Firing up an SX 1980 after recap - Need Help

JohninOOB

Active Member
I've been lurking in the background for months reading, researching, and learning a ton and decided to take the plunge and recap my SX 1980. I've followed to a tee advise and direction from the likes of EchoWars, MarktheFixer, matted, and many others and it finally came time to put it to the test. The mods I did were all on the PSB with EchoWars Current Sources (his design), and new relays (LY1-0-DC24 & MY2-02-DC48) with the jumper wire running from the + of the 3300 cap to pin 2. The Sources were tested good. All caps on all boards were replaced and the receiver put back together except the amps are not hooked up. I left those unattached in case something happened. I finally bit the bullet and did the DBT with 100W, 150W, and 200W bulbs and sadly to say all were bright. :thumbsdn: Things I noticed are neither relay kicked on. Nothing, however I did notice the Current Sources light up briefly for about a second before turning off. I turned off the DBT and turned it back on and the Current Sources lit back up for the second then off. Nothing else was noticed, no pop, no smoke, no lights, no relays kicking on. I checked for loose wires everywhere and found none. I suspect the S1 relay even though it's been replaced but who knows. I'll will be honest and say my electrical experience is limited. I can read schematics, do all the mindless mechanical stuff but when it comes time to actual troubleshooting I'm lost. I know this is not the best way to introduce myself and I apologize but for those of you that know this unit well I would certainly appreciate the help. Thank you to those who are so generous with your expertise! John
 
number one: the parts lists have 24 and 48v relays on them.
you used LY1-0-DC24 - what did you do about switching the circuit over from 48v to 24v, link us to the directions you followed. Did you remove R102 3.3k, (fabric covered usually) up by the big 160v caps, it has another 3.3k R368 right next to it. Because adding the wire to the 3300uf cap from pin 2 and not removing R102 would cause the two power supplies to fight. I usually pull the resistor, use one of the holes for the wire and the other end of the wire goes to the 3300uf cap's + terminal.

if that doesn't get it:

number two: with it dropping out after a second, I wonder if the primary wiring around the soft start relay is a bit scrambled.

what did you unhook to get at the bottom of the power supply board?
I need both wire color as well as the pin number.
 
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Hello Markthefixer,

Thank you for the reply. I did indeed remove the R102 resister. I ran a wire from the pad connecting to pin2 and over to the + side of the large 3300 cap. The directions I followed were from both you and Mattsd's recap list.

Mattsd: "S1: Relay (Soft Start) ASR-046: 653-LY1-0-DC24 (Achtung! Using this relay requires you to remove R102 and run a jumper wire from the + terminal of the 3300uF 35v axial cap over to the pad of R102 that connects to pin 2. Be very careful, if you put it to the wrong side of the R102, you will short the 24v supply to the 100v supply. Not good. To be extra safe, you can just remove R102 and connect the jumper wire straight to pin 2)"

http://www.audiokarma.org/forums/showthread.php?t=440844

Markthefixer: "653-LY1-0-DC24 soft start replacement, 24v version where I remove one resistor (r202 3300 ohms 2 watts ) and take a wire from the resistor pad TO the 24v at the positive (+) terminal on the big low voltage capacitor c203 3300uf 35v"

http://www.audiokarma.org/forums/showthread.php?t=378925&page=5

One thing that confuses me is I never ran a "jumper wire" from post to post on either relay which is what I read somewhere in the posts. I can't remember which one but I snipped two posts off one of the relays because there were no holes in the PCB. It was a while back so I don't remember. Looks like I'm going to have to pull the board again and see. Speaking of, I did not disconnect any wires while doing the PCB. It was a bear but I managed without cutting, disconnecting, or overly stressing any wires. I have the original relays that worked fine. I'm tempted to put those back in but would rather not if I can fix whatever is ailing me with these new ones. If it is in fact the relay(s). Thank you! John
 

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Without analysis, just commenting, the S1 soft start relay shorts across the 3.3 ohm 20 Watt resistor, so if it does not operate, I can't see the power disappearing after a few seconds.

What are the chances that someone rearranged the connections to pins 26, 27, 28?

One thing you said has me leery: snipped off two posts. The S1 relay mounting area has a hole in it to accommodate the normally closed pin. The protection realy doesn't have holes for the normally closed pins.

also check the clearance between the relay tops and the bottom plate, It's usually close, use a straightedge across the bottom of the unit.


