Oh boy!.....got one!! Sx 1980!!!! Booyah!

YEEEHAAAAA!.........I was crappin' me'self with nervousness before I got the nerve up to test on full power. It seems all went well........immediately after the power switch was selected ON, the SS relay clicked.......5 sec. later speaker relay clicked!!!!!!!!!!!!!!!!!! Current sources are glowing green.
KAPOW............I am e-friggin-lated!.....................now I will turn it ON for some minutes and check voltages. I am just happy it don't blow up on me. I only had it on for about 20 sec..............

EDit: I tested for some minutes......all voltages are spec!!!!!!
 
Last edited:
I have the unit up and running..........after setting the DC-offset and idle current(went quite smoothly) for both channels......I proceeded to connect a cd-player(aux) and try the tuner.
All seems to be working.......on the RIGHT channel only. I swapped the pre-out/main-in jumpers around and still only RIGHT channel sound. I may have a slight problem on the LEFT channel. Any ideas? I'll look into it......

The tuner tuned.........but quartz-lock and stereo light never came on. Fine Tune light came on a few times. There was nice reception.
 
I'll respond with some good advice I received from MTF when I had a similar problem after fixing the protection circuit on my SPEC 4.

With the unit powered off, slowly go through and tug on all of the wires that you moved around as part of your repair work to check and see if any are broken. Takes only a few minutes to check before you get too deep into troubleshooting.

http://www.audiokarma.org/forums/showpost.php?p=6357748&postcount=27
 
That is good advice.......which I have followed.....I re-checked all wires with a tug and a prod...all are good.
I am quite certain it is a signal problem. The left amp gets nice and warm, exactly as the right side amp. DC/bias and heatsink-temp. are equal. Since I swapped the pre-out/main-in jumpers and the problem did'nt move, I suspect a problem in the left amp not getting signal.

The left power meter has no reaction either.
 
not really, that would put the amp "out of balance" and the outputr voltage to the rails. The signal has to be interrupted before the base of Q1. R1, C9, a foil or connection.

You can induce noise with your finger along that path to see where the sound restarts.

also check the pin 4 to amp in jack center terminal resistance - (close to zero means continuity) and pin 4 to ground (short = bad)
 
Ok Mark...will do. I will test pin4. I have continuity-tested that a couple of times with the amp OFF. Should the amp be ON? I was diagnosing for some hours today..........the unit was ON with FM or AUX selected.........I tested everything........checked everything over........then I tapped the protection relay. This caused the sound to become interrupted/fuzzy. I wiggled the relay a bit and was able to replicate it. The relay is brand new........
 
Just checked pin4......unit OFF.......amp in to pin4=continuity OK. Pin4 to ground 63k Ohm.....swings a bit...at least not 'OL'.

I also just checked R1.....2.21K ohm=OK. C9 was ok too.

The relay is looking more and more suspect.......................................
 
Ok...I dug into the PS again......checked the protection relay......whad'ya know.....a miniscule hairline trace from pin 3 to relay.........I fixed the trace....I now have sound in both channels! YEY!
Stereo light does not seem to be working even with strong stations.............
The FINE TUNE led glows red once in a while and the QUARTZ LOCKED green led comes on and off quickly.................

Is there a tr(Q11?) for the stereo led? Or does it run of the pa1001?
 
Here's a few pictures. Check out the little green 'eyes' starring at ya'! The unit has been running for more than 1/2 an hour now.........

Now I'll clean up all the horrible solder connections..........wash knobs/buttons/ faceplate. Polish up the wood again. Refinish-paint the top-plate.

The heat-sinks will be painted too................

Gosh....golly...and wazooo!.......a saved sx1980!:thmbsp:
 

Attachments

  • IMG_4412.jpg
    IMG_4412.jpg
    86.3 KB · Views: 61
  • IMG_4413.jpg
    IMG_4413.jpg
    67.6 KB · Views: 49
  • IMG_4414.jpg
    IMG_4414.jpg
    61.2 KB · Views: 45
The unit has been playing FM and AUX for some hours now........it gets nice and warm. No funny sounds, smoke, smell or anything.
I am not sure if it is due to the former tech 'operating on the tuner board OR my re-cap of the board, but the tuner doesn't seem very sensitive(compared to sx1250,kr9940). It tunes and holds stations fine with good sound, but the signal needle never goes past 3. And the tuning meter is always slightly of. I am able to get the FINE TUNE light ON(with a high pitch tone in the speakers, but QUARTZ lock just flashes green for an instant. The stereo light has not come on yet........maybe defective bulb? PA1001A?
Any ideas? I don't have advanced equipment for alignment procedures.
 
Is the FM in stereo? If not it might be the IC chip. Or a bad bulb if you have stereo.
 
