Sansui 9090 -Protection Mode

[tiga]

So I posted recently how much I'd like to have a Sansui 9090. Well as luck would have it I came across one on CL and picked up last night. Cosmetically it's in very nice shape with a few light scratches and very tiny nicks on the wood. (I'd say it's a 8.5 -9 / 10 ) All the lights work and the tuner appears to be pulling in stations but the unit will not come out of protection mode. (I knew of this issue when I purchased).

I'm not much of a techie but I can do some basics. What are some easy things I can check first to see what the issue may be?

I'm curious how this is going to compare to my Sansui 5500 - anyone heard both? I know the 9090 is much more powerful but I'm wondering about overall sound quality. Thank you!

Tiga

 

[ManyMoonsAudio]

I suggest putting this up on the sansui forum.

 

[Hula Pie]

It could be issues on your drive board, as I had one last year also that was in protection. I opted to ditch my own since it was only in 6/10 condition. If you're good with electronics, it's an affordable fix, but it can cost a lot if you have to take to someone to have fixed. If it's the driver board, chances are there could be issues elsewhere in the unit also. Good luck....

 

[Alan NY]

my 8080DB

Did the same thing, my tech (who undercharges for his time) fixed it for $75. Said it was a fairly common fault with the Sansuis. He found his info somewhere out there on the net, so try the Sansui section.

9090s are sweet rigs. My friend has a 5050, as expected pretty similar to my 8080, just much less grunt. Sound change probably depends more on what speakers you are trying to drive. The 9090 would really open up bigger or inefficient speakers. FWIW my 8080s were rated at 85 wpc and benched out at 97.5.

 

[w1jim]

On the center mounted driver board check all of the fuse-resistors. This board pops out easily. Betcha some are open. Then search the Sansui forum for more details. I've fixed 2 like this recently.

 

[avionic]

Green lines depict suspect "out of tolerance" fusible resistors on the F-2436 driver board. One can use 1/2 watt metal film

 

[tiga]

That's great help- Thank you! I'll pull this board first and check these resistors. From what i've read if this board is the problem it should come out of protection once its out. Where is a good place to purchase replacement resistors? Any chance that anyone can point me to a service manual? So how does the sounds quality of this unit compare to other Sansui models? I have a 771 and a 5500 - both of them just sound great!

Green lines depict suspect "out of tolerance" fusible resistors on the F-2436 driver board. One can use 1/2 watt metal film with exception of R19 & 20 these are 1 watt(8K2 ohm). My personal preference is KOA Spear 1%...

 

[trwham]

http://www.hifiengine.com/

HiFi Engine has the 9090 manual. Yes, the receiver will come out of protection with the driver board out, unless there is some other reason it is in protection. There are several versions of the 2436, so read the SM with care, as the board in your unit may very well be different than shown. Mine has the late version with fuses.

 

[tiga]

Thank you Trwham. I see you also have both the 5500 and the 9090. How would you compare them?

http://www.hifiengine.com/

HiFi Engine has the 9090 manual. Yes, the receiver will come out of protection with the driver board out, unless there is some other reason it is in protection. There are several versions of the 2436, so read the SM with care, as the board in your unit may very well be different than shown. Mine has the late version with fuses.

 

[avionic]

That's great help- Thank you! I'll pull this board first and check these resistors. From what i've read if this board is the problem it should come out of protection once its out. Where is a good place to purchase replacement resistors? Any chance that anyone can point me to a service manual? So how does the sounds quality of this unit compare to other Sansui models? I have a 771 and a 5500 - both of them just sound great!

Do the majority of my shopping at Mouser
http://www.mouser.com/
Or Digikey
http://www.digikey.com/

 

[trwham]

Thank you Trwham. I see you also have both the 5500 and the 9090. How would you compare them?

I'm afraid I cannot offer any good comparison. The FM tuner in my 5500 is not working and I found the 9090 before I rehabbed the 5500 and put it in regular service. One of these days I'll pull the 5500 out and compare the amplifier performance, but it's not high on my current list of priorities.

 

[tiga]

I understand this driver board was upgraded at some point and the fuses were added with later models. If I were to find a working 9090 with the newer board - would the circuit board be swappable with the older 9090 version? Or could that cause an issue? Thank you.
Tiga

http://www.hifiengine.com/

There are several versions of the 2436, so read the SM with care, as the board in your unit may very well be different than shown. Mine has the late version with fuses.

 

[tiga]

I pulled out the driver board tonight and the unit came out of protection. So that should mean that the problem is with the driver board correct? I also found that 3 out of the 4 125v 6a fuses were blown. Would they have blown because of the issues with the driver board? Thank you.

Oh - can anyone point (link) me to where I can order the correct fuses?

 

[w1jim]

The fuses likely blew due to a short at the speakers leads or someone abusing the amp. Worst case the driver transistors are toasted.
I'd put in these 5 amp fuses from RadioShack
http://www.radioshack.com/product/index.jsp?productId=2102766

 

[avionic]

The fuses likely blew due to a short at the speakers leads or someone abusing the amp. Worst case the driver transistors are toasted.
I'd put in these 5 amp fuses from RadioShack
http://www.radioshack.com/product/index.jsp?productId=2102766

or
http://www.mouser.com/ProductDetail...GAEpiMZZMseCiJT91fwIlkSJP0U3KIzU5PKPgFh%2bLA=

You can get the fuses just about anywhere that sells fuses..ie Lowes,Homedepot,Menards,Walmart,radioshack ,Ace hardware.. 2AG-5 Amp fast acting 125/250volt

 

[tiga]

So going with 5a fuses in lieu of 6a (what's in there now) is not an issue?

 

[tiga]

Update - not good

So tonight I decided to replace the blown fuses and turn the unit on and see what happens. (I haven't had a chance to check the fusible resistors on the driver board yet). Well I power the unit on and I get smoke and then flames from the lower left corner of the driver board. Yikes! Two of the new fuses blew as well.

So is this an indication of another problem besides bad resistors on the driver board? Or is smoke/fire a possible result with bad fusible resistors?
Tiga

 

[avionic]

So tonight I decided to replace the blown fuses and turn the unit on and see what happens. (I haven't had a chance to check the fusible resistors on the driver board yet). Well I power the unit on and I get smoke and then flames from the lower left corner of the driver board. Yikes! Two of the new fuses blew as well.

So is this an indication of another problem besides bad resistors on the driver board? Or is smoke/fire a possible result with bad fusible resistors?
Tiga

Shorted driver transistor(s) most likely culprit. They are the four TO-220 transistors fastened to the little aluminum heatsinks.The smoke and flames were probably the fusible resistors burning up . Your going to have to t-shoot the board.

 

[avionic]

Holy Smokes Batman

So far ,besides the obvious burnt resistors. Found a shorted (emitter-collector) driver and a vented cap.Marshmellows anyone

 

[tubeboob]

Great post, as I have the same problem with my 9090.

Tho mine is in 6/10 cosmetic condition.

Cheers