Resto-Modding a Master 128

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Remklep
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Resto-Modding a Master 128

Post by Remklep » Fri Jan 31, 2020 11:25 pm

I recently received a Master 128 that I purchased from forum member marcusjambler.
If anyone is interested I thought I might do a thread on me Resto-Modding this machine that was responsible for me becoming the computer-nerd that I am...
If noone is interested... I'm doing the thread anyway... :P

Even before I received the Master itself, I had started collecting hardware to upgrade it with.
The following is going to be installed in it:
  1. Gotek Floppy Emulator
  2. VideoNuLa
  3. 2 ARA II from Retro Hardware
  4. Internal PiTube with Pi Zero
  5. hWMultiOs - IDE 4in1 ROM switcher from Retroclinic
  6. TurboSPI MMC
Marcus had sent me pictures which showed me that with as good as all retro hardware the case had yellow from UV radiation.
It isn't too bad, but I still wanted to have a go at restoring the case.
IMG_1279a.jpg
So I went out to my local hairdressers and got some 40 Volume (12%) H2O2 solution that has the consistency of shampoo.
I also bought a UV fluorescent tube.

All electronics were removed from the case, the keyboard are was taped off.
IMG_5796.JPG
I botched together some feet to hold the UV light over the case.
IMG_5800.JPG
I then poored some of the H2O2 solution in a cup and used a brush to smear it all over the top of the case.
After switching on the UV light, I checked the color once an hour and reapplied the H2O2.
After about 8 hours I called it good enough and here is the result:
Before:
IMG_1279a.jpg
After:
IMG_5802.JPG
The difference can be seen especially well if you compare the color of the top cartridge slot-cover (was still in original color) to the rest of the case in both the before and after pictures.

Now I have to do all 4 sides of the top and bottom case halves also.
Last edited by Remklep on Fri Jan 31, 2020 11:37 pm, edited 3 times in total.
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

Remklep
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Re: Resto-Modding a Master 128

Post by Remklep » Fri Jan 31, 2020 11:34 pm

Because of the regulations of shipping Lithium batteries, Marcus could not ship the Master 128 with the CMOS battery installed.
So I had to build a new one.

I bought:
  1. Battery-holder for 2 AA batteries
  2. 3.6V lithium thyonyl chloride ER14505V battery
  3. 1N4005 diode
  4. 120 Ohm resistor.
For a power lead with suitable connector, I sacrificed an old 80mm PC-fan to the Retro Computer Gods...
A piece of Velcro will be used to secure the pack to the inside of the case.

I then put the battery in one side of the holder and soldered the diode and resistor in the other side, attached the power leads and shrink-wrapped the pack.
IMG_5797.JPG
IMG_5798.JPG
IMG_5799.JPG
Last edited by Remklep on Sat Feb 01, 2020 11:41 am, edited 1 time in total.
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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tricky
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Re: Resto-Modding a Master 128

Post by tricky » Sat Feb 01, 2020 9:47 am

Looking really great.
There isn't any need to change what you have done as it seems that you will be taking great care of you beeb, but you can put the batteries to the left of the keyboard for a little extra safety.
PS My personal belief about yellowing is that it is caused by heat and that UV can actually contract it.

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marcusjambler
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Re: Resto-Modding a Master 128

Post by marcusjambler » Sat Feb 01, 2020 11:20 am

Wow... Looking great :shock: :lol:

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1024MAK
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Re: Resto-Modding a Master 128

Post by 1024MAK » Sat Feb 01, 2020 1:24 pm

Good work =D>

However, I just want to make you aware of Lithium cell and battery safety when used in memory backup applications (like the backup supply for the BBC Master CMOS RTC chip).

The value of 120Ω was used by Acorn when alkaline cells were used to make up the backup battery pack. These are manufactured so that if reversed charged with a limited current, they will not fail suddenly and cause an explosion.

The value of the resistor when used with other technology cell(s) or battery/batteries may be different. Here is some information from a German manufacturer.

Looking at the size of cell that you have used (AA size), it looks like a 120Ω resistor in series with a 1N4005 diode is okay. But if a smaller cell is used, then the value of the resistor should be higher to restrict any fault (charge) current (if the diode was to fail short circuit) to a safe value.

Mark

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Re: Resto-Modding a Master 128

Post by Remklep » Sat Feb 01, 2020 1:43 pm

Hi Mark,

Thanks for the info. By the looks of the document an alternative solution would be to use 2 diodes in series.
However, as I'm using a 1N4005 that is rated for 600V at 1A, I think just using 1 diode should be fine.
I will however pick up a couple more 1N4005's when I'm near the electronics shop again, adding an additional diode in series is easy and cheap.

