CS 721 starts smoking after SAS install on V15 IIIDU .... ?

[samosui]

No connection between replacing the existing stylus with a VN35HE and then smelling burning electronics but give me a break! Three minutes into listening to an album and I start smelling something. Then a minute later, smoke is coming out.

The capacitor in the lower center of this photo apparently gave up the ghost. I hope that finding a replacement power supply does the trick.

Any suggestions?



Cheers,
John

 

[petehall347]

you could replace the capacitor instead of a whole supply .
it looks like it may have been worked on before looking at the resistor next to the blown cap . might be wrong though but worth checking against the schematic if available .

 

[NoTransistors]

The caps and resistors are only for the strobe. The tranny, is only for the mother board. The 0.125 amp fuse is for all. Fix the little board and forget about it. If you need schematic, I begrudgingly suggest vinylengine.

 

[slimecity]

Someone has done a shocking "repair" job on that resistor - as above, yes check if this is the correct type. Also, one leg appears to be touching one leg of the rectifier diode - hard to tell if these components are connected by the PCB traces anyway. If not.....that coud be an issue.

I would replace the cap then fire the PS up again thru a dim bulb tester to ensure there are no shorts......

 

[NoTransistors]

22K and 2.7K
This is the value of the two resistors.
.047U and .068 U are the cap values.

The power box is the only thing this shares with the 701. The motor circuit boards are very much different.

 

[samosui]

Thanks Pete, NoTransistors, and slimecity .....

you could replace the capacitor instead of a whole supply .
it looks like it may have been worked on before looking at the resistor next to the blown cap . might be wrong though but worth checking against the schematic if available .

Yes, just replacing the cap was a thought. But I have no way of knowing why it got burnt up. And am afraid that there's something else amiss that I'd have to fight to troubleshoot

The caps and resistors are only for the strobe. The tranny, is only for the mother board. The 0.125 amp fuse is for all. Fix the little board and forget about it. If you need schematic, I begrudgingly suggest vinylengine.

Thanks. After the smoke cleared, nothing works. I might be able to identify components and follow the path that electrons may flow through but my understanding of electronics isn't sufficient to "troubleshoot" root causes. I'd have to "experiment".

Someone has done a shocking "repair" job on that resistor - as above, yes check if this is the correct type. Also, one leg appears to be touching one leg of the rectifier diode - hard to tell if these components are connected by the PCB traces anyway. If not.....that coud be an issue.

I would replace the cap then fire the PS up again thru a dim bulb tester to ensure there are no shorts......

Yes, it looks like they are touching. Didn't notice that before.

22K and 2.7K
This is the value of the two resistors.
.047U and .068 U are the cap values.

The power box is the only thing this shares with the 701. The motor circuit boards are very much different.

Bottom line is that I'm not that capable and don't have the much time to devote to this. Yeah, that's another issue.

I was thinking that a simple replacement of the whole unit would be something not too difficult and not too expensive.

Cheers,
John

 

[NoTransistors]

You still need to replace the single large electrolytic filter cap on the motherboard. It is an absolute must. Your blown cap on the little board is known to ignite without any provolcation whatsoever. I must warn you that the circuit board is thin and the copper traces too easily lift from heat of even the most anemic soldering pencils.

 

[AdamAnt316]

Completely coincidental. That is a line filter capacitor, likely made by RIFA. The resin case cracks over time, letting moisture in, and once a big enough spike comes along, this happens:

Said capacitor was pulled from an early Apple Macintosh computer. When it blew up (with the computer turned off, BTW), a huge puff of smoke rose out of the ventilation slots. Here's an example of said blown capacitor sitting next to a brand new capacitor of the same type:

Replace it with an X-class capacitor of the same rating, in this case 0.047µF. Such capacitors can be purchased from Mouser, among other sources.
-Adam

 

[lini]

John: Yup, as Seth and Adam already hinted to, you merely encountered, what the Dual community over here refers to as "Knallfrosch" (the German word for this kind of firecracker: https://cdn.duden.de/_media_/full/K/Knallfrosch-201020549537.jpg). There probably is another one with 10 instead of 47 nF in parallel to the main switch, serving as anti-sparking cap, which you might want to at least check for cracks in its case or simply replace in any case.

