The 500 ohm Trimmers worked on F-2835 (I was able to adjust within specs but only after a voltage drop everytime I check it)but after I put those in F-2833s voltages are all over the place and it went into protection..
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- Thread starter Willy6
- Start date
The F-2835 offset voltage will wander all over the place +/- 100mV or more - it is normal, it doesn't affect sound quality and unless wildly out is not enough to trigger protection.
Regarding F-2833 - check you have the +/- 10V adjusted correctly.
Regarding F-2833 - check you have the +/- 10V adjusted correctly.
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there is either some bad resistors or bad jfets on f-2833 voltages are all over the place..
Lets hope it isn't any of the JFET's
- check the +/- 10V regulators - and then do a wiring check (did you completely disconnect the board?), and double check other work done on the board if any. 
Or would the KSC-2073 be better then the MJE-15032G for the 2SD-357?
Differential pair? These are pass transistors on the supply board, aren't they? The choice is not critical here. I would put the MJE15032/33 here.
They are OK to use but significant overkill, the suggestion/confirmation by Lee will get the job done, if those are the transistors being referred to.
When transistors behave like fuses, I'd rather they pass a couple of amps before they go pop! rather than the 8 amps the MJ's will pass.
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These are on board F-2835..
Those are what are called bjt pass transistors, used to regulate current flow through a circuit, the voltages after the transistors are set using resistors (or zener diodes in some cases). I would first be checking voltages at both ends of the connections between the 2833 and 2835 boards, if a ribbon cable was used they can be problematical. You also could probe voltages around those transistors and see if one is truly at fault. Finally, if you replaced any resistors due to glue damage are you sure the correct values were used. Tough one to diagnose without hands on.
-Lee
-Lee
Ok so my problem is that I'm getting a perfect +,- 10V on the right side of f-2833 and a bad +,- 35mv on the left which led me to these regulators.Im not sure if this is the problem or not but I found one of those regulators with the collector touching the heat sink?so I put some heat shrink tube on it.
If you look at the schematic and locate where the heat sink attaches to the circuit board you will note that the locating solder points are not actually part of the ground plane traces, not to say that having that transistor collector leg touching the heat sink is a game changer but if you actually trust the schematic drawing should not have caused the loss of voltage.
I double checked the board itself and the heat sinks are not grounded..I started checking voltages on F-2844 and the schematic shows -40v on pin 06 and I'm getting -38v and +40v on pin 04 and I'm getting +20 on that one. the resistors test good but some are different from what the parts list says for that board..
Well, you know what to do about that
- if you feel the need to replace some, copy the values on your board now - ignore the 'parts list'.
They are not all the same on the schematic as they are on the board either. I guess I'll write everything down the way it is and then change it the way the schematic says it is and see what happens..Well, you know what to do about that
NO ! - copy the values in your unit now - don't use the parts list or the schematic.
It was tested at the factory with the values you have in there now, so unless you have a conflicting Sansui Service Advisory - follow the above advice - pretty please.
(Unless you have reason to believe someone has 'been in there' changing components for some nefarious purpose of course).
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NO ! - copy the values in your unit now - don't use the parts list or the schematic.
It was tested at the factory with the values you have in there now, so unless you have a conflicting Sansui Service Advisory - follow the above advice - pretty please.
(Unless you have reason to believe someone has 'been in there' changing components for some nefarious purpose.
