Unusual element on the Onyx's backplane - Printable Version
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Unusual element on the Onyx's backplane - mosiniak - 11-18-2018
Hey,
inside Onyx Deskside on its backplane (kona ready version) there is unusual element - transistor/ic named TS1 (TO-92 package). This element is soldered facing down and there is quite big label near it. Do You know what's going on with this elements, why is it facing down and what is the reason for placing such big label near it?
![[Image: olx-001.jpg]](https://image.ibb.co/dC0HH0/olx-001.jpg)
RE: Unusual element on the Onyx's backplane - mamorim01 - 11-18-2018
That looks like a transistor. This is just an opinion, but I think they want it to be stowed as securely as possible in a position where the legs (typically one for base, one for collector and the third one for emisor) are safely placed with no risk for them touching each other. It is common for one of the legs to be the common ground, so if that leg might touch another with voltage, you could easily fry a good number of components on the board.
With the transistor in the upright position, it is very easy for somebody to touch it and twist it inadvertently when working on the board, etc. The moment you power the board, bad things happen. If you solder the transistor so the legs are as short as possible, and fold it as in your picture, this possibility disappears.
I have seen this problem in several computer repairs. The attached picture was taken during the repair of a Laser computer, the leftmost leg and the center leg were in contact (I had already separated them with the tip of a screwdriver at the time the picture was taken) resulting in a short between one of the rails and the common ground.
![[Image: IMG_20150418_013403.jpg]](http://thegarage.space/wp-content/uploads/2015/04/IMG_20150418_013403.jpg)
Of course, it can be something else entirely but, as I said, I have found this exact type of issue in several ocassions before. There is no real need for the transistor's face to physically touch the board, there is no conductive surface there. It has to be to minimize the exposed footprint so as to prevent damage from ocurring or the legs from touching each other resulting in an electrical short.
RE: Unusual element on the Onyx's backplane - BrainStorm - 11-18-2018
Evaluation Lot? Could be pre-production developer machine? I own a couple Apple developer PowerBooks, but every aspect of them is very obviously pre-production.
Is that component the same on like boards without that warning label?
RE: Unusual element on the Onyx's backplane - mosiniak - 11-18-2018
(11-18-2018, 04:09 PM)mamorim01 Wrote: That looks like a transistor. This is just an opinion, but I think they want it to be stowed as securely as possible in a position where the legs (typically one for base, one for collector and the third one for emisor) are safely placed with no risk for them touching each other. It is common for one of the legs to be the common ground, so if that leg might touch another with voltage, you could easily fry a good number of components on the board.
With the transistor in the upright position, it is very easy for somebody to touch it and twist it inadvertently when working on the board, etc. The moment you power the board, bad things happen. If you solder the transistor so the legs are as short as possible, and fold it as in your picture, this possibility disappears.
I have seen this problem in several computer repairs. The attached picture was taken during the repair of a Laser computer, the leftmost leg and the center leg were in contact (I had already separated them with the tip of a screwdriver at the time the picture was taken) resulting in a short between one of the rails and the common ground.
Of course, it can be something else entirely but, as I said, I have found this exact type of issue in several ocassions before. There is no real need for the transistor's face to physically touch the board, there is no conductive surface there. It has to be to minimize the exposed footprint so as to prevent damage from ocurring or the legs from touching each other resulting in an electrical short.
I don't think this is a transistor. I guess it is some kind of serial number chip or other id chip.
RE: Unusual element on the Onyx's backplane - mamorim01 - 11-18-2018
(11-18-2018, 05:26 PM)mosiniak Wrote: I don't think this is a transistor. I guess it is some kind of serial number chip or other id chip.
Can you take a closer picture of it?
RE: Unusual element on the Onyx's backplane - mosiniak - 11-18-2018
This chip is connected to System Controller (I think all 3 legs). Is it possible that marking TS1 - stands for Temperature Sensor? This chip is located in the top of the machine, where the temperature is highest. What do You think?
(11-18-2018, 05:34 PM)mamorim01 Wrote:It could be hard, because backplane is installed in the machine.(11-18-2018, 05:26 PM)mosiniak Wrote: I don't think this is a transistor. I guess it is some kind of serial number chip or other id chip.
Can you take a closer picture of it?
RE: Unusual element on the Onyx's backplane - mamorim01 - 11-18-2018
(11-18-2018, 05:35 PM)mosiniak Wrote: This chip is connected to System Controller (I think all 3 legs). Is it possible that marking TS1 - stands for Temperature Sensor? This chip is located in the top of the machine, where the temperature is highest. What do You think?
I think it is a transistor alright.
RE: Unusual element on the Onyx's backplane - BrainStorm - 11-18-2018
It's a tripod from War Of The Worlds at actual size. lol
Looks like triode to me, but could be any number of things put into that package.
RE: Unusual element on the Onyx's backplane - mamorim01 - 11-18-2018
(11-18-2018, 05:51 PM)BrainStorm Wrote: Looks like triode to me, but could be any number of things put into that package.
That is probably the best answer. It could also be a voltage regulator or a temperature sensor, but there is really no context to know for sure. No damage can be done by rising the component face and checking the component legend, though, that is the only way to know for sure. I still think it was installed in that manner so as to avoid shorts between legs. So very easy to fry an expensive board with such a silly mistake on a 30 cent component...
RE: Unusual element on the Onyx's backplane - BrainStorm - 11-18-2018
My question still remains unanswered. Is that component there on other Onyx boards of same revision?
And my guess would be that SGI boardviews/shemas do not exist as far as we should expect. They would probably be stored on the far side of Neptune, safely out of reach of children like us.