Soyo 24" stopped, help!

[freelander]

Re: Soyo 24" stopped, help!

I double checked pins 1-2 and they are open loop to each other. Pins 1/4 and 2/5 are shorted in pairs out of circuit.

I noticed a little chunk broken away from the thermistor (?) early in the AC power circuit. I don't know what this does but could this be a problem?

[retiredcaps]

Re: Soyo 24" stopped, help!

Since removing the different transformers, I no longer have a short between the two pins mentioned in circuit.

Okay, I marked up this diagram. Can you measure, record and report the following ohms (all in circuit)? Please record the actual ohm reading. If your multimeter is not autoranging, set it to 200 ohm setting.

A to B
C to B
C to E
C to D
E to F
E to G
E to H
E to J

For each letter above, what is the corresponding component?

I know that C and E are pins 1 and 4 of BSFP24L1B. What is

A, B, D, F, G, H, and J?

There is no letter "I".

edit: It could very well be that the design is to have pin 1 and 4 connected because you tested the rectifier out of circuit and found them all open. I'm just trying to trace this circuit to see where they connect.

[retiredcaps]

Re: Soyo 24" stopped, help!

I noticed a little chunk broken away from the thermistor (?) early in the AC power circuit. I don't know what this does but could this be a problem?

I don't know enough about that component to say yes or no. I'm sure someone else will chime in.

[freelander]

Re: Soyo 24" stopped, help!

Have a look at the following:

A to B = .1 Ohm
C to B = .1 Ohm
C to E = OL (1.03M Ohm)
C to D = .1 Ohm
E to F = .1 Ohm
E to G = .1 Ohm
E to H = .1 Ohm
E to J = .1 Ohm
For each letter above, what is the corresponding component?
A= one side of jumpers
B= the other side of three jumpers
C= pin 4 (positive) of bridge rectifier
E= pin 1 (negative) of bridge rectifier
F= leg of the heat sink
G,D,J,H= see picture for top side of board (note that I have edited the previous post so the burn marks and components aren't from my board)

[retiredcaps]

Re: Soyo 24" stopped, help!

Have a look at the following:

A to B = .1 Ohm
C to B = .1 Ohm
C to E = OL (1.03M Ohm)
C to D = .1 Ohm
E to F = .1 Ohm
E to G = .1 Ohm
E to H = .1 Ohm
E to J = .1 Ohm
For each letter above, what is the corresponding component?
A= one side of jumpers
B= the other side of three jumpers
C= pin 4 (positive) of bridge rectifier
E= pin 1 (negative) of bridge rectifier
F= leg of the heat sink
G,D,J,H= see picture for top side of board (note that I have edited the previous post so the burn marks and components aren't from my board)

I can't tell from the top picture what G,D,J,H are.

Okay, this may be a total red herring and my tracing could be wrong, but one way pin 1 and 4 of the bridge rectifier can be shorted in circuit and open out of circuit is if BSFP24L1B pin 1 and pin 2 are shorted. However, you have verified that BSFP24L1B pin 1 and pin 2 are open using a multimeter.

From tracing, another way is if diode 1 (D1) is bad. So test D1 in circuit with your diode check function on the multimeter. You should get 0.4 to 0.7 one way and 0L the other way.

I hope I'm not leading you down a wild goose chase here.

[PlainBill]

Re: Soyo 24" stopped, help!

I double checked pins 1-2 and they are open loop to each other. Pins 1/4 and 2/5 are shorted in pairs out of circuit.

I noticed a little chunk broken away from the thermistor (?) early in the AC power circuit. I don't know what this does but could this be a problem?

That is a NTC thermistor. It's resistance decreases as it heats up. Measure thee resistance when it's cold; it should be something in the range of 10 - 50 ohms. If it's lower, it's shorted. I'd order a new one when buying parts.

PlainBill

[freelander]

Re: Soyo 24" stopped, help!

The thermistor is measuring 3.7 Ohm at room temp. Diode D1 is good measuring .48 V in one direction only.

The picture shows a big brown thing that I can't identify in the picture. Point G is one side and D is the other. Point J is one lead of the resistor to the right of the big capacitor. Point H is the negative lead of the big capacitor.

[freelander]

Re: Soyo 24" stopped, help!

There are a number of surface mount diodes and one zener diode (Top right corner but I don't really know the difference) that measure shorted when tested with the DMM diode function in circuit. I have circled them. There is one diode (circled in purple) that is a normal diode on the top side of the board that is reading shorted.

[Th3_uN1Qu3]

Re: Soyo 24" stopped, help!

If they're reading shorted, they probably ARE. But the only way to truly know is of course removing them from the board and testing them that way.

[freelander]

Re: Soyo 24" stopped, help!

I scraped off some of the glue to reveal the labelling for what I previous called transformers. BSFP24T1 is lavelled T1 so I am assuming that it is truly a transformer. BSFP24L1B is labelled L1 so I am assuming that it is an inductor. Either way, I don't think these components should have any opens so I think that they need to be replaced. I would love if someone could confirm my line of thinking.

I can't find replacements on digikey...any suggestions?

[freelander]

Re: Soyo 24" stopped, help!

I haven't ordered replacement diodes or zener diodes before and I'm not sure how to figure out which one I need just by looking at it. Any suggestions?