Need some help/input on repeating a Pioneer SX1980

Hi guys, long time lurker, but I finally made an account to post for some help.

So I'm finally getting around to trouble shooting my pioneer SX1980. Everything appears to work properly except I'm getting no sound. The speaker protection relays cut on as soon as I fire up the unit. So I got the service manual and started taking some voltages. I'm getting about 108v on the + rail of the PSU, where it should be 80. The - side is fine. Then I notice that the transistor q212 (c1318 written on the side) is literally broken in half.

So my question is, what are my options for repair? I know I need a new transistor, but are c1318 even produced any more, is there a drop in replacement, what other considerations should I take into account before I begin surgery? Before you guys chime in, I'm familiar with working with high voltages.

I'm no pro, but I know when to stop working on something if there is a chance I'm going to ruin the work piece or fry myself haha. So no worries, I won't hurt myself or this beast of a receiver.

Here's a link to some shots of the PSU board and a screen shot of the PSU schem. If any one needs a higher quality image of the PSU schem I can email you the .pdf
http://m.imgur.com/a/5Pa35

Thanks for any help guys.

Welcome to the forum,
I suggest that you look at this thread (and others) as it involves power supply issues , provides a list of replacement parts, hints etc
http://www.audiokarma.org/forums/showthread.php?t=631288
Good way to get to know other owner of these beasts.
Sounds like the series pass transistor is gone, possibly also the driver, the jfet as part of the constant current source(cc) is known to go too, so it needs a complete power supply re-build, with the CC source upgrade by user "echowars" or "mtf" suggestions. Search the forum for the bom lists etc.

I rebuilt my PS using the EW/MTF CCS's and the whole process went very smooth. It's not really a job for a novice. Not that I know what I am doing but there is some experience needed. The board is relatively accessible but will be flopping around due to the harness being attached to pins surrounding three sides of the board. A solder sucker is a must in order to prevent any butchery (Worth every penny considering the value of the set).

This is the bible for the restoration of the 1980:

1980 Thread

Page 5 is of particular importance to you as the CCS's are discussed, built and installed.

A possible candidate. Desoldering tool No affiliation!

Welcome to AK and good luck!!! You came to the right place!!!

One more thing. Don't turn it it on anymore until you are ready to tackle it.

The zener diode has the factory mod. Two diodes in series. Factory or tech afterward?

But HOW did the C1318 Q212 +80v regulator's feedback transistor get either broken or burned legs, and the R216 12k (brown red orange gold) 1/4w resistor looks burned.

Oh well... a 1/4 watt 12k resistor is at it's dissipation limit at about 55 volts, so 80 to 100 volts will fry it.

You have a sick board there and just a rebuild won't cut it, all the resistors have to be checked, and every semiconductor replaced - at least in the +80v regulator.

So, is that c1318's leads mechanically broken or burned?

You are definitely diving into the deep end to learn how to swim....]

Do NOT turn on the power again until I tell you it's ok, and THAT will take quite a while.

markthefixer said:

Do NOT turn on the power again until I tell you it's ok, and THAT will take quite a while.

Click to expand...

Can do boss haha. She hasn't been turned on since I took the voltage reading 2 nights ago.

As far as the diode mod goes, I can't be positive. I know my dad had a friend service it (local guy who has been running a stereo shop ~30 years) but I don't know the extent of the service.

From my dad recalls post servicing her used for a few weeks, then heard a loud pop, then the sound cut out. From what I can tell that "Pop" was Q212 literally exploding ha. Q212 is broken in half on my board. As far as the bubled resistor goes, I can't be sure if that is an artifact from the iphone cam or if it is actually burned out. Safe to assume it is burned out though.

So where should I start from here, repair wise. I think I can handle the project, skill wise at least. Cash flow may be a different story haha. Could you give me an outline of what the next steps are, and how will I know what all parts I'll need? From what I gather some of these transistors/fets are no longer in production.

I appreciate the help.

The first step is to restore the Power supply. All the parts needed are in the list on The thread I posted a link to:

1980 Restoration Thread

The part numbers are for Mouser Part numbers.

The CCS's Part numbers are on the link starting here:

CCS's parts and instructions

Reading the links I referenced is a must.

Mark is the expert on theses sets and that I'm sure is a understatement but I can help in getting you started in the process.

The recap list posted on page one, is for the entire set, so if you want to get the set up and running just order the power supply components. If you want to restore the entire set - order the whole list and save on shipping. Some items will require an order from other sources, like for the large filter caps. The whole restoration cost in parts will run close to $350.00. For just the PS, maybe $55.00.

