MIJ_Pioneer
Super Member
Yes, please build it before touching anything. It is essential, especially for a 919. 60w may not be enough to kick it out of protection, I believe a 100w (maybe even 75w) bulb would be enough for the 919 (I use a 150w).
Leestereo's Restoration and Upgrade Of A Sansui AU-919
- Thread starter Leestereo
- Start date
Yes, please build it before touching anything. It is essential, especially for a 919. 60w may not be enough to kick it out of protection, I believe a 100w (maybe even 75w) bulb would be enough for the 919 (I use a 150w).
le_syd1961
Active Member
I will need one lamp of this wattage ... I guess an halogen lamp is not advised ?
Thanks MIJ for all these priceless advices
MIJ_Pioneer
Super Member
Of course!
I'm not sure about Halogen. I did the quickest 2 second google search and I didn't get an obvious answer so I cannot advise. I would try to find a standard incandescent. If you are having a tough time sometimes they can be found at thrift stores or other donation/second hand stores.
If you do start a journey with your 919 you should make a new thread, others will be glad to help!
le_syd1961
Active Member
It's more than started ! I am close to finish the recap ... I will nevertheless create one new threat sith some pics I took.
I'm starting to feel a bit worried with reassembling the unit. I managed so far not to cut any wires and soldering the parts required in an uncomfortable position sometimes.
I need to get access to recap the last two boards (2844 and 2845) and change the main oval caps before to reassemble everything ! wish me luck
Yves
MIJ_Pioneer
Super Member
It sounds like you are doing a blanket recap and then turning it on. I don't recommend that, makes troubleshooting that much more difficult. One board at a time and test.
There are much more stringent procedures, mainly involving measuring and recording voltages before/after but I think we are past that.
Put it back together now and test. 919 will not be an easy amp to troubleshoot.
Pre amp power supply just pops up from it's plastic fasteners, maybe two screws you need to undue. Nothing major.
Psu for the main amp - if you've already done the driver amp board it should be easy to remove. Just unscrew the filter caps and with some wire management it will be free. TAKE DETAILED PHOTOS before hand. You need to clean the glue and replace anything touched by the glue that appears damaged.
You may not need to replace the main filter caps, can be saved for another day. Get it singing first.
There are much more stringent procedures, mainly involving measuring and recording voltages before/after but I think we are past that.
Put it back together now and test. 919 will not be an easy amp to troubleshoot.
Pre amp power supply just pops up from it's plastic fasteners, maybe two screws you need to undue. Nothing major.
Psu for the main amp - if you've already done the driver amp board it should be easy to remove. Just unscrew the filter caps and with some wire management it will be free. TAKE DETAILED PHOTOS before hand. You need to clean the glue and replace anything touched by the glue that appears damaged.
You may not need to replace the main filter caps, can be saved for another day. Get it singing first.
le_syd1961
Active Member
New thread created as per your advice ... I started it and will keep on editing pictures later
https://audiokarma.org/forums/index...p-another-one-but-by-a-foolish-rookie.940372/
Thanks MIJ
Spendor
New Member
Hi there - I am re-capping a newly acquired D907 and this thread is invaluable so thanks very much to Lee and other contributors. I just wanted to confirm a few cap values on the driver board:
C51,52 - on my board and on the schematic these appear to be 1uF, but Lee has placed with 0.47uF. Any reason for the change?
C19,20,45,46 are 3.3uF - they are upgraded with 47uF which is about 15x original value and seems extreme. I'm just wondering if that is a typo and should be 4.7uF?
Thanks!
C51,52 - on my board and on the schematic these appear to be 1uF, but Lee has placed with 0.47uF. Any reason for the change?
C19,20,45,46 are 3.3uF - they are upgraded with 47uF which is about 15x original value and seems extreme. I'm just wondering if that is a typo and should be 4.7uF?
Thanks!
I should probably let Leestereo answer this but, here goes.
https://audiokarma.org/forums/index.php?threads/au-d907-for-restoration.980756/
I am copying the approach used by Leestereo for this restore.
