Sansui 9090DB Receiver Repair I - Protection Mode On

This is a video for repairing a Sansui 9090DB with protection mode on problem. The troubleshooting tactics I used on this unit is similar to the last video for repairing a Pioneer SX-3700. In this project, I have to give the credit to the website of Audiokama.org. Without this resources, I may need to do more work so I can get the unit fixed (since it is a common problem for the 9090DB). Next video I will continue on the adjustments for bias and DC offset.

[@hdgboy]

I get goosebumps watching this man work. Another lesson learned. As always. Thanks.

[@craigm.9070]

Those are fantastic receivers, you are right, the tuner is one of the better ones to come in a receiver in the 70's.

[@VW--mo3zt]

Hi, where did you get you r33, r34resistor? Thanks for you video tutorials. Hoping i could get mine to work.

[@alexzildjian]

Thanks 🙏😃

[@williamchow1624]

Great repair.

[@Dslats]

GREAT JOB! THAT WAS THE PROBLEM WITH MINE .

[@katlum7836]

Hi have the same one 9090DB can you repair it for me Protection green light is on. But no sound.

[@Stranded360]

I like your old fluke =) also thank you for the video- helped me start to troubleshoot my own 8080

[@VintageAudioFan]

Thanks. The vintage Fluke multimeter works very good, precise and reliable.

[@user-mq8ne1fs2r]

9090DB question: If you fire up the unit w/o the Driver board, what does the Protector light do? Blinking Red as well? Also, w/o the driver board AUX, AM, FM Phono 1 and Phono2 will not light as well when the input selector is turned ? Thanks!!

[@VintageAudioFan]

It depends on if there is a defective part in the power transistors or protection circuit. But it is a good way to troubleshoot the problem when repair the power amplifiers. Usually when you remove the driver board, the outputs DC offset is still detected by the protection circuit. If it shows blinking red, then there are two scenarios: (1) defective power transistor (2) defective power supply or components in protection circuit. So you have to check the power transistors first. If the power transistors are OK and the driver board is out, then the problem is the the protection circuit which is required to check the power supply and the components on the protection circuit board.

[@user-mq8ne1fs2r]

@@VintageAudioFan Thank- They were 3 bad power transistor - after removal Protection is now green- ordered replacments . Thank you again!

[@user-mq8ne1fs2r]

@@VintageAudioFan Thank you

[@tomiossi8092]

❤️👍🏽

[@rollingwheelspinas]

Hi I tested my sansui 9090db dc offset it reads negative 50 DC. Is this normal? My unit is under protection mode.

[@VintageAudioFan]

The reading of DC offset needs to be close to 0 V in order to get out of the protection mode. So there is a problem in the power amplifier on your 9090DB.

[@juanplayas606]

Hi my friend. I love your channel. I tell you a problen I have, I need a clear outline with the original components and names. Can you help me with my A 60? Thanks so much.

[@VintageAudioFan]

Could you send your inquiries to my email (listed in my KZbin Home page?

[@nick3200]

Music in background is louder than your voice !!!!!