Sansui ba-3000 issues need help

Ok well 1 channel is KERPLUNK NOW ( if you dare and I assume you do not have a DBT online yet ) ....
You COULD unplug 19 and see if the unit comes out of PROTECT.

-16 is odd PROBABLY points to a pre driver board...
You could pull em ( ONE AT A TIME ) there is one phillips screw per board, holding those boards in the chassis
You need a LONG screwdriver,, AND I would heat shink it up to the tip..
The area where you going into has ALOT of exposed power points ( transistor tabs etc ) .. and just because it's been OFF for a while I would not trust that....
( Ask me how I KNOW )


I noticed that the boards are hard wired in. Someone was in here. Is their something I can look for on the board that would be the issue. Will post results after I get the bulb tester up.
 
OH you have an EARLY pre driver, that's actually "normal ".....BUT it makes things a PITA to work on, There is a 7 pin version of the 2507 and a 10 pin that doesn't use that " extra wiring "...... Hope your soldering skills are 100%, you will have ( at some point ) lift out the " final amp bricks " ) That have all the TO-3 output drivers and MOST of the connections are SOLDERED to a board.....that the pre drivers & reg board plug into ( F-2512 ). NOW is a REALLY GOOD TIME to take detailed pix's and DOODLES of the AS BUILT.
 
Last edited:
The difference between the 7 and 10 pin 2507's is the bias transistor on the brick was moved back to the driver board
 
I made a DBT.
Turned on the unit bulbs were dim for a second then went out unit fired up but did not come out to protect. I remeasured 18 and 19 one was 15 V and the other was 50 V
 

Attachments

  • F8D4EA54-AB2F-4E08-B9F0-47C7CC29E142.jpeg
    F8D4EA54-AB2F-4E08-B9F0-47C7CC29E142.jpeg
    65.8 KB · Views: 12
  • 300ED8E6-6EA1-417E-9690-2CD56E40B352.jpeg
    300ED8E6-6EA1-417E-9690-2CD56E40B352.jpeg
    114.9 KB · Views: 14
  • BCB91AC8-2A98-47C7-A37D-A40B8AE179E1.jpeg
    BCB91AC8-2A98-47C7-A37D-A40B8AE179E1.jpeg
    66.4 KB · Views: 12
  • 2F6AAB34-8507-4BC0-87D0-CB431E51C254.jpeg
    2F6AAB34-8507-4BC0-87D0-CB431E51C254.jpeg
    63.9 KB · Views: 12
This is the board soldered in
 

Attachments

  • 8F69C37B-FC4C-47C9-ADF7-3C63FAE7009A.jpeg
    8F69C37B-FC4C-47C9-ADF7-3C63FAE7009A.jpeg
    57.7 KB · Views: 16
  • 19E6F3AF-A95F-473E-B2EA-401DE6CCAFBE.jpeg
    19E6F3AF-A95F-473E-B2EA-401DE6CCAFBE.jpeg
    51.7 KB · Views: 15
For starts you will need a better DVM, this will only allow the MOST BASIC testing.
You will HAVE to make careful drawings ( with wire colors ) for the jumper wires from the 2512 ( Connector circuit board ) to the 2507 ( Pre drivers ) .
I have to ask,how many Hi Fi restorations / repairs have you done ?
 
I assume the measurements on each pin , was the black probe pin hooked to chassis ground?
The + 15 Might be a pre driver issue.
The MINUS 50 is a blown brick ( best guess from this far away ) .
It is not clear in the picture....
When you tested this the 1st time I assume 18 & 19 were still connected to the protect board.
The leads ( female ) for 18 & 19 are the actual wire coming from the output sections ( AKA Brick's )
The male connectors on the protect PCB are the relay input & the sense circuit picks off those wires on the PCB to see if it's cool to close the relay.

For remote assistance... Detail is everything So tell me exactly how you did your last measurements.

At this point whatever is blown has blown, so the next test would be unplug 18 & 19 and see if the unit flips out of protect
 
IF the unit comes out of protect, all that is telling us is that the protect board is functioning properly.
The next battery of tests will be to verify all the DC supply's are up and running.
Since you have the unit upside down, this should be EASY.
Starting with the BIG CAPS , the RED should have ~ +68 volts , Black is GROUND ( and is jumped BETWEEN to the 2 caps ) and BLUE is ~ -68 volts.)
This is a Bi Polar supply so IF you measure from Red to Blue it should be ~~ 130 volts... probably SLIGHTLY less for ALL SUPPLIES due to the DBT in series with the AC mains.
 
2512 J test points.jpg
The next BIT O INFO will be on this road map.
Coming in from the far right will the OTHER big power but NOT the same as the BIG CAPS.
This is the 2nd winding , fused on F-01 which provides the RAW POWER for the regulator board
So ANOTHER Bi-Polar supply +/- 85 ( ish ) volts.
Verify the 85 ( both polarities ) are there .
THEN the reg board does it's thing, moving left you get ( yes you guessed it ) ANOTHER BI-POLAR supply of +/- 35.
This is for the meters ( 2515's ) ( which get THEIR input from the output drivers ) and the input board ( 2513 )...

Oh wait there's MORE the board silk screen states +/- 60, it's more like 65.. this is for the MOST of the 2507 predrivers.
BUT the last 2 transistors on the 2507 are powered from the BIG CAPS...

So take a few measurements and report back
 
In your very first post, pix #2, to the right of the bricks, there is a metal cover that " protects " the regulator board & the pre drivers. Could you remove that cover & take a pix of the top of the driver boards ( high detail is better ) .. Also smell for SMOKED PARTS !
 
I assume the measurements on each pin , was the black probe pin hooked to chassis ground?
The + 15 Might be a pre driver issue.
The MINUS 50 is a blown brick ( best guess from this far away ) .
It is not clear in the picture....
When you tested this the 1st time I assume 18 & 19 were still connected to the protect board.
The leads ( female ) for 18 & 19 are the actual wire coming from the output sections ( AKA Brick's )
The male connectors on the protect PCB are the relay input & the sense circuit picks off those wires on the PCB to see if it's cool to close the relay.

For remote assistance... Detail is everything So tell me exactly how you did your last measurements.

At this point whatever is blown has blown, so the next test would be unplug 18 & 19 and see if the unit flips out of protect


Yes, I did ground to the hook. Should I be grounding someplace else?
 
The " BEST " ground ( for what we are doing ) is where the black wire ties on the buss bar between the 2 big caps & goes to Chassis
 
Here are some of the pics of the boards from the top
 

Attachments

  • 3E05B956-2F8B-4C9A-B079-D519B002A3EE.jpeg
    3E05B956-2F8B-4C9A-B079-D519B002A3EE.jpeg
    93.7 KB · Views: 15
  • 3D727C84-B92D-4213-AEE2-C67492ADE2B2.jpeg
    3D727C84-B92D-4213-AEE2-C67492ADE2B2.jpeg
    75.3 KB · Views: 15
  • DA24D09E-460C-4EDF-8E4D-05B9B8AC8D13.jpeg
    DA24D09E-460C-4EDF-8E4D-05B9B8AC8D13.jpeg
    69.7 KB · Views: 14
  • 8B45FC85-3D3C-4721-B578-DC269191B51B.jpeg
    8B45FC85-3D3C-4721-B578-DC269191B51B.jpeg
    73.5 KB · Views: 15
  • 08653A8E-7F12-403E-87E5-5ED0709546B6.jpeg
    08653A8E-7F12-403E-87E5-5ED0709546B6.jpeg
    59.4 KB · Views: 14
Back
Top Bottom