Wrong forum. This forum is for the emulation of old PCs, not for actual hardware.

It's not a diode, it's a coil. As these are usually used for filtering the supply voltage probably something else has shorted.

h-a-l-9000 wrote:

It's not a diode, it's a coil. As these are usually used for filtering the supply voltage probably something else has shorted.

UMM... No. Its a resistor. It's also highly likely its still okay, the regulator right next to it is likely bad. (the black part with the heatsink attached)

UMM... No. Its a resistor.

UMM... No. It could be either, but it's probably an inductor. Usually the green color indicates an inductor. However, there are green resistors in existence too, so there's really no way to tell for sure without being able to see the printing on the PCB.

But regardless, the regulator probably is bad. Inductors don't usually get smoked without some external cause.

Old Thrashbarg wrote:

UMM... No. Its a resistor.

UMM... No. It could be either, but it's probably an inductor. Usually the green color indicates an inductor. However, there are green resistors in existence too, so there's really no way to tell for sure without being able to see the printing on the PCB.

But regardless, the regulator probably is bad. Inductors don't usually get smoked without some external cause.

QFT & agree with that!

Is there a chance for a regulator to be bad even if there is no visual damage?

Yeah, those sorts of things can often go shorted without any visible signs. What's the part number on it? And do you have a multimeter (or ohmmeter)?

Hey all thanks your reply's ill tell you what I did to get me in this situation I stupidly in a rush inserted the cpu in the wrong orientation only had it on for a sec before knew what I did

The cpu is still good I tested it on anther board but this is the only board that I have that I have a case for . The only thing I can see burnt is the inductor or resistor what do I need to show you guys cant even see any burn marks on the socket I can take it to some one with multimeter (or ohmmeter)? what should I be testing for

On the regulator the thing with the heat sync it has printed on it ST 9544 Malaysia tip127
cheers

- High resolution close-up of the burnt component.

- High resolution close-up of the voltage regular (item with the aluminum heatsink)

- High resolution close-up of the back side of the PCB in the location of the burnt components.

On that green component, I see 3 or 4 colour bands, which is indicative of a resistor. This is probably the voltage set resistor for the voltage regulator. If you are lucky, only that component needs to be replaced.

For how long was the system powered up with the CPU inserted in the incorrect orientation?

What symptoms do you get when you insert the CPU correctly and power on the system? Did you check what voltage you get on your Vcc and Vss pins on the open socket 3 pins?

Wrong CPU insertion orientation with problematic symptoms can be tough to solve, especially if Vcc shorted to GND, other components on the board could have been damaged. It is really too bad that socket 3's weren't keyed.

On that green component, I see 3 or 4 colour bands, which is indicative of a resistor.

No, it is not indicative of a resistor. Inductors use the same color codes.

Hey here are the pictures
http://www.mediafire.com/view/kse5iwbyrhu3xfr … ack_of_PCD1.jpg Back of PCD
http://www.mediafire.com/view/hz8vla4lz9a16wu … t_component.JPG Burnt component
http://www.mediafire.com/download/8j88cax6dk8 … 2/regulator.JPG regulator

only on for a few sec I did smell burring heat sync was hot to touch
no black marks on the socket or on back side of pcd where socket is

What symptoms do you get when you insert the CPU correctly and power on the system? umm powers on and no screen no haven check voltages as I don't have a multimeter at home
umm what pins do you check ?

Old Thrashbarg wrote:

On that green component, I see 3 or 4 colour bands, which is indicative of a resistor.

No, it is not indicative of a resistor. Inductors use the same color codes.

how to find out ????

I personally haven't designed anything using or run into any of these green style inductors. It is good to know that there are inductors disguised as resistors. I definitely have green resistors in my bin. It is curious that they use all SMD resistors around the voltage regulator and then plop down this one big green inductor. So it is probably an inductor. I do see what looks like L4 next to it, so, inductor.

Ranil, is this the component that released smoke? If it were me, I'd check the resistance/inductance of the component in circuit with an LCR meter first. If resistance is 0, it is probably an inductor. If resistance is other than zero, I'd probaby desolder it. Compare the resistance of it on your multi-meter with what matches up on the resistor code chart. If it is an inductor, compare the inductance on your LCR meter with what matches up on the inductor code chart. After seeing that L4 next to it though, pretty sure inductor. Good catch Old Thrashbarg.

Ok thanks ill have to go buy LCR meter metre first
http://www.mediafire.com/?g414irekpxzbxy0
surrounding area
such a shame I was ready to add components to the case etc. hopefully that's the only damage
btw have you ever seen one of these boards the heights a killer cant find a desktop case high enough
http://www.mediafire.com/view/os6o1dbp3tbhp94/P1010212.JPG

If it were me, I'd just replace the inductor with one of the same inductance (use the colour codes to determine). Or just desolder it and take it to the electronics store and ask for a new one.

If it were me, I'd check the resistance/inductance of the component in circuit with an LCR meter first.

That's great if you have an LCR meter. Most people don't. You don't really need to know the actual inductance anyhow... with those things, they're either good or they're dead, there's not much in between.

It's a fairly small inductor, so I would expect there to be some measurable DC resistance... but anything under ~ 3 or 4 ohms would indicate it's probably still good. It really doesn't look bad anyway... it looks to me like it's just the outer coating on it was discolored by heat from the voltage regulator.

And the thing we're calling a 'regulator' is actually just a Darlington transistor. Desolder it and check it... with it laying on a table printed side up, legs facing toward you, the leads are arranged B,C,E. (B->E) should show somewhere in the vicinity of 17kOhms. Then switch your meter to the 'diode' range and check (C->E) and (E->C). Different meters show different things for that test, but it should indicate some continuity one direction and not so much the other.

If you have any doubts about the results you get, just replace the thing. The TIP127 is common and cheap.

hey
Brought the inductor see picture apparently R = resistor and L= inductor there's a little L on the board on one end of the inductor
http://www.mediafire.com/?8k4a5t6s26vmar7
http://www.mediafire.com/?kd3t9gd50cd00ly
umm ill have to wait till Monday to get some one to solder the parts, im no good 🤣 and to see if the same electronic shop has them or if I need to buy some TIP127

Haven't seen this style coil in anything since the mid 90s and would very easily pass its self off as a resistor but chances are you can replace it with a standard coil. Wouldn't be surprised if to much current went through and overheated the coil, if any coil gets to hot the insulation inside starts to breakdown and shorts the coil causing yet more heat. The mosfet near by can also be bad and testing that is a job in itself. You best bet is to replace both with similar or equal to rated parts.

Try a 5V CPU. These boards usually have TIP107's which allow for 3.3V to 3.45V. These power transistors sometimes go. I know because it happened to me with one of these boards.

Try to boot it with a 5V CPU first.