SX 1980 fm issue

sendust

Music feeds the soul
Hi guys just received a SX 1980 and when i set unit to fm the dials move, tuning and signal strength work but no sound out of speakers, am works fine. the unit was just shipped so something may have shifted. Any idea what i should look at. ( the person i purchased from said it was working before shipment. thanks for any advice
 
Did you try turning the FM muting off?
You were right turning the muting off was the issue thanks. I also have the right side cutting out on all modes, the last time I tried, switching from fm to am made it come back, any ideas
 
A really good Deoxit cleaning on all switches and pots. Even if it’s only in the few switches concerning the FM - you should do all the controls.
 
Do yourself another favour and pull the bottom off it and see how scorched the regulated supply board is, SOP for these is to completely rebuild it if it is original.
It is a failure and weak point in these and if it hasn't failed it is surely going to sooner rather than later.
I would hedge a bet it has been repaired before...
 
A really good Deoxit cleaning on all switches and pots. Even if it’s only in the few switches concerning the FM - you should do all the controls.
I was told it was cleaned before it was shipped but i will clean with Deoxit D5 . I find that when it cuts out the tone switch affects it the most, or is the best way of getting it to return, im not sure if that info changes anything. Also i have a low hum coming through the speakers, I ran a wire directly form my electrical panel ground to the ground screws at the back but no change. not sure if that is normal for such a big receiver.
 
Do yourself another favour and pull the bottom off it and see how scorched the regulated supply board is, SOP for these is to completely rebuild it if it is original.
It is a failure and weak point in these and if it hasn't failed it is surely going to sooner rather than later.
I would hedge a bet it has been repaired before...
will do
 
This is what was on the listing before i purchased . Listed is a sx1980 that has been serviced and repaired. There were a few transistors, diodes, resistors and caps that needed to replaced on the power supply board which is prone to have problems. Of course I didn't use any of that nte crap some repair shops use to cut cost. The nte components are unreliable and prone to have issues. I used all premium parts(fairchild, on-semi, etc). The power supply voltages has been adjusted to factory spec and is stable. The bias and dc offset has also been adjusted to factory spec. All pots and switches were cleaned and lubricated.
 
This is what was on the listing before i purchased . Listed is a sx1980 that has been serviced and repaired. There were a few transistors, diodes, resistors and caps that needed to replaced on the power supply board which is prone to have problems. Of course I didn't use any of that nte crap some repair shops use to cut cost. The nte components are unreliable and prone to have issues. I used all premium parts(fairchild, on-semi, etc). The power supply voltages has been adjusted to factory spec and is stable. The bias and dc offset has also been adjusted to factory spec. All pots and switches were cleaned and lubricated.
Yeah all good to repair it, but there are things that need to be modified in order to give it some reliability, just repairing puts it back to square one where it runs way way way too hot and will fail again.
A couple of things are remote mounting the 80V and 30V pass transistors on the main heatsink, building the Current Source circuit which is well documented here, as the FET's in there are fairly stressed and are prone to fail. Also the relays really need replacing at this stage, and there is a mod to change them to use 24V relays instead of the increasingly difficult to get 48V relays.
I would hope all the caps have been replaced on the regulator board as well due to the fact that things get super toasty in there.....
Here's a pic of the one I did recently.., you can see the small transistors mounted on the big heatsinks in the first pic.
The second pic is what it looked like before I did the work on it..
So best to have a look anyway and make sure things are good...

IMG_4635.JPG IMG_4580.JPG
 
Yeah all good to repair it, but there are things that need to be modified in order to give it some reliability, just repairing puts it back to square one where it runs way way way too hot and will fail again.
A couple of things are remote mounting the 80V and 30V pass transistors on the main heatsink, building the Current Source circuit which is well documented here, as the FET's in there are fairly stressed and are prone to fail. Also the relays really need replacing at this stage, and there is a mod to change them to use 24V relays instead of the increasingly difficult to get 48V relays.
I would hope all the caps have been replaced on the regulator board as well due to the fact that things get super toasty in there.....
Here's a pic of the one I did recently.., you can see the small transistors mounted on the big heatsinks in the first pic.
The second pic is what it looked like before I did the work on it..
So best to have a look anyway and make sure things are good...

