"Stereo" Light SX-950 Just recapped

B

Bubba57

Active Member
I need a little help here if y'all don't mind. I have a SX950 that all works but the FM {Stereo} indicator. The signal meters work and is going up to about about half scale. The FM works good. It's just the Stereo light not coming on.

I have traced it back to pin 17 of the AWE-066 Tuner board and if I ground pin 17, the light comes on.

If I go further into the board and ground pin 9 of the HA1196 chip, the light comes on.

Furthermore if I ground pin 8 of the HA1196, the light comes on. I have +3.9 VDC going in to pin 17 of the 066 tuner board. It is just begging for a ground but the HA1196 ain't giving it up. What is my next step here?

Thanks
Bubba57
 
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Half scale on the signal meter may not be enough. Have you tried a piece of wire or something for an antenna to get a stronger signal?
 
Thanks Sriskie for your help. I have a 75 ohm twin lead "T" type antenna on it. You may be right though. What type of antenna would be the best or what do you use?

I do need to clarify though, that I recapped all of the receiver except the tuner board. I didn't touch it.

Thanks again
Joey Bubba57
 
Orient the antenna so it's perpendicular to the direction of the stations antenna, to pick up the most signal.

What type antenna depends on distance from the transmitting tower, obstructions between you and the transmitter, and how crowded the FM band is in your area. It also may need an alignment.

If you can get the dipole up as high as you can (attic) and away as far as possible from any electric sources in the area. You can add 300ohm twin lead to the down drop without affecting the cross piece.
 
I don't know how strong your local stations are but I just use a single piece of speaker wire hooked to one of the 300 Ohm connections to get near full strength on the signal meter. Works better for me than a dipole.
 
Bubba57 said:
I need a little help here if y'all don't mind. I have a SX950 that all works but the FM {Stereo} indicator. The signal meters work and is going up to about about half scale. The FM works good. It's just the Stereo light not coming on.

I have traced it back to pin 17 of the AWE-066 Tuner board and if I ground pin 17, the light comes on.

If I go further into the board and ground pin 9 of the HA1196 chip, the light comes on.

Furthermore if I ground pin 8 of the HA1196, the light comes on. I have +3.9 VDC going in to pin 17 of the 066 tuner board. It is just begging for a ground but the HA1196 ain't giving it up. What is my next step here?

Thanks
Bubba57
Click to expand...

Pin 8 of the ha1196 is SUPPOSED to be grounded according to the schematic.

Grounding pin 9 is NOT recommended...

The 3.7v reading on pin 17 of the tuner board is very suspicious. Check pin 2 of the power supply board (5.4v). What are the other lamps doing?


Did it work before the recap? Did the FM mono volume drop at all? Does the FM mono volume differ when probed at the FM DET out plug on the back panel?

Check to see if VR1 got bumped.

Can be set manually, need to split the difference between the TURN_ON points when rotated CCW and CW when receiving a Stereo signal. Do NOT use a turn off point - they are all wrong for this.
 
SX-950 Stereo light test

markthefixer said:
Pin 8 of the ha1196 is SUPPOSED to be grounded according to the schematic.
Grounding pin 9 is NOT recommended...Thanks for telling me that. Now, I know.
The 3.7v reading on pin 17 of the tuner board is very suspicious.

Check pin 2 of the power supply board (5.4v). Pin 2 of the power supply is +5.38 vdc.
What are the other lamps doing? All other indicator lamps are functioning normal.

Did it work before the recap? Yes

Did the FM mono volume drop at all? No change at speakers between stereo and mono. I believe it is in mono.

Does the FM mono volume differ when probed at the FM DET out plug on the back panel? I'm not sure what your asking here.

Check to see if VR1 got bumped.

Can be set manually, need to split the difference between the TURN_ON points when rotated CCW and CW when receiving a Stereo signal. Do NOT use a turn off point - they are all wrong for this.
Click to expand...

I get no affect when turning VR1. From stop to stop no sound difference or signal strength difference on the meter of the receiver. The light did not come on at any point while turning VR1. I put it back where it was.

I really appreciate your response and help with this MTF.

Bubba57
 
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There are only 2 caps in the signal path between the fm detector out and the stereo decoder in. The stereo signal isn't likely getting lost in between, so something is unhappy in the ha1196 circuit.

