacitor is the original filter cap for the first pre-amp tube V1 (12AX7A / ECC83) and should be connected to pins 1 and 6. On some Sunn amps, one of the stages of the 4-section can capacitor was not used (or was used in parallel with another section) and a discrete capacitor was used locally next to the tube it served (in this case V1). It appears that the silver Mallory was left in place and bridged with a new gold-colored capacitor.
Ryan
And both of those are bad too most likely. On the schematic it would be the electrolytic for the first stage...either the supply cap, or the cathode bypass cap. What is the value of that gold cap in the pic?
Greg
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The silver one sais 20uF and the golden one sais 50-60uF.
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Both of those caps are physically too large to be cathode caps. And by their values, it's apparent that they are power supply filter caps. The "+" side should go to pins 1 and 6 of V1 and the "-" side goes to ground. The gold cap is too large (in capacitance) for filtering at the 1st stage. And Soundmasterg is right, they are both too old. They should both be removed and replaced with a single 20uf x 450V electrolytic capacitor.
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Do I need to put a bigger output transformer if I want to use KT88 tubes in this amplifier?
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Do I need to put a bigger output transformer if I want to use KT88 tubes in this amplifier?
No, but don't expect any increase in power. Your output power may in fact be slightly less with KT88s.
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Thank you, and if I would like to have more power, what kind of a transformer should I be looking for?
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I'd say that, if you're looking for significantly more power, you should be looking for another amplifier.
A pair of 6550's can put out around 80 watts. A pair of KT88's can put out around 100 watts. That's a difference of only about 1dB. Hardly worth it. Even compared to the lower 60 watt output of the tube-rectified Sunn amps, it's still only 2.2dB.
If the Solarus is giving you the tone you want, and no other amp will do, then either mic the speaker, arrange for a line out, or get another amp and speaker.
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I changed that gold and silver cap to one new 22uF capacitor, but I still have the same loud hum.
The hum is present even when the guitar is not plugged in. So does anyone has any tips how to start searching for the source of this hum, without simply replacing all kind of parts? I have a scope and a signal generator, but I can not find any usable info on how to utilize this equipment to find hum, at least not yet. All info is welcome.
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First test: Do any of the volume, tone or reverb controls affect the amount of hum?
Since at last report you did not have a reverb tank, you need to short the connection at the reverb footswitch to ground. Those big caps on the reverb PCB will allow hum to get into the signal path if they are bad or missing. Have they been replaced?
Second test: When you flip the Standby switch to the down (no signal) position does the hum stop immediately, or does it fade out over a period of several seconds?
What kind of probes do you have for the oscilloscope? What is the voltage rating? What is the maximum voltage allowed on the input of your oscilloscope? Most tube amps have enough voltage to damage an oscilloscope if it is not used properly.
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Thank you for the walk through.
Here are my findings.
First of all the hum gets louder when I turn the volume up.
Bu turning up the reverb knob hiss gets introduced to the overal sound. If the reverb is down all the way, no hiss.
Those broken capacitors on the reverb pcb have been swapped for new ones.
When the amp is on and I flipp the stand by switch to off, the hum is gone immediately.
When I pull out the first preamp tube (ECC83), hum is completely gone.
Also when I pull out the phase inverter the hum disappears.
I do own a reverb tank from another amplifier which I can connect, I however do not have a switch with correct connections. I might bridge it later to test.
I own a Tektronix 454 scope with probes which are X1 and X10 switchable.
Looking forward to your reply.
p.s. I also swapped 2 other electrolitics. Here is the new picture. The golden once on the reverb PCB are new and the 2 black capacitors are new as wel.
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/photo1.jpg)
On this picture the blue 22uF capacitor is new.
(http://i642.photobucket.com/albums/uu144/kupervaser/Sunn%20Solarus/photo2.jpg)
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Another small thing I just noticed on the picture. The 4ohm output connection on the OT (brown wire) is hanging loos. Is this ok or not? Because I see on pictures of other amps it is connected, like here:
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/ss_7.jpg)
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I soldered the 4 Ohm tap of the transformer to the negative side of the 22uf (blue in my picture) capacitor.
Well, the amp works, but the sound is distorted, as if i am playing with a tube screamer in front of the amplifier, very nice sounding distortion, but not that loud. So to my understanding this is not right, so I desoldered the 4 Ohm tap and it is hanging loose again, the sound is again clean now and loud. Why is this 4 Ohm tap connected on other pictures of these amplifiers?
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Normally the 4 ohm tap is soldered to an otherwise unused lug on the terminal strip.
