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SX-850 low voltage on dial lights

Things that make you go HMMM. Is R23 on the AWR-101 10Ω? Have you cleaned the FU6 fuse clips (deoxit) and put in a new fuse? I am scratching for answers now . . .
Power off. Pull the fuse out.
Measure the resistance of the winding, it should be just a fraction of an ohm, if your meter can go that low.
Measure the resistance of the lamp circuit to ground.
Power on.
Measure the output voltage of the winding with the fuse out, see what the unloaded acv is.
 
Shoot I just buttoned it all back up. I was thinking about how you said 8 volts was nominal but not an exact thing. No, I didn't deoxit the fuse clips. I did all the switches and pots when the boards were out. I didn't change the fuses. I didn't think they were bad if they weren't blown. I'm glad you gave me something to try though. I need to look at the fuses I have here to see if I have proper replacements. I need to pull one side of R23 to test it correct? When you say measure the resistance of the winding you're talking about putting the probes on each end where the fuse clips in right? Just want to make sure I'm understanding everything. The lights look dim to me but maybe it's not actually that dim? I'm used to looking at leds at this point. I still want to install leds so I want to figure out what exactly I need to do to make it work. I've been putzing around with the stereo all day. Need a break today. I'll check some stuff out tomorrow and report back. I took a photo of it in the dark. Problem is that the photo makes it look 3x brighter than it is.
20200613_195246.jpg
She isn't the best looking. Should be called Frankenstein at this point. Been searching high and low for a faceplate. It's not obvious in a photo but it's got a few battle scars.
20200613_191436.jpg
Thank for the help btw. I really do appreciate it.
 
You are welcome!
Fuse out.
To measure R23 put the red lead on pin 29, the black on pin 22 and it should read fine.
To measure the transformer winding clip the black lead to chassis ground and measure pin 24, (blue wire). The other end of the winding is grounded. This will also check for a grounding problem for the lamp circuit supply side.
 
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merlynski said:
You are welcome!
Fuse out.
To measure R23 put the red lead on pin 29, the black on pin 22 and it should read fine.
To measure the transformer winding clip the black lead to chassis ground and measure pin 24, (blue wire). The other end of the winding is grounded. This will also check for a grounding problem for the lamp circuit.
Click to expand...
Thank you for the clarification. I was a little off with my guess. I'll dig into it tomorrow. I'm just thanking my lucky stars that it sounds amazing. I had it at 3/4 full volume for about an hour with no issues except for the fact that I can't hear now.
 
Kinda looks normal for incandescent lamps. If you want it brighter stick some cool white T-10 LEDS in there. Joseph Mirabella has them. I use them all the time and brightened the dial scale and meters beautifully. These are 8v lamps you are looking for.
 
tsd71 said:
Kinda looks normal for incandescent lamps. If you want it brighter stick some cool white T-10 LEDS in there. Joseph Mirabella has them. I use them all the time and brightened the dial scale and meters beautifully. These are 8v lamps you are looking for.
Click to expand...
I ordered some cool whites yesterday. They are in my opinion the best looking led color for these stereos. The reason I started this thread was because the led lights I have here were fIickering while playing at louder volumes. I'm starting to think maybe it is normal for incandescent lamps but I was wondering why the voltage at the lights was not 8v.
 
merlynski said:
You are welcome!
Fuse out.
To measure R23 put the red lead on pin 29, the black on pin 22 and it should read fine.
To measure the transformer winding clip the black lead to chassis ground and measure pin 24, (blue wire). The other end of the winding is grounded. This will also check for a grounding problem for the lamp circuit supply side.
Click to expand...
R23 measured 10.1 Ohms. Winding measured .1 Ohm. Fuse that was in there was .2 Ohms. Cleaned fuse socket. Getting 7 vac when checked at light panel.

EDIT: pin 24 is getting power straight from the transformer. There it measures 7.5 vac. So it's already low before it goes through the fuse.
 
mstewart said:
R23 measured 10.1 Ohms. Winding measured .1 Ohm. Fuse that was in there was .2 Ohms. Cleaned fuse socket. Getting 7 vac when checked at light panel.

