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Radioputer - Part 1


This is what happens when you have too much time, an old radio case and a laptop motherboard which desperately needs a new home.

This is an ongoing project, so please bare with me as I write as some of it is complete, and some of it hasn't even reached the drawing board yet.

The original concept of this thing was to have a computer which could be left on for long periods of time, without using huge amounts of electricity. Primarily it is to act as a sort of 'clever' NAS (Network Attached Storage) but with full computer functionality, such as being able to play video's, music and of course, online Radio stations.

As luck would have it, I had just repaired an ADVENT 5712 laptop which is a 'budget' computer, but actually, for the money is absolutely packed with features. Obviously it has the obligatory Wireless network card, wired gigabit lan, 3x USB's, SATA HDD and DVD drives, external e-SATA and possibly most importantly of all... HDMI. One of the sort-of usable leftovers of the repair was the motherboard.

I didn't want to have a horrible, plastic looking laptop hanging around all the time, with limited connectivity and expensive (slow) laptop sized drives. I wanted something which would look aesthetically pleasing and functional, but unobtrusive. Quiet, but relatively powerful.

Some months ago, while visiting a car boot sale, I found a couple of valve sets for sale. The seller wanted £10 a piece and I only had £10 with me, but also wanted a look round, so vowed to return later, which I did. What I found abandoned when I returned was the following...


At the top we have a Philips BG400A and a GEC B5441 underneath, the philips came off worst and was stripped for spares, the GEC however only had a smashed Dial glass but I wasn't interested in restoring it so it got shoved into the loft until I had this idea.

I decided that the case would make a nice home for my computer project, its a little tatty and could do with a refurb, but certainly looks the part. The opening on the front is 13" wide, and 6.5" tall, quite a lot larger than the original 15.6" laptop screen so I knew I couldn't use that. 

I decided to search for a screen and found that a standard aspect (not widescreen) 10" LCD display would fit to one side of the hole leaving a space to the other side for other things such as ports, speaker, or whatever else you fancy. Obviously there were other requisutes to be fulfilled before the project could be started, such as making sure the motherboard would physically fit.

Here's the radio chassis removed from the case.
Plenty of salvagable bits here...

So I set about removing the original radio components, nut by but, bolt by bolt and wrapped solder tag by wrapped solder tag. I was tempted to simply snip and rip but it was actually quite theraputic to remove everything exactly how it was installed over 50 years ago and gave an impression of just how much work went into building one of these things. No plastic case, no captive screws, not even metric nuts and bolts, these were built to last.

Meanwhile, I searched for a screen as it was something that could put a stop to the whole thing if it couldn't be found.

Plenty of google and ebay browsing turned up nothing immediately usable. I was gifted a 10" IBM computer monitor by a kind forum member but unfortunately this was a non-starter as it wouldn't power up. Eventually a candidate turned up in the form of a Fujitsu-Siemens ST4110 tablet computer. Quite an old machine based on a P3 with a 10.1" LCD running at 1024x768. This doesn't sound like much of a high resolution but in fact because its so small the screen is very usable. The panel in question is a LTM10C321F, made by sharp.

Interfacing the (relatively ancient) LCD panel to the modern motherboard was something which provided probably the most frustrating part so far.

A little background about LCD and LVDS...

LCD screens in laptops aren't connected to the main board using a conventional VGA (D-sub, 15 way) connection, VGA is only used for longer cable runs where you can afford heavy cabling and loss of some signal quality. Instead, they use a system based on LVDS, which stands for Low Voltage Differential Signalling, a very VERY high speed, low voltage data transfer system.

Some early LCD and plasma televisions use this system with a separate 'Media' box which has all the inputs, then the screen is a simple LVDS connection to the box.

The original ADVENT screen is what is considered 'normal', having a 30 pin flat low profile molex connector carrying the 3.3v supply to power the LCD display, 8 conductors carry positive and negative pixel information (Lines L0, L1 and L2) and the clock information (C1) to keep everything timed correctly. Crucially, these 'normal' LCD displays also have 3 pins (plus ground) dedicated to a very small (256 byte) EEPROM which holds very crucial information about the display, this is called EDID data.

The EDID data makes sure that the colours are calibrated correctly and that the screen is being driven at the correct resolution/clock frequency etc. So, what happens if your screen has no EDID data?....

The donor screen is quite old, but from the little information I could find on the internet it shows that it uses conventional LVDS signalling but on a 14 pin connector with no EDID information. The datasheet contained information that should have been sufficient to rebuild the EDID data, but unfortunately I wasn't able to get it working. First things first were to get the data and power TO the screen, even if its not talking the same language.

Obviously you can't fit a square peg into a round hole, and you can't fit a 30 pin connector into a 14 pin recepticle. This calls for science...


The Left hand picture is the ribbon from the screen, complete with power and data wires soldered on. This connector is less than 2cm wide.

The right hand picture is an adaptor lashed up using part of a smashed LCD screen (the 30 pin connector), and just to the left of centre of the picture is the EDID EEPROM connected to the adapter with the yellow wires.

The results on powering up weren't encouraging...

Black and white stripes, fetching...

More on EDID...

When your computer boots, it pulls the EDID data from whatever screens are connected and stores it in the registry. This just makes it easier for windows to access the information as required.

If your computer starts, then you can pull enough data from the registry (the first 128 bytes) to upload into your EEPROM, so to get the information I loaded windows onto the Fujitsu Siemens tablet base that the LCD came from, then used an EDID extraction program to pull the data. Nothing needs to be modified, simply save the data as a .bin file, then upload it to the EEPROM using an I2C interface (a Win98 machine with a printer port is useful here) and a program such as PonyProg.

After sorting out some shorted data lines, and uploading the EDID data I was greeted with the following...
   
Glorious 1024x768.




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