I think you have misread the text - he doesn't change these values.
Not a typo, they are for local filtering of the power amp main supply rail, so the value increase is beneficial. I am also reconditioning an AU-D907 here:
https://audiokarma.org/forums/index.php?threads/au-d907-for-restoration.980756/
I am copying the approach used by Leestereo for this restore.
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Spendor
New Member
Thanks for the info. I wonder why the values of C51,52 differ between models (and the schematic)? Also my version had no black flags on this board - just ceramics for the 3pf and 22pf values. The board seemed to be like this from factory as all the soldering seemed undisturbed and equally tarnished. I have since replaced with COG equivalents.
The amp was steady on zero Dc and 20mV when adjusted and was sounding great. My problem now is that the EL transformer runs extremely hot. I left the amp on overnight and it now lets out a loud sharp cracking noise intermittently. Looks like I'll have to get back in there. I have only restored the main power supply and driver boards so far, but checked the caps on the +/-40V reg supply and they all seemed OK. Any tips from someone who has been there? Thanks again.
The amp was steady on zero Dc and 20mV when adjusted and was sounding great. My problem now is that the EL transformer runs extremely hot. I left the amp on overnight and it now lets out a loud sharp cracking noise intermittently. Looks like I'll have to get back in there. I have only restored the main power supply and driver boards so far, but checked the caps on the +/-40V reg supply and they all seemed OK. Any tips from someone who has been there? Thanks again.
They probably aren't, I suggest you change them anyway. Don't forget C07 & C08 silk screening orientation mistake on the +/-40V PSU - take 'before' pictures - and install replacements the same. OR check Leestereo's pictures - or mine.
Leestereo
Super Member
Component differences between what is in the schematic and what is actual installed on the boards are not that uncommon. This may be due to an error or a change made during manufacturing. As mentioned by @ghamilton above, the safest approach is to use a replacement that matches the original, however, if there is a performance gain to be made by installing a different component, it is worth considering.
ghamilton
Super Member
Same thing happened to me when I tried a different value cap from the factory value. I put the correct value back in there and it stopped the El core from heating. Stay with factory values for safe operation!
Spendor
New Member
Thanks - which caps in particular did you change that caused the overheating?
One or more of the power rails attached to the two separate windings of PT702 must be pulling too much current. Try disconnecting them, to see if it still overheats and if not, add the windings back one at a time - giving at least ½ hour monitoring period before adding the second one. Something like leaky electrolytic capacitors might cause the problem you are seeing.
Correct, but doing this would be very unlikely to stop the EI transformer from overheating.
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ghamilton
Super Member
Well it
Well it did.
Leestereo
Super Member
To clarify, the capacitor C43 is a 0.47uF film capacitor and is in the signal path not the power supply. As per post no. 15 in this thread: "...the film by-pass capacitors (C43 and C44) for the output capacitors which were 0.47µF polyester film types, were upgraded to 1.0µF polypropylene film types."
I am not disputing that @ghamilton did have an issue with the EI transformer in his AU-919, and that when C43 was replaced back to the stock value the issue was resolved; I am suggesting that this was a coincidental event rather than a causal one.
I am not disputing that @ghamilton did have an issue with the EI transformer in his AU-919, and that when C43 was replaced back to the stock value the issue was resolved; I am suggesting that this was a coincidental event rather than a causal one.
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ghamilton
Super Member
If it works ok then go for it.
That wima improved the sound over the stock cap.
Freedon_road
New Member
I inherited a Sansui AU-919, I recently had it checked due to not working.
The estimate came back for repair and full restoration at $1200 USD.
I need some help deciding if this this worth it for a total investment of $1200?
Visually the case and front are in really good shape appearance wise.
They also said that if I didn't want it, they would give me $400.
Need your inputs.
The estimate came back for repair and full restoration at $1200 USD.
I need some help deciding if this this worth it for a total investment of $1200?
Visually the case and front are in really good shape appearance wise.
They also said that if I didn't want it, they would give me $400.
Need your inputs.