Fixing a DAC-19M005 Power Supply - check my DX:

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

You mean on the power supply board to find a sort ? Can you give me a primer on doing this tracking ? I haven't been able to track down a schematic for this model. Have you anything ?

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

yes on the power supply.
You're going to try to analyze the circuit ,trace it back from the fuse see if you can see a component that shows low resistance similar to the fuse .If you find one remove it from the circuit and retest the fuse to see if it's still shorted .I don't think we will find a wiring diagram.
Al

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - tracing down a short

Two things..
Ok, both my F101 and F200 have a zero reading to ground on one side, so I assume I have to start with the F101 since it also shows infinity across itself ?
Also do you have a component/wiring layout for a typical or similiar power supply board ?
well, Three...Happy New Year !

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Yes I have a 005 board it has been scavenged of some parts ,But there should be enough left to trace the 5V and 12v circuits.
Look closely at the schotty diodes D103 and D102,One is a SBT100 and I am not sure of the other, but it will be similar. Search the data sheet as for as testing goes, you most likely will find these shorted.
Al.

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Al...I had tested both diodes as the same 'good' and even took the D103 Shottky out during last repair and it still read good.
Just Now I've re-tested both this way in circuit, with my analog VOM , for SBT 150 the legs 1 and 3 anode, 2 cathode....red to anode with black to cathode appears open (infinity no reading), reversing probes get about 6 ohms, other leg tests the same open and 6...and the other D102 same readings as the first.

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Al...I had tested both diodes as the same 'good' and even took the D103 Shottky out during last repair and it still read good.
Just Now I've re-tested both this way in circuit, with my analog VOM , for SBT 150 the legs 1 and 3 anode, 2 cathode....red to anode with black to cathode appears open (infinity no reading), reversing probes get about 6 ohms, other leg tests the same open and 6...and the other D102 same readings as the first.

Man I was hoping you were going to make this easy for me.
I forgot you are using an analog meter .Try checking the resistance [lowest scale possible]of the two anode pins.
Al

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Al...I had tested both diodes as the same 'good' and even took the D103 Shottky out during last repair and it still read good.
Just Now I've re-tested both this way in circuit, with my analog VOM , for SBT 150 the legs 1 and 3 anode, 2 cathode....red to anode with black to cathode appears open (infinity no reading), reversing probes get about 6 ohms, other leg tests the same open and 6...and the other D102 same readings as the first.

My mind is having a little problem with not being able to focus today.
I just found my analog meter, on a new diode I measure Red lead to Cathode- Black to anode reads open.
Red lead to anode-Black lead to cathode reads very low resistance.
Checking red to anode- black to cathode reads open both ways.
Al.

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Sorry had bad luck with my other meters, so appreciate the learning experience, and not to over-test your skills. I got zero ohms either way on the anodes of both diodes, after recalibrating on lowest scale.
But, ..so you got the same with your know good one out, as I did with mine in circuit?

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Just a guess, but on the fuses try reversing your leads of your meter see if the readings are the same.
Al

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

Yes both fuses both ways show open readings.

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

No I was wanting you to check for a low Ohm reading to ground.
Al.

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

I think I did that at post #38, no?


QUOTE=alexanna;143547]No I was wanting you to check for a low Ohm reading to ground.
Al.[/QUOTE]

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

I think I did that at post #38, no?


QUOTE=alexanna;143547]No I was wanting you to check for a low Ohm reading to ground.
Al.

[/QUOTE]


An analog meter flows more current in the circuit than a digital meter dose, it probably flows enough to be able to go through the diode. I am just trying to rule out all possibilities.
Al

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

OK, checked them again with careful low ohm recalibration... F100 is open to either probe way on one side , then open one way and 14 ohms when reversed leads on other side.
F 101 is open either way on one side, and 0 ohms either way probed on the other. Pretty sure its 0.0 ohms not 0.5 or such.

