EVF CRT wires troubleshooting

Suitable cams for use as nv, with specs here too. Wiring help for cam viewfinders.
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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 24 Sep 2014, 10:24

That could be good news then, Bruce! :thumbup:

Thanks for the link, I am going to have a think about what else I should get also, I would need a small 5v regulator for the final build I guess. Will he same one you used on your dimmer works? Any ideas about low cost items that could come handy for a learner in electronics? :angel:

Regarding the broken tracks... The one leading to the 2 pin wire socket, it seems to go to the black wire, not the red one. I am just commenting from what I can see and not what the manual possibly point to. I get a continuity from the tiny copper tab at right side hole to the inner pin, which when the board is flipped over, the black wire is connected to. I can't see another track from that hole pointing to the red wire as you mentioned. :think:

I do appreciate your expert help Bruce, and I thank you. :thumbup:

The manual was a lucky find and it will add few more CRT viewfinders models to the other thread, about wiring layout.
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

phoenix
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Re: EVF CRT wires troubleshooting

Post by phoenix » 24 Sep 2014, 11:45

You'll need an LM7805 5 volt regulator rated to supply 1 amp.
The 1st version of the dimmer used this regulator, but the second version used a much lower power version (100ma) which will not be suitable
You need a small soldering iron (around 15 watt rating) with a fine tip and some thin solder wire to work on these types of circuit board.
Put the new capacitor in position making sure you put the positive leg into the hole marked + (it will probably explode if you get it the wrong way round!)
It looks like the positive leg of the capacitor goes to the inner pin on the 2 way connector
On the underside of the circuit board, bend the capacitor wires so that they hold the capacitor in position.
Don't try to solder the capacitor wires to the broken ends of the solder tracks, instead, solder the capacitor legs to the point where the track ends or where it has another component soldered to it.
Make sure the bare capacitor legs don't touch anything other than the points where they should be soldered.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 24 Sep 2014, 11:58

Thanks Bruce, great tip. :thumbup:

I am a bit stubborn, so I investigated a bit more for the proper manual (my board is VF-42P not VF-42)
I could not find one but I found photos of the identical board as mine, which confirm that the positive leg of the capacitor goes to the inner pin...

Image

..and the other side...

Image

Good fun... Good fun... :thumbup:

Thanks, Bruce.
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 24 Sep 2014, 16:22

I had a look on RS for the LM7805 and there is one 1A that operates with a 10v input. There is another one that that has a maximum input of 35v and a maximum output current of 2.2A.

Am I right in thinking that:
1) if I use the 10v one, I must add a resistor of some sort, inline with my 12v power supply? Then I would need to know which one... :think:

2) If I use the one with 2.2A maximum output, the battery would run out quicker?
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

phoenix
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Re: EVF CRT wires troubleshooting

Post by phoenix » 24 Sep 2014, 17:17

Don't bother with a regulator than can only handle an input voltage of 10 volts - too much faffing around with a resistor to get the voltage down to where you need it.
If you use a regulator rated for 2.2 amps that simply means that the maximum current it can handle without failing is 2.2 amps, so there's no difference in the rate at which it will discharge your battery comapred to say a 1 amp regulator
These regulators will do the job nicely
http://www.ebay.co.uk/itm/2x-L7805-LM78 ... 4897.l4275
The only thing to remember is that the metal plate at the back of the regulator is not connected to ground - it's usually connected to the input voltage, so don't let it or any heatsink connected to the metal plate come into contact with anything that can't handle 12 volts

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 24 Sep 2014, 17:49

Just ordered 2, Bruce.
You are THE man... ...man! :thumbup:
I would have never thought that the heat sink attached to the regulator would carry voltage.

Just last week I removed some components off a printer, two of which resembled the regulator that you linked. I don't know what they are but I was interested on the heat sink they were attached to, as I was thinking to cool the regulator I just ordered (if required). So, if I insulate the heat sink all should be fine.

Cheers, Bruce.
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

phoenix
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Re: EVF CRT wires troubleshooting

Post by phoenix » 24 Sep 2014, 17:54

Yep, insulate the heat sink and all should be well.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 06 Oct 2014, 17:15

An update to the above posts...

I did receive the capacitors (minimum order, 50 pieces, from Germany), added/repaired a clean track, soldered the new capacitor in, switched the viewfinder on and... I get a white screen but no video.

Either another component has failed or I must have moved one or more of the preset metal pots out of sync/alignment.

I am done with it... unless you, Bruce, John or anyone that knows "electrikery" likes to give it a go, purely for curiosity that is. :D
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

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AirRifleSport
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Re: EVF CRT wires troubleshooting

Post by AirRifleSport » 01 Apr 2016, 02:14

Hi guys. Long time has past since my last post...

This post is to let you know that I have finally sorted out/repaired the viewfinder! :D
Yes, I did say that I had enough trying to repair it, but I couldn't throw it away... I decided to store it in the garage and I would have another go at some point.

Yesterday, decided to have another go at it... before I would throw it away. :angel:
I am glad I did, as I found out that there were two more problems with it.

1) there was a loose wire.
2) the brightness pot was all maxed out, washing the video image out.

The viewfinder works well and it does not require the 4th wire named TALLY.
All of this comes a bit late, as I completed the project by purchasing another viewfinder.
I wanted to post this as to say, it pays to be stubborn sometimes, and thanks again Bruce, your help was not a wasted of time. I now have a backup viewfinder, maybe I should investigate if I could make use of that TALLY wire? :crazy: :crazy: :lol:

Regards,
Franco
...the doctor said that I need to do gentle exercise... I said to him that I already did... trigger squeezing!

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