Sansui QRX 9001 CD-4 problem

[Quadmanfinally]

Well she has been working great since the recap, until I went to adjust the CD-4 rear speaker separation. The two pots on the back. The right channel will adjust with the pot, but the left channel will not. The left pot set in the middle position is the lowest sound. From there when you turn it left or right it gets louder. Never turns off like the right channel that will go quiet turned fully counter-clock wise and slowly gain volume when turning back. I Deoxed the pot, checked the ground and measured resistances in which both pots match. When I leave the left pot at its quietest and play an album I get static/scratchy sounding like a worn record in both left speakers. It comes and goes. I tried several albums and the same thing. It is only when I play CD-4 and didn't do it until I messed with the rear separation. I am thinking it may be the CD-4 board or switch. Am I looking in the right direction?? Any help will be appreciated!!!! Thanks!!!!

 

[Circular Vibes]

One thing you could try is to reverse your phono plugs. That way you can see if the problem travels with the channel. If it does, your problem lies in the turntable. If it stays the same, your recceiver has an issue. My experience is that it should be quietest in the rears around the mid point, but then you may need to change the carrier setting. It may be a case of trial and error. Also, I don't know which setup record you use, but I have recently discovered that most off mine are wrong. I have been using a set up LP from Victor (Japan) rather than the 45rpm EP's. I hope this helps a bit for you. Good luck and keep us posted.

 

[Quadmanfinally]

Thanks for the reply. I will try to reverse the phono plugs and see what happens. I used the record that came with the unit. So if you are saying that the middle position is the quietest like what the left pot is doing, then the right channel pot that will go silent when turned all the way counter clock wise has a problem? I did not find a carrier signal adjust on this unit. I believe it is factory set. I could be wrong and not looking in the right area! What is the name of the set up LP you are using?
Thanks again!!!

 

[Circular Vibes]

This is Victor's (JVC) 4 channel set up LP. It is number 4D-109. I am sure there are others that are good. I have had my best experience with this one. For some reason I get bad results from the 6 or more 7 inch 45's that I have tried, even the EP's that have the same narrative and music as my LP. They can be found on Japan's Yahoo auctions. You can bid by using a proxy service like Buyee. This is how I get my Japanese gear and records. I have a QRX 7001 and it may be your carrier adjustment is in a different placce to mine. I have three controls on the back near the phono inputs. After having looked at the user manual for your 9001, I see the carrier is automatically set. I wonder if an adjustment inside is necessary after changing caps inside, or a control or trimpot needs cleaning. Even a simple thing such as reseating your headshell or removing and reinserting your stylus can affect things. I had to finnd shorter screws because one cartridge I had, the stylus was VERY slightly cock-eyed and the signal broke up on CD4. I don't know which cartridge or turntable you are using, that may lead to ann answer too. Is there any chance your stylus has reached the end of life for CD4? Hope this helps a bit until someone else chimes in.
Edit: I just read your about me page and see you are using a AT440MLA on a Pioneer PL530. I see no reason for the equipment to be at fault unless there is something not seating right or is oxidised. Check your stylus for proper insertion and cleanliness before going further. Good Luck.

 

[Quadmanfinally]

I switched the phono plugs and still in the left, not as bad though! I am now using a Pioneer Pl55DX, but may go back to the PL530(miss all the features). I have several cartridges I use and all do it. I have a Sure M24, Pioneer PC-1 and a Empire 4000 D/lll each with their own head shell and unique sound. I thought at first the cartridge, but after testing with all three, the static and CD-4 controls were the same. I also used an Atlanta/Electra test/set up LP with tones and music to no avail!! Yes my carrier is set and there is no adjustment. I guess I could go over all the internal adjustments again. It has been awhile since I recapped and something else may have changed causing something to go out of slight calibration! Thanks for all the great advise!! And I will look at getting that test LP.

 

[Quadmanfinally]

OK went through all the adjustments only the milliamps were a little of at the speaker fuses. The voltage reg was at 25.1v. can't get any closer then that. So I swapped the CD-4 board with the original not recapped that came with the unit and it worked. Both rear sep. adjustments are a little of center counter clock wise in about the same position, but both rear speakers were distorted. So while listening to a CD-4 LP I turned them both more in the same direction until they were clear. So I think on the other board one of the IC's is bad. I traced the inputs and they go through a cap, then a resistor before the chip. Both caps and resistors measured the same also matched the original board values. I don't think the IC chips are available so I may switch the chips or recap the original board. Haven't decided!!

 

[Circular Vibes]

Before changing anythiing more, try measuring the separation control to make sure both are good, then clean the RCA jacks to be free of oxidation. As to the IC's, I think they can be found either as new old stock, or from parts units. The same IC was likely used in standalone demodulators as well. I would feel like a transistor is more likely than an IC, but anything is possible.

 

[Quadmanfinally]

Thanks for the replies!! I cleaned and checked both rear separation pots and they were the same resistance and the resistance was smooth through out the the full turn. My jacks are clean and all other forms of LP's play great it is just the CD-4's. I think the distortion when I turn the pots to get the lowest setting might be that the caps on the board I am testing with are original. The one that was in there was recapped a couple of years ago with Nichicons and work good until this problem crept up. Tomorrow i will test the caps and resistors on the affected board just to rule them out!! So much fun!!!!