Danny
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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1024MAK
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Re: Resto-Modding a Master 128

Post by 1024MAK » Sat Feb 01, 2020 2:06 pm

Danny, I mainly posted so that anyone else (as well as you) reading the thread would be made aware of why the value of the resistor is not always 120Ω.

With the size of Lithium cell that you used, there is no problem. There is no need to change or add anything. The likelihood of a 1N4005 diode failing is so small, that it is not worth worrying about. And if it did fail, the 120Ω resistor would limit the current to less than 41.6mA which is NOT a dangerous level.

If however someone wanted to use a 3V Lithium coin cell, then I recommend a 4.7kΩ resistor.

Mark

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Re: Resto-Modding a Master 128

Post by Remklep » Tue Feb 04, 2020 10:37 pm

Today I finished the "Mod" part of the RestoMod project, by desoldering the Video ULA and replacing it with a 28pin IC-socket.
IMG_5815.JPG
IMG_5816.JPG
At first I thought I couldn't fit the VideoNuLa because the internal Pi-Tube was in the way, until I realized, it just fit under the Pi-Tube PCB.
I don't like to use fly-leads for permant installations, so I soldered a signal-lead to pin 37 of the 6522 (IC6).
IMG_5817.JPG
This is a topview of all the mods:
IMG_5819.JPG
And a final picture of the color-corrected finished outside:
IMG_5820.JPG
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by Remklep » Tue Feb 04, 2020 10:46 pm

An interesting phenomenon I found when installing the VideoNuLa ROM.
I opted to install the ROM in a Cartridge (Dave's excellent ARA Cartridge), so I don't loose any sideways RAM.

When I insert the cartridge in the upper slot and run ie. Elite (Master, or Tube) All I see is a large totally white window on the screen.
No graphics, but when I press the right buttons from memory, I can launch my Cobra Mk.III, so the game is running correctly.
Moving the cartridge to the lower slot, makes the graphics behave again and I can play.
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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tricky
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Re: Resto-Modding a Master 128

Post by tricky » Wed Feb 05, 2020 7:44 am

Does it show with *ROMs (sorry if you have already checked). I think that the slots can be jumpered out, but may be making that up!

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Re: Resto-Modding a Master 128

Post by Remklep » Wed Feb 05, 2020 7:54 am

Hi Tricky,

Yeah the Rom shows up in both slots and i van Access the Build in setup from both slots.
I‘m sure the slots can be jumpers out, maybe you are thinking of the jumpers to select between ROM or sideways RAM for 2 of the 3 optional ROM slots on the motherboard?
But just in case you’re right, I’ll have a look under the keyboard tonight.

Danny
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by Remklep » Thu Feb 13, 2020 1:55 pm

The saga continues, as I bought (admittedly for too much, but that's what happens if you snipe an eBay-auction) a BBC Master Plinth with 2 5.25 drives.

The Plinth itself is in fairly good condition, there are some small rust spots here and there and there was a slight bend in the lower tray.
The bend was easily fixed.
I removed the rust carefully with a Dremel and a rotary grinding tool, being careful not to do too much damage to the paint.

After thinking about how to proceed for a while, I decided that the best would be to repaint the whole thing.
A friend of mine runs a car-paint shop, so we compared what feels like hundreds of paint chips, to find one that comes closest.
Unfortunately, as the paint is flat and has a structure, we couldn't use his paint scanner.

We decided that RAL 1015 came closest and ordered a 1L can of 2K Acrylic flat paint.
The color is just a hair lighter than that of the plinth itself, if I take into account the fact that the plinth probably has yellowed slightly over time, I'm confident the color is as close as one can get to the original.
IMG_5837.JPG
IMG_5838.JPG
IMG_5839.JPG
IMG_5840.JPG
IMG_5841.JPG
IMG_5845.JPG
As a test I airbrushed one layer the rear-panel (with the serial number on it) to compare the color, I guess I will have to do at least 3 layers.
Close enough...
IMG_5846.JPG
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by RobC » Thu Feb 13, 2020 2:28 pm

tricky wrote:
Wed Feb 05, 2020 7:44 am
Does it show with *ROMs (sorry if you have already checked). I think that the slots can be jumpered out, but may be making that up!
I think only slots 4,5,6 & 7 can be jumpered out with each jumper replacing one of the two sideways RAM banks with one of the 32KB ROM slots on the PCB. The cartridge slots (0-3) are always available.

