Just got a Au x1 and of coarse need info

Discussion in 'Exclusively Sansui' started by Bigdrive, Aug 5, 2017.

  1. Bigdrive

    Bigdrive Member

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    Fair enough, these numbers are nowhere that I can find on posts about the X1, short of Amp8, but he is a pro and his were 162 I believe. You have to remember it was reading 120, so since it only can up to 152, I do not know if I still had a problem without posting the question, but I appreciate your answer. Now I know.
     
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  2. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    You have done very well to get this far, you should be proud of yourself, an AU-X1 can be a difficult piece of gear to restore. :thumbsup:
    @Bigdrive
     
    Last edited: Jan 3, 2018
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  3. Harolda

    Harolda Active Member

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    I have 163Watts:banana:

    Sorry, just a joke. Like John said you should be proud and you will not notice the difference ;) :thumbsup::thumbsup::trebon:
     
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  4. Harolda

    Harolda Active Member

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    And a good start for 2018, best wishes to all
     
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  5. Harolda

    Harolda Active Member

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    I will also continue on some work on my AU-X1 soon. I do not yet like the MC stage yet (too much hum).
    First i have to finish some other Sony stuff.
    I will keep you informed when i continue
     
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  6. smurfer77

    smurfer77 Super Member

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    As John says, don't worry about it. If you want to worry about it:
    - measure you 8 Ohm load resistance, both at ambient temperature and fully driven (they will likely heat up and change resistance). Does the load have an inductance in additional to resistance?
    - as John also says, what is the accuracy of your measuring device at that range? Also, note that the TRUE RMS multimeter typically assumes sinusoid waveform, so when you go into clipping it will not be accurate and in fact under report as you go more and more towards square wave like waveform.
    - related to the last point, are you determining the 'clipping' as per manual, i.e. at a given distortion rating, or just visually via scope? If you are just doing it by scope, within 10% is as good as you can hope for.
    - again as John meantions, is your line voltage exactly spec?
    - are you sure the preamp isn't clipping (try lowering the input voltage and turning the volume knob on amp up)?

    Basically, the few % difference could be easily accounted for by measurement issues. Maybe the amp really is lacking a few Watts; maybe Sansui over quoted the output power (maybe others with AU-X1 can comment). You need not worry about it, but if it truly bothers you, you will have to confirm the various factors listed, and then if the few W are still unaccounted for I would hear from someone else with an AU-X1 that is actually making spec output before going too nuts (in which case it would be great to know a few things like max preamp output in AU-X1 etc etc).
     
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  7. Harolda

    Harolda Active Member

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    426
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    I did it like this:

    1) Use per channel: 300Watt 8.1 Ohm (3*2.7Ohm in series) resistors mounted on a large aluminum heat sink.
    2) Drive both channels into their respective 300Watt 8.1 Ohm resistors. This will be the real test for the power supply.
    3) Use a scope and look at the sine wave shape on both channels simoultaneously make sure that you set the volume such that the sine wave is close to distorting (clipping)
    4) read the voltages over both resistors with a DMM and calculate the Watts.
    5) I repeated this procedure for different frequencies, and I was always close to the specified 162Watts per channel, both channels simoultaneously driven.

    Before performing this measurement look at all the signal from the flat amp. I connected my scope on the pre-amp output (always both channels simoultaneously) and looked at the output signal with different input signals high into the Khz range to look at oscillattions, clipping etc.
    This gives you an idea of the performance of the complete pre-amp. I will now redo this with the MC and MM boards placed.

    Also look at the influence of the two smaller volume pots for the left and right channel. So look at what happens to the ouput signal when turning them to max volume! When they are complete open (max volume) they introduce some instability. I always have them at +/- 90% setting. Their quality is not so good and i still have to find an alternative. The discs in the pots also have the tendency to crack easily, i think that there not much units without broken discs which is an effect of the joining procedure in producing the pots, the ageing of the plastic and the presence of so called "weld" lines from the injection moulding of the discs.

    The complete amp was refurbished to the last detail, but it still has the original PSU Caps for the power amps.

