Sansui 5500: FM Stereo and Crackling at power up/down issues

Crang

Well-Known Member
Hi All- just starting to go through a new to me Sansui 5500. Not the QRX or G, just plain jane 5500. It sounds great and loving it!

It has been cleaned out, pots and switches deoxit/lubed, offset/bias set, new heat compound on outputs, fuse bulbs replaced by leds, and case polished up. So now time to get into the real issues of which I have found four. One is all sorts of noise coming from the phono section, but I will save that for another thread another day. Another is a burned our power lamp and that I should be fine to fix. So the two for the topic of this thread:

1) There is static out the right channel on powering up and powering down. It does this on both AUX and FM inputs. Havent tried it on the others but assume its the same. It runs quiet other than the 3 seconds or so when hitting the power button, at which time ist about 3 seconds of crackling static from the right channel only. Ideas?

2) The FM tuner has issues. It pulls stations great at the low end of the dial- even hard ones. Great signal strength. Seems to pull in less near the top end of the dial but still gets the big ones. It does drift after about 45 minutes of warming up. The big issue is the FM Stereo light does not come on, and even strong signals are coming through in mono- no stereo separation. I put a meter up to the FM STEREO light when dialed into a strong station and there is no voltage, so doubt the light is burned out. Its just not getting juice. While I havent played with the AM much, it seemed fine when I tried to find stations.

I spoke with the local tech who did my last tuner allignment and he has a new policy. He will only do it on units that have been completely recapped- with the power supply and tuner section(s) recapped at a minimum. This 5500 is unmolested and there is quite a bit to it. While I plan to recap it eventually, its not on my short list of things to do. I would love to get the FM Stereo working without a full recap and allignment.

I read the excellent thread on cleaning the tuner. Problem is I don't have access to the VC. It has a cover on it. When I unscrewed the cover from the chassis, the entire VC is attached from the inside and would come out still inside the cover. Since it has the flywheel with the the string on it, I rather not take it out as it would likely mean removing the wheel and then a restring just to clean it. I have read some other posts on other units you can bump some of the VRs to try and adjust the stereo. And Idea how to do it on this one? Kind of in over my head with tuners. Also noticed one of the VRs on the schematic/spot on the board isnt there. Doesnt look like it was removed, just was never there. Just a single metal post coming up where it should be. Cant recall which, wil have to open it back up for the specifics....

Anyway, all ideas welcome. Thanks in advance for the help-

Chris
 
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Hi All- just starting to go through a new to me Sansui 5500. Not the QRX or G, just plain jane 5500. It sounds great and loving it!
It has been cleaned out, pots and switches deoxit/lubed, offset/bias set, new heat compound on outputs, fuse bulbs replaced by leds, and case polished up. So now time to get into the real issues of which I have found four. One is all sorts of noise coming from the phono section, but I will save that for another thread another day. Another is a burned our power lamp and that I should be fine to fix. So the two for the topic of this thread:
1) There is static out the right channel on powering up and powering down. It does this on both AUX and FM inputs. Havent tried it on the others but assume its the same. It runs quiet other than the 3 seconds or so when hitting the power button, at which time ist about 3 seconds of crackling static from the right channel only. Ideas?
What you describe sounds typical for equipment of this age, it could be a lot of things, but very likely some transistors that have gone noisy, or some 'dry joints' somewhere.
2) The FM tuner has issues. It pulls stations great at the low end of the dial- even hard ones. Great signal strength. Seems to pull in less near the top end of the dial but still gets the big ones. It does drift after about 45 minutes of warming up. The big issue is the FM Stereo light does not come on, and even strong signals are coming through in mono- no stereo separation. I put a meter up to the FM STEREO light when dialed into a strong station and there is no voltage, so doubt the light is burned out. Its just not getting juice. While I havent played with the AM much, it seemed fine when I tried to find stations.
Again this sounds typical for the performance of a receiver of this age, the stereo problem could be alignment related, but sounds a bit more like component failure to me. It could only be tracked down properly if an alignment was attempted by someone familiar with this age of unit.
I spoke with the local tech who did my last tuner allignment and he has a new policy. He will only do it on units that have been completely recapped- with the power supply and tuner section(s) recapped at a minimum. This 5500 is unmolested and there is quite a bit to it. While I plan to recap it eventually, its not on my short list of things to do. I would love to get the FM Stereo working without a full recap and allignment.
You are lucky to know someone who will do an alignment for you, I can completely understand why he would want the recapping done first. If you don't want to recap it first, all you can do is appeal to him (or pay him extra) to try the alignment without the recap. I don't see another solution, but be prepared for the alignment to fail without the recap, I would definitely do the power supply, absolutely essential to get this refreshed.

I read the excellent thread on cleaning the tuner. Problem is I don't have access to the VC. It has a cover on it. When I unscrewed the cover from the chassis, the entire VC is attached from the inside and would come out still inside the cover. Since it has the flywheel with the the string on it, I rather not take it out as it would likely mean removing the wheel and then a restring just to clean it. I have read some other posts on other units you can bump some of the VRs to try and adjust the stereo. And Idea how to do it on this one? Kind of in over my head with tuners. Also noticed one of the VRs on the schematic/spot on the board isnt there. Doesnt look like it was removed, just was never there. Just a single metal post coming up where it should be. Cant recall which, wil have to open it back up for the specifics....