I would try cleaning the PCB cartridge socket with IPA - cleaning the cartridge connector too might help.

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tone76
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Re: Resto-Modding a Master 128

Post by tone76 » Fri Feb 14, 2020 1:58 am

Nice.

Whilst I enjoy watching way too many videos of classic microcomputer restos on YouTube, there's something satisfying about the classic forum thread. Especially as it can take weeks or months to play out, with feedback/suggestions along the way.

Looking forward to seeing how the resto plays out.
Acorn Electron
BBC Model B (either too many or not enough)
BBC Model B+ 128K
BBC Master 128 x 2

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tricky
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Re: Resto-Modding a Master 128

Post by tricky » Fri Feb 14, 2020 10:33 pm

Retromancave just resprayed a beeb and quoted a colour, but I seem to remember something about a green tinge.

Remklep
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Re: Resto-Modding a Master 128

Post by Remklep » Fri Feb 14, 2020 10:37 pm

Gray primer...
IMG_5852[1].JPG
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by Remklep » Tue Jul 14, 2020 2:57 pm

Finally I had some time to continue work on my project.
In fact I just completed it.

The plinth received 2 coats of paint (Ral 1015).
I then proceeded to install 2 5.25" floppy drives but soon decided I was being silly as I primarily use the Gotek for games/programs.
I want to use the Gotek as Drive 0/2 and the 5.25" Cumana as Drive 1/3.
The appropriate jumpers were set to make the Gotek S0 and the 5.25" Cumana S1.

Then I modified a 5.25" Data cable by removing the Cumana drive connector on the end and replacing it with a 3.5" floppy connector that would fit the Gotek.
I also extended (by replacing) the wire connecting the 40?80 track switch, so I could install the switch just below the Cumana drive in the plinth.

A test was done (successfull) before everything was installed into the plinth.

I recently received 2 1MHz port level shifters and will be installing one in my Master 128 and B+ 64K as soon as the Pi Zeros arrive.
Attachments
IMG_6752.JPG
IMG_6753.JPG
IMG_6754.JPG
IMG_6756.JPG
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by RobC » Tue Jul 14, 2020 3:22 pm

Remklep wrote:
Tue Jul 14, 2020 2:57 pm
The plinth received 2 coats of paint (Ral 1015).
Nice job. Can I ask where you got the paint from? I've just got hold of one of those Master plinths and would like to respray it...
Remklep wrote:
Tue Jul 14, 2020 2:57 pm
I then proceeded to install 2 5.25" floppy drives but soon decided I was being silly as I primarily use the Gotek for games/programs.
I want to use the Gotek as Drive 0/2 and the 5.25" Cumana as Drive 1/3.
One of the really nice things about these Master plinths is that they can actually house three drives side by side if you remove the 'M' ident plate.

I'm thinking of putting a Gotek and two 5.25" drives in mine or maybe two 5.25" drives and two 3.5" drives.

Remklep
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Re: Resto-Modding a Master 128

Post by Remklep » Tue Jul 14, 2020 6:54 pm

I went to an automotive spray shop to see if they could scan the paint and match it, but as the original paint is matt, it couldn’t be scanned.
The we compared hundreds of paint chips and found RAL 1015 to be the closest match.

Cool, 3 drives. I didn’t know the Master could use more than 2 drives.

Danny
BBC Model B+ 64K, 128K Memory Mod, RetroClinic External PiDirect with Raspberry Pi 3B.
BBC Master 128, RetroClinic Internal PiDirect with Raspberry Zero, TurboSPI MMC, RobC's VideoNuLa, Gotek Floppy Emulator.

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Re: Resto-Modding a Master 128

Post by RobC » Tue Jul 14, 2020 7:09 pm

Remklep wrote:
Tue Jul 14, 2020 6:54 pm
I went to an automotive spray shop to see if they could scan the paint and match it, but as the original paint is matt, it couldn’t be scanned.
The we compared hundreds of paint chips and found RAL 1015 to be the closest match.

Cool, 3 drives. I didn’t know the Master could use more than 2 drives.
Thanks - that's really useful.

I think the Master needs a hardware mod to handle 3 drives (and the filing systems don't support it). However, my idea was to have a selector switch to choose which two drives to use.

My other thought was to fit a hard drive in the spare bay...

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