View attachment 1206568 View attachment 1206570
Do you know anyone in Montreal that is a member and can do this work, if not do you have specs etc for me to give to a tech? thanks
 
Do you know anyone in Montreal that is a member and can do this work, if not do you have specs etc for me to give to a tech? thanks
Of course I happen to live completely on the other side of the world.
There must be a reputable tech you can use in your area, the AK collective here will have the connections. There is a lot of information in this forum about it, I have a SX1980 folder with all the stuff you need to know.
It annoys me when people say "serviced" because in this case if it was there would be no original caps on that Regulated Supply board and the relays would be replaced. At least.
But hey you have a working SX1980 which is really cool but I strongly suggest investing a bit more into it and get the work done to the AWR154 board (regulated supply) with new relays, the rest of the amp you could do yourself in stages....
Maybe start another thread titled SX1980 Tech in Montreal or something like that.
 
Of course I happen to live completely on the other side of the world.
There must be a reputable tech you can use in your area, the AK collective here will have the connections. There is a lot of information in this forum about it, I have a SX1980 folder with all the stuff you need to know.
It annoys me when people say "serviced" because in this case if it was there would be no original caps on that Regulated Supply board and the relays would be replaced. At least.
But hey you have a working SX1980 which is really cool but I strongly suggest investing a bit more into it and get the work done to the AWR154 board (regulated supply) with new relays, the rest of the amp you could do yourself in stages....
Maybe start another thread titled SX1980 Tech in Montreal or something like that.
Thanks will try
 
I will add, after having a close look at those pics, your board doesn't look nearly as scorched as the one I was working on...

Give a shot, I can send you info if you have trouble finding it here...
 
It looks like it's been repaired. Q210? The positive side of the regulated 80 volt supply.
It doesn't mean its bad. If it's working :dunno:
There are plenty of ways of maintenance and money you could spend on it.
 
I will add, after having a close look at those pics, your board doesn't look nearly as scorched as the one I was working on...

Give a shot, I can send you info if you have trouble finding it here...
I would appreciate any info you can send me on any must need upgrades or which boards are critical to recapp
 
Do you have any thoughts on the hum . it sounds like a ground hum, i connected a direct ground to back of unit but no change at all, the hum is loud you need to increase volume on an lp to at least a third to drown it out, comes out of both speakers equally also the right side pops every once in a while.
 
Do you have any thoughts on the hum . it sounds like a ground hum, i connected a direct ground to back of unit but no change at all, the hum is loud you need to increase volume on an lp to at least a third to drown it out, comes out of both speakers equally also the right side pops every once in a while.
I would say, you're hum may well be originating from the power supply somewhere, none of those caps have been replaced, the phono board is another one that will need attention too.
The pops are probably transistors in the pre-amp, these amps are full of dodgy transistors which all need replacing...
It really needs a full restore, otherwise you'll be fixing one thing and then something else will go wrong. It will be in and out of service like a yo yo.......So might as well do the whole thing...
Especially if you intend on using it often.

I have a SX1250 here which is in for full restoration because the owner got sick of having it in for repair all the time, fix one thing two weeks later its something else....
 
The power supply voltages has been adjusted to factory spec and is stable.

FYI... There is no adjustment for power supply voltages. They are fixed.

The mute function should work. With the mute on you should get no static or sound between stations. You should get sound if you have some signal and your close to a station frequency.

Do the fine tune, quartz lock and stereo indicators work?

If you remove the pre amp to amp jumpers do you still get a hum?
 
I found a guy in Montreal that can recapp the unit, he works on vintage equipment and is an authorized repair shop for Pioneer. I feel its best just to have the entire unit redone.. thanks for all the advice.
 
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