A Couple Issues With SX 980- Indicator Lights- First

[zenarrrow]

So, when I power up my SX 980, Everything works good. I can tune into AM/FM play a TT use my CD player through the Aux inputs. I have recently used the monitor with a Bose EQ so every thing is working properly. 2 issues I will try and solve the first one before I move onto the 2nd problem.

The only Indicator light I am getting is the STEREO light, when indeed I am dialed in on a good FM station. When I flip into Phono 1, Phono 2 Mic, Aux, AM I get no indicator lights. (Main lamps, all 3 working)

Everything is running properly just no lights. Bulbs are fine as I have pulled them out and inspected them.

I notice that the Stereo Indicator blue wires are running to the Power Supply board (?) and all the other indicator light wires are running to GWS 125 Function and Equalizer board. (?)

Could something be awry with that board where all the other wires are running?

2nd issue (in case related) right power meter not operating (If not related I would like to address this separately).

 

[zenarrrow]

OK, so I checked DC power at pin 18 on the PS board, should be at 7.5v not showing any voltage to the best of my abilities. Any ideas friends?

 

[Watthour]

Check R18 on the PS board. Since the Stereo indicator works and you apparently have functioning FM, the13V power supply is obviously present.

 

[mattsd]

What is the voltage at pin 16? That will tell us for sure if it's R18.

 

[zenarrrow]

apparently have functioning FM

Yes I did check while the FM was on, and the stereo indicator was on.

I did, before hand, take out all the fuses and check them with the ohm meter, all are in good working order.

That will tell us for sure if it's R18

My understanding is 18 is the power supply to pin 5 on the Function and EQ board which too has no voltage. I will go and check 16. Just to be clear I am checking DC voltage, I assume that is correct, from what I have been researching. Thanks for stepping in and offering your ideas.

 

[mattsd]

Yes, DC volts. The indicator lamps run off of the 13v supply through a dropping resistor which is R18. If that resistor is open you lose your lamps. The same 13 volt supply also runs the tuner and the power meter drive circuit. I am assuming that the 13v supply is fine, but I'm making double sure so it doesn't come back and bite us.

 

[zenarrrow]

I will be disposed of until Monday when I can take a look at it again.

 

[zenarrrow]

Not that I am out of town or anything, but I have to work 12 hour graveyards until Monday morning at 6am.

This unit is important to me and it is out on my work table all stripped down to the skeleton of the unit. So I plan on working on it until fixed.
I am sure many people get this far into any project and retreat from the message board , but this is not the case.

Also while here I will take advice on any type of logical recap issues that I may address while in here.
So once again I do earnestly thank you guys and please know I will attend first thing Monday morning. Joe

 

[zenarrrow]

Alright, before I go to bed this morning I will run down and check the voltage on pin 16, How much voltage should I have going through on that? I will report my findings this afternoon hopefully if I don't wake up too late.

 

[zebulon1]

Around 8v

 

[mattsd]

On pin 16 you should have around 13v, pin 18 is 7.5v.

 

[zenarrrow]

Alright, pin 16 is right around 13v. 12.85 or so. So that is good. pin 18 still reading Zero. Joe

 

[zenarrrow]

Need I flip it on it's side and check the voltage from the bottom of the board? Or is checking from top alright?

 

[mattsd]

Checking from the top is fine. R18 is open, it is a 120 ohm 1/2w, replacement from Mouser is 660-MF1/2DCT52R1200F. How are your soldering skills? You will need to de-solder that resistor and solder the new one in. To get to the underside of the board you need to remove the two screws that hold it and then pull it off of the 2 plastic standoffs. You can pinch them using needle nose pliers and lift the board over them. Then the board is able to be flipped to get to the underside. If you are up to it, I recommend rebuilding the whole board with new caps, diodes and transistors.

 

[zenarrrow]

Soldering skills are good. I enjoy it and take pride in it. So, I will take another look at it and find the resistor . On the way to work now. So if I can again in the morning check it out . How to get to it and physically see what you speak of. Yes I may just want to replace everything on that board. Somewhere I saw a parts list. So until tomorrow or if too tired when I get home Sunday or Monday, thank so very much.

