Has anyone got a copy of the simple se schematic from tubelab.com? I am having difficulty with my amp as it is constantly blowing fuses on start up and I would like to take it to a friends who has neither internet nor a pc. I have seen the schematic on tubelab.com website but the values are far from clear (by that I mean the print is fuzzy).
Regards
Regards
I have a PDF schematic but it is too big to attach to a post on this forum. Send me an email and I will reply with the schematic. If you were the person that recently sent me an email requesting a schematic, it is coming soon.
My computer died last weekend. Fortunately I was smart enough to have it all backed up this time (I lost my entire web site 2 years ago), but retrieving almost 1 terrabyte over USB takes a while. I may be able to send the schematic tonight, worst case this weekend.
Does the fuse blow instantly on turn on every time? If so the problem is likely in the solid state diodes. If you are always using a tube rectifier, remove the diodes. They are only used in the SS rectifier mode. There have been some failures with the IXYS parts. This appears to be batch related, some never die 9the older ones) but there have been some recent failures.
Does the fuse blow after a few seconds, and not necessarilly every time? It could be the 5AR4, especially if you are using JJ.
My computer died last weekend. Fortunately I was smart enough to have it all backed up this time (I lost my entire web site 2 years ago), but retrieving almost 1 terrabyte over USB takes a while. I may be able to send the schematic tonight, worst case this weekend.
Does the fuse blow instantly on turn on every time? If so the problem is likely in the solid state diodes. If you are always using a tube rectifier, remove the diodes. They are only used in the SS rectifier mode. There have been some failures with the IXYS parts. This appears to be batch related, some never die 9the older ones) but there have been some recent failures.
Does the fuse blow after a few seconds, and not necessarilly every time? It could be the 5AR4, especially if you are using JJ.
talk about a glutton for punishment.George,
It does blow the fuses instantly. I will only ever be using tube rectifiers, is it just a case of removing the diodes and not replacing them with anything?
It was me that emailed for the schematic and I would still appreciate the pdf if and when you can get around to it. Good luck with the 1tb transfer, it will take a lot of coffee to get it done.
Regards
It does blow the fuses instantly. I will only ever be using tube rectifiers, is it just a case of removing the diodes and not replacing them with anything?
It was me that emailed for the schematic and I would still appreciate the pdf if and when you can get around to it. Good luck with the 1tb transfer, it will take a lot of coffee to get it done.
Regards
Yes, leave them out.
If I get home from work early enough tonight, I will do it, but probably over the weekend.
Most is done already, but I want to keep the mess from getting disorganized. My new machine has over 2 TB of storage capability. A 1TB drive is now $129 USD. I am slowly copying all of my CD's to the 1TB drive. I play music with new modern 24 bit 192 KHz technology feeding a pair of 77 year old vacuum tubes, a Tubelab SE with NX-483 tubes.
Yes, they are only used for the solid state rectifier option.
They have zapped in Tubelab SE's as well. I bought 50 of the IXYS diodes about 5 years ago and never had an issue. I got 100 from Digikey about a year ago and several have blown without provocation even in low (150 volt) voltage applications. The diode blows when the amp is turned off, which then blows the fuse the next time the amp is turned on.
The IXYS diodes are not "avalanche rated" which means that they can not handle transients that go over 1200 volts in the reverse direction. This can happen in some cases on amp turn off. Some batches of diodes can dissipate these transients, while others fail. There are "avalanche rated" diodes that can deal with thiss effect.
I am investigating some Fairchild "Stealth" diodes. The number is ISL9R8120P2. I have been told that "even I couldn't blow them up". So far that statement is true, but these guys aren't cheap.
I have a list of other, lower cost diodes to try, but health issues have limited my Tubelab time lately.
I am assuming that this amp was working, and then died, which implies that everything is built correctly. If this is not the case, let me know and we will approach the troubleshooting a bit differently.
I am not sure exactly what you are saying, how are you determining that the rectifier has no power? Does the rectifier tube light up?
Connect a voltmeter negative lead to ground (right end of R2 or any of the 3 resistor leads along the front edge of the board). Set the voltmeter to its highest DC voltage range.
Check for voltage at the left end of R2? There should be around 500 volts. If there is voltage on R2 the rectifier is working. If there is no voltage, switch the meter to AC volts and check for voltage at the T1-red connector. There should be about 375 volts on the two outside screws. If not, there is a problem with the transformer wiring. Is the center tap connected to the T1-red-yel terminal?
If there is AC voltage, and the 5AR4 is lit up, and no DC voltage on R2, the tube is likely bad. If there is voltage on R2, check for voltage on each end of R1. If there is voltage on one end only the resistor is bad (or choke if you are using one).
I am not sure exactly what you are saying, how are you determining that the rectifier has no power? Does the rectifier tube light up?
Connect a voltmeter negative lead to ground (right end of R2 or any of the 3 resistor leads along the front edge of the board). Set the voltmeter to its highest DC voltage range.
Check for voltage at the left end of R2? There should be around 500 volts. If there is voltage on R2 the rectifier is working. If there is no voltage, switch the meter to AC volts and check for voltage at the T1-red connector. There should be about 375 volts on the two outside screws. If not, there is a problem with the transformer wiring. Is the center tap connected to the T1-red-yel terminal?
If there is AC voltage, and the 5AR4 is lit up, and no DC voltage on R2, the tube is likely bad. If there is voltage on R2, check for voltage on each end of R1. If there is voltage on one end only the resistor is bad (or choke if you are using one).
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