Greetings from Munich!

Manfred / lini

 

[samosui]

You still need to replace the single large electrolytic filter cap on the motherboard. It is an absolute must. Your blown cap on the little board is known to ignite without any provolcation whatsoever. I must warn you that the circuit board is thin and the copper traces too easily lift from heat of even the most anemic soldering pencils.

Thanks for the heads up. If I go the replacement route, I’ll be careful.

Cheers,
John

 

[samosui]

Completely coincidental. That is a line filter capacitor, likely made by RIFA. The resin case cracks over time, letting moisture in, and once a big enough spike comes along, this happens:

Said capacitor was pulled from an early Apple Macintosh computer. When it blew up (with the computer turned off, BTW), a huge puff of smoke rose out of the ventilation slots. Here's an example of said blown capacitor sitting next to a brand new capacitor of the same type:

Replace it with an X-class capacitor of the same rating, in this case 0.047µF. Such capacitors can be purchased from Mouser, among other sources.
-Adam

Thanks, Adam. Yup, that’s what my cap looked like, except it was a slow death with smoke leaking out slowly until I thought that turning off the power would make sense. Before the smoke there was that awful smell for a bit.

And thanks for the info and Mouser link.

Cheers,
John

 

[samosui]

John: Yup, as Seth and Adam already hinted to, you merely encountered, what the Dual community over here refers to as "Knallfrosch" (the German word for this kind of firecracker: https://cdn.duden.de/_media_/full/K/Knallfrosch-201020549537.jpg). There probably is another one with 10 instead of 47 nF in parallel to the main switch, serving as anti-sparking cap, which you might want to at least check for cracks in its case or simply replace in any case.

Greetings from Munich!

Manfred / lini

Lol! And thanks for the illustration and info and greetings, Manfred.

Been to Munich a couple of times. There’s a company I used to work for that’s headquartered there, Rhode & Schwarz. Great company.

And greetings from Southern California (Santa Monica)!

Cheers,
John

 

[AdamAnt316]

Thanks, Adam. Yup, that’s what my cap looked like, except it was a slow death with smoke leaking out slowly until I thought that turning off the power would make sense. Before the smoke there was that awful smell for a bit.

And thanks for the info and Mouser link.

Cheers,
John

In my case, it was a series of firecracker-like crackling sounds, followed by a big *POW!* and a nice big cloud of smoke from inside the case. Immediately unplugged the computer, opened the case, and this was what I saw:

Note the residue on the blue electrolytic capacitor, which seems to have weathered the explosion fine.
-Adam

 

[MRL_Audio]

@AdamAnt316 - wonder why your images do not show in my browser... all I see is . I can right click and view it but can't see it directly in your post.

 

[petehall347]

@AdamAnt316 - wonder why your images do not show in my browser... all I see is View attachment 1572760. I can right click and view it but can't see it directly in your post.

showing fine here

 

[MRL_Audio]

Guess I need to check some browser settings. Works fine on my phone. Apologies for the diversion.

 

[AdamAnt316]

@AdamAnt316 - wonder why your images do not show in my browser... all I see is View attachment 1572760. I can right click and view it but can't see it directly in your post.

Guess I need to check some browser settings. Works fine on my phone. Apologies for the diversion.

I believe it's some sort of forum issue. Not sure if it's related to the http/https switchover from some time back, but that's about when the issue started appearing. Not sure if it's because my site uses old-fashioned http or what. For those unable to view the photos, here are some direct links:

Blow'd-up RIFA capacitor
Old RIFA vs. new
Capacitor on board as blow'd-up