    Still to do:
    - Optimisation with MC and MM boards installed
    - Alternative solution for the small ALPS volume pots. I know Mr. Kuehne sourced an alternative (according to his website)
     
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  8. Vintagear

    Vintagear Super Member

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    I think the MC phono stage of the X1 was designed to work best with a cartridges that have very, very low output...and I mean REALLY low.

    I only have a handful of records and am definitely not an expert in phono stages or cartridges but when I was testing out the restored MC stage on my X1 I was using a cartridge with an output of 0.33mv and there was IMO way too much gain. Those very low output cartridges do exist but I believe they are rare and expensive.

    I used the calculator linked below and if I entered everything correctly it seemed to confirm that a 0.33mv cartridge is not a good match for the gain of the X1's MC amp. If I recall, I believe an idea MC cartridge would be in the 0.10- 0.15mv output range.

    https://www.kabusa.com/pregain.htm

    Also, I don't remember if you replaced the relays on the phono motherboard. If not, start there and that will reduce quite a bit of that hum. After that my tech replaced more parts the second time he was in there and that made it pretty quiet but ultimately there was just too much gain for the 0.33mv cartridge I was using.

    Good luck and keep us posted.
     
  9. Bigdrive

    Bigdrive Member

    Messages:
    96
    Location:
    Kelowna
    I will try and answer some thoughts,

    Yes it was by scope only for the distortion

    The load was 200watt 8 ohm non inductive load on each channel. A true rms meter (all be it cheap) was used but at the speaker output on one test and at the load on the other tests

    See above answer

    I did the same as you however, only at 1k and I think 15k. Since I was trying a lot of configurations the loads eventually got hotter than I wanted to run them.

    As far as the volts were concerned it was not even close. If memory serves, 34.85 vac when it was suppose to be 35.5 say.....I would need to re look it up to give you actuals, but it was not close. The meter is accurate to .1mv in that range.

    I will check the preamp output for waveform and influence. I had read about that cracking and last time it was on the bench I had checked it and it was OK and not cracked. I run them at 100% once it is started and it has a signal source. in other words all volumes at 0 until I see source output then drivers to 100 and preamp volume as required. I have not pushed the MM yet just played some vinyl but I want to play more, its just the volume is low and I don't want to push it as volume needs to go to -22 and if it starts to wobble on me......

    Usually pretty close here, but no, I did not check that day. I will though next check.

    Since you and John have mentioned this I marked on the signal gen exactly where 1.000 volts are and will have a meter on it to be sure. But I hold high hopes the "problem" is there.

    Its not a great concern that I got this reading and like John and others have mentioned, I would never notice and its probably me, my test gear or a hobbiest restore. But I want to learn and if it is those things I want to correct them short of $$$$$$ in test equipment. I know Harold has spent 6 months working on his unit but says he aways gets around 162 watts. I want to say the same. What to me is very suspicious is I changed R601 from the temporary one where I only got 120 watts to a unit at 4.0 ohms instead of 3.9 and get a increase to 152watts. The only other person I know that changed that resistor was Willy6 and he changed to a 3.9 which is not available.

    Thanks to all with input, more testing is required. I cannot get it on the bench for about 3 weeks as I am in the middle of a 717. P.S. it made spec for power that same day I tested the X1. Can you imagine the shock when the X1 only did 120. Bench or no bench the X1 was apart that day!

    Gord
     
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  10. Bigdrive

    Bigdrive Member

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    Sorry wrong reference to resistor it have stated R621 above. The voltages were measured at 34.8 when they should be 35.8 for 160watts on both channels with both channels driven. Scope was also on both channels.
     
  11. Willy6

    Willy6 AK Subscriber Subscriber

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    3.9 ohm 25w wire wound cement filled ceramic power resistor's are still available at mouser.
     
  12. Harolda

    Harolda Active Member

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    Dear Vintagegear, thx for the response. I will have a look at the calculator as well and i will also try only MM. I have replaced those relays on the phono board just like Ronito advised with the omron relays. At the moment i am using a Sony XL55 MC cartridge that has a 0.2mV output.
     
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  13. Harolda

    Harolda Active Member

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    These are the specs from the brochure:

    Capture_aux1_specs.PNG

    Sansui states a maximum input capability of 40mV for MC cartridges!
     
