With analogue TVs (the ones I've tried at least) there are a series of trim pots that adjust the picture size and shape. On my Blaupunkt you have to take the plastic casing off to access them. They're also on the mainboard at the very rear. To adjust them, watch the picture and also avoid getting electrocuted is pretty hard to do! So, I got thinking: "what if I ran a patch cable from the mainboard to the front of the TV so that I could adjust the picture and see the resultant changes?" Well, today I did just that! Instead of attacking the Blaupunkt straight away, I decided to mess with my analogue Grundig first. Since GroovyMAME can be setup to provide near perfect resolutions for each game with only height adjustments needed on the monitor, I decided to start with this control.
The great thing about this Grundig is that there are a series of daughter boards that can easily be removed for servicing. All the controls for size and geometry are on the one card.
First, I desoldered the vertical size trimpot using some solder braid:
|Nice clean holes|
|100 ohm variable resistor|
|Nothing beats colour coded heatshrink!|
|Where's my V-size pot gone?!|
|Various daughter boards including RGB, audio, tuner, etc.|
|The vertical amplitude pot is on the floor in front of the screen|
|The other trim pots removed|
The long term plan is to get hold of some proper panel mounted pots and drill holes into the front panel of the TV, underneath the front of the screen. That way once GroovyMAME has done it's best to get everything sized and centred I can do the last few tweaks with hardware. I reckon it's going to be a killer system!
Now... this is where the day got wacky. After the success of my trim pot experiment I couldn't help fiddling with some other stuff. Long story short, I ended up performing a full tube swap! I took the awesome Phillips tube out of a faulty Loewe CT1170 and attached it to this Grundig chassis. Amazingly, it worked first try! Considering that I'd never even discharged a monitor before today I was pretty pleased with myself. The best part is that this old school Grundig chassis hooked up to the high-end Loewe tube looks AWESOME.
This whole process is worthy of a blog entry in itself but time is getting away from me... crazy day of television hacking. Gotta get some sleep then clean up the huge mess I made in the morning.
|Grundig analogue chassis with the tube from a Loewe digital! Oh yeah!|
|Minecraft at 240p anyone?|
|Home made discharge tool|
|Super vivid R-Type Leo|