I also want to look at the current sources a bit more carefully. Tell me about them.

have you seen my posts (#73, 75) in this thread: Pioneer SX-1980 recap and restoration thread!

edit - I fixed the erroneous R202 and made it R102, must have been a typo, luckily in all my posts I did it just the once...
 
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Sorry to see the amount of users that tackle a SX-1980 (or any other device) re-furb keeps growing and admitting that they can't read a schematic, is depressing. Also the fact that locally they can't find anyone/experienced technically, that are local & capable of sorting out the mess. The biggest problem is for these owners, is to have to ship for qualified repair (very expensive/risky) or re-sell the units when they wave the white flag = monkey.
MTF, your head banging man is right on the mark :)
What to do with these folks?
 
I stand corrected when I said I did not disconnect anything. When you mentioned pins 26-28, I noticed the AC power outlet on the back plate came into play. After re-assembling the PSB I replaced the original outlet that was crumbling with one I picked up online (off a 1980 parts unit). I checked the continuity between hot and cold on the new outlet before installing and re-soldered the wiring. I doubled checked the wiring with the schematic and as far as I can see all looks good. The only thing that concerns me a little is one leg of the .01uF capacitor between the outlet and the 15 amp fuse is crumbling a little bit, probably from over stressing from moving it around, but I don't think that affected it where it won't work properly.

For the relays, I can't recall which pin(s) I snipped but I seem to recall it was a spot that had no foil and I felt comfortable at the time doing it however perhaps it rendered the relay useless(?) I was hoping I may be able to test the relay(s) without removing the board but if that what it takes I can do that. I wish I had taken more pics when installing those.

The Current Sources were made per instructions from the link you sent ( I copied Overundr1's design), checked both with a 9V battery (good) and also checked out at 2.2 DC. I installed them per your diagram, also in the link. The pics show the connection points I used to do the install. The small black dots on he ends of the boards signify +.

I also wanted to point out I installed the 35V zener retrofit which is shown in one of the pics This is done for both positive and negative. To be honest I've seen in posts these installed where I have them and also right next to it instead. I hope mine is correct.

Clearance between the relays and bottom plate are too close for comfort. About even with the plate so any plate deflection and they will contact. I have not installed the plate yet but I will need to install some sort of spacer to keep the plate from contacting the relays. I have something in mind but that's easy stuff, mechanical…right up my alley.

One more thing I wanted to mention is I double checked my DBT and all looks good there (120V) and I checked voltage at the AC outlet (with the DBT-100W bulb) right where the wires connect and it was 20V. Does that make any sense? At this point I'm not making any moves unless directed otherwise.

Update: My curiosity got to me and I pulled the board out just far enough to see the underside of the relays. The S1 is plug and play. I did some continuity checks from relay posts to pins and all looked good however there was a slight gap between the bottom of the relay and the board so I re-soldered to fix that. The two pins snipped looked to be on the S2. The two pins far opposite the philips screw. I would post pics but I'm maxed out on those. Thank you again!
 

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I have never worked on or touched a 1980, so I only can go by the docs and pics that people post. I suggest you PM user "Omri', that way you guys can cross check each others units and also share ideas, since I believe you both have similar tasks to accomplish.
Also user "pognoot" has a hurting unit, is major bummed out, can't blame him, and can't seem to get anyone to fix it for him.
 
I have never worked on or touched a 1980, so I only can go by the docs and pics that people post. I suggest you PM user "Omri', that way you guys can cross check each others units and also share ideas, since I believe you both have similar tasks to accomplish.
Also user "pognoot" has a hurting unit, is major bummed out, can't blame him, and can't seem to get anyone to fix it for him.

Hey Rick, That's not fair, his last post in that thread is 3/20/14 - leaving at:

Hey guys, I decided to pull the plug because the issues at hand were beyond my skill level and it got to the point where the endless trouble shooting was no longer an enjoyable experience for me. After 6 months of having opened up and it pieces, I was ready for a functional receiver to listen to music. After all, that's what it's about.

I want to extend my thanks to Rick, Mark, and Glenn for your help here.. THANK YOU. You guys are great.

Absolutely, no different than restoring a classic car. There's some things you can do, and other things you can't...

