CurtPalme.com Home Theater Forum

[Nashou66]

[CxTurbo]

Someday I might have to get a scope so that I can learn more. I do not have the time at the moment much as yourself to sit and diagnose for hours on end. I enjoy a challenge don't get me wrong. I would just rater have the correct tools and a better understanding of what part is doing what before I do.

Like with cars I believe that you need to understand how something works before you can fix it.

[Nashou66]

[CxTurbo]

Fished up my VNB's yesterday. Image is becoming more stable. Now to finish the FCM.

Feeling ambitious I started to look into some problem VDM boards that I have and found four bad 1N4003 and a bunch of bad 1N914's.

I'll try to change up those and see what happens.

James

[Nashou66]

[CxTurbo]

Have to play with the diodes out of circuit before I determine 100% if they are bad.


I have the SBYV's in all the back plane boards and in the VNB's. The Image seems to be much more stable now but I did everything at once with no critical viewing in between. I am happy with how everything is coming along now.

I am looking to see if I can find a good sub for the 400V 1N4004 diodes in some other locations as the SBYV's are only available in 600v after the 200v we used in place of the 1N4003.

I have to tell you though the Marquee VDM's seem to hate me. LOL!

Thanks for all the help by the way Nash. It is appreciated as I know you are a very busy man.

James

[Nashou66]

I think the 600v's would do fine. You just do not want to go lower.

Where are the 1N4004's?


Athanasios

[CxTurbo]

The 1N4004's are in the HDM from what I can see so far. There are some big voltages on that board from the looks of it.

Mouser did not stock the 600v ones so I might have to get them elsewhere. I was looking at what they stock to see if I can find something that specs out the same or better.

James

[Nashou66]

Ok, I never looked on the HDM for diode replacement yet after I discovered the SBYV's

Athanasios

[barclay66]

Hi,

When replacing a 1N4004 You will be perfectly safe with 600V replacements as the 1N4004 is rated at 400V. The last digit indicates the voltage rating. Not quite linear as the 1N4001 is rated at 50V and the 1N4007 at 1000V but it gives You an idea...

Regards,
barclay66

[Nashou66]

^^^ Thats what I thought.

Thanks Jorge

Nashou

[CxTurbo]

Thanks Barclay.

I have been looking into diodes a bit here lately and am trying to find a Fast/ultrafast soft recovery with a lower leakage current then the original part. Not sure what kind of effect it will have but lower leakage can be a bad thing.

James

[CxTurbo]

Gentlemen,

My HDM dropped again and shorted something as the fused resistors R92,94 2R2ohm and R5,6 1R0's blew. I changed them out so no more V-Fail. There is however a problem remaining with this board. All three tubes are showing the same issue and it goes away when swapping out another VDM.

The vertical size is very small but shows the whole image. When I try to increase the Vertical height the image starts to get smaller and disappears almost as if the blanking circuit is being triggered from the bottom of the image up.

What on the VDM affects all three colours like this.


I really need to get a Scope sooner then later but, for the life of me I can't seem find one I like in Canada at a reasonable price. I would ship in from the US but USPS almost doubled the international postage rates at the end of January. I might just have to resort to it should the need arise and there is always FedEx and UPS :\


Any thoughts off the top of the head?

James

[Nashou66]

Check the side pin, skew and Keystone as well and see what that does.

might be the DAC , I was going to say the op amp but one of the colors is run by U701 and the rest are U901.

Nashou

[dvh99]

[CxTurbo]

The HDM dropped on the lid in the cage. For what ever reason this shorted out something that caused the VDM resistors to blow.

I will test the voltages this weekend on the VDM with issues and go from there. Hopefully it is just some more blown resistors and not any of the IC's

Thanks for the input

James

[dvh99]

you should place some foam on the inside of the lid.
seems to be a common problem as many have done this before you.

[CxTurbo]

Yeah, Tell me about it. I told myself that I was going to do this the last time it happened and the problem was fixed by replacing a pair of fused resistors. I was not that lucky this time.

Regardless, the foam will be replaced now. Once I find a suitable replacement. I know Tim suggested several layers of duct tape in place of the foam or this purpose.

James

[CxTurbo]

Is it still recommended to do the "line fix" tech bulletin?

I could be mistaken but I thought I read that it was not.

I am still waiting on the Pico fuses for my faulty HDM and will be finished the maintenance to most of the boards. I am hoping to move on to the performance end of things by replacing the recommended I.C's and Precision shunts.

I also ordered some Snap on Ferrite filters for the Stigmator wires to try to stabilize the image as Nash showed in his video. I am having the same type of stability issue. When I do the maintenance on the HDM that will be the final test as it is the last board other then the CLM and VIM that I need to do.

James

[dvh99]

the line fix is a no go.... just put a switch to disable the internal video.