[alexanna]

Re: Fixing a DAC-19M005 Power Supply - check my DX:


An analog meter flows more current in the circuit than a digital meter dose, it probably flows enough to be able to go through the diode. I am just trying to rule out all possibilities.
Al[/QUOTE]

The whole confusion is we are using an analog meter. Were probably chasing a problem that does not exist. There is nothing wrong with using an analog meter but testing is going to be just a little bit different.
Re check both sides of the fuses for a low reading to ground, If you read a low resistance reverse your ohmmeter leads see if the ohm reading changes to a high reading.
Al.

[retiredcaps]

Re: Fixing a DAC-19M005 Power Supply - check my DX:

The whole confusion is we are using an analog meter.

You can purchase very good used digital multimeters on ebay for very little. Some older working Flukes (like 7x, 80xx) go for as little as $30 or less. 3 or 4 working Fluke 77 III sold for $35 USD. A new Fluke IV is over $250 USD.

If you search for brands like Amprobe, Meterman, Wavetek, you will find some very good deals. A top of the line Amprobe from 9 years ago sold for $5.35 a few days ago. I got a working Meterman 15XP, 9V battery, leads all for just 99 cents from a USA seller a few months ago.

If you live in the USA, you have a LOT of options (I'm jealous).

[kingofcoins]

Re: Getting a used dgital mulitimeter

Thanks for this feedback...so when I buy used, what features will I definitely need to do in circuit and out, typical components and chip diagnoses for LCD repairs....considering I already have a good analog VOM, and an ESR meter ?

....and Yes, I will stay away from the rat-shack boxes

You can purchase very good used digital multimeters on ebay for very little. Some older working Flukes (like 7x, 80xx) go for as little as $30 or less. 3 or 4 working Fluke 77 III sold for $35 USD. A new Fluke IV is over $250 USD.

If you search for brands like Amprobe, Meterman, Wavetek, you will find some very good deals. A top of the line Amprobe from 9 years ago sold for $5.35 a few days ago. I got a working Meterman 15XP, 9V battery, leads all for just 99 cents from a USA seller a few months ago.

If you live in the USA, you have a LOT of options (I'm jealous).

[retiredcaps]

Re: Getting a used dgital mulitimeter

so when I buy used, what features will I definitely need to do in circuit and out, typical components and chip diagnoses for LCD repairs....considering I already have a good analog VOM, and an ESR meter ?

....and Yes, I will stay away from the rat-shack boxes

Multimeter features to help round out what you have

a) capacitance measurement (if the ESR meter doesn't do it) up to 5000uF because some TVs have 3300uF caps

b) good sharp probes for measuring multi legged ICs without shorting out other components

PS. I have nothing against RadioShack multimeters.

[kingofcoins]

Re: Fixing a DAC-19M005 Power Supply - the fuses

Looking closely at these SMD fuses, they are see-through and the 'S' F101 looks intact and just like my good F200, but the 'N' one F100 appears open or fried inside (using a 10-14X loupe). I can't find a value for the 'N' code, as I have for the 'S' = 2amps. So why don't I try a 1 amp or 1.5a auto fuse soldered across the leads for a test ?
Anyone know the actual replacement for a N marked fuse on these Delta boards ?

OK, checked them again with careful low ohm recalibration... F100 is open to either probe way on one side , then open one way and 14 ohms when reversed leads on other side.
F 101 is open either way on one side, and 0 ohms either way probed on the other. Pretty sure its 0.0 ohms not 0.5 or such.

[kingofcoins]

Re: Getting a used dgital mulitimeter

What do you recommend for the meters capabilities to do diodes, mosfets, and transistors ?

You would not be so happy with the rat-shack if you had one fail on you...then again my VOM is the R.S. brand and about 15 years old.

Multimeter features to help round out what you have

a) capacitance measurement (if the ESR meter doesn't do it) up to 5000uF because some TVs have 3300uF caps

b) good sharp probes for measuring multi legged ICs without shorting out other components

PS. I have nothing against RadioShack multimeters.