Found this mini CRT inside a JVC GR-AX35 video camera.
The label boldly stated that its the “Official Camcorder of the World Cup USA 1994”. Found it interesting that I was taking it apart 28 years after, during another World Cup, the Qatar World Cup 2022.
A general overview:
Opening up
JVC cameras seem always to pose some challenges when opening them up, this one was no different. There is a hidden screw under the Eject button.
The Electronic Viewfinder itself was easy to detach. Inside, there is a clean single board with no bodges on it. Date code is Jan 1994.
Electronic View Finder unit
This one was very easy to open, and inside I found a CRT branded Citizen 2400-56 and driven by an AN2514S IC. The image was almost inverted and looked very blurry at 5V, I had to bump the voltage higher, to 5.3V to get it sharper and swap the two capacitors (10µF @ 10V and 3.3µF @ 50V) to get the correct levels back.
The CRT has a label reading Citizen 2400-56 (Oriex) Japan. Hardly discernible, under a lot of goop, I think I can also pick up the MO1KTA80WB marking written on the picture tube itself:
Identifying the signals was tricky. I was able to locate one pin that has a direct connection to the Fly Back Transformer case (the GND), but usually, there is a VCC connectivity to one of the other FBTs pins (of course, not the GND pins). Not in this case. No schematic manual for the camera either. I was able to find the schematic manual for the next iteration of the camera. There was one pin less going to the EVF unit, but there was an REC EN (active high). Uhuuuuum.
So with a bit of trial and error, I was able to identify the two pins (one VCC, and the REC one), and then the Video IN:
First power on – the black levels seem wrong, the image is blurry at 5V and very low brightness. Upping the voltage to 5.3V got some clarity back, but levels and brightness were still way off (a hint of dead electrolytic capacitors).
I decided to swap the two small capacitors, since the 10µF was measuring as an Open Circuit, and the 3.3µF was reporting an ESR of 17Ω:
As comparison, here is how bright the image is now (using same camera settings):
Not only the brightness has restored, black levels are good too. Unfortunately, the image is still rather blurry – and the board has no focus adjustment that I could see.
Another mini CRT salvaged from the dump ..
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