Sansui 9090 blinking protect light question

KillerAudio

New Member
Hello all just bought a 9090 today at a yardsale for 10 bucks. The problem is when I plug it in and turn it on the Protect Light just blinks continously. I can still use it as a preamp to my Phase Linear 400 but the Sansui has no output. I read that may be a problem with the Driver Board # F2436? I pulled the board and turned the receiver on the light blinked about 3 times and then kicked onto green. Also the entire tuner area lights don't come on pulled the bulbs and they checked out good but the only thing that lights up is the power meters. New to the world of Sansui any help or ideas would be appreciated. Thanks!
 
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All of your fixes for this receiver are in the FAQ sticky at the top of the forum. Good read! Replace the fuse resistors on the driver board and it will likely work.
 
Wow! I was in the FAQ's for like 5 minutes and found the answer to the lights on the display! Went and tried what it said and they worked! Took like 45 seconds to fix. I sould have looked harder at the info that was already on here. The thing that I am stuck on is the fused resisters? I was looking for some pics as to what ones I need to test but haven't found anything yet but I am going to keep digging. Would it help if I posted a pic of my specific driver board on here? Thanks again!
 
Sure, but just get the manual, and a decent meter, and check some values..
Be careful, that board can go back in one pin off, do not ask me how I know, just trust me.
 
Sure, but just get the manual, and a decent meter, and check some values..
Be careful, that board can go back in one pin off, do not ask me how I know, just trust me.

I don´t imagine that was a pretty sight....:no:
 
Are we talking about a 9090 or a 9090DB? They are different animals. Easy to get the driver board one pin off on the DB model. Pretty hard to make that mistake on a 9090.

If it's a 9090DB, the fuse resistors are the first place to start. There are many many posts on this topic.

If it's a 9090, the fix is not that clear. It take a bit more digging around. You need to get a volt meter and measure DC offset. Since it's in protection, you need to locate a test point before the protection relay to get a valid reading.

- Pete
 
Hey Pete, It is a plain 9090 not the DB model. I have a volt meter so how do I go about measuring offset you seem to be the gentleman to talk to looking through the FAQs. I think you are on about every solution! Thanks
 
Are we talking about a 9090 or a 9090DB? They are different animals. Easy to get the driver board one pin off on the DB model. Pretty hard to make that mistake on a 9090.

If it's a 9090DB, the fuse resistors are the first place to start. There are many many posts on this topic.

If it's a 9090, the fix is not that clear. It take a bit more digging around. You need to get a volt meter and measure DC offset. Since it's in protection, you need to locate a test point before the protection relay to get a valid reading.

- Pete

I assumed a db, but OP didn't state that.....and it was a db that I screwed up on.:thumbsdn:
 
I have a volt meter so how do I go about measuring offset

With everything plugged in and turned on, volumn set to 0 ground the - lead of your voltmeter to the chassis and measure the voltage on the protection board, F2547 at the junction of resistors R5 and R6 for one channel and R4 and R7 for the other channel. If I'm not mistaken, that should be the audio signal. Now that I think of it, there is probably a blue and a grey wire that runs from the power supply board to the protection board. You should be able to take a DC offset measurement from them. Sansui was pretty good about designating the audio signal wires with those colors.

- Pete
 
Approx what shold the DC offset be on the two channels? Basically at what point do I raise an eyebrow? Is this info in the FAQ for the 9090? I didn't see it or overlooked it I would hate to be wasting your time if it is somewhere else. But I really appreciate the help so far! I am going to go try a reading right now and see what I come up with.
 
As the name suggests, ideal offset is 0VDC, but if you measure more than about 1.0VDC or so, then you may have a problem.
 
Ok not to sound like an idiot but I am new to the repairing world. On the gray wire side I was reading right around 530mv but on the blue wire side it was off the charts. If I was reading the meter right when I adjusted the setting so it wasn't pegging it looked like 64 volts?? I know I sound like a rookie and I am. Would love to learn more can't get enough of the vintage stuff. So anyway I am assuming a blown channel?
 
EW just read your article on DC Offset in the FAQ that was an excellent post! Helped me to understand that I have a major problem with the 9090...... bummer. But hey for 10 bucks with what I have learned so far it was worth it. Just not sure where to go from here and what to test.
 
Pull the outputs & test if think you're really ready to troubleshoot. If not, get the unit to a pro.
 
There are fuse resistors on the 9090 and they do open. Change them. If it don't work your out a couple more bucks. I bet you got an open one. The fuse resistors are the dull looking ones. The values are 150ohm x2, 390ohm x2 22ohm x2, 4.7ohm x2 and 10 ohm x2 I believe.
 
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I thought he measured 64V with the driver board removed?

Too many cooks in this kitchen. See ya...
 
No the 64V reading was with the driver board installed. From what I was told earlier the DC Offset needed to be measured with everything installed in a stock configuration but before the protect circuit due to the fact that it wouldn't come out of protect mode. Ok wether it is right or wrong with the entire unit assembled (thats with all boards installed) seeing that I had a freakishly high reading on the blue wire(right channel) going into the protect board I though that I would try disconnecting it at the board to see if the left channel would work. It did so the problem has been isolated to the right channel. Now do I pull outputs? or what next? I had read that the 9090 (non-DB) board didn't have the fused resistors? So any help from anyone is welcome and appreciated and I will do my best to test all aspects that you all have patience enough to walk me through. Pics if you have them would be great if not I'll do my best. I just downloaded the service manual and am going to try and sift through that tommorrow after I get some sleep! lol Thanks again
 
I had read that the 9090 (non-DB) board didn't have the fused resistors?
You have been misled.Big time.There is about 14 of them on that F-2436 driver board.
 

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I thought he measured 64V with the driver board removed?

Too many cooks in this kitchen. See ya...

Don't go! LOL The kicker was that the unit comes out of protect with the board pulled.
 
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If he has 64v on the output, he either has blown output transistors or a fault on the driver board that is holding the outputs wide open. I don't think the fuse resistors will do that but it's always a good idea to replace them.

The number of fuse resistors on that board is dependent on the when the board was made or modified. There were several "iterations" of the driver boards used in the 9090/8080. There is also a service bulletin that outlines a major modification.

Avionic, your board is a very early production board. The later production boards have fuses on them.

- Pete
 
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