VA902b Shakey jittery image

[blues]

Re: VA902b Shakey jittery image

OK. I nmanaged to get the voltage regulator off as instructed by jetadm123 and then I installed the new one. I checked with my meter and got...
Pin3 5.00 VDC
Pin2 1.80 VDC
pin1 0.00 VDC
which was correct. I metered the ohms on the resistor and got 009, was 000 just touching the pos and neg together without anything in between, so I thought it was worth assembling and testing. To my surprise the no signal message was steady so I hooked up the monitor to a laptop and to my wonderment, the problem is solved. No more shakey jittery video. I am not to sure about my soldering, but hopefully it holds and will get better with time. Some assembly required.

Props to retiredcaps, selldoor and jetadm123, I couldn't have done it without you. You guys rock and so does this forum! You made a believer out of me, thanks!

[jetadm123]

Re: VA902b Shakey jittery image

Thanks, very helpful. My eagerness may have gotten me into trouble. I think I may have damaged the resistor above it, see post #13 for a picture of the resistor. I damaged the outer coating. Will this need to be replaced and does anyone know what type and value resistor I need?

If you scraped off some of the outer coating, it should still be ok. Do a quick check with your ohm meter. It's not the most accurate check, since the resistor is still in the circuit and you could be reading the resistance of other components, but still worth a try.

[selldoor]

Re: VA902b Shakey jittery image

Id say white brown gold gold from ebay pic http://www.auctiva.com/hostedimages/...0,0,0&format=0

[blues]

Re: VA902b Shakey jittery image

I think it looks more grey than white. I will need to follow your advice and meter it when I get home today. I read it as Grey, Red, Gold, Gold but from the picture it is hard to tell. Will als try to post a new picture later.

[retiredcaps]

Re: VA902b Shakey jittery image

I think I may have damaged the resistor above it, see post #13 for a picture of the resistor. I damaged the outer coating. Will this need to be replaced and does anyone know what type and value resistor I need?

From the picture, it looks like white, brown, gold, gold so according to

http://www.hobby-hour.com/electronic...calculator.php

that is 9.1 ohms 5%. I would measure it and see if it is close to 9.1 ohms or not.

Since this is a low ohm resistor, touch your leads of the multimeter together. It should read around 0.2 to 0.3 ohms. If you reading of the resistor is 9.3 or 9.4 ohms, then the actual reading will be 9.1 ohms taking the resistance of the leads into account.

[blues]

Re: VA902b Shakey jittery image

Thanks, very helpful. My eagerness may have gotten me into trouble. I think I may have damaged the resistor above it, see post #13 for a picture of the resistor. I damaged the outer coating. Will this need to be replaced and does anyone know what type and value resistor I need?

[retiredcaps]

Re: VA902b Shakey jittery image

Since I can't justify buying a hot air rework station, I borrowed a heat gun from my friend and have been experimenting with it removing smd components like sot-223 voltage regulators off old junk boards.

It works great, but there is no fine level control with the heat gun. So I ordered some Kapton tape and plan to cover up all the area to protect the other components from the heat.

I also plan to remove any capacitors that are close by in advance so they don't get killed by the heat.

[selldoor]

Re: VA902b Shakey jittery image

It sometimes helps to heat the general area you are working on with a hair dryer so the heat from your iron isnt dissipated so quickly.

[jetadm123]

Re: VA902b Shakey jittery image

I received my part today and am about to try to uninstall the old IC voltage regulator. I am new and this and need some tips here. Are there four points of contact to the circuit board of just the 3 pins? How should I approach unsoldiering the old one?

1) hopefully, you have at least a 40W soldering iron.

2) with small diagonal wire cutters, cut each of the 3 legs all the way through. Using your soldering iron, heat up one of of the legs and remove it with a pair of small pliers or tweezers. Do the same for the other 2 legs.

3) the tab is the hardest, since it requires the most heat to remove. With your soldering tip held against the tab, use your pliers to grasp the plastic body of regulator. When it looks like the solder is starting to melt under the tab, apply a very gentle twisting motion to the pliers. This should hopefully free the regulator from the board. If the solder is not melting, apply a little of your 60/40 solder to the tab, which should lower the melting point of the lead free solder underneath the tab.

[blues]

Re: VA902b Shakey jittery image

I received my part today and am about to try to uninstall the old IC voltage regulator. I am new and this and need some tips here. Are there four points of contact to the circuit board of just the 3 pins? How should I approach unsoldiering the old one?

[retiredcaps]

Re: VA902b Shakey jittery image

I looked at digikey and mouser and I cannot find the voltage regulator category.

http://search.digikey.com/us/en/cat/...ors-linear-ldo

[blues]

Re: VA902b Shakey jittery image

Thanks, your help is much appreciated. I looked at digikey and mouser and I cannot find the voltage regulator category. What should I be looking for?

[retiredcaps]

Re: VA902b Shakey jittery image

This should work.

http://search.digikey.com/us/en/prod...9-5-ND/2472287

Get 2 just in case one is bad or you make a mistake so you don't have to pay the $8 shipping/handling again.

[blues]

Re: VA902b Shakey jittery image

I get it. Looked at digikey to see what info is there about the part, but was unable to find voltage regulator. What category should I be looking under? By the way, thank you for your help thus far, you have been invaluable, much appreciated.

[retiredcaps]

Re: VA902b Shakey jittery image

Part number AS1117-18 (position of component is above)
Pin 3 = 5.05
pin 2 = 1.24
pin 1 = 0.00

AS1117-18 is definitely bad and probably the cause of your shaky images.

The fixed 1.8V regulator is a highly used part so it should be available at your local favourite electronics store. If you have old junk boards, you can look there and reuse the old one. I found one on my old sound card.

Otherwise, order online, but ordering from digikey, mouser, etc is going to cost you $8 USD in just shipping/handling.

[blues]

Re: VA902b Shakey jittery image

Part number AL1117-33 (position of component is below, slightly left)
pin 3 = 5.10
pin 2 = 3.30
pin 1 = 0.00

Part number AS1117-18 (position of component is above)
Pin 3 = 5.05
pin 2 = 1.24
pin 1 = 0.00

power was on all connectors connected.

[retiredcaps]

Re: VA902b Shakey jittery image

They are marked as follows:

Part number AL1117-33 (position of component is below, slightly left)
pin 3 = 5
pin 2 = 3
pin 1 = 0

Part number AS1117-18 (position of component is above)
Pin 3 = 5
pin 2 = 1
pin 1 = 0

The values are read on an analog meter and are not exact. Taken with power on the board.

Voltage regulators are usually +/- 1% of their stated output. The suffix in the AL1117- part number denotes the expected output voltage. For example, AS1117-18 denotes 1.8V DC output.

With your analog multimeter readings, both regulators would be bad.

It would help to redo the readings with a digital multimeter.

[blues]

Re: VA902b Shakey jittery image

Sorry, didn't get your response until after I posted. Do you need me to re-take them with the LCD wires connected?

[blues]

Re: VA902b Shakey jittery image

They are marked as follows:

Part number AL1117-33 (position of component is below, slightly left)
pin 3 = 5
pin 2 = 3
pin 1 = 0

Part number AS1117-18 (position of component is above)
Pin 3 = 5
pin 2 = 1
pin 1 = 0

The values are read on an analog meter and are not exact. Taken with power on the board.

[retiredcaps]

Re: VA902b Shakey jittery image

Do I need to connect this board to the power board and plug in AC to measure the DC here?

Yes connect both boards. All voltage measurements require the lcd to be plugged in and powered on.