9090db....

john42

New Member
im working on a 9090db the board in question is f 2619,,,,in skematic r3 is 5.6k in my board its 2.7k.....the power resistors r1 and r3 are very hot any hepl on this would be apreciated
 
im working on a 9090db the board in question is f 2619,,,,in skematic r3 is 5.6k in my board its 2.7k.....the power resistors r1 and r3 are very hot any hepl on this would be apreciated

R1 & R2 on the board in front of me are 270 ohm at 5 watt large square ceramic wirewounds.Yes they will get extremely hot.Thats why they are 5 watters..
R3 is a 2.7 Kohm 1/4-1/2 watt metal film. Red-Violet-Red. Always go with whats installed unless it looks like someone else has replaced it. Service manuals and schematics frequently have mistakes.
 
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thank you for your advice,,,i replaced all the transistors on that board and it isnt working the collector of tr1 is reading 30v not 14 v....
 
thank you for your advice,,,i replaced all the transistors on that board and it isnt working the collector of tr1 is reading 30v not 14 v....

Houston you have a problem. TR1 should have 14v on the collector,12.5v on the emitter and approx 13.4v on the base.
 
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Yes ,,avionic i have problems.....i have sound but no panel lights...any help would be apriciated,,,,,
 
Yes ,,avionic i have problems.....i have sound but no panel lights...any help would be apriciated,,,,,

Check fuse F03 in the main power supply.F-2619 is the power supply for the tuner(RF power supply)Also the circuit board that the lights plug-in to is notorious for bad solder connections on the lamp clips.Usually need to be resoldered.
 
thanks again...the fuse is good ,,, will follow up tomorrow.....as my day is over now..
i bought this reciever in 1978 and it has been very good to me i have AR 9ls speakers hooked up to it and Love the sound originally the protector circut was acting up i cleaned the relay and got that working and now lost all the lights will work more tomorrow
 
Check the voltage at the signal meter lamp and the tuning meter lamp should have about 6.5vac.If both of these are burnt out, it will take out most of your lamps( series wired) except for the power meter lamps.If no voltage then you probably have a broken wire going to PL708 & 709(tuning meter and signal meter lamps) from the main power supply board F-2656 pins 11 & 12.
 
thank you for your advice,,,i replaced all the transistors on that board and it isnt working the collector of tr1 is reading 30v not 14 v....
If you haven't already I'd recap this board with all 105 degree caps.
 
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Hello Avionic,,,,, got the lights working....was a bad connection on f3 fuseholder ,,,
now that power supply board has got me stumped....I had replaced all the caps and all the transistors the problem is still there . voltages are TR1 c31v b13v e12.5v....TR2 e13vb13.7v c31v....TR# e5.6v b6.2v c 13.7v.....resistors are good .......any suggestions ,,,,,you seem to know this reciever very well and i thank you for your expert advice........thanks again ,,,JOHN
 
The collector voltage should be around 31-32 volts on TR01 and TR02 .Not the 14 volts thats printed in the schematic(misprint!!!) I just verified the voltage on a 9090DB I have here.I measured 32.5 volts. Your getting the 12.5 volts on the emitter of TR01 which should be the correct output on pin 01 of the F-2619 board. This board is working correctly.


Dave
 
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hello Dave...I would like to thank you for all your effort in helping me with this problem..I was stumped ...sometimes the only way to fix these problems is to compare to a working good unit...My original problem was the rectifier supplying the relay .I repaired that and saw the resistors were very hot on the power supply board .there seems to be many mistakes on that small board.
 
Working on a Sansui 9090DB - with board F-2619. I believe someone has replaced a capacitor - and it shows signs it has failed. the position on the board is C05. The damaged cap is rated 16V / 470uf. Can anybody out there confirm that is correct?
 
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