• 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

Sansui 771 bulbs power issue

robz2000

robz2000

New Member
I've made a mistake replacing bulbs on a sansui 771 stereo indicator bulb. in the process of re-soldering that grain bulb, i accidentally unplugged the blue and purple lead wires that terminate on the tuner board . now, no matter how i plug those in, i am not getting any power to the housing unit. (none of the bulbs light up)
anyone have any experience in this, possible the exact terminals for the purple and blue. all the fuses seem good, as i've checked them all.
the rest of the unit is fine, just nothing getting to the housing unit.
 
Last edited:
Register to hide this ad
Looks like Pin 12 to the Stereo beacon and Pin 13 to the other lamps where the D01/C01 diode/Capacitor are connected to. Look at the traces on the board.

upload_2022-9-27_17-42-49.png
 
appreciate the reply. Gave this another try, no luck. i believe i connected pin 10, which is at least 12v, maybe even 13 or 14 to the unit. when it stopped working, the bulbs lit for a few seconds then went out and hasn't come back since but everything else works fine. like i said, relooking at this, i think i mistakenly put the blue and/or purple wires on pin 10. any idea what parts i can or what on the housing unit might have blown? there is a cap and a diode. everything else looks very straight forward. really appreciate your responses. ty
 
i traced the yellow wire back to the in line fuses . the 5a one all the way to the left was indeed blown. dumb. i didn't test those. ordered some in line's and will replace them tomorrow.
 
Is this f05 fuse that’s soldered to the board itself? I have this fuse removed as I believe it to be the issue with mine and am looking for a replacement fuse
 
Did you review Section 5 of SM? Troubleshooting on Power Supply Section
Did you check fuse with ohmmeter?
Looks like there are 8 fuses on the F-1500 Power Circuit board. F-05 = 5 Amp in manual.
 
I did test it and found it was blown. Seems common on these as I found other threads with the same issue/results. I’m just curious since it was soldered to the board like a pigtail fuse, can I resolder a new 5a fuse to the old leads? Or do I need to order a 5a pigtail replacement specifically?
 
Are all the fuses attached that way? If so I guess do it that way. If it is supposed to have a proper fuse holder, I would get one and install it. Unless you are just testing it for now.
Bigger question is do you know why the fuse blew in the first place? What caused high current to blow the fuse.
Neg side of C01 is ground. Check C01 and D01 to make sure not shorted.​
Did you get the wires back to the original locations you mentioned in earlier posts.​

Check all the solder joint on the lamp board. Those are known to crack and open so the lamps do not get power. Inspect and reflow all of them with fresh solder.
 
You must log in or register to reply here.
Back
Top Bottom