• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

AU-919 PS Modification

EchoWars

Hiding in Honduras
Sponsor
I wasn't able to get the transistor modification done on this one, but I did at least get one problem area redesigned... No real big shakes, but for anyone who has had to remove the heatsink/driver boards, or the power supply board on the 919 (the one that covers the bottom of the big oval caps), this is what they are dreaming of while they battle globs of solder.

In stock form, all these wires you see in the pics at the yellow circles are soldered in place. It makes for an unbelievable mess to desolder and put them back (ESPECIALLY at the ground terminals). On this one, (and I really screwed up by not taking a 'before' pic here, as it was amazingly laughable), the last guy was not of the school of 'keep it neat' by any stretch of the imagination. I desoldered the wires, removed the power supply board, and cleaned up all the excess solder.

The four capacitor 'clips' at the top of the pic had to be removed from the PS board, and I stuck in a #6 SS screw and locked it in place with a standard nut. On the two lower ground connection points, I used a #10 SS screw, and also locked it in place with a nut. Then, after cleaning up all the glue (this PS board was bad, and required about a 95% component replacement to get rid of the contaminated parts) and replacing the caps and the regulator transistors, the previously soldered wires all got ring terminals soldered to them.

With the board reinstalled, the wires simply slip onto the #6 and #10 screw threads, and I lock them down with Nylox nuts.

I can remove this PS board now in less than 10 minutes, and no desoldering. :yes:

The sharp-eyed will see that the two violet wires running to the middle-left of the board have a length of red wire spliced in, and the stock Sansui plastic ends for the connection point are MIA. The last guy must have done something horrible, as about 5" of the violet wire was badly burned, and the plastic ends melted. I had to cut one of the wires back about 5" to find unburned copper to solder to (burned copper don't solder too well, and carries current even worse). The ends being destroyed, I spliced some connectors from a computer power supply to the wire ends and shrink-wrapped 'em. The power supply connectors are the perfect size to mate with the male pin on the PS board.
 

Attachments

  • 919_PS_Mod.jpg
    919_PS_Mod.jpg
    86.9 KB · Views: 847
Register to hide this ad
Echowars,

What a mess that board is! This mod is really helpful to understand because I found this one the most difficult board to remove on the whole unit. I ended up basically taking off both transformer blocks and the output/driver/heatsink assembly in an effort to avoid dealing with all that solder. That sucked. **** dangling everywhere and the stress actually broke off a few hookup wires where they joined the driver board. That sucked also.

Besides, it looks so much more welcoming now to a would-be restorer. Thank you very much for noodling this one out, EW.

I have a question, however. I noticed you did not replace the large fusible resistors next to the outboard diode bridges. Many people find them unreliable and thus replace them all, but do you have a differing opinion?

Thanks again,

Collin
 
Are you talking about the large 3.3K 2W bleed resistors? They certainly aren't fusable. AAMOF, there are no fusable resistors on that board. I don't think the 919 has any fusable resistors in it anywhere.
 
Thanks for sharing your solution to this problem. This is excellent material for future reference. :yes:
 
Are you talking about the large 3.3K 2W bleed resistors? They certainly aren't fusable. AAMOF, there are no fusable resistors on that board. I don't think the 919 has any fusable resistors in it anywhere.

Yes, those resistors are the one's I'm seeing. So are those light-blue Non-Inflammable Resistors not the same as the light-blue fusible resistors that are discussed in the FAQ area of this forum? Humbling... :scratch2:

Collin
 
Nice work, EW, but that's just normal for you. :thmbsp: I really like the idea of using the nuts & bolts, because even if you never have to work on it again, it just makes a lot of sense, for "just in case". And it looks better too. :smoke:
 
All of EW's work could be featured in Home & Garden :thmbsp: because they look so great! (and, of course, they work great too).

Paul
 
Au 919

Hi Glenn

It would be great if you would tell us how many hours you put in on this one, if you keep track, once you are finished. What amazing work.

Marc
 
noveltone said:
I found this one the most difficult board to remove on the whole unit. I ended up basically taking off both transformer blocks and the output/driver/heatsink assembly in an effort to avoid dealing with all that solder. That sucked. **** dangling everywhere and the stress actually broke off a few hookup wires where they joined the driver board. That sucked also.
Most Sansui units of this vintage use small tin connectors that friction-fit into solder holes, but are easy to remove. Heat the solder, and pull the connector out of the hole with a pair of needlenose pliers. You'll have to clean the old solder from the connector and the hole to reinsert it, but it beats broken wires. On this unit, the previous tech just clipped them off, and solder-blobbed them back in place during reassembly. Stupid, since the wires are so easy to remove. I put new connectors on the old clipped wires, so it looks original now.

Yes, those resistors are the one's I'm seeing. So are those light-blue Non-Inflammable Resistors not the same as the light-blue fusible resistors that are discussed in the FAQ area of this forum? Humbling... :scratch2:

Collin
The small light-blue resistors are 10 ohm, 1W resistors to replace the original 10 ohm 1/2W resistors that were slimed with glue. The 3.3K 2W resistors are simple bleed resistors...there to drain the power supply caps once the unit is powered down.

Hi Glenn

It would be great if you would tell us how many hours you put in on this one, if you keep track, once you are finished. What amazing work.

Marc
This was a mess. Shipping damage plus a very long list of issues, mostly due to unbelievably crappy work done before. 50+ hours in this one.
 
...... a very long list of issues, mostly due to unbelievably crappy work done before. 50+ hours in this one.
Beautiful work!

Based on what I think your time is worth ($$$) I'm guessing you are discounting the labor on this one big time.
 
EW...Please let us know your opinion of the difference in sound quality between the 919 and, say, the 717. My understanding of the 919 is that it shares alot of design with the acclaimed BA-F1. I know you have stated in the past that some of your faves are the Kenwood 700M and the BA-F1.

Just curious.

Grazie!
 
EW...Please let us know your opinion of the difference in sound quality between the 919 and, say, the 717. My understanding of the 919 is that it shares alot of design with the acclaimed BA-F1. I know you have stated in the past that some of your faves are the Kenwood 700M and the BA-F1.

Just curious.

Grazie!
 
The 919 is an 'everything but the kitchen sink' method of design. Sansui missed no opportunity to toss in another feature or design trick. I'm not particularly crazy about its ease of service, but the sound quality is easily superior to the 717, and does have characteristics reminiscent of the BA-F1. It's lineage is apparent.
 
The 919 is an 'everything but the kitchen sink' method of design. Sansui missed no opportunity to toss in another feature or design trick. I'm not particularly crazy about its ease of service, but the sound quality is easily superior to the 717, and does have characteristics reminiscent of the BA-F1. It's lineage is apparent.
Any thoughts on sound quality and design/build between the 919 and the AU-11000/D11/D11 II?
 
Very little design similarities with those units, but the 919 and AU-11000 are near the top of Sansui's 'food chain'. I think it'd be a toss up between the 11000 and 919. I really don't know enough about the D11 or D11II to comment.
 
Back
Top Bottom