Soldering Power To The Main Board
After about an hour of fiddling around managed to solder the 4 wires which will take the power from the external socket to my board and back. The solder on the machine is lead and it does not want to melt. I had an absolute nightmare getting the wires through the board and getting the solder to melt on both sides. Finally after lots of fiddling got the wires soldered on.
Next tested that it actually will work from the battery. Machine initially kept powering off after a few seconds. I found the reason, i'd managed to short two of the connections on the back my perf board. Sorted that out and it works ok.
Next thing to do is cut the tracks so that the input wires are separated from the output ones, the input will power the charger and the VGA convertor board. The power from the battery board will then go back into the machine (or be powered via the input if the switch is in the correct position).
Due to the VGA converter drawing lots of power I have decided to make it available when the machine is powered via mains. It adds too much drain to the battery and is not really useful unless you are at a desk anyway.
Originally I was going to have everything powered by the battery and the unit could be powered off via a switch but would always be charging if plugged in.
The machine will now do the following...
1) Always charge when plugged in.
2) The VGA convertor will be powered when plugged in only (from the incoming 5v).
3) The machine can be powered externally while the batteries are charged or you can use the battery to power the machine and the small screen. Thus the small screen is only available when on battery power and turned on. Where the machine is available if using battery or on external power (as the original machine was) dependant on the switch position.
Tested the battery (2000mah) and found that with the small screen and the machine powered it will provided about 45mins to an hour. Have managed to get the battery I was originally going to order (but was out of stock) which is 6000mah so gives several hours of usage.
Mounted the screen in the case.
Firstly marked out where the screen should go and used the dremel to cut out the hole. I left a small set of lugs from the lower plastic area so that the screen can sit on them. It turns out the screen was exactly the same height as the indent in the air slots so it fits nicely.
Inserted screen and adjusted to fit correctly.
Hot glued the screen and the board into place.
Tested to check everything works ok.
Installed SD Card
Dismantled the Compact and installed the GoSDC into the ROM slot.
Tried to power the small TV display from the machine but found it requires 6v. Going to have to add another Step-Up to the power board to provide the 6v it requires.
Update: Wired in the extra Step-Up, Adjusted the voltages on the Step-Up boards so that one is 5v and the other 6v.
Connected the power board to the BBC externally and checked that everything works ok. Board is powering the screen, Gonbez board and the BBC from the battery.
Then tested the TV board, connected to the external video out and got the following.
You can just about make out the Acorn MOS and the command prompt. This looks better in real life the camera doesn't do it justice. Next step is to get it to run something on the screen.
Battery & Charging Circuit
Well some parts I'd ordered arrived so I decided to solder them together to test out the chargeable battery.
Here is the current charging circuit connected to the mains and the Gonbez. I can remove the power from the main socket and the battery takes over.
This should hopefully provide a 5v input which will charge the LiPo battery when the unit is plugged in. I intend to wire a switch in between the charging board and the step-up board so that I can turn off the machine without stopping it charging.
The charge circuit takes 5v in but the battery is 3.7v. To be able to supply the 5v needed for all the internal boards I am using a step-up board that will take the 3.7v to 5v. I have tried it with the Gonbez board and it runs this ok.
Mini TV Screen
I have a very small TV screen which I bought. The next step is to wire up the screen check it works with the output from the BBC.
I currently have a BBC Master setup on the desk in my office. The problem is that its not very portable, if I want to take it anywhere it requires a large CRT monitor or my recently acquired Gonbes VGA convertor board, a modern monitor and a set of power supplies.
You then also need to take either a disc drive or the DataCentre to give me access to disc images so that I can actually do anything.
I have a spare BBC Master Compact which I intend to make much more portable.
To do this I intend to add the following to the machine...
1) As the original BBC Master Compact uses a large desk unit to house the disk drives I need an internal method of storing software to run on the machine.
So I bought a GoSDC board which adds an SD card allowing me to store all of the software I need to use. The device plugs into a spare ROM socket internally in the machine.
John Kortink who designed the board was kind enough to supply one without the headers as he thinks the Compact may not have enough room inside with them attached. If this is the case I will need to wire a set of switched to the board to enable and disable it for updating the firmware.
2) So that I can run the machine away from any kind of power supply I want to add an internal rechargable battery.
Probably a lithium one with a charging circuit to provide a few hours of usage without needing a power supply. Obviously when the power is supplied it should cut off and charge the battery instead.
As part of this I will add in a power switch so that the machine can be easily turned off and will allow for charging without the machine being powered up.
3) To provide a VGA output I will fit the Gonbes board internally and provide a VGA socket on the back for connecting an external monitor.
This will require the power to the board and the TTL RGB output from the BBC to be wired to the board,
4) So that I can use the machine while on battery and without a VGA monitor or TTL RGB one I intend to provide a small screen built into the machine. This will probably be a 3-5 inch screen added to the top area of the case. Depending on the screen type this will either be wired to the composite out or to the second port on the Gonbes board.
This should be a mirror of what is output to the VGA / TTL RGB. I might put a switch in to be able to turn it off as it will display even when connected to an external monitor. If I have time it would be cool if when the external monitor is connected it displayed a cool logo.
Well we are at the end again and I'm pretty pleased with what I've managed to get done.
