Leestereo
Super Member
+1
This is speculation, based on a relatively small sample size, but the MV types do seem to be more robust than the VD types. I now leave the MV types in place unless I know they have failed.
Ronito6
Super Member
As long as we are on the subject... (from http://www.audiovintage.fr/leforum/viewtopic.php?t=50351&start=40)
Isn't the MV-12 black and gray (grey) and the VD-1212 red and gray?
Isn't the MV-12 black and gray (grey) and the VD-1212 red and gray?
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I have asked one of AK's most distinguished tech's about MV12's, he says all 2 junction 'bead' diodes seem to be problematic - and he always changes them.
Thanks Lee, this was definitely my first thought, but I am very much persuaded by the view of the above tech.
Update:
The MV12's in the PSU are history...
Thanks Lee, this was definitely my first thought, but I am very much persuaded by the view of the above tech.
Update:
The MV12's in the PSU are history...
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The rebuilt PSU has been re-installed and tested.
The 47.5V adjustments went like a dream, and with 2 resistor value changes I can now easily adjust the two other regulators to -11V
The 47.5V adjustments went like a dream, and with 2 resistor value changes I can now easily adjust the two other regulators to -11V
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Ronito6
Super Member
And with 2 resistor value changes I can now easily adjust to -11V
Good going
In fairness to Harold, he has reported his problems with VR1 and 2 are solved and settled.
Harold found his VR1 and VR2 problem to be a grounding issue.
The fault occurred after he previously had no problem adjusting those trimmers to the proper voltages of 10.5.
Once he found and corrected the gap in his grounding loop (a bad wire) his VR1 and 2 problems were settled.
I guess my main point is, should you lose adjustability to VR 1 and 2 look to old wires.
May I however ask...
You needed to change resistor values?
Why? Which resistors / which positions? What were the previous values and what are the new values?
May I however ask...
You needed to change resistor values?
Why? Which resistors / which positions? What were the previous values and what are the new values?
I don't think I have any issues with grounding, and pre/post rebuild the voltage available from the 11V regulators was the same. I think Harold was, at least for a time, testing his with the power amp modules absent, this may have caused the grounding anomaly he experienced, mine are installed.
The trimmer was set for 0Ω to achieve the highest (numerical) voltage available, about 10V, so it followed that if I reduced the value of the series resistors, R73 and R74 from 5.6KΩ to 3.9KΩ I could use the reduction in resistance to bring the adjustment in range of the trimmer adjustment. The setting of the trimmer is now around 700Ω - so the total resistance in that chain has gone down by 1KΩ to achieve the correct setting, a current increase of ~0.5mA only in that resistor chain.
It's a bit academic really, providing the voltage is stable and approximately right it won't make a lot of difference. It is the supply for the MC head amps, so in operation if it wasn't actually + / -11V it would just reduce the headroom of the MC head amps a little. However the setup procedure says set for -11V that is what I can now do.
Obviously if I do find some grounding issue, the voltage out of the regulators will presumably then be too high. A sign for me to revisit the situation and reverse the resistor value change, but I don't think that will happen.
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I just bought the one on ebay and might aquire another one in a few days and they both need work so I'm keeping a close eye on this thread..I don't think I have any issues with grounding, and pre/post rebuild the voltage available from the 11V regulators was the same. I think Harold was, at least for a time, testing his with the power amp modules absent, this may have caused the grounding anomaly he experienced, mine are installed.
The trimmer was set for 0Ω to achieve the highest (numerical) voltage available, about 10V, so it followed that if I reduced the value of the series resistors, R73 and R74 from 5.6KΩ to 3.9KΩ I could use the reduction in resistance to bring the adjustment in range of the trimmer adjustment. The setting of the trimmer is now around 700Ω - so the total resistance in that chain has gone down by 1KΩ to achieve the correct setting, a current increase of ~0.5mA only in that resistor chain.
It's a bit academic really, providing the voltage is stable and approximately right it won't make a lot of difference. It is the supply for the MC head amps, so in operation if it wasn't actually + / -11V it would just reduce the headroom of the MC head amps a little. However the setup procedure says set for -11V that is what I can now do.
Obviously if I do find some grounding issue, the voltage out of the regulators will presumably then be too high. A sign for me to revisit the situation and reverse the resistor value change, but I don't think that will happen.
Ronito6
Super Member
Another X1-er . The more the merrier!
You may also wish to check out Harolda's X1 resurrection at
http://audiokarma.org/forums/index....-au-x1-output-transistor-replacements.684619/
There is a lot to learn and like there I think.
Also Kale has renovated more than one X1 and has posted his work on AK too.
Absolutely, but get ready for one hell of a ride Willy6, my AU-X1 feels like around DOUBLE the work of an AU-919 (or more) - the AU-919 was once described by a very well known AK'er as, and I quote, "A butt-load of work" - I have done two AU-919's, but this AU-X1 is testing me.
My restore in this thread is quite a bit less detailed than Harold's. It is thanks to that thread, and Ron's excellent support there and in this thread, that I can gloss over much of the things going on in the background here. For example, after 5 different parts orders, from 3 different suppliers, I have all the parts for this phase of the restore. The 'can capacitors' will be the second and final phase of this restore, although I can assure you that there will be an extensive 'listening test' before I begin the second phase.
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Absolutely, but get ready for one hell of a ride Willy6, my AU-X1 feels like around DOUBLE the work of an AU-919 (or more) - the AU-919 was once described by a very well known AK'er as, and I quote, "A butt-load of work" - I have done two AU-919's, but this AU-X1 is testing me.
My restore in this thread is quite a bit less detailed than Harold's. It is thanks to that thread, and Ron's excellent support there and in this thread, that I can gloss over much of the things going on in the background here. For example, after 5 different parts orders, from 3 different suppliers, I have all the parts for this phase of the restore. The 'can capacitors' will be the second and final phase of this restore, although I can assure you that there will be an extensive 'listening test' before I begin the second phase.
Hopefully it doesn't arrive in pieces like my g9000 did.
I might consult with you from time to time if you don't mindAbsolutely, but get ready for one hell of a ride Willy6, my AU-X1 feels like around DOUBLE the work of an AU-919 (or more) - the AU-919 was once described by a very well known AK'er as, and I quote, "A butt-load of work" - I have done two AU-919's, but this AU-X1 is testing me.
My restore in this thread is quite a bit less detailed than Harold's. It is thanks to that thread, and Ron's excellent support there and in this thread, that I can gloss over much of the things going on in the background here. For example, after 5 different parts orders, from 3 different suppliers, I have all the parts for this phase of the restore. The 'can capacitors' will be the second and final phase of this restore, although I can assure you that there will be an extensive 'listening test' before I begin the second phase.
That's fine, of course I will help if I can.
Hyperion is the number on the black flags the Pf value?For example according to the manual I downloaded on board f-2918 c12 and c13 are 125v 30 pf but the number on the black flags is 91?see pic.
Correct, always go by what is installed now, use the schematic as a guide for the location of these components. 91pf is a value I encountered in my restore.
NB: Please post questions about your restore on the end of your thread - this is my restore thread
- thanks 
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Ronito6
Super Member
OK sorryCorrect, always go by what is installed now, use the schematic as a guide for the location of these components. 91pf is a value I encountered in my restore.
NB: Please post questions about your restore on the end of your thread - this is my restore thread