Toshiba C660 -1MK Completely dead, no lights at all.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Ok, i'm away from city for 2 days, i will return on Friday, first thing to do when return will be to measure all voltages on all pins and i'll reply again then.
Wait for me, don't leave me in darkness

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Ok back.
Got all measures so here we go :
1. 1,47v
2. 0
3. 2v
4. 2v
5. 0
6. 1,47v
7. 0
8. 3,3v
9. 4,5v
10. 0
11. 0
12. 0
13. 3,3v
14. 2v
15. 0
16. 19,7v
17. 5v
18. 0
19. 0
20. 0
21. 0
22. 4.5v
23. 0
24. 0

That's all.

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Okay, great. Those readings are perfect (except for the outputs being off).

Now is a good time to check the MOSFETs. Unfortunately, they cannot be tested in circuit. Remove each one and then perform the following test:

Source = Pins 1-3 (doesn't matter which)
Gate = Pin 4
Drain = Pins 5-8 (doesn't matter which)

Red/Black refers to the multimeter probe of that color.
Multimeter must be set to diode mode.
The expected reading is in parenthesis.

Test procedure:
1) Red on Drain, Black on Gate (No connection. This also turns the MOSFET off)
2) Red on Drain, Black on Source (No connection)
3) Swap the probe positions. Red on Source, Black on Drain (One diode drop, approximately 0.5V)

4) Red on Gate, Black on Drain (No connection. This also turns the MOSFET on)
5) Red on Source, Black on Drain (Less than 0.2V)
6) Swap the probe positions. Red on Drain, Black on Source (Less than 0.2V)

7) Repeat steps 1-3 to make sure MOSFET turns off again successfully

I say "less than 0.2V" because sometimes the multimeter voltage isn't high enough to turn the MOSFET fully on. So instead of reading 0V (completely turned on), you will read slightly above 0V.

It's important that steps 2 and 3 are performed immediately after step 1 so you know the gate is turned off during those steps. It's important that steps 5 and 6 are performed immediately after step 4 so you know the gate is turned on during those steps.

Report back whether any of the tests showed an unexpected reading.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

I tested the PQ331 and PQ551
The results are like you said except on both Red on Source, Black on Drain the results are 0.5v and not 0.2v
Do you want to test PQ332 and PD352 too?

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Yes, test them all. It sounds like those 2 are okay.

In diode mode, the multimeter outputs a voltage. But every multimeter is different and some use higher voltages than others. Also, every MOSFET is different.

So when you see one MOSFET shows 0.5V when turned on, it might cause a little bit of worry. How do you know it's good? Maybe it is bad and has high resistance. Fortunately, you can easily compare the MOSFETs to each other. As long as they all act the same way, they are almost certainly good.

[cyberhack]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Sorry to butt in again but if pin 23 is no good then replace pu330 and as there are no shorts on your pcb

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

@cyberhack PGOOD (pin 23) indicates the outputs are within 10% of their rated values. Nothing else. I think proper diagnosis is important. Otherwise you may end up destroying your new part. Or worse.. have a situation where certain controllers and high-side MOSFETs keep frying each other unless you replace them both at the same time.

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

So far so good, next step?
Remember that propably we are talking about a broken line or solder since the board was working before shipment to me....

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

At this point we know:
- The problem is in or around PU330 since it still doesn't work when the solder jumpers are removed.
- No shorts have been detected.
- The MOSFETs have no dangerous faults and are very likely working (like 95% sure, but you'd need a curve tracer to test them 100%).
- All the inputs to PU330 are exactly what they should be, but the outputs still don't turn on

Another quick test you can do is to check that the resistance of the feedback resistors PR362-PR365 are correct.

And then, since we know it's safe to do so, I would just replace PU330 to see if that fixes it. But you can try resoldering it first if you want to make sure there aren't any bad solder joints.

I can think of a few more unlikely things to check also. But they normally aren't worth the effort unless you are really, really trying to avoid replacing PU330 for some reason (e.g. money, soldering difficulty, etc.)

[Andreasbest]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Ok will change the U330 and i'll upload results, although it will take some time to arrive from Asia
I will buy a RT8205 right?

[BlueMidnight]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Right. There are a few different versions (RT8205A, -B, and -C), but any of them will work for this.

[rtra]

Re: Toshiba C660 -1MK Completely dead, no lights at all.

Right. There are a few different versions (RT8205A, -B, and -C), but any of them will work for this.

Hi, do you have any news on this repair? have you replaced the RT8205A and it worked? Thank's