  14. Bigdrive

    Bigdrive Member

    Messages:
    96
    Location:
    Kelowna
    Thanks Willy6, I will order it and install before next test so that I can be sure its not that. Schematically, to me I don't see how it could be....but I do know that at least on mine that resistor gets very hot when this amp is being tested and if it is only a 15watt the amp is 40watts short on power. I was hoping the 4.0 I got out of china would be low and come in at 3.9 but no luck they both were 4.2 ohms.

    FYI, MM phono. My mm cartridge puts out 330mv the max per the specs and volume is low. I have followed Harolds quest on that board, sad to hear your not happy with it. I do not have any hum, but since the volume is up so high the floor noise is not where I want it to be. I will be hunting the problem down on the next bench visit and will be concentrating on the pre amp ( like someone mentioned) make sure its 100% and the MM cards.
     
  15. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    That resistor should not get hot, it is in circuit for a fraction of a second - then is shorted out by a relay - suspect a defective relay? - either not being energised, or with burnt contacts.

    The resistor is only 'high power' rated to be able to hold up under fault conditions.
     
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  16. Bigdrive

    Bigdrive Member

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    Location:
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    I agree. The relay is very suspicious. It is new but was exposed to the same fault when I blew the original 3.9 20 watt. Like you say it is there for a fault. I was just thinking while I am writing this that the sequence was 1)fault 2) resistor heated up 3) resistor blew. To me, the resistor was no longer protecting that relay as it was fully now fully exposed to the fault. I guess it would now depend on whether the relay was closed or not at the time. In any case I have a spare, so out it will come.
     
  17. Vintagear

    Vintagear Super Member

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    1,463
    Yikes!

    FWIW I was able to play the MC with that .33mV cartridge at reasonable SPLs but I just felt that it was not ideal. If you raised the volume too much it seemed as if the cartridge was "picking-up" too much, if that makes sense. Felt like a mismatch to me and with all the potential pops and clicks on records I didn't want to take a chance.

    Either way, I think your cartridge will be a much better match for the X1's MC stage than mine was. As for me, I sold the .33mV cartridge and unless I come across a VERY LOMC I'll stick with the MM stage which on the X1 is really superb.

    P.S. Gotta love all the AU-X1 avatars in this thread. :D
     
    Last edited: Jan 4, 2018
  18. Bigdrive

    Bigdrive Member

    Messages:
    96
    Location:
    Kelowna
    Stopped the work on 717, and did some more pre investigation testing. 1.006v input@1k hz to aux in. Amp to separated and sampled voltage and waveform on both channels. Initially 0 and went up to full volume 5.0v and it rolled back to about 4.85. Waveform was good and no clipping. The 20watt resister was 85f and heatsinks were 74f.

    Put on load bank, swictched to integrated. Scope and voltmeter on each channel and out not changed on signal gen. Started to clip at 26v:eek2: Had to change settings on scope and tried it again, same. Tried it one more time,same. Load bank still cool, resister at 176f. Anybody got some eggs that need frying?

    Warming up the souldering iron.......
     
  19. Vintagear

    Vintagear Super Member

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    1,463
    I'll take mine over easy. I hope they go well with my :lurk: as I watch this thread.
     
    Last edited: Jan 5, 2018
  20. Bigdrive

    Bigdrive Member

    Messages:
    96
    Location:
    Kelowna
    Well power supply board is out. I removed rl02 which had been replaced. Now for the "not my finest hour". Get your popcorn ready, and flip your eggs. Cold soulder joints! I had ordered Ormon ly2-24 and not the ly2-0-24 which has the pcb feet. So in a poor choice I decided to cut and file the feet. I believe they were too short and were never souldered in correctly. This set up the power to go through the resister as it was easier. It cannot be confirmed until its back together and I have several other changes I want to make before that happens. I did also chech all diodes and pulled several transistors and checked them. Nothing else wrong there.

    Still to do,
    1) find out why mm phono is so low
    2) disassemble amp selector, it acts up when the x1 and 717 play together
    3) install upgraded speaker bindings
    4) replace all rca jacks
    5) add some capacitance to drivers

    Suspicious this post does not have a picture.....not my finest hour
    I hope this give me back the missing 10 watts it owes me!!
     

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