Ordering the minimum quantity is not advisable. Look at the quantity discounts and order at least 10 of each transistor and ordering 10 diodes is equal to ordering 100, so look at the costs. Same when ordering the caps. You may need the extra for messing things up :yes:

There are two relays located on the PS board. One is the protection and the other is the softstart relay. The latter is no longer found but the Part number on the list subs a 24v in its place. There is a mod that converts the original 48v's to 24v's so the relay can operate. Its easy but careful connections are required. Ask questions if not sure!!!

Your going to need a DBT (Dim Bulb Tester) You can make one if you don't already have one.

You did the right thing by joining AK and posting the issue with the set. Don't jump ahead - only in research to understand what your steps will be. Even this post should be read by Mark to insure I am providing good advice.

I'll start combing my way through the restoration post in a bit. Gotta go cut my hair cut in a bit, I'm starting to look like a dirty hippie haha.
Thank the Lord for having all the part numbers and such already nice and played out. Makes the process of getting all the needed parts that much more simple.

If I remember correctly, I've checked out several posts by Mark in my days as a lurker haha. I'm glad to that he (and you) are on board to help guide me through this process.

A little modding shouldn't be an issue for me. Like I said, I'm no pro; but I know my way around the ole parts bin. Fingers crossed I won't burn anything out when I'm restoring the PSU, but I always pick up double what I need (at least on the cheaper parts) whenever I start a project.

I don't have a DBT, I'll do some googling on how to put one of those together after I get home as well, and maybe make a run to ratshack and grab whatever I'll need to piece on together.

Thanks for the official welcome, I feel like part of the squad now haha
I'm eager to get this started, but I gotta keep myself on a short leash. It's going to be a big under taking, and I need to make sure I know all sides of the problem and solution before I start prodding around inside this mammoth. Again, thanks for the help.

"jcsul", you are in good hands now, one way or the other you are going to need to replace parts (many of them). As mtf suggests this is not a piece of cake repair as it needs some mods too.
I made a DBT using a few electrical boxes screwed together. I included a bypass switch, so that I could switch in/out the lamp(in series with the load) and used another switch for line switching. You will need a 150W lamp too.
I am sure you have a decent DMM too.

I forgot to mention that you will probably going to order some resistors from Mouser, so wait to order until your preliminary inspection is complete.

I forgot about the toasted resistor(s).

Where do you reside or where is the 1980 located? Nearest city and state is good enough.

Zebulon: I pulled together a spreadsheet to do a BOM import on Mouser based on the post you linked. I noticed there were only a couple resistors on the list (used for the voltage regulation boards) so I figured I'd need to replace. I've got a DMM that can check resistance, so I can check each resistor to see which ones are ruined and which ones aren't.

The 1980 and I live together. We cohabit pretty well together, but the wife is getting about annoyed by the massive piece of "junk" taking up space in the guest room. I love in Hattiesburg MS, down here in the dirty south.

rcs: After a little googling, making a DBT will be pretty easy. I may try to add an ammeter and/or voltmeter along with it to make it a bit more useful. I have Fluke 117 DMM, pretty solid little guy as far as my knowledge of DMMs goes. Thanks for the advice.

The 117 is perfect!
Junk?????

zebulon1 said:

Junk?????

Click to expand...

Hey man, her words not mine haha. She would just rather sell it and get what its worth as is and buy a working receiver, as opposed to going all open-heart surgery like I want ha.
I love my 117. Nice and hefty, feel like a real piece of gear in your hands. Plus it does the job with no sweat.

I'll trade you for a beautifully restored sx-1250. I'll pay the shipping costs.
I'm not kidding! PM me.
Back to the Thread!

Once she enjoys HER music on the lady, she will no longer think of her as "junk".

Sure as shootin there's SOME type of music she loves to "CRANK UP"... lol...


here's a sample/example of the resistor lists I would have to enter, if you care to beat me to it. My "input data" so to speak:

(the spreadsheet entries get messed up by the forum display, I CAN accept a .xls spreadsheet by email instead of trying to post it and then subsequently inhale it - this is seven columns)

sx-1980 gwh-109 R21 RD1/4PS 393J NL carbon film 39K 1/4w
sx-1980 gwh-109 R23 RD1/4PS 393J NL carbon film 39K 1/4w
sx-1980 gwh-109 R25 RD1/4PS 242J carbon film 2.4K 1/4w
sx-1980 gwh-109 R27 RS1P 513J metal oxide 51K 1 WATT
sx-1980 gwh-109 R29 RD1/4PSF 221J carbon film 220 ohms 1/4w

sx-1980 gwh-109 R31 RD1/4PS 623J NL carbon film 62k 1/4w
sx-1980 gwh-109 R35 RD1/2PSF 221J carbon film 220 ohms 1/2 WATT
sx-1980 gwh-109 R37 RD1/4PSF 101J carbon film 100 ohms 1/4w
sx-1980 gwh-109 R39 RD1/4PSF 101J carbon film 100 ohms 1/4w

notice the line gaps, just like in the pdf...
(makes it easier to visually cross check)

never mind, I just did it... goofing off again... :sigh:

r211, r213, r214, r214 obsolete with EchoWars 2mA current sources. Harder to get because they were flameproof.
That leaves six flameproof 1/2 watt carbon film resistors.
Four 1 percent metal film resistors 1/2 watt

zebulon1 said:

I'll trade you for a beautifully restored sx-1250. I'll pay the shipping costs.
I'm not kidding! PM me.

Click to expand...

Ha I posted this on reddit as well and have had several people PM me offers to buy or trade. I feel like I may have to insight a bidding war :scratch2:
In all honesty this kinda becoming a family piece. It was my uncle's, then my dad's, and now it has been passed to me. If I have a change of heart I'll let you know. I do have an unopened Shure V15 though, looks I'll have to sell that or some plasma to finance components haha.

markthefixer said:

Once she enjoys HER music on the lady, she will no longer think of her as "junk".

Sure as shootin there's SOME type of music she loves to "CRANK UP"... lol...

Click to expand...

Ha she has a few records she likes to jam every now and again. I think she's just afraid to mess with the TT because she knows I'm particular about it.
Do you think I should just scrap every resistor on the board, or go through with the ole DMM and hit each to check and see if they're still throwing up the proper resistance? If some or all need to be replaced, there's a local electronics store in town that has a bizarrely broad range of resistors. So I should be able to find what I need there. I'll just print the service manual pages I need, unless you recommend a change in some of the resistor values. Online is cheaper, but shop local, local economy, mom and pop shop, etc etc.
Also, what should I do from here? Some time soon I plan on ordering all the components for a PSU rebuild. Aside from that am I clear to go ahead and begin removing all of the old parts from the board, or do I need to wait/do more testing before I whip out my old Weller?

I was scared you were gonna get this way... running off on your own without understanding the implications contained in the parts list without using the tuning fork guides to guide you....

wide ranging resistor replacements are NOT recommended.

counter help resistors are also not recommended. Not for this level of equipment.

I'm gonna have to recreate almost 10 years of posts?

here's my preliminary resistor work:
NOTICE THEY DO NOT YET HAVE MOUSER PARTS NUMBERS, AT LEAST THE MAJOR FACTORS HAVE BEEN GROUPED.

sx-1980 awr-154 r214 RD1/4PSF 220J carbon film 22 1/4w flameproof 5% obsolete w EchoWars 2mA
sx-1980 awr-154 r215 RD1/4PSF 220J carbon film 22 1/4w flameproof 5% obsolete w EchoWars 2mA
sx-1980 awr-154 r211 RD1/4PSF 101J carbon film 100 1/4w flameproof 5% obsolete w EchoWars 2mA
sx-1980 awr-154 r213 RD1/4PSF 101J carbon film 100 1/4w flameproof 5% obsolete w EchoWars 2mA