Anyway, all ideas welcome. Thanks in advance for the help-

Chris
Do not try to clean the VC, from what you say it will be difficult if not impossible to gain access on this model without triggering a forced re-alignment due to disturbing the delicate adjustments. Do not try to make any adjustments to the tuner section, as you will almost certainly make matters worse, and give your trusty re-alignment tech much more of a job when he comes to do it. It is good that you acknowledge that you are 'over your head with tuners', most people on here are - including me to be honest. The last part about the missing trimmer, don't worry about this you are probably correct, it was very likely never there. Maybe it is for an adjustment on another model of tuner that uses the same board, or just a production change where the board was never updated.

I think you can see the way ahead, at least now, and I'll remind you again how fortunate you are that you have someone to do the alignment. ;)
 
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Thanks for that. I saw on the MPX FM board there is VR402 to adjust the FM Stereo indicator. May be worth marking the current position and twisting it both ways a bit to see if it comes back on? If not, no harm in just putting it back where it was.....
 
May be worth marking the current position and twisting it both ways a bit to see if it comes back on?
You could try this, try adjusting it just a little either side of its current position to see if this makes any difference - choose a strong station (that you know broadcasts in stereo), and avoid adjusting it to the extreme in either direction.
 
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The crackling sound might be coming from a capacitor. And the lengthy time period might indicate a large cap. Probably in the output amplifier section for that channel. If this receiver has plug in circuit boards just switch from side to side and see if the noise follows the board.
 
1) There is static out the right channel on powering up and powering down. It does this on both AUX and FM inputs. Havent tried it on the others but assume its the same. It runs quiet other than the 3 seconds or so when hitting the power button, at which time ist about 3 seconds of crackling static from the right channel only. Ideas?

Not to in any way say you shouldn't check the items mentioned in other responses, but I had the same issue on a Marantz integrated recently, but on the left channel. Not long after, I noticed that the left channel was very low and distorted. It turned out to be the internal pre out/main in jumpers built into the RCA jacks. A little deoxit and it was all better. I left jumpers in however so I don't have to pull it down again in another couple years.
 
Not to in any way say you shouldn't check the items mentioned in other responses, but I had the same issue on a Marantz integrated recently, but on the left channel. Not long after, I noticed that the left channel was very low and distorted. It turned out to be the internal pre out/main in jumpers built into the RCA jacks. A little deoxit and it was all better. I left jumpers in however so I don't have to pull it down again in another couple years.

Just swapped the boards and crackle stayed on the right side. Oh well. Plan on recapping the power supply and drivers first, so hopefully the PS ones resolve it.

I did just bump VR402 for the Stereo Indicator lights. It lit right up! Only moved it a hair. At least one mystery solved.
 
Well just put in an order with Mouser- caps to do the power board plus the 2 smaller filters next to it, both driver boards, the fm board, the equalizer block, plus a few random ones. Will still need to do the tone block, mpx block and the 3 big filter cans.....but this will definitely keep me busy for awhile! Debating mightily what to replace those big cans with. Strange it doesnt have a dedicated phono board?
 
Did Sansui glue some of the boards down? I am trying to remove the FM and FM MPX boards up top. Took the screws out but they are still on there rock solid. Dont see anything obvious from underneath that looks like more screws. Prying up with moderate pressure they wont budge and dont want to go any harder for fear of breaking the PCBs. Assume the AM board next to them is on the same way.

Good news is I have recapped the driver boards, power supply board and 2 smaller filters next to it, the equalizer block, the lamps and cap for that, and some others I am already forgetting. The crackling on power up/down is intermittent now and not as loud. Ordering the 3 big filter cans today, so hopefully that finishes it off. Pretty much just the 3 radio boards and part of the tone block to go. Not going to bother with the mic block. Been using Elna Slmic IIs where it matters. Its already sounding pretty sweet! :banana:
 
Did Sansui glue some of the boards down?

I recently worked on a 3000 and am now on a 3300 and both have boards that are screwed to the chassis from above and soldered to the chassis below. Not sure of the situation with your model specifically though.

Good luck,

Mark K.
 
I recently worked on a 3000 and am now on a 3300 and both have boards that are screwed to the chassis from above and soldered to the chassis below. Not sure of the situation with your model specifically though.

Good luck,

Mark K.

Ahh thanks. This one is the same series as the 3300 so thats really helpful. Betting its the same. Did you desolder the boards or work on them where they are?
 
Well I finished recapping everything (all boards, big filter caps, etc.) other than the FM MPX block. Good news is the crackling at power/up down is gone. Noticed some crackling hitting the Speaker A switch so will give that another pass of Deoxit.

2 issues now (and bear with me as this is only the second time I have ever done this so in over my head I am sure).

1- one channel sounds muddy and the other sounds bass shy twisting the balance back and forth. They sound very different- both the FM and using the AUX input.

2- I went to do the current adjustment as per the instructions in the Service manual. Following the instructions I am supposed to adjust one trim pot on the L driver board to get a 20mA reading at a fuse and then adjust the pot on the R channel to get a 25 to 30 mA reading on the other fuse. Problem is, the lowest I can adjust either channel is about 36mA. I did take readings here before trying the recap so I would have a baseline and they were both about 36mA as well with someone having already turned the pots down. I dont have a signal generator and an o-scope to do the Output adjustment.

Ideas or am I just doing something wrong?
 
Makes no sense to have different bias current on L and R channels. I smell a typo. If you can't get the amp boards to bias within spec, then there is a problem somewhere. Did you power up on a dim bulb tester to make sure there aren't any shorts? Is the power supply making all the correct voltages? Does B1=91v and does B2=87v?
 
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