The unit is currently with a guy named Bruce at Bob's Electronics in Lakewood. I should have an estimate by Friday.

and NARY A WORD about it in any of his subsequent AudioKarma posts, you know something we don't?
 
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edit - I have been thinking this backwards. Try removing the relay coil power to S1 and see what happens - run it only for a minute or so because the big resistor will start to heat up. That is the extra wire going over to pin 2 from the + side of the 3300uf capacitor.
I think a possibility is that the relay might be shorting out the transformer instead of the surge suppressor resistor after it's charging delay, should the wiring be a bit scrambled.

If that has happened, the DBT has saved the relay contacts and the 12 amp fuse.


That height thing has been a pita for me too. If the board supports didn't have such a weird mounting strategy, I would have found and recommended some about 2mm shorter because the board usually does bow in that far with the central mounting screw when tightened.

I shave the pins with a dremel tool to get rid of the metal shoulders and bottom nubs on the relay, pictures to follow, gotta take one off a finished, boxed board, but the record will be valuable... eh, I already have them, did them as I did this separate board.

The one relay cover did not fit tightly to the base, there are internal adjustments needed to close up the 1-2 mm gap.

attachment.php
 

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That's interesting grinding down the relays. I should do that considering I have the board pulled out a bit. I'm also very glad to see my relays are the same. It looks like you snipped the 2 on the Protect relay as well. Also noted was you left off the taped on magnets on the Protect relay. Not needed on these? I kept them on mine but will remove them if not needed.
 
The magnets WILL go on, the factory went to the trouble of installing them, I'm not going to argue. DC high current arcs are hard to quench, BUT since they are highly magnetic, they bend just fine.

It's just that this board when it came in, didn't HAVE magnets to transplant. YET, when it goes to the place it is intended if there isn't magnets on that relay to scavenge, it will get some rather powerful ones.

I use locktite superglue.

Grinding takes some careful planning and fancy footwork with the dremel tool and a thin abrasive disc.

PLEASE look back to that post I added in something to try at the top:
edit - I have been thinking this backwards. Try removing the relay coil power to S1 and see what happens - run it only for a minute or so because the big resistor will start to heat up. That is the extra wire going over to pin 2 from the + side of the 3300uf capacitor.
I think a possibility is that the relay might be shorting out the transformer instead of the surge suppressor resistor after it's charging delay, should the wiring be a bit scrambled.

If that has happened, the DBT has saved the relay contacts and the 12 amp fuse.
 
Hello Mark,

Just a quick update. I have not yet disconnected the 24V supply but because I re-soldered the relay I wanted to re-check with the DBT to see if that made any difference. It did not however I did notice the 4 main illumination lamps did light up VERY dim. I didn't notice it before because of daylight but I could see them light up in the dark and stay on. At this point I'll go ahead and disconnect the jumper wire and see what happens. Updates to come.

Update: I disconnected the jumper wire from pin 2 to +3300uF. Ran the DBT and I get the same results. The Current Sources light up for a second then turn off and the 4 main illumination lamps glow. I ran the DBT for just a few seconds cause I didn't want to burn anything up.

BTW, thank you for keeping the instructions in layman's terms. Engineer I am, only mechanical, not electrical :)
 
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WHAT WATTAGE are you running on the DBT? 200?

Is it a single voltage unit? No switch in back with extra wires to the transformer?

and what's about this "maxed out" on pictures? maybe for one post, but not in the thread.

get some pictures of your DBT wiring. I am starting to get into the "trust nothing" mode.

I'm also going to have to dig out mt deep documentation on the SX-1980 line power wiring.

plus, what about the amplifiers, are they completely disconnected?
 
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When I first tested I used 100W bulb which stayed bright, moved to 150, then 200. Same results. During the last two tests (re-soldering the relay and with jumper disconnected) I went back to 100W. Same results only that is when I noticed, in a darker environment, the 4 main lights glowing ever so dim. Same results with the Current Sources, on then off.

My receiver is a single unit. No switch in back.

What I meant by "maxed out" was the number of pics per post.

The amps are completely disconnected. All 4 places per amp.

While I have the board out a bit I thought I'd snap a couple shots of the AC wiring and what pins they are attached to. The outlet was replaced so I thought you might want to verify the connections. I double and triple checked that but it's always good to have another set of eyes check it. Also wanted to mention the ground clip you see on the resistor was attached to the chassis during the test as was the other on the top end of the PSB.

