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SGT 250 audio issue

 
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cedwaechter



Joined: 10 Dec 2012
Posts: 52

PostPosted: Fri May 05, 2017 12:13 pm    Post subject: SGT 250 audio issue Reply with quote

I am working on an SGT 250 and am having trouble with audio output level. The picture is perfect and I have checked the player with several know good stylus and still no increase in volume. Switch in the back is set to normal. Everything else seems to work properly. Where is the audio output adjustment located? Is it on the stereo board? I don't have the schematic for it, but I believe it should be possible to adjust output. The odds of the stereo board going out are pretty small. I even swapped out boards and had the same thing with the other board. It is possibly I could have bumped something when I had it apart. Any help is appreciated.
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kitchensynch



Joined: 24 Feb 2013
Posts: 915

PostPosted: Sat May 06, 2017 11:35 pm    Post subject: Reply with quote

So you tried mono discs and a dual soundtrack disc if you have it (others suggest Jane Fonda's Workout or one with a alternate language/descriptive track)?
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jsdspif



Joined: 16 Jan 2016
Posts: 120

PostPosted: Sun May 07, 2017 2:38 am    Post subject: Reply with quote

you may want to read thru these 2 topics a couple times. My posts can be a bit confusing. They are problems I and someone else were having.
http://www.cedmagic.com/forum/viewtopic.php?t=2658
http://www.cedmagic.com/forum/viewtopic.php?t=2672

My 250 is still open from doing the repair. There are 2 audio demodulator ic's . one is u4101 on the pw4000 board it's labeled u101 and u3601 on the main board is labeled u601, it is located underneath the pw700 board.
with the player powered on and in the load position The voltages at the pins of u101 on the stereo board (since it's easier to check that one first) are as follows
pins 1,2, and 3 3.13 volts
pin 4 is grounded
pin 5 and 6 7.2v
pin7 6.5v
pin 8 .17v
pin 9 5.9v
pin 10 2.2v
pin 11 5.9v
pin 12 .15v
pin 13 5.86v
pin 14 11.8v
pins 15 and 16 5.3v

when you check yours the numbers should be pretty close to those. The voltages on the u3601 (labeled u601 on the main board) are pretty much the same as the u101 on the stereo board except
pin 8 4.24volts
pin 10 is grounded
pin 12 is not used
pin 13 1.25volts

on my u3601 the bad one had no voltages at pins 1,2 and 3 on my u4101 I don't remember what voltages were not there/off by quite a bit but I also had to replace that. The chips in the f/g style players were more prone to failure and the newer chips that later became available are more dependable.
You might also try a mono disc and a stereo disc. with stereo see if the stereo indicator lights up. With each disc also move the audio selector switch to each of the three positions and see how they sound.
I really doubt you bumped the audio level adjustment and even if you did just moving it slightly wouldn't have much effect. I'd start with playing a mono disc and a stereo disc to see what is and is not working and then check the pin voltages and then report back ?
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SelectaVision420



Joined: 25 Mar 2012
Posts: 1325
Location: Hartford

PostPosted: Wed May 10, 2017 7:59 pm    Post subject: Re: SGT 250 audio issue Reply with quote

cedwaechter wrote:
I am working on an SGT 250 and am having trouble with audio output level. The picture is perfect and I have checked the player with several know good stylus and still no increase in volume. Switch in the back is set to normal. Everything else seems to work properly. Where is the audio output adjustment located? Is it on the stereo board? I don't have the schematic for it, but I believe it should be possible to adjust output. The odds of the stereo board going out are pretty small. I even swapped out boards and had the same thing with the other board. It is possibly I could have bumped something when I had it apart. Any help is appreciated.


i will try to get you pics of the schematic as soon as i can
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cedwaechter



Joined: 10 Dec 2012
Posts: 52

PostPosted: Fri May 12, 2017 7:46 pm    Post subject: Reply with quote

Thank you for help. I think the issue is on the main board. I tried another stereo board and got the same results. There is sound in stereo and mono modes, but it is faint. Also tried 3 known working stylus. Same issue.
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SelectaVision420



Joined: 25 Mar 2012
Posts: 1325
Location: Hartford

PostPosted: Tue May 16, 2017 10:02 am    Post subject: Reply with quote

do you still need the schematics?
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(2)Sears 274 & 934(80150,10&11350),sft100,sgt250,sjt 090-400,vp550, VP4000!
'84 Dimensia Owner
caddy.daddy.fleetwood@gmail
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cedwaechter



Joined: 10 Dec 2012
Posts: 52

PostPosted: Tue May 16, 2017 6:50 pm    Post subject: Reply with quote

Any thoughts are appreciated. If it is not too much of a headache I could sure use them. Any possibility it could be the stylus assembly or something related? I don't think their are too many issues with the circuit boards in RCA players to the best of my knowledge. Picture is perfect bit sound is very faint.
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cedwaechter



Joined: 10 Dec 2012
Posts: 52

PostPosted: Tue May 16, 2017 6:51 pm    Post subject: Reply with quote

Any thoughts are appreciated. If it is not too much of a headache I could sure use them. Any possibility it could be the stylus assembly or something related? I don't think their are too many issues with the circuit boards in RCA players to the best of my knowledge. Picture is perfect bit sound is very faint.
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jsdspif



Joined: 16 Jan 2016
Posts: 120

PostPosted: Wed May 17, 2017 5:07 am    Post subject: Reply with quote

I've pretty much posted what the problem/s is/are and I'd almost bet money on it and I'm pretty much an anti gambling kind of guy. The players I just repeired were doing the same thing, I'd have to re-read my posts to see what was what.
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