It depends on the threshold of what you meter considers a "short", but it's possible that the B+ winding is open. Check for a "short" between each of the red wires and the center tap (red/yellow). If one is a short and the other is not, then there's a good chance the winding is open. I'm surprised that an open winding would blow the fuse unless it shorted to the transformer core itself.
What meter do you have? Look for a setting with an omega symbol "Ω" or upside-down "U". That will measure resistance. If you have to manually set the range, start with the lowest range. You may also have to move the red test lead to a different jack on the meter, but usually it is the same jack that measures voltage.
What meter do you have? Look for a setting with an omega symbol "Ω" or upside-down "U". That will measure resistance. If you have to manually set the range, start with the lowest range. You may also have to move the red test lead to a different jack on the meter, but usually it is the same jack that measures voltage.
I had thought that I Toasted my power transformer too. Turns out I smoked the FREDS. Seriously. Try what Tubelab suggests.
I would expect a lot of effort would be needed to fry a power transformer.
I would expect a lot of effort would be needed to fry a power transformer.
Allied is sending me another one for free. I don't even have to send in my old one. Kudos to Allied.
I'll do the resistence checks later. And see what I come up with.
What I'm worried about now is another Break down. I wonder if my B+ voltage is too much. The last time I checked it. It was close to 490v
Do you think this is too much for the Allied or was my was last one just a fluke break down?
I wonder if I should drop the B= a litte? Maybe to around 440-450.
What do you guys think?
Nick
I'll do the resistence checks later. And see what I come up with.
What I'm worried about now is another Break down. I wonder if my B+ voltage is too much. The last time I checked it. It was close to 490v
Do you think this is too much for the Allied or was my was last one just a fluke break down?
I wonder if I should drop the B= a litte? Maybe to around 440-450.
What do you guys think?
Nick
If the current draw is low I would expect the voltage to be up around about 490v as you indicate. The voltage will drop as current increases.
The folks at Allied are a pleasure to work with.
The folks at Allied are a pleasure to work with.
Well, if you look at George's chart here:
http://www.tubelab.com/AssemblyManualSimpleSE/TubesAndTransformers_SSE.htm
You can see that KT88s at 500V should yield about 80mA per tube. That's 160mA total, plus a few mA for the two triodes in the 12AT7 plus losses. That put you well over the 150mA rating.
That said, folks seem to get away with it. I would say, take the free replacement a use it. If you blow that one, look elsewhere.
Russ
http://www.tubelab.com/AssemblyManualSimpleSE/TubesAndTransformers_SSE.htm
You can see that KT88s at 500V should yield about 80mA per tube. That's 160mA total, plus a few mA for the two triodes in the 12AT7 plus losses. That put you well over the 150mA rating.
That said, folks seem to get away with it. I would say, take the free replacement a use it. If you blow that one, look elsewhere.
Russ
nikolas812 said:
FWIW, I took some measurement from my Allied transformer using my el cheapo DDM:
Black to black: 1.7R
Red-Red: 120.9R
Yellow-Yellow: 0.3R
Green-Green: 0.2R
Probe to Probe: 0.2R
If the black to black is really shorted like the yellow and green pairs, you may have a shorted primary.
I have a question about the heatsink(s). On Tubelabs parts list it lists a Digi-Key #HS189-ND, which is no longer carried. I think I plunked HS198-ND into Goggle and got an HS194-ND as a replacement. I should have asked someone here before I ordered because the 194 is longer and would short on the R24 (inverted). Could I take a hacksaw to one fin on the heatsink!?
I have a couple of other things that I thought I could buy where I live, but no luck. So if someone knows of a heatsink that will fit from Digi-Key, I will be putting in another order from them.
Thanks.
I have a couple of other things that I thought I could buy where I live, but no luck. So if someone knows of a heatsink that will fit from Digi-Key, I will be putting in another order from them.
Thanks.
Well.... were back in business.😀
It bothers me that I don't know what went wrong. I have tested and tested and compared measurments to the new transformer. And everything checked out the same.
I had a bad feeling that it might not be the transformer. But regardless I figurded I would wire it up and flip the switch. All the tubes lit and everything seemed fine. Weird.
I'm just glad to have it back. I listen to it daily so being with out it SUCKS!!
Thanks for everybodys help.
Nick
It bothers me that I don't know what went wrong. I have tested and tested and compared measurments to the new transformer. And everything checked out the same.
I had a bad feeling that it might not be the transformer. But regardless I figurded I would wire it up and flip the switch. All the tubes lit and everything seemed fine. Weird.
I'm just glad to have it back. I listen to it daily so being with out it SUCKS!!
Thanks for everybodys help.
Nick
You'd be surprised on what can go wrong-when I finished my Simple SE i was scratching my head for ages trying to figure out why 1 channel was not playing any sound...turned out it was my ipod's left channel giving away
It makes great sounds now with jj el34 in tirode, transcendar opt, obbligato 70uf cap and ...and a sony mp3 walkman 😉
It makes great sounds now with jj el34 in tirode, transcendar opt, obbligato 70uf cap and ...and a sony mp3 walkman 😉
output tranny ???
Anybody try the Magnequest 10 watt Robin Hood RH-60's? Would the 15 watt RH80 be required?
Anybody try the Magnequest 10 watt Robin Hood RH-60's? Would the 15 watt RH80 be required?
dubdub said:
Yeah. I'm just glad its back. I still don't know what caused the problem. I'm just hoping it was a QC issue with the transformer. The new one hasn't missed a beat..
I think I'll be trying some EL34's pretty soon. I 've noticed a lot of people here like them with the SSE.....
Nick
I can check again if need be. But the last time I checked my B+ voltage was around 489 volts.
My question is. Can I run EL34's with a B+ voltage this high? Or do I need to take it down a little?
If I need to take it down a little. What size resistor do I need to be looking at. I believe there is a 560ohm resistor in there now. What ever George recommends on his site is whats in there.
I have an itch to try some El34's.....
Nick
My question is. Can I run EL34's with a B+ voltage this high? Or do I need to take it down a little?
If I need to take it down a little. What size resistor do I need to be looking at. I believe there is a 560ohm resistor in there now. What ever George recommends on his site is whats in there.
I have an itch to try some El34's.....
Nick
I think it will be a little on the hot side for them. 680 or 750 would be a better choice. 560 is a little hot on my amp, which has about 460 B+. Not plate glowing or anything, but pushing them hard.
I can't remember which OPTs you have. If you put a 6-ohm load on the 8-ohm secondary, you can then apply that factor to the primary. So if you have a 5000 ohm primary, the tubes will see a 3750 ohm load.
Of course, it's not quite that simple. Since the transformer was designed for a certain primary impedance, doing this will saturate the core more than intended and so forth. If you are keeping well under the power rating of the OPT, then you should be able to get away with it. When you push it, you will start getting more distortion than you would have otherwise. Adding CFB can help compensate for this a bit.
Of course, it's not quite that simple. Since the transformer was designed for a certain primary impedance, doing this will saturate the core more than intended and so forth. If you are keeping well under the power rating of the OPT, then you should be able to get away with it. When you push it, you will start getting more distortion than you would have otherwise. Adding CFB can help compensate for this a bit.
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