I know I'll say this a million times but thank you for your help.
 

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ok, without going deeper yet, going back to the 100w bulb wasn't the best idea, stay with 200 watts or more. 150's tend to be marginal for 1980's, causing rather than solving problems.

also, the dbt socket has two links between the upper and lower sockets, you show one side chewed away, is the other side removed as well?

so please try the 200w lamp (if you can - it looks rather disassembled lol)
 
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OK. I ran the DBT with the 200W bulb and I got the same results as before. The only difference I saw was the Current Sources were a little brighter when they came on (then off). The main lamps "looked" to be just as dim as with the 100W bulb but that could just be my eyes. Incidentally, the pin 2 jumper wire is still disconnected. Should I connect and try again? I'm not sure it will matter because I ran the 200W bulb with my initial test. I will however continue to use the 200W bulb for all future tests. Also, I tried running the DBT with a simple desk lamp and the lamp lit up and the DBT bulb was very dim so assume the DBT is working properly.

Also, you asked about the DBT outlet tab shown cut, it is also cut on the opposite side.
 

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try dbt with pin 2 disconnected on 200w
edit - whoops it IS disconnected.

OK, the output transistors are still connected. The bases and emitters should be "floating". IF they are all good, they will not conduct current.

I am vacillating between removing the connections to the output transistors completely and grounding the emitters and bases to be sure they are completely shut down - BUT if there's a fault with the output transistors that wouldn't help.

SO, the easiest thing will be to disconnect the secondary AC input to those two rectangular rectifier boards on the bottom.

On the left side it is the gwr-106 board, pins 3 and 4 violet STRANDED (not solid) wires
On the right side it is the gwr-107 board pins 7 and 9 red STRANDED (not solid) wired.
It would be best if you can desolder the pins from the boards.
INSULATE those pins & wires when loose, all hell can break loose if they short, and I don't think you want to get hit by them.


Did you change the big beer can sized capacitors?

if you did were you VERY careful to install the ground bar on them with one negative terminal and one positive terminal ?
The terminals on the originals have
the red wire going to a plus, the negative is grounded,
and
the white wire going to the other big cap's NEGATIVE terminal with that cap's POISITIVE terminal grounded at that heavy bar.

now, viewing from the bottom of the chassis:
on the left side gwr-106 the red wire is on the cap closer to the faceplate and the white wire is on the cap closest to the back .
on the right side gwr-107 the WHITE wire is on the cap closer to the faceplate and the RED wire is on the cap closest to the back .

these are from my sketches.

If that doesn't bring it up continuously, then I dig out the AC wiring sketches and try to convey them while checking your posts.
 
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BINGO!! See anything wrong with that second picture? The large filter caps, that were indeed replaced, have the ground bar running across BOTH negative terminals of the caps. I corrected this and will run the DBT again. My concern, if this works, is I need to discharge the big caps before I stick my fingers back in there which I'll need to do to button things back up. I take it this can be done by running a resistor or bulb across the red and white terminals of each rectifier(?)

UPDATE: Reconnected the jumper. DBT PASSED!! :yes: 200W dimmed way down and the S1 relay kicked on immediately. The Protect relay kicks in after about 7-8 seconds.

The Current Sources are constantly glowing and the main lamps are bright and steady. Disconnected the DBT and ran full power with no issues. At this point I will wait for feedback on the next step. I still have to button things back up but I'm leery of those big caps now that they are juiced.

Took some voltages:
Pin 18 = -76.5
Pin 17 = +77.5
Pin 9 = +34
Pin 8 = -28.8
Pin 13 = +12.8
Pin 14 = +12.8
Pin 16 = +7.6
Pin 15 = +4.7
Pin 6 = +.02 (amp not connected)
Pin 3 = -.02 (amp not connected)

Regarding the amps, those were recapped as well and I also changed out the pots to the ones on the recap list. I have not messed with those but I assume I can set the Idle Current all the way CCW and the DC offset to the middle to do the DBT with those? Again, I'll wait for further feedback.

THANK YOU!!

Kids, please make sure your big caps are in correctly.
 

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<good natured LOL..>

hold off on disconnecting those boards I mentioned.

idle current pot to ZERO measured ohms. halfway up for DC offset pot.

Find and read up on "tickling the dragon".

I have company over, but was doing a quick check...
 
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