Wasn't expecting to do much this time round and we are now less than 3 weeks away from the baby being here.
Glad I managed to get a bit of time in to do something I've been trying to have a look at for ages.
Using The MDFS
So now that the MDFS is up and working ok I've started to load some games onto it so I don't have to go routing through disks and can easily setup a machine to play on when I get the chance.
Well there is one game that needed to be played to signify the completion of my Retrochallenge, that game is Elite...
Can't wait to read everyone's write up and catch you all in the summer.
Risc OS North West User Group (RONWUG)
Took my kit over to RONWUG to demonstrate how to setup an Econet network.
We started by setting up the MDFS and I explained the workings of the box. I decided to leave the tape unit at home as the thing is pretty heavy so it just has the floppy and hard disk units attached.
We looked at the serial connection and the built in administration menu, then I showed how to change disks using the "Release Discs" button on the front, how to shut down the unit and how the key on the front works.
I had wired up a set of socket boxes to use as a backbone on the network, the socket box below has a machine connected and a terminator as it the end of the network. There is another terminator at the other end.
The socket boxes basically sit on a five core cable that is Krone connected to the box. The cable is basically a bus network with 2 data lines (+/-), 2 clock lines (+/-) and a ground cable.
We then added in the clock between the 2 segments of the network and connected the 2 lines to each side of the network.
The clock should be as central in the network cable as possible.
Once we connected this the red "No Clock" led on the MDFS went out showing it was seeing the network clock.
We then connected a BBC Master and an Archimedes to the socket boxes. On resetting the Master using Break + N the screen shows "Econet Station 194" and then runs the !Boot file from the MDFS.
We then used the *DIR and *CAT commands to view the files on the MDFS. We found a games called IMOGEN and loaded that from the MDFS to show it working.
Upton typing the *STATIONS command we got back a list of machines connected to the network, the Archimedes was in the list showing as station 130.
On the Archimedes we checked out the NETFS filer that allows the system to browse the file shares on the MDFS, you enter your login details and it opens the filer window showing the contents of the MDFS.
I also showed how to upgrade the BBC Master to use Econet. Below shows the installed Econet card in the internal slot.
The Master uses the same card as the Archimedes range and the A3000 and A5000.
All in all we had a good night. The next job is to make the Archimedes bridge to a TCP/IP network so that I can access the MDFS via the network.
Sorting Out The BBC Master
After the initial BBC power supply failed I grabbed a BBC Master out of storage and brought it over.
As usual I then found that I couldn't for the life of me find the BBC to SCART cable for the monitor, I was using this a while ago but since then I've been moving house and have boxed up lots of my stuff and put it in storage.
After searching every box in storage I gave up and ordered a new one from the Retro Computer Shack I have had several cables from here an they are very nicely made.
Thankfully it arrived today so I manage to get the Master working ok.
While I was at it I ordered a few repair kits for the BBC power supplies and will at some point try and refurbish the capacitors in them.
After getting the Master working I opened the case up and removed the dead and corroded batteries that had been left inside, luckily they are contained in a plastic wrapper so haven't leaked anywhere.
The machine doesn't have an Econet card installed so my next job is to go off to the storage locker and find some Econet cards and the ANFS roms that are in boxes somewhere in there.
I did manage to find some extra Econet boxes, cables and a set of terminators, these are home made but should hopefully do the job. I also found that I have an SJ split Econet box, this is for putting in the middle of the network and attaching the clock, the normal way to do this is to have 2 segments and attach the clock between the ends of 2 of them. The SJ box allows me to do this without having to use multiple boxes and is much neater.
Found the issue with the tape drive, it was as I had read on the internet. The capstan roller that moves the tape is covered in rubber, due to the rubber not being cured correctly it has degraded into a pile of goo.
You can see the roller inside its the orange bit, it should be round but has melted and dripped into a pool of goo on the bottom of the drive.
Fixing The Drive
Well I decided to remove the roller from the old unit and replace it on the new one, the new drive works apart from the issue with the roller where the other drive was dead but had a good roller that is intact.
I opened up the casing on the unit that has the old drive and found the reason it wasn't working, the power lead had fallen out inside the casing.
Checking The Tapes
Once I had the unit working ok I powered up the MDFS and went to the tape menu.
I had a brand new tape in its packaging so I decided to try to backup the hard disk.
After formatting the tape (which took about 40 minutes) I selected the backup option and entered the first partition to backup, the drive took a while and finally started to check the backup. Once done I tried to verify the tape just to check everything was ok.
I had a bunch of opened tapes and put them through the verification, they were mostly ok but there are parts where the tape has oxidised and they are basically dead.
Going to see if I can find some new ones on ebay so that I can backup the other drives.
Got out one of my nice looking and clean BBCs thinking that it would be less likely to have issues.
Plugged the machine in and connected to the monitor.
Nasty smell and the famous white smoke started pouring out of the power supply.
Guess that's another one that needs the capacitors replacing.
Got the new tape drive unit from storage and plugged it in, all looks good it has the correct lights etc and tries to load the tape.
Unfortunately nothing is moving inside the tape, looking inside the unit it looks like the pinch roller inside has perished, apparently this is quite common. So now need to see if I can replace it with a suitable alternative.