CAREFULLY re-double check ALL work done in the area. Also the fm muting and stereo/mono switching, false indications of low level signals might be keeping the stereo decoder turned off.

LOOK at FM auto out on pin 21, and back in on pin 16 going straight to the pin 12 of the ha1196.
 
SX-950 Stereo light Checks

markthefixer said:
There are only 2 caps in the signal path between the fm detector out and the stereo decoder in. The stereo signal isn't likely getting lost in between, so something is unhappy in the ha1196 circuit.

Mark, just a question here. The service manual talks about the HA1196 and says if the pilot signal is present then switching signal is applied to the demodulator and the stereo indicator lights up. It goes on to say if the FM muting signal is also applied to pin 12(I assume of the HA1196) the detector circuit becomes grounded. Therefore switching signal to the demodulator is not supplied and mono reproduction is obtained. I don't even know what they are talking about. How can I check for this?

CAREFULLY re-double check ALL work done in the area. Also the fm muting and stereo/mono switching, false indications of low level signals might be keeping the stereo decoder turned off. I went through every wire on the tuner board.
All were correct except:
Pins 5,33 of the 066 tuner board per the schematic, were supposed to go to pin 1 of the 093 switch board. These instead were connected to pin 2 of the 093 switch board. Pins 18,21 of the 066 tuner board were supposed to go to pin 2 of the 093 switch board. Pins 1 and 2 wires were reversed on the 093 switch board. This looked original though. I reversed these 2 wires at the 093 switch board. However this made no difference in the Stereo light illumination.

I have found a few stations today where the meter goes up to the black and still not even a flicker in the stereo light. Still no effect between the switching of stereo/mono.

LOOK at FM auto out on pin 21, and back in on pin 16 going straight to the pin 12 of the ha1196.
Click to expand...
I was a little puzzeled here. Per the schematic, Pin 21 of the 066 board goes to pin 18 of the 066 board, not the pin 16 as you referenced. The schematic does show pin 18 going straight to pin 12 of the HA1196. Anyway right now pin 18 of the 066 board goes to pin 21 (066) and then goes to the 093 switch board pin 1.

On a side note here, I see you answered me back last night. It had to be late wherever you are and don't get me wrong, I really appreciate that. But you have to get your rest and spend time with your family. Don't kill yourself over this stuff. I have had this receiver since i bought it new in 1976. After the recap it works fine all except that blame stereo light. I don't even listen to FM that often. So work on this when you have time and just let me know what you or anybody else comes up with. Alright I didn't mean to chastize you there but don't put me on the top of your list. The family should be #1.

Thanks Mark
Joey Bubba57
 
just for fun ground pin 8 whilst its NOT tuned to a stereo station ...see if the stereo light doesn't come on ...
 
I am glad you asked that Pete. As you see in my posts earlier, I was able to make the light come by grounding Pin 17 (board) or pin 9 of the HA1196 chip and even pin 8 of the chip. I found a couple of wires that were reversed and corrected that. Now to get to your question. I just checked and the light comes on, regardless of dial position when I ground pin 17 (board). I just tried it grounding pin 8 of the HA1196, and the light did not come on. I also (don't tell Mark) grounded pin 9 of the chip and the light still did not come on.

While checking per your request, I decided to jumper pin 17 (board) and pin 9 (chip), bypassing that resistor, and the light came on. It seems to work normal. with the jumper in place the light goes off when tuning and stays on when station is dialed in. I think maybe that resistor is open? What do you think?

Thanks for your help Pete.
Joey (Bubba57)
 
pin 8 should be at ground as per schematic .. so grounding it shouldn't make any difference ...this is what mark was saying earlier ...i just explained it differently ..
pin 9 is what becomes ground when a stereo signal is received thus lighting the lamp ..
without the ground at pin 8 the lamp cannot light .
and yes don't go grounding pin 9 again .. the chip may not like that ..
anyway reading between the lines ..remove the stereo lamp and check value of r40 180 ohms
 
Ok Pete. Thank you very much for your help. When I swapped them 2 wires, I must have done something to take out that resistor. It may be a cold solder joint too. I will look at this in the morning.

Thanks again and I will let you know what I find.

