Problem with my SPX90

[thomasdf]

Hi all

I'm a long time reader of this forum, and a newly registered member, from Paris, France.
I bought a Yamaha SPX90 yesterday for about 30€ in a garage sale.
The thing is... it doesn't work haha
So here's a few pics and measures I made in order to ask you guys help.

When it's turned on, nothing happens on the screens and the vumeter lights up completely (the input in on 0 and nothing is plugged)






Any idea of what could be the problem?

Many thanks

Thomas

[Steck]

Okay, the low-hanging fruit would be:

1) If you have a voltmeter, check the power supply voltages. This is easiest done without service docs by looking for either labeled "test points" that are labeled as such. *or*....

If there's no labeled test points, look for integrated circuits that are commonly available. for example 4558 or or TLO072 or LF356 or 4052 chips (there's many beyond this), which have standard pin-outs. See one of the sticky posts on this this board for a site that has this type of info. (I have one of these, but I've never popped the cover, so I can't give you specific places to check).

2) With the power off and the unit unplugged, verify you don't see any electrolyic caps that are "bulging" or "puffy" (note to self, need some pictures!). If that's the case, they could be shorted out, and causing the difficulty. To repair them, if you can still read the writing on the case of the cap, you can obtain replacements, then desolder the old ones and put new ones in. (Hopefully that fixes the problem....) (do you have experience soldering and desoldering? If not, you're going to need help from someone).

3) With the power off and the unit unplugged, push down on every integrated circuit, and make sure they're fully seated. They can "walk" out of the socket with repeated power-cycling (going from cold to warm and back).

4) With the power off and the unit unplugged, unplug and replug every connector that goes between all the various boards and assemblies in the unit. Be careful, as some connectors such as the flexible circuit board type, are tricky, and easy to break.

There's folks selling service manuals for audio gear on eBay, if you're not able to find anything else. That'll help because you'll then have a schematic, and perhaps a block diagram, and so forth.

HTH

John

[thomasdf]

Thank you for your answer Steck. I'm fine with soldering and got all of your informations. I'll give it a look tomorrow and will keep you updated!

As far as the chips are concerned, I'll try to find databases on the internet, and then check every of them.

I was thinking that this may be a common or known failure on this piece of gear, but it appears it's not!

To be continued...!

edit: I found this : Yamaha SPX-90 Display/Sound Issues seems like I'm not the only one Anyway.

[Steck]

You're welcome.

Here's the link to the topic here about chip mfg data sheets.

The unit I have is second-hand, and right before I got it, the prior owner had to replace some of the electrolytics caps in the power supply. I don't know what the visual symptoms were, but whatever it was, it didn't work!

John

[necromunger]

i have a spx 90mk2 which i got for free about 10 years ago with the same sort of problem.

with mine the screen was flashing on and off and the guy that gave it me said it needed a whole new psu and it cost more than it was worth to fix it so i got it for free.

took it to my tec guy and he fixed the psu that was in it for £30

still works to this day.

[thomasdf]

is psu a power supply? the guy who sold it to me said it needeed the power supply to be fixed... But I don't see what's wrong on it.

Well, thank you guys, I'll tell you more about it tomorrow, it's about time to go to sleep here in Paris

[Steck]

Originally Posted by thomasdf

is psu a power supply?

Yep. "Power Supply Unit".

[mjrippe]

Yamaha used a strange sort of switching power supply in the SPX90. I have one that was totally shot when I got it. I tried cleaning off all of the brown gunk that appears on these and re-capping it, but it still didn't work. I am simply replacing it with a linear PSU. All you need is +/- 18 volts and +5 volts.

[thomasdf]

Thanks!

mjrippe, do you know where I could find one of these psu?

Every chip looks in its right place!

I just had a quick look at my SPX90 psu and it appears that 2 capacitors where taken off... C21 and C23.

Pictures





I'm now looking for someone that can tell me what caps I need to buy to replace those two. May that be my problem?

[mjrippe]

Well, yes those missing caps could be the problem, or just part of it. You see the brown crud around them and other components? All of that has to be removed. Also check all of the diodes and caps and replace if needed.

[thomasdf]

Mmh...

I thought that brown stuff was some kind of glue or whatever. Ok, I'll remove it all. Should I change all the caps and resistors that have that brown thingie at its base?

If anyone can open his SPX90 and give me the values my 2 missing caps, it would make my day!!

[mjrippe]

Oh right, the cap values!

C21 = 470mfd/25v

C23 = 1000mfd/10v

It would not be bad idea to replace all the electrolytic caps.

You can download the entire service manual by following the info on this page: SPX90 Schematic It does not have a lot of PSU info, but it does have schematics.

[thomasdf]

awesome! many many thanks mjrippe!
I'll have a look at that next week and sure will keep you posted

[thomasdf]

Sorry for the delay.
I have found the schematics and manuals, I unsoldered all of the caps that are dead, I need to find replacement ones now. I will go to my local electronic shop asap and will solder them in order to fix the psu.

To be continued!

[S2udio]

I would start looking at FR2 first...looks like a fusible resistor to me .
How do you know the caps are dead.......
Of course replacing them is a good move especially the missing ones !......
Funny how many so called techs nowadays always shout
"Its the caps"
Its an SMPS ...so watch you fingers stike

[thomasdf]

I had noticed that most of the caps from the PSU had that brown stuff coming out of them, so I took them out, cleaned up a bit and I now need to replace them.