Look at the pictures in this thread: http://sunnforum.ampage.org/index.php/topic,4844.msg18880.html#msg18880
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So when I remove the Ecc83 preamp tube the hum is completely gone. Does this mean there is a component around this tube which produces the hum? I tried several other preamp tubes, it makes no difference.
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The hum in your amp is probably caused by a bad ground. The way to tell is that the hum will stop immediately when the Standby switch is moved from the "Play" position to the "Standby" position (down). A slight hiss will continue to be heard for a couple of seconds.
One possible cause is corrosion between the input jacks and chassis and around the pop rivets that hold the terminal strips to the chassis. You can solder the terminal strips to the chassis if you have a really big soldering iron. The input jacks will have to be removed, clean around the threads, star washers and chassis holes, then re-install. Tighten the nut well.
Some of these amps have a problem caused by the common ground in the big Can Cap. The axial cap near the preamp is supposed to fix this, but there needs to be a resistor between the B+ from the Can Cap and the plus side of the axial cap. The axial cap needs to get it's ground on the preamp end of the chassis.
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Ok, let me recheck the inputs first. Now I am reading the topic i want to clarify that it is not hiss I am hearing, there is no hiss at all, it is a hum or I am not sure something like a low zoom, sounds like a sound a big power transformer would make, and it comes out of the speaker.
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I soldered the 4 Ohm tap of the transformer to the negative side of the 22uf (blue in my picture) capacitor.
Well, the amp works, but the sound is distorted, as if i am playing with a tube screamer in front of the amplifier, very nice sounding distortion, but not that loud. So to my understanding this is not right, so I desoldered the 4 Ohm tap and it is hanging loose again, the sound is again clean now and loud. Why is this 4 Ohm tap connected on other pictures of these amplifiers?
Soldering the 4 Ohm tap where you did directly connects it to ground, which is incorrect. it's normally soldered to the tab on the far left, which is connected to nothing.
So you can either leave it unconnected, or solder it to the far left tab. Both are the same as far as the amp is concerned.
As far as your hum, have you replaced the cap can yet? All of the Sunns I own including my Solarus have needed new cap cans due to humming. They all quiet right down and have no noticeable hum now.
One more thing, your Solarus is 100% positively an EL34 version. I have both versions and the 6550 version has much larger transformers. The pic you posted looks exactly like my el34 Solarus.
You can get the cap can here for the EL34 version, the voltages don't run as high for that version so this can will work great.
http://www.tubedepot.com/cp-ce-30-20x3-525v.html
The 6550 version requires a higher voltage cap can, which can be found but they are expensive.
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Thank you, yes I am aware that mine is a EL34 model which is 40 watts. The transformers are smaller than the 6550 version.
I haven't replaced the can cap yet. I already have this capacitor at home:
http://store.triodestore.com/40uf50clammo.html
I think it would work too.
I didn't want just go on and replace all kind of parts. I wanted to see whether I can find the source of hum and than replace suspicious parts. This is why I asked how to debug such hum issues with the oscilloscope because I own one.
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As long as you don't have more than 500V for the B+ voltage in your amp that cap will work.
Any more than 500V and your pushing your luck.
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So I have been looking at the power supply with the oscilloscope. I have checked for AC on each of the capacitors in the multicap.
Here are some results.
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/Sunn%20Solarus%20Schematic.gif)
First capacitor after the standby switch:
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/My%20Solarus/Measurments/photo%201.JPG)
Second capacitor (Point A on the schematic)
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/My%20Solarus/Measurments/photo%202.JPG)
Third capacitor (point B on the schematic)
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/My%20Solarus/Measurments/photo%203.JPG)
Fourth capacitor ( point C on the schematic)
(https://dl.dropbox.com/u/3131065/Amps/Sunn%20Solarus/My%20Solarus/Measurments/photo%204.JPG)
In my opinion, this could be the hum I am hearing, can anyone support this?
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I would say yes it is.
You should not have that much noise especially at point A
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For points B and C the pictures don't show what position the scope's Volts/Div knob is in.
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Looks like 5 mV/division to me.
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Here are the VOLTS/DIV:
First capacitor after the standby switch - 1 V
Second capacitor (Point A on the schematic) - 0.1 V
Third capacitor (point B on the schematic) - 5 mV
Fourth capacitor ( point C on the schematic) - 5 mV
The probe I am using is x 10.
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Did the replacement of the Can fix the hum? Just wondering what the fix was as
I have a similar issue in my amp.