Joey (Bubba57)
 
PeteHall347,I didn't want you to think I forgot about you. I checked R40 and it is reading 177.35. I counted this as good. I then decided to flip the 066 tuner board over and the solder joint at pin 9 of HA1196, looked like something that come from the back end of a chicken. I resoldered this. I got to looking at the rest of the board and there was a dozen or so others that looked just about as bad. I reflowed nearly all of the board. In the morning I will put it back together and test it, and let y'all know how it turned out.

Question: I bought me one of the wire wrap tools for 22/24 ga wire. It works very well. However the only solid core wire I could find in this ga, is copper. I am concerned the copper may turn green down the road and start causing problems. What do y'all think? Anybody else reading this please feel free to chime in to, please. What type of wire (alloy) does Pioneer use for these wire wrapped connections? Where would a fellow get this wire?

I want to thank both you Pete and Markthefixer for y'alls help with this. It has been a blast. I am so proud to be a paid subscriber to such a high class club and nice group of guys.

Thank You
Bubba57
 
Bubba57 said:
PeteHall347,I didn't want you to think I forgot about you. I checked R40 and it is reading 177.35. I counted this as good. I then decided to flip the 066 tuner board over and the solder joint at pin 9 of HA1196, looked like something that come from the back end of a chicken. I resoldered this. I got to looking at the rest of the board and there was a dozen or so others that looked just about as bad. I reflowed nearly all of the board. In the morning I will put it back together and test it, and let y'all know how it turned out.

Question: I bought me one of the wire wrap tools for 22/24 ga wire. It works very well. However the only solid core wire I could find in this ga, is copper. I am concerned the copper may turn green down the road and start causing problems. What do y'all think? Anybody else reading this please feel free to chime in to, please. What type of wire (alloy) does Pioneer use for these wire wrapped connections? Where would a fellow get this wire?

I want to thank both you Pete and Markthefixer for y'alls help with this. It has been a blast. I am so proud to be a paid subscriber to such a high class club and nice group of guys.

Thank You
Bubba57
Click to expand...

As a rule, we don't unwrap wires. Once unwrapped the wires will break as each time the wire contacts the pin it creates a notch in the wire. If you need room, there are wire holders that you can remove the wires from that will give you the needed room.
 
It called solid core "hook-up wire" and 18 to 22 gauge is used.
If you like I can send you a few feet. I have two guy's life time supply in all colors and gauges.
 
Thanks Zeb, I am just going to use 22 Ga solid COPPER that I got from Radio Crack. I was concerned it may turn green in 10 to 20 years but what the hay, it's mine and I will replace it then. You being in Vegas and me in Phoenix, you know we ain't worried about the humidity causing corrosion any time soon. Thanks anyway and take care.

Bubba57
 
Craxx6969, thanks for the reply about this. I try not to disturb the wraps, as this group has taught me. I recapped the entire receiver without unwrapping the wires. I did end up breaking a few and had to rewrap them but it wasn't many. But I tell you what, I am a rather smart man, at least I think so. I've got almost a 10th grade education, fairly mechanically inclined and for the life of me I could not figure out how to flip that 066 tuner board in this SX-950 without unwrapping 3 or 4 wires. Then of course they were too short to rewrap so I had to replace the wires. That is what brought this up. Thanks again for your help and happy 4th of July.

Bubba57
 
Bubba57 said:
Craxx6969, thanks for the reply about this. I try not to disturb the wraps, as this group has taught me. I recapped the entire receiver without unwrapping the wires. I did end up breaking a few and had to rewrap them but it wasn't many. But I tell you what, I am a rather smart man, at least I think so. I've got almost a 10th grade education, fairly mechanically inclined and for the life of me I could not figure out how to flip that 066 tuner board in this SX-950 without unwrapping 3 or 4 wires. Then of course they were too short to rewrap so I had to replace the wires. That is what brought this up. Thanks again for your help and happy 4th of July.

Bubba57
Click to expand...

Bubba57,
I often wonder how to get at the bottom of a tuner without desoldering a few pins. It looks menacing.

Happy 4th of July. Peace out
 
craxx6969, You're right. That leads to another question. You can heat the pins, with the wrapped wires attached, but how do you get underneath the board te Re-solder the pins you just removed back in place? Actually there may be a technical reason not to, but unwrapping and rewrapping the wires is a piece of cake with the proper tool. I bought just one, for 22/24 gage and it was $40 I believe. If I done this for a living, or even a hobby, a few more times, and I might look for something POWERED.

Bubba57
 
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