Varying black level

beerNpretzels

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I have a G07 tube with a unidentified Wei-Ya chassis. Only markings are ProMax, chassis looks exactly like the one pictured in this document:

http://arcarc.xmission.com/PDF_Monitors/Eygo chassis Replacement for G07.pdf

It was pretty dorked up when I got it but using the TPG I have it looking much better. However one problem that remains is that the black level seems to change depending on what is on the screen. Using the TPG most patterns look OK but the full screen red, green, blue and white start very bright for just a second and then quickly dim to the point where the colors look dull. Other colored patterns look nice and bright and saturated. On the falling blocks pattern when it starts the black level quickly ramps up to grey, then as the blocks fill up the black level slowly fades toward black.

Is this a defect that is familiar to anyone or do I still have something maladjusted? I hooked up a Dig Dug PCB to the monitor and was able to dial the brightness in to look pretty good but this is going to be a bench monitor I think and I want to make sure it's solid. As is I can't dial in brightness with the TPG.

The only rework I've done is cleaning the pots on the neckboard and the remote board. I'm not certain enough about the model number to try and order a cap kit so if anyone knows exactly what to buy that would be a help too.

Thanks!
 
If you have the original g07 tube and yoke, I'd think about buying a G07 chassis here. They're cheap because everyone has the chassis but no one has the tubes.

Friends keep friends from buying Wei-Ya.
 
If you have the original g07 tube and yoke, I'd think about buying a G07 chassis here. They're cheap because everyone has the chassis but no one has the tubes.

Friends keep friends from buying Wei-Ya.

I considered it but the tube has pretty severe burn, hence relegating it to bench monitor status. As such I can probably live with weird fluxuating black level. In the future if I ever end up with a spare chassis I'll think about swapping it out.
 
i make cap kits for a bunch of the G07 import replacement chassis on our site and if there is ever something you can't find we can make any kit from a customers list of caps and locations. if needed pm me and we would be happy to do it for you.
 
This has been my experience with the cheap replacement chassis as well. They have some sort of AGC that dims the image significantly when it's bright and brightens it when it's dim. They look like garbage.

One Internet to whomever figures out how to disable that and replace it with a pot.
 
I have a G07 tube with a unidentified Wei-Ya chassis. Only markings are ProMax, chassis looks exactly like the one pictured in this document:

http://arcarc.xmission.com/PDF_Monitors/Eygo chassis Replacement for G07.pdf

However one problem that remains is that the black level seems to change depending on what is on the screen.


Thanks!

Yes it is exactly the same. Promax as well as Eygo rebranded the Wei-ya chassis. Use the schematic in that linked document.

The brightness flucuation is a known problem that some have attributed to a weak B+ power supply section of the chassis.

If your monitor main board is mostly green in color on the component side, it's likely a Wei-ya model 820H. If the main board is white, then it is the model 1520H.
 
Wow guys thanks, that's great info!

This one is staying on the bench. If/when I end up with a spare G07 chassis I'll see about swapping it out.
 
Yes it is exactly the same. Promax as well as Eygo rebranded the Wei-ya chassis. Use the schematic in that linked document.



The brightness flucuation is a known problem that some have attributed to a weak B+ power supply section of the chassis.



If your monitor main board is mostly green in color on the component side, it's likely a Wei-ya model 820H. If the main board is white, then it is the model 1520H.



Digging up this thread as I have an Eygo 1520H board that I recapped including replacing the filter cap. It fixed a ton of issues except the brightness is still pretty weak (during testing with a screen generator if you select a fully blue, red or green screen the monitor will always show the correct color and brightness for 1/2 a second and it will then very quickly dim. I poked around at the B+ adjustment but it just made the screen brighten only briefly before dimming again within a second later. Did this thing ever look good? Is there a replacement flyback for it, perhance? The picture gets brighter (But in a crappy way) over time.
 
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