What is the dc offset as measured at centre/emitter resistors?
-
Feeling lucky? Check out the AK 24th Anniversary Giveaway thread and join in the fun!
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Sansui 5050 total rebuild
- Thread starter Vtince
- Start date
-
- Tags
- 5050 list sansui sansui 5050
Now im thinking it could be the R612 and R613 resistors. I get ~15VAC after the resistor, and I cannot get a resistance reading (showing 0.0ohms on meter with unit powered off).
I used RES 2.2 OHM 1/2W 5% AXIAL (https://www.digikey.com/en/products...oric-bc-components/SFR16S0002208JA500/5064957) to replace those old fuse resistors. Should I have used different types if this is the problem?
I used RES 2.2 OHM 1/2W 5% AXIAL (https://www.digikey.com/en/products...oric-bc-components/SFR16S0002208JA500/5064957) to replace those old fuse resistors. Should I have used different types if this is the problem?
Yeah, that's too high, would expect sufficient to trip protection..667vDC an .673vDC
Never measure resistance with the amp powered up, sparks may fly...I cannot get a resistance reading (showing 0.0ohms on meter with unit powered off).
Resistors don't fail short, they may drift high before failing open/OL/open loop,circuit
There must be some continuity in the resistor since you are getting something (15Vac) on the other side.I get ~15VAC after the resistor
Suggest slow down and recheck your work. Measure Vac on one side of R612 then repeat for other side. Repeat for R613.
Measure R612,3 resistance with unit powered off, OL?
Fusibles are increasingly difficult to find Those resistors are fine. Perhaps a better choice would be to use a "flameproof" type and mount off the circuit board for better air circulation/cooling. Take a look at,I used RES 2.2 OHM 1/2W 5% AXIAL (https://www.digikey.com/en/products...oric-bc-components/SFR16S0002208JA500/5064957) to replace those old fuse resistors. Should I have used different types if this is the problem?
https://www.digikey.com.au/en/produ...loric-bc-components/NFR25H0002208JR500/614131
appears to be fusible and flameproof
OK, so pulled and checked the R612 and R613:
2.867kOhm
2.605kOhm
Also checked the diodes and they all measured good, phew.
So I replaced the 2 resistors and now it's working again.
Reflecting on why the resistor went bad, I recall when powering it on previously for the first time, I was excited that the receiver was working and I was confused to why the volume on FM was so low, even with volume cranked up all the all to 100%.... then I heard the speakers go loud for a split second.... that could be when the resistors failed.... then only afterwards, I realized FM Muting was on! **Facepalm**
Now I've had several power cycles and been listening for a while and still working good!
2.867kOhm
2.605kOhm
Also checked the diodes and they all measured good, phew.
So I replaced the 2 resistors and now it's working again.
Reflecting on why the resistor went bad, I recall when powering it on previously for the first time, I was excited that the receiver was working and I was confused to why the volume on FM was so low, even with volume cranked up all the all to 100%.... then I heard the speakers go loud for a split second.... that could be when the resistors failed.... then only afterwards, I realized FM Muting was on! **Facepalm**
Now I've had several power cycles and been listening for a while and still working good!
Also, any insights on when there is bass heavy/ loud music on a track, the dim bulb tester will light up. And I notice the signal and tune meters will get dim, Is this normal?
Video:
https://imgur.com/gallery/wLd5Jhf
Video:
https://imgur.com/gallery/wLd5Jhf
The DBT is a current limiting device useful for troubleshooting and first power up after parts replacement. You should not attempt to play music while on DBT, the DBT will choke the amp so it is effectively running on 6, not 8 cylinders. The DBT lighting up corresponds to higher current demands from the amp. Warning, if you have set the bias with DBT connected then need to reset bias to 0mV then disconnect the DBT then reset the bias as per the service manual.Also, any insights on when there is bass heavy/ loud music on a track, the dim bulb tester will light up. And I notice the signal and tune meters will get dim, Is this normal?