I assume the caustic glue has been removed? The one I did last year had diodes, resistors and transistor legs eaten clear through. If I recall it was the amp driver board.
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Sansui AU 717 rebuild and questions .
- Thread starter Txsaxkat
- Start date
Yes the glue is a PITA and has been removed.
I used the BOM list from MIJ Pioneers thread .
MIJ Pioneer thread show some transistors that need matching my question has to do with matching different PNP and NPN groups . First looking at the schematic on 2720 do TR07,08 & TR13,14 PNP hfe need to match TR07,11 & TR09,13 ? I did those and installed them before thinking about this . The PNP set was matched at 330hfe and the NPN were 420hfe. The other group of six were matched and all groups are matched within 5 hfe . Thats without touching them with my fingers and after letting them sit for a while after taking them out and setting them down on some paper.
When I bought the transistors from mouser the 30 1845 were on tape and alot closer group than the 30 loose 992s trying to figure out if I need to get 100 on tape 992s on tape if possible .
So being a DIY I dont have a complete grasp on matching transistors so I tend to match all groups of 992 and 1845 if possible and then the question of matching groups of PNP and opposing NPN groups is of serious concern .
I used the BOM list from MIJ Pioneers thread .
MIJ Pioneer thread show some transistors that need matching my question has to do with matching different PNP and NPN groups . First looking at the schematic on 2720 do TR07,08 & TR13,14 PNP hfe need to match TR07,11 & TR09,13 ? I did those and installed them before thinking about this . The PNP set was matched at 330hfe and the NPN were 420hfe. The other group of six were matched and all groups are matched within 5 hfe . Thats without touching them with my fingers and after letting them sit for a while after taking them out and setting them down on some paper.
When I bought the transistors from mouser the 30 1845 were on tape and alot closer group than the 30 loose 992s trying to figure out if I need to get 100 on tape 992s on tape if possible .
So being a DIY I dont have a complete grasp on matching transistors so I tend to match all groups of 992 and 1845 if possible and then the question of matching groups of PNP and opposing NPN groups is of serious concern .
So I was able to match up transistors from the 30 992's and the driver board were matched board to board as should be. I did have to get more 1845's 30 was not enough . Maybe because I matched all pairs and pairs of 4 or 6 when needed .
At this point Power supply board F2663 is done and the EQ F2723 done and Driver boards F2721 , F2722 done , Tone Control board F2720 done . Last thing that was done was the transistor matching and replacement . This was time consuming because I used the schematic looking at every set of pairs what ever number of them . And then double triple checking to make sure they are not backwards I know that's over the top but as a DIY it was a safety issue for me to be done with it and not have to go back in a second time in theory .
When installing TR12 &13 on the driver boards I measured the metal plate under them that dissipates the heat and its 1.4mm thick so I found some synthetic cork I use in sax repair and cut a piece and used it to shim the height of those when soldering in . I would just solder one leg flip it over and put slight pressure on it and heat that solder joint up and then it would lay flat and the check the screw hole alignment and repeat if necessary . That for the DIY guys you pros are way beyond that I'm sure . Pictures incoming
What deoxit do I use on the volume controls after I drill my 2 small holes F5 I have that and D5 . I think I used F5 on my citation 17.
At this point Power supply board F2663 is done and the EQ F2723 done and Driver boards F2721 , F2722 done , Tone Control board F2720 done . Last thing that was done was the transistor matching and replacement . This was time consuming because I used the schematic looking at every set of pairs what ever number of them . And then double triple checking to make sure they are not backwards I know that's over the top but as a DIY it was a safety issue for me to be done with it and not have to go back in a second time in theory .
When installing TR12 &13 on the driver boards I measured the metal plate under them that dissipates the heat and its 1.4mm thick so I found some synthetic cork I use in sax repair and cut a piece and used it to shim the height of those when soldering in . I would just solder one leg flip it over and put slight pressure on it and heat that solder joint up and then it would lay flat and the check the screw hole alignment and repeat if necessary . That for the DIY guys you pros are way beyond that I'm sure . Pictures incoming
What deoxit do I use on the volume controls after I drill my 2 small holes F5 I have that and D5 . I think I used F5 on my citation 17.
On my friend's AU-717 I didn't have to drill any holes. I left the wires all in place and removed the control from the front. Once removed I rotated it until I had good access to the tabs the wires are connected to.
At each of the tabs there are tiny openings where I was able to spray the F5 in. I then worked the control back and forth dozens of times to clean it. I next used canned air carefully to blow into the openings which helped remove the excess. When I put it back together the next day it worked great.
Since yours is out it will be very easy to clean.
This is my transistor cheat sheet hope I don't get too much flack about it . Also the side notes on the 3 matching groups half way down on the right might have been for the 2720 so don't pay attention to those .And feel free to let me know if any of it is wrong or not needed . The back side of the 2663 just shows how clean it is . Crazy amount of work doing clean up.
Just curious about what you did on the EQ board in the C27-30 area. Are those b2b film caps? You should only need one 4.7uF in the bypass cap location.
For generic transistors that get used all the time, 992s, 1845s, 1815s, 2383s, or anything that's only a few cents each. When you look at the discount, it doesn't usually make sense not to if you are going to continue down this path. I need to match another batch of 1845s. Pretty much gone through the 30 or so I did a while back. It's why I like getting them on cut tape, you just write the hfe on the strip by the transistor.
Do I have those 2 pin connectors right at the top of the driver boards I have the blue harness in front and gray in the rear . They were marked over ten years ago but one must have not been marked on the plug. The harness seem to fit and have that bend in it for the gray one. I had been using Austor solder which was working great and could not find 100g roll so I got some china no name and it is crazy bad . I ran out half way thru soldering the power supply caps and the last set looks like DO DO . I put the ground buss bars on backwards but soldered one before I snapped so I just went with it. Cant believe I got this much back together after having it apart for between 10 and 15 years . I am missing the 2 covers on the inside for the back of the front panel controls and then the other one over the EQ board .