Bad IC....shucks...I was hoping you wouldn't say that.....the bulb is an LED.....is the stereo light driven by the IC(PA1001)? Or does Q11 do something too...?
I think I may need a tuner cap cleaning too....CRC QD followed by Cailube......no spraying.

To me...it sounds as if I have stereo FM....just the bulb don't light up to indicate it. Quartz lock never really comes on.....it just flashes quickly on/off.
 
Last edited:
And thus starts the GODDAMN DISASTER. DAMMIT!!!!!!!!!!!!!!!!!!

ANYBODY THAT HASN'T ACTUALLY DONE SX-1980 TUNER ALIGNMENTS HAS NO BUSINESS GIVING ADVICE ON SX-1980 TUNERS,

IT IS A COMPLETELY DIFFERENT BEAST THAN THE LOWER MODEL TUNERS.

EVEN PIONEER DID IT DIFFERENTLY IN LATER MODEL LOCKING TUNERS.

Anders, as for the cleaning, others report that using WD-40 to clean the ground clips on the center shaft works. Those grounding clips are the source of tuning capacitor noise. It's brass on brass, so deoxit really doesn't seem to have much of an effect. PLUS there either seems to be corrosion products generated that are "wipeable" or Piomeer put on some sort of anti-corrosion goop that has worn out. So after the shaft and the wipers are clean, THEN use zero residue cleaner (plastic safe) to flush out the fins, after which you will have to relube the bearings without getting the lube into the rest of the cap...

Tuners ARE the hardest part of doing a SX-1980

AFTER all this is done, then an alignment can be done and expected to "hold".

Q11 does "something", it turns on the power to drive all three LEDS (stereo, tune and lock), the stereo led is driven (sunk actually - it provides the ground) by the PA1001 chip directly. If any of the three leds ever light, q11 is blameless.

REPEAT AFTER ME:

It needs an ALIGNMENT, there is nothing electronically wrong with the tuner.
It needs an ALIGNMENT, there is nothing electronically wrong with the tuner.
It needs an ALIGNMENT, there is nothing electronically wrong with the tuner.

got it?
 
Last edited:
Anders - your FIRST step with the tuner is to see whether or not you can get "clean dead air" on this tuner by taking a bare wire and connecting ALL the antenna terminals except the AM (on the end ) together, and that includes the half moon ground strap for the 75 ohm cable clamp.

Then you need a plastic hex undercut alignment tool. The following thread has parts sources and specs for the tool.

Read this thread AS A GUIDE!! Not explicit instructions

IN YOUR CASE: you only want to manipulate the LOWER slug of T1
AND
for the 1980, connect terminals (pins) 25 to 12 WITH A RESISTOR OF 4K TO 100K OHMS to make the tuner act more like a normal tuner.
 
Last edited:
Wow....."disaster' you say........I am pretty happy with my new 'disaster'! Everything apparently works as it should. I have done nothing to the tuner, except the re-cap. I am more nervous about what happened BEFORE I did my re-cap.

Anyway, I am happy to hear that there is nothing wrong with the tuner. The friggin' hard part is finding someone who can align it!

I thought WD-40 was a BIG no-no..........? But I get ya'.......drip wd40 on the shaft....flush out with non-residue cleaner(even the fins)........and the lube with Cailube(ONLY the shaft). That I can do.

The unit is playing 92.5 KISS FM right now.........it holds the station well and it sounds like stereo to me. AUX-wise the unit sounds fantastic!!!! Great power and clarity...I was playing some jazz yesterday....and the upright-bass sounded awesome! Piano was amazing too...........real 'goose-bumpy'-sound!

So...........................who in Singapore can do tuner alignment?.......Anyone?
 
Mark...I just saw your second post......I will try to do as you say...hopefully things will work...........but, I have no confidence with (alignment of) tuners. And then of course the sx1980 tuner is especially touchy.....................I'll try cleaning the tuning cap.....and then do what you mention in post #156.
Again...I am pretty happy that you say there is nothing 'electrically' wrong with the tuner. I just can't get a single peep from the stereo light.............even if out of alignment, shouldn't it pop on here and there?

I got the new glass glued in the faceplate....cleaned the face-plate/knobs.....it is startin' to look real nice now. I have sanded off the rust from the top-cover...and will be painting it today.
 
Last edited:
You CAN check continuity from the stereo LED to the board, and then to the resistor, the resistor itself and to the chip.

You can even disconnect the led itself and test it OUT of circuit.

BUT, IF the stereo led ever flashed in your sight, that proves it is ok.
 
It has never flashed. I will test the stereo-LED today. I also ordered the tool-kit mentioned in the other thread.

Now work is going to get in the way;-)......I'll be coming State-side to pick up some more plunder!
 
Back
Top Bottom