Instruments/tools needed for TV repair

[tibimakai]

Thank you budm for your help, but the big question still remains unanswered.
Do I need it?

[budm]

You will need it if you want to see: the SMPS output drive is putting out, if the switching transformer is putting out the signal (typical AC meter will not have enough bandwitdth to measure AC in 30k~100KHz), AC ripple at the power supply DC output, Video signal, LVDS, clock signals, etc. I would say yes if you are want to really dig deep into the troubleshooting world. But like I said, play with it at your work place first to get use to how to operate it and what you should see and what the waveform of all kind of signals look like, etc.

[tibimakai]

OK, I have purchased the Rigol DS1052E for $314 shipped which soon will be a 100MHz scope

[tibimakai]

Here is a video about the hack:
http://www.youtube.com/watch?v=LnhXfVYWYXE
There is a forum called eevblog where they talk about this mod.

[tibimakai]

OK, I couldn't wait for Ebay. I had to have one, do you know how it is
I have purchased a Fluke 87-5 from Amazon(VIPMART) for $250(!!).
I have called the guy and he confirmed that it's indeed is new and comes with the full manufacturer's warranty.
There is a promotion going on now at Fluke. Here is the link:
http://support.fluke.com/find-sales/...06_ENG_A_W.PDF
I have selected the bag. Hats I'm not wearing, I'm not electrician, so I don't need those magnetic holders and flashlight I have.
I have got the Rigol scope and successfully converted it to a 100MHz scope!
Very easy, just downgrade the firmware, run a tool which changes the model and serial number and upgrade the firmware and it's done.

[budm]

Another thing you should have is the Isolation transformer, do not use your new scope on the Hot side of the circuits withouit having what ever your arfe working on powered by the Isolation transformer! otherwise you will blow up your scope and the bridge rectifiers, and etc. in the hot side of the circuits since your scope probe ground is more likely to be connected to the scope power cord ground prong.

[tibimakai]

Thank you, for letting me know. I will look into it.
By the way, thet Vizio PS acts the same way when it's in the TV.
24V, 3.3V comes on(don't remember the 12V what it does) for a second and drops down.

[budm]

Without having the inverter boards attached?

[tibimakai]

yes. it's something with the PS, but I can't figure it out what went out.
I try to understand this PS. The big transformer gets one voltage from the primary and transforms it into two on the secondary?
Soon I will get the ESR meter and I will check all the capacitors to make sure that they are all OK.
It seems that the 24V does not have enough juice and the 12V has to much.

[budm]

"The big transformer gets one voltage from the primary and transforms it into two on the secondary"
Yes, that is correct, there are two secondary windings, one fo the 12v and one for the 24V. I still cannot see how you can have much higher12V output, but not the 24v output since they are generated by the same transformer which it will affect both outputs. There must be open Ground return connections some where.

[tibimakai]

Both are higher, 13.3V and 26.6V, basically it's exactly doubled the 13.3V.
The 13.3V under load goes higher and the 24V under load drops to I guess to 0V(never waited because it goes down slowly.

[tom66]

Originally Posted by budm

Another thing you should have is the Isolation transformer, do not use your new scope on the Hot side of the circuits withouit having what ever your arfe working on powered by the Isolation transformer! otherwise you will blow up your scope and the bridge rectifiers, and etc. in the hot side of the circuits since your scope probe ground is more likely to be connected to the scope power cord ground prong.

If you can get one, I would highly recommend a variac too. They can be very useful to slowly power up a circuit after you have replaced some expensive MOSFETs or bridges. The components will get hot before they fail and smoke if there is a fault somewhere. You can get isolated variacs which combine the two features. If you have a powerful variac like mine (4000VA) you -will- need an inrush limiter, or you will trip the breaker all the time when you switch it on.

[budm]

That does not make sense since the primary circuits is still driving otherwise you will not have the 12v output on the 12v winding, so it means that the 24v winding must still be putting out the AC but the rectifiers are not. You can use your new scope to look at the 24v output winding.
But you ar saying that the 12v under load the out put gets higher also and it stays like that? Check the ground traces of the 12v and the 24v section, when you mount the board into the chassis, see if the 12v ground is still connected to the 24v ground. Also measure the DC of the 12v ground pin and the chassis, and also 24v ground pin and the chassis.

[retiredcaps]

Originally Posted by tibimakai

I have purchased a Fluke 87-5 from Amazon(VIPMART) for $250(!!).

Excellent deal if it comes with full warranty. In Canada, I would have to pay $500 get a new 87V.

[tibimakai]

Why not buy it from Amazon US then?

[tibimakai]

http://www.ebay.com/itm/ws/eBayISAPI...:B:WNA:US:1123

[retiredcaps]

Originally Posted by tibimakai

Why not buy it from Amazon US then?

1) Amazon.com says for the Fluke 87V

Shipping: Currently, item can be shipped only within the U.S. and to APO/FPO addresses.

2) There is also the question of warranty. Typically, most Canadian HQ will NOT provide warranty unless it is purchased in Canada from an authorized dealer. As a Canadian, buying a new Fluke 87V from an authorized USA Fluke dealer is considered "gray market"/invalid when it comes to warrany claims.

3) The above is also common "practice" for TVs, cars, PCs, etc.

4) Right now, I have more multimeters than what I need, but I'm willing to get an Fluke 87V or 87IV or 89IV at the right price.

[retiredcaps]

Originally Posted by tibimakai

http://www.ebay.com/itm/ws/eBayISAPI...:B:WNA:US:1123

If this auction is directed at me, it states (like most professional sellers)

ABSOLUTELY NO INTERNATIONAL BIDS will be accepted (including Canada)

[tibimakai]

I haven't checked that. Sorry.
Your right, I forgot about the warranty. Maybe for this price you could trust the meter and you could lose the warranty.

[Jasgriff]

That fluke is looking like it will go cheap. Get Budm to buy it for you.