EDIT: pin 24 is getting power straight from the transformer. There it measures 7.5 vac. So it's already low before it goes through the fuse.
Click to expand...
That looks pretty normal. What is the winding voltage with no load? Pull fuse FU6, measure pin 24 for vac.

EDIT: If you look at the ac detector input on the protection circuit (AWM-062 pin 12) the schematic shows "AC 7.5v".

On the other schematics the blue lamp winding is typically listed as 7.5vac. Running an incandescent lamp at lower than max rated voltage (8v) prolongs its life, because it runs a bit cooler. Pioneer seems to do this a lot.
 
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merlynski said:
If you look at the ac detector input on the protection circuit (AWM-062 pin12) the schematic shows "AC 7.5v".
Click to expand...
There I am measuring 7.08 vac

This is a list of what I replaced on the protection board:

AWM-062: C1: .22uF 10v CSSA: 505-MKS2C032201BKI00 .22uF 63v
AWM-062: C2: .22uF 10v CSSA: 505-MKS2C032201BKI00 .22uF 63v
AWM-062: C3: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-062: C4: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-062: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWM-062: C6: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v
AWM-062:Q1: 2SC869: 2SC945A 512-KSC1845FTA
AWM-062:Q2: 2SC869: 2SC945A 512-KSC1845FTA
AWM-062:Q3: 2SC869: 2SC945A 512-KSC1845FTA
AWM-062:Q4: 2SC869: 2SC945A 512-KSC1845FTA
AWM-062:Q5: 2SA733: 512-KSA992FBU
AWM-062: Q6: 2SC945: 512-KSC2383YTA
AWM-062:Q7: 2SC1384: 512-KSC2690AYS

I also added a flyback diode between pins 9 and 10. Hopefully I didn't use the wrong one.
 
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mstewart said:
I was just about to say I realized you told me to check that yesterday. With no fuse installed the measurement is 7.75 acv.
Click to expand...
So you are 'losing' 0.25v under load. The fuse is rated 1.5A. 4 8v lamps rated at 0.3 amps each makes the lamp load 1.2A. The other two loads on that windings are too small to worry about, 47kΩ and 22kΩ in comparison. So R = E/I, 0.25v/1.2A = 0.2Ω. I don't see anything here out of line, no significant loss in the transformer.

From what I have seen on other units yours is behaving just like many others who's owners put LEDs in the lamp circuits. LEDs are intolerant of too low a voltage and will flicker at a rate visible to human vision. There is just no headroom in the voltage generated by that winding. If the new LEDs you ordered draw significantly less current than the incandescents you may have more options, including using a different supply source.
 
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merlynski said:
So you are 'losing' 0.25v under load. The fuse is rated 1.5A. 4 8v lamps rated at 0.3 amps each makes the lamp load 1.2A. The other two loads on that windings are too small to worry about, 47kΩ and 22kΩ in comparison. So R = E/I, 0.25v/1.2A = 0.2Ω. I don't see anything here out of line, no significant loss in the transformer.

From what I have seen onther units yours is behaving just like many others who's owners put LEDs in the lamp circuits. LEDs are intolerant of too low a voltage and will flicker at a rate visible to human vision. There is just no headroom in the voltage generated by that winding. If the new LEDs you ordered draw significantly less current than the incandescents you may have more options, including using a different supply source.
Click to expand...
It's good to know everything is looking normal. We'll have to see about these other leds. I just have to wait until I receive them. I'm all for making modifications that would get them working correctly if I experience the same issue. However, I don't have the expertise to work it all out. I would need some help. If I may ask you down the road if you could help me figure out a solution I would be very thankful. I already am thankful for your help along with the help of everyone who chimes in. Audiokarma is a great place with a lot of very intelligent people as members!
 
mstewart said:
It's good to know everything is looking normal. We'll have to see about these other leds. I just have to wait until I receive them. I'm all for making modifications that would get them working correctly if I experience the same issue. However, I don't have the expertise to work it all out. I would need some help. If I may ask you down the road if you could help me figure out a solution I would be very thankful. I already am thankful for your help along with the help of everyone who chimes in. Audiokarma is a great place with a lot of very intelligent people as members!
Click to expand...
Sure, glad to help!
 
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