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**alez** · 10-20-2011, 03:53 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

The transformer is connected between pin7 of the TOP and +160VDC. So 160VDC found on pin7 means that the TOP is frozen (and the MOS permanently off), isn't true?
Unfortunately I can't connect the oscilloscope because the probe ground is connected to earth, and even if I have fed the PSU with a 220V to 110V insulating transformer my RCD trips! I don't know if it is safe to disconnect oscilloscope earth from mains plug to do these tests.
So there are more cases:
1. My TOP is already blown
2. My TOP works and my meter cannot read 160VAC@130kHz
3. The little differences in pin voltages do make the difference

**Toasty** · 10-20-2011, 08:08 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

>>So 160VDC found on pin7 means that the TOP is frozen (and the MOS permanently off), isn't true? <<

Correct. That is not true.

>>Unfortunately I can't connect the oscilloscope because the probe ground is connected to earth, and even if I have fed the PSU with a 220V to 110V insulating transformer my RCD trips! I don't know if it is safe to disconnect oscilloscope earth from mains plug to do these tests.<<

You can simply hold the probe next to the standby transformer and turn the voltage selection down. You should see waveforms in the 20µS (or less) sweep range.

My scope is connected to the mains with ground. When testing items connected to the isolation transformer I have no problems. It sounds as though something is not connected properly or it is really not "isolated".

What is a RCD?

Toast

**alez** · 10-23-2011, 10:49 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

I think that if i feed in the digital multimeter a square waveform running at 130kHz I should see about half the voltage.. where I am wrong?

However I don't see nothing on the scope

RCD=Residual-current device aka "differential switch" aka "life saver" ...

**Th3_uN1Qu3** · 10-23-2011, 10:55 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Originally posted by alez View Post

RCD=Residual-current device aka "differential switch" aka "life saver" ...

What most people know as GFCI (Ground Fault Circuit Interruptor). Check the transformer, isn't it an autotransformer by any chance? Those aren't insulated.

If it truly is insulated you can run the power supply without the GFCI so you can scope the primary.

**Toasty** · 10-23-2011, 12:47 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Originally posted by alez View Post

I think that if i feed in the digital multimeter a square waveform running at 130kHz I should see about half the voltage.. where I am wrong?

However I don't see nothing on the scope

RCD=Residual-current device aka "differential switch" aka "life saver" ...

If it trips the GFCI, then you're not insulated and not isolated. Answer T_U's question.

What brand/model scope. Most have a CAL or calibration output that you can verify the operation of the scope and probe.

Toast

**alez** · 10-24-2011, 07:47 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

T_U you're right the transformer is not insulated at all

and..yeah... GFCI, wikipedia told me it is known this way in the USA

Toast, the scope is a digital cheap one (the analogue is under repair) but it works good. I see only 50Hz near the supply, nothing at higher freq

-Alez

**olivere** · 11-22-2011, 03:43 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Hi, i have a dead G5 powersupply, the U801 (TOP249) expodes and i replaced the Q856 (MMBT2907A) and OPTO851 although the opto seems ok ... well now, when i press the power-button, the relais klicks once, but nothing else happens ... does someone have an idee or a schematic?
thanks

**Toasty** · 11-22-2011, 09:18 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Welcome!

Please fill out your in your profile.

Do you have the same G5 LiteOn power supply?

Do you have 5v & 25V standby voltages?

Toast

**olivere** · 11-23-2011, 05:06 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

thank you for your fast reply

i have the Model: PA-6601-1

i have 5,35V at the P1/Power ON Green Connector
and
i have 24,95V at the P2 +25V White.

when i connect the P1/Power ON Green Connector to GND, the relais is ticking every few seconds.

would be nice if someone has a schematic.

Oliver

**Toasty** · 11-23-2011, 10:22 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Connected to the computer? I think these need to be loaded before they will run.

There is also mention towards the beginning of this thread of replacing the 47uf/25v {C852} cap in the TOP's circuit. Did you do that?

Relay clicking is typically a protection circuit kicking in. Can you see any voltages on the 3/5/12v lines? Even momentary pulses?

Also, check the output MOSFETs 20N60C3 for shorts and damage in that area. Also covered in this thread. Is there any discoloration of the output (orange poly film) capacitors? See Post 48 pictures.

Toast

**olivere** · 11-24-2011, 09:21 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

thank you for your help.
yes i have also replaced the C852.
I have short pulses (in sync with the relais clicking)with the correct voltage for a few millisconds on each connector.

The Mosfets are ok and the caps are also looking great.
Oliver

**olivere** · 11-28-2011, 03:52 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

I think i'll bridge this relais. Then it could work - maybe there is a failure in the relais drive.

**Toasty** · 11-28-2011, 09:45 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Doing so may cause further problems. There is a problem with the output or another segment of the circuit. Overvoltage, Undervoltage, Overcurrent - that it why the relays cut out. It is -not- because there is a problem with the relay control circuit.

Is this connected to a load (computer)? Some PSUs won't run correctly unless there is sufficient load attached.

**olivere** · 12-02-2011, 09:20 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

I have connect it to the Powermac G5 - but it is doing nothing. It even does not tick any more - i did not have bridged the relays by the way - i don't have an idea what his could be

**olivere** · 12-02-2011, 09:32 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

update: sometimes it is ticking when i often push the power button

**Toasty** · 12-02-2011, 11:27 AM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Checked the output FETs?

**godonr** · 01-18-2012, 05:06 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

fixing to get rid of a bunch of these supplies... did think you could just jumper 13 & 14 (power on) to get readings. hate to throw in the towel on these supplies since there are still a bunch of G5s using and losing them. But, we are going cheap with HP Compaq 6200s and elite books. olivere sounds like you have a combination of the blown TOP and R302 failure. you did look there didn't you.

**Toasty** · 01-18-2012, 05:20 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Needs to be hooked to system.

**godonr** · 01-18-2012, 06:20 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Toasty.. given the way it sits underneath everything, what did you do? Make a special harness to hook up without place the p/s in the case?

**Toasty** · 01-18-2012, 07:06 PM

Re: LiteOn PA-6601-1A (600w) blows its TOP

Cardboard & a zip-tie

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