 

[mattsd]

Here is the full list for the power supply, caps, transistors and all the zener diodes. All the parts are from Mouser, you can copy paste the BOM list here and it will import all the parts into your cart.

Power Supply Assembly (AWR-156)

AWR-156: C11: 220uF 80v CEA: 647-UPW2A221MHD6 220uF 100v
AWR-156: C12: 220uF 80v CEA: 647-UPW2A221MHD6 220uF 100v
AWR-156: C13: 220uF 35v CEA: 647-UPW1H221MPD 220uF 50v
AWR-156: C15: 220uF 80v CEA: 647-UPW2A221MHD6 220uF 100v
AWR-156: C16: 220uF 80v CEA: 647-UPW2A221MHD6 220uF 100v
AWR-156: C17: 47uF 16v CEA: 647-UPW1E470MDD 47uF 25v
AWR-156: C18: 47uF 16v CEA: 647-UPW1E470MDD 47uF 25v
AWR-156: C19: 4.7uF 50v CEA: 647-UPW1H4R7MDD 4.7uF 50v
AWR-156: C20: 4.7uF 50v CEA: 647-UPW1H4R7MDD 4.7uF 50v
AWR-156: C23: 2200uF 35v Snap-In (10mm LS): 661-EKMH500VNN222MP3 2200uF 50v
AWR-156: C24: 47uF 25v CEA: 647-UPW1E470MDD 47uF 25v
AWR-156: C25: 47uF 25v CEA: 647-UPW1E470MDD 47uF 25v

AWR-156: Q1: 2SD712: 863-MJE15032G
AWR-156: Q2: 2SC1735: 512-KSC2383YTA
AWR-156: Q3: 2SA850: 512-KSA1013YBU
AWR-156: Q4: 2SB682: 863-MJE15033G
AWR-156: Q5: 2SD712: 863-MJE15032G
AWR-156: Q6: 2SC945: 512-KSC2383YTA

AWR-156: D8: MZ-140: 512-1N5244B
AWR-156: D9: MZ-130: 512-1N5243B
AWR-156: D10: LZ230: 512-1N4748A
AWR-156: D11: LZ230: 512-1N4748A

BOM List:

647-UPW2A221MHD6 | 4
647-UPW1H221MPD | 1
647-UPW1E470MDD | 4
647-UPW1H4R7MDD | 2
661-EKMH500VNN222MP3 | 1
863-MJE15032G | 2
863-MJE15033G | 1
512-KSC2383YTA | 2
512-KSA1013YBU | 1
512-1N5244B | 1
512-1N5243B | 1
512-1N4748A | 2

 

[zenarrrow]

I enjoy it and take pride in it

With that statement, please assume that I have done some and I am at the stage where I am still very slow but confident, I enjoy doing it and understand what issues may come from cold solder joints and take my time to do it right. I look forward to doing it.

Here is the full list for the power supply, caps, transistors and all the zener diodes.

Thank you so very much for taking the time and helping me out step by step, I cannot thank you enough. I am going to order the BOM list now and hopefully start on the project soon.

With that being said, should I undertake any other problem areas in this unit whilst it is open? Any other board to re-cap to improve sound per se? Or should I just concentrate on the PS board, and keep most of it orig if no issues? Thanks, Joe

 

[zenarrrow]

Mouser is 660-MF1/2DCT52R1200F

Oh no, looking through the parts list, I received my order yesterday. Was this included in the PS rebuild parts? I didn't think this would be separate from the order. Should have I ordered the list you gave me in addition to the that part?

 

[mattsd]

Yes, the resistor was supposed to be added to the list, the big list is the standard recap list for that board and did not include the resistor. I apologize, I should have made that clear. Let me see if I have one.

 

[zenarrrow]

No big D. I will order that, whilst I work on recapping the rest of the PS board.

When I do order it, should I order more parts do do another board? Or any other issues that may arise with the SX 980?

I should have checked to make sure that that part was part of the list. Thanks for the quick response, Joe