FR2 seems fine, not burned or anything.

I need to find an old tooth brush and some nail polish remover to get that PCB perfectly clean. It has a some grease/weird/rust/dirt stuff on it.

I dunno what that the previous owner did with this unit...!!

[S2udio]

Originally Posted by thomasdf

FR2 seems fine, not burned or anything.

Well thats as maybe did you measure it with a DMM
Expect a low reading on ohms with one end lifted

There is common misunderstanding that if its not burned or
broken its alright.......not so most of the time !

[thomasdf]

Ok, I'll check it then because I just finished soldering new caps, replacing a resistor dans was lookin bad.
I plugged and turned the unit on, and it's still the same. No sound coming out of it, and the vumeter is lighten all the way up....

[aramism]

i have this same problem with my spx 90.... happened 2 days ago.

help? lol

[thomasdf]

not yet but I am hangin out with a techie that should sort it out.

do you have the exact same problem? or just the vumeter and screen thing? Does it come from your PSU?

[Radardoug]

The brown stuff does not come out of the caps. Yamaha glued them in when they assembled the unit. Having said that, the first thing I would do is replace them.

[thomasdf]

mine is now working perfectly the problem came from L5 which was dead.
I changed it and the unit is bangin

edit: schematic uploaded (european model)

[aramism]

i'm having the same issue with mine. it doesn't fully turn on. just the meter is constantly lit up but nothing else turns on or works.

am going to follow all the diagnostics here and see how it goes.


question though, if it ends up being the power supply. can someone help me determine which is the right psu to purchase for it?

[Ike Zimbel]

It's not a separate supply, it's built-in. So you will need to fix it, or get it fixed if that's beyond your level. BE CAREFUL, there are lethal voltages in that part of the unit.
best,
Ike

[aramism]

thanks for the heads up. luckily it didn't get to that. just by cleaning some of the brown stuff it was able to work. sometimes still is a bit fidgety but it still works and sounds find.

thanks

[aramism]

ok it stopped working again!!!

thomasdf did you manually check each cap and resistor and part with a meter to make sure it was working and then find the l5 as the faulty one???

i have the exact same issue as you.

[jumunius]

Originally Posted by aramism

thomasdf did you manually check each cap and resistor and part with a meter to make sure it was working and then find the l5 as the faulty one???

I guess you might have fixed a problem by cleaning off the brown gunk, if maybe the cap had leaked a bit and the leakage caused a short or something. I think the brown gunk is just aged glue and not necessarily a problem. Cleaning it off and chipping it away is nevertheless a fine idea.

I found myself with 4 dead SPX90s and fixed them all the same way: simply replaced all the electrolytic caps in the power supply unit. Even if a single cap is the culprit, those caps are pushing 30 years old and ready for a change.

For that matter it doesn't hurt to recap the whole thing (electrolytics only, that is). Particularly those around the inputs and outputs.

But as Ike warns there are lethal voltages in there so if you don't know what you're doing, learn how to discharge a cap before you get started.

[aramism]

jumunius,

yeah i'm gonna try that as well. the first attempt i made with the cleaning of the "brown stuff" made it work for like a week then the same problem came back. so now i guess i'l try the recapping thing.

my question still stands for thomasdf as far as the procedure he used to test and change.

[Ike Zimbel]

It's not the brown gunk, which is just some kind of glue. The problem is almost certainly a broken/ cold/ dry solder joint that you are temporarily "fixing" by moving the caps around while trying to clean the glue off. One trick you can try is gently rocking the caps back and forth in the direction of the leads. Use the band marking the negative end of the cap to get your bearings...you should be rocking the cap towards and then away from the band. A cap with a broken solder joint will rock, that is, come up from the board on the loose end. Note that ALL the caps will rock from side-to-side, so make sure you are going the right way. Re-capping the unit "fixes" this problem because you are making new solder joints when installing the new caps. It's not a bad idea to re-cap, but may not be necessary. Yamaha used good caps...I have very, very rarely come across a failed cap in a piece of Yamaha gear, but I have seen lots of broken solder joints because of their nasty single sided phenolic circuit boards.
best,
Ike

[aramism]

Originally Posted by Ike Zimbel

It's not the brown gunk, which is just some kind of glue. The problem is almost certainly a broken/ cold/ dry solder joint that you are temporarily "fixing" by moving the caps around while trying to clean the glue off. One trick you can try is gently rocking the caps back and forth in the direction of the leads. Use the band marking the negative end of the cap to get your bearings...you should be rocking the cap towards and then away from the band. A cap with a broken solder joint will rock, that is, come up from the board on the loose end. Note that ALL the caps will rock from side-to-side, so make sure you are going the right way. Re-capping the unit "fixes" this problem because you are making new solder joints when installing the new caps. It's not a bad idea to re-cap, but may not be necessary. Yamaha used good caps...I have very, very rarely come across a failed cap in a piece of Yamaha gear, but I have seen lots of broken solder joints because of their nasty single sided phenolic circuit boards.
best,
Ike

thanks dude. will try this for sure.