Tangent AMP-50 LCD Mod
This is a Tangent AMP-50 Integrated amplifier:
I bought it off Ebay for 4.99 GBP as it was faulty. So far I have found no fault with it, except that I really don't like its LCD display. It is too small and too bright, making it both useless to read from a distance and bright enough to be distracting under low light conditions (so most of the time for me).
As is usually my procedure when I buy a faulty item, I first dissasemble it to make sure there is no obvious fault with it (like burnt components, burnt fuses, etc...) or anything that could be a danger to my life (like a short to the metal case with improper grounding). While doing this I noticed that the Tangent is not only solidly built, but it is modular. Every single stage is seperate, with clear definitions and pin marking telling you what that part does. Even the connectors are labelled with what signals/voltages they carry. I realised that this would be quite a cool amp to mod.
As I didn't like the LCD Display I decided that it be the first thing to be changed. This is how the original display looks like:
One thing I would like to try is to invert it (i.e. make the background dark, with white text. I disassembled the front panel and had a look at the LCD interface:
LCD on the left, main control circuitry on the right. Initial tests look good. The interface is a standard HD44780 4-bit mode, so I could in theory install any HD44780 compliant device. I would have loved to put a VFD in there, but as of yet I cannot find any that are 16x2. While I had a 20x2 that could fit, I am presuming that the software is designed for 16x2 display, and anything else would cause issues. So for now I will stick with the original LCD.
I desoldered the LCD, disassembled it and reversed the polarizer. This has the effect of inverting the colours. You can see this in the before and after pics.
Before:
After (minus black case, which I had not put back yet):
And the final result:
It worked, but it is a real pain to actually take a picture. In real life the blocks are not so visible, the text is brighter and it has a light blue tinge in the background, not bad at all in my opinion. I would prefer to alter the contrast of the LCD, but at the moment the contrast is fixed. I would need to add a variable resistor, which I might do later on. Its ok for now (when placed in its place, my viewing angle doesn't see the blocks).