sx-1980 awr-154 r230 RD1/4PS 111J carbon film 110 1/4w 5%
sx-1980 awr-154 r218 RD1/4PS 102J carbon film 1,000 1/4w 5%
sx-1980 awr-154 r219 RD1/4PS 102J carbon film 1,000 1/4w 5%
sx-1980 awr-154 r226 RD1/4PS 102J carbon film 1,000 1/4w 5%
sx-1980 awr-154 r227 RD1/4PS 102J carbon film 1,000 1/4w 5%
sx-1980 awr-154 r206 RD1/4PS 122J carbon film 1,200 1/4w 5%
sx-1980 awr-154 r205 RD1/4PS 132J carbon film 1,300 1/4w 5%
sx-1980 awr-154 r229 RD1/4PS 132J carbon film 1,300 1/4w 5%
sx-1980 awr-154 r306 RD1/4PS 132J carbon film 1,300 1/4w 5%
sx-1980 awr-154 r207 RD1/4PS 152J carbon film 1,500 1/4w 5%
sx-1980 awr-154 r204 RD1/4PS 242J carbon film 2,400 1/4w 5%
sx-1980 awr-154 r208 RD1/4PS 332J carbon film 3,300 1/4w 5%
sx-1980 awr-154 r302 RD1/4PS 103J carbon film 10,000 1/4w 5%
sx-1980 awr-154 r307 RD1/4PS 113J carbon film 11,000 1/4w 5%
sx-1980 awr-154 r216 RD1/4PS 123J carbon film 12,000 1/4w 5%
sx-1980 awr-154 r217 RD1/4PS 123J carbon film 12,000 1/4w 5%
sx-1980 awr-154 r303 RD1/4PS 133J carbon film 13,000 1/4w 5%
sx-1980 awr-154 r201 RD1/4PS 223J carbon film 22,000 1/4w 5%
sx-1980 awr-154 r304 RD1/4PS 753J carbon film 75,000 1/4w 5%
sx-1980 awr-154 r305 RD1/4PS 753J carbon film 75,000 1/4w 5%
sx-1980 awr-154 r311 RD1/4PS 624J carbon film 620,000 1/4w 5%
sx-1980 awr-154 r310 RD1/4PS 155J carbon film 1,500,000 1/4w 5%

sx-1980 awr-154 r202 RD1/4PSF 3r3J carbon film 3.3 1/2w flameproof 5% 13v drop
sx-1980 awr-154 r210 RD1/2PSF 5r6J carbon film 5.6 1/2w flameproof 5% +80v drop
sx-1980 awr-154 r212 RD1/2PSF 5r6J carbon film 5.6 1/2w flameproof 5% -80v drop
sx-1980 awr-154 r209 RD1/2PSF 390J carbon film 39 1/2w flameproof 5% +8v to 5v apc drop
sx-1980 awr-154 r301 RD1/2PSF 222J carbon film 2,200 1/2w flameproof 5% +34v to 13v prot drop
sx-1980 awr-154 r309 RD1/2PSF 362J carbon film 3,600 1/2w flameproof 5% -34v prot drop

sx-1980 awr-154 r222 RN1/2PT 5102F Metal Film 51,000 1/2w 1% feedback dividers +80v
sx-1980 awr-154 r223 RN1/2PT 5102F Metal Film 51,000 1/2w 1% feedback dividers -80v
sx-1980 awr-154 r220 RN1/2PT 5902F Metal Film 59,000 1/2w 1% feedback dividers +80v
sx-1980 awr-154 r221 RN1/2PT 5902F Metal Film 59,000 1/2w 1% feedback dividers -80v

sx-1980 awr-154 r202 RS2P 332J Metal Oxide 3,600 2w 5% relay.coil
sx-1980 awr-154 r308 RS2P 332J Metal Oxide 3,600 2w 5% relay.coil

sx-1980 awr-154 r203 RS3P 470J Metal Oxide 47 3w 5% 8v drop

sx-1980 awr-154 r101 ACN-009 wire wound 3.3 20w 10%? soft start main load

markthefixer said:

I was scared you were gonna get this way... running off on your own without understanding the implications contained in the parts list without using the tuning fork guides to guide you....

Click to expand...

Don't worry, I'm eager not foolhardy haha. I'm not going to run off and do anything before I know exactly what needs to be done and why.
Also, I'll try my best not to drag you through the trouble of recreating a decades worth of posts ha.

What exactly do you mean when you say "wide ranging resistors"? I assume you mean the manufacturer's tolerance since most of the ones you posted are either 5% or 1%

Edit: I can probably convert all the resistor stats from the .pdf of the service manual to an .xls or similar format. Then add mouser part numbers/other source links along with that, and post it as well if you (or any on else) want it for personal use in the future or anything like that.

well, if you want to - I cant stop you

and I can compare your results to mine, maybe I'll farm some of my resistor work out to you. :thmbsp:

wide ranging resistors -
whatever the over the counter store sells you.
precise info may not be as forthcoming as with a huge supplier letting you make your own choices.

Once I get this current SX-1980 shipped, a small amount of the pressure will be off.

Haha I'll go ahead and get to finishing pulling the part #'s/links today at work. Shouldn't take too long honestly, I think about 9/10ths of what's needed will be available through mouser. I could be wrong though, wouldn't be the first time.

Sounds like you're swimming in 1980s haha. I guess there are worse situations to be in, that's for sure. Good luck with the current repair.

rebuild. perhaps restore, but remanufacture is closer to it.

only 3 resistors left, everything else done.