Rack kit #232

[John Stout]

I received my kit last week and started building it last night. Almost built the rack case, just a bit more soldering to do today (about 2 hours work for me, eyesight and steadiness of hands is a problem these days!)

One or two components missing from my kit but José replied promptly and they are on their way. 

I've lent my 7" Raspberry Pi screen to someone but can't remember who. If the worst comes to the worst I'll have to buy a new one. The plan is to get it finished by Christmas to show the grandchildren Spacewar.

When it's completed it can join the -8 (on which I started my programming career in the 70s), the -11, and the -10 (still cosmetically unfurnished!)

John Stout

[John Stout]

Another two hours or so yesterday soldering up the rack case and then doing the diodes on the main PCB. Two hours is about all I can do at a time!

One question: the PCB has a diode marked DI39 (I think) but this isn't populated on the picture:

b-diodes-IMG_20250605_134048.jpg (4080×3072)

I've put one in on the principle that it won't do any harm, and can always snip it out.

John

[Matthias Barthel]

Its the diode under the single-instruction-switch right ? Just solder these diode is, its soldered on both of my pipd's and borh works fine 🙃

Matthias

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[John Stout]

Session last night got the resistors and connectors soldered to the main PCB. The 'missing' diode of day 2 is referred to in the instructions for the resistors (step 3 of Top PCB - Soldering the small parts).

My Ottopanel top, and the blue and white front panels are slightly bowed, whether because of shipping or my storage. I've put a weight on them to see if that will straighten them out, but I'll carry on and see if it makes any difference.

John

[Matthias Barthel]

John,

My panels were slightly bowed, but in the end it doesn't matter,my rack and the console kit looks very good 👍

Matthias 

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[Malcolm Ray]

Mine were bowed too. But soldering the ottopanels in place takes care of that, and I found that the few nuts you're able to use on the switches flattens the front panel nicely.

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[John Stout]

Great. I'll leave them as they are. Spent an hour or so today 

putting the spacers on the LEDs but won't get round to soldering them 

until tomorrow at the earliest. 

Does anyone have any suggestions for a 7" HDMI display? I'm

Currently looking at a Wave share one.

[Bill E]

I used this waveshare for my front-panel mod, works great: https://www.amazon.com/dp/B083V7WK15

Bill

[Malcolm Ray]

Here's the Waveshare one I use. From the pictures of the PCBs, I think it's slightly different from yours:

https://www.amazon.co.uk/dp/B07CPBCZHB

This one has good and bad points when used in the PiDP-1.

Good:

The tabs on the bottom fit neatly in the slots on the console top panel, and the pressure of the HDMI plug against the speaker mounting panel holds the display in place by friction.

Bad:

The size of the HDMI connector means that, for me, the display ended up noticeably angled from top to bottom.

I solved that minor problem by replacing the spacers between the front and back panels with longer ones (20 mm, I think).

Two other things help with mounting:

1. A right-angle male-to-female HDMI adaptor makes plugging in the HDMI cable easier. You can get these cheaply in pairs (left and right handed), to save you the frustration of getting the wrong one.

2. Small rubber self-adhesive feet stuck to the back of the aluminium strip act as bumpers for the top of the display to rest against.

This display has an audio output jack, so I suppose you could dispense with the USB audio dongle, saving a USB port. But I haven't tried that.

On Thu, 2025-12-11 at 11:10 -0800, Bill E wrote:

I used this waveshare for my front-panel mod, works great: https://www.amazon.com/dp/B083V7WK15

Bill

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[John Stout]

Thanks Bill, I'll get one of those ordered. 

John

[John Stout]

Sorry Malcolm, quite why I thought your name was Bill I have no idea! 

Anyway, Wave share ordered from ThePiHut in the UK.

Today's job is the LEDs on the main PCB.

Did real PDP-1s have incandescent bulbs, all soldered in by hand? My only relevant experience

is with a Data General Nova 1220 front panel. I think I still remember the postal boot sequence

to load RDOS and start it running:

376/Examine/060133/Deposit Next/377/Deposit/376/Examine/Reset/Start

John

[John Stout]

Ah, I see, two very similar first line messages, one from Bill, to which I replied correctly, then

the second from Malcolm! Apologies all round! 

I'll order some of the right-angled connectors Malcolm so I'm ready.

[Paul Birkel]

Well the red LED wasn't invented (much less commercialized) until 1962, and the blue LED not until the 90's, so no white LEDs until the 90's as well.  Ergo, in 1959 necessarily incandescent bulbs!

[John Stout]

I was being lazy by not looking up dates. Thanks for the timelines.

I assume I am now in the position of the workers at DEC who soldered in 119 bulbs by hand - or possibly 119 sockets since I imagine they might have had a high failure rate. Mind you we ran our Nova for a long time and I don't remember any of the bulbs going. Looking at a YouTube video (The Data General Nova 1210 Lives!)  it does look as though they were soldered directly on to the front-panel.

John

[Paul Birkel]

The wise designers at DG, as well as other firms, included keep-alive circuitry that limited the thermal-cycling otherwise involved with on-off-on transitions.  if you look at their front panels carefully you'll see that the "off" state still has a dim glow.  Some designers did use pin-style bulbs mounted in plastic base-shells to ease replacement at increased expense for the bulb plus the PCB pin-sockets.  DG was about the height of frugality, so (de)soldering was a lifestyle :-}.  The leads were fragile and you had the joy of aligning all of the bulbs to properly fit into the light shield block when reassembling.

[John Stout]

All LEDs soldered in yesterday and switches inserted, but it appears some of the LEDs, despite my every effort, weren't properly seated so I'll take the switches out and do the LEDs again. 

Missing posts arrived by DHL yesterday, well ahead of schedule. Thanks José.

John

[John Stout]

All switches soldered in yesterday with just the middle pin, BUT in trying to reseat one of them in the ADDRESS BANK I've managed to ruin the track on the upper face of the main PCB.

I can't clear the middle pin hole of solder in order to put the switch back in. Is the best thing to try and drill it out, then put a jumper between the ruined track around the middle hole to a nearby one (this assumes that the centre pins are common)?

Alternatively can I snip the centre pin, jumper wwhat remains of it to another switch's centre pin, and then just solder the upper and lower pins for stability?

I've had problems with the switches in all my PiDPs, down to my soldering technique and equipment I'm sure.

John

[Matthias Barthel]

John , can you make a picture? 

On the debugging website from oscar isnthe complete kicad-project, there you can trace the middle-pin and see if you can make a wire from another pin to get the signal, i think the middle pin is a row pin and its needed for full function.

Matthias

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[Matthias Barthel]

John,

You need a solder sucker to get the holes free.

https://ebay.us/m/Q1sqJm like this.

Matthias 

[John Stout]

Matthias

Thanks for your prompt reply.  I have a solder sucker and I think that's how I managed to remove the trace, I think it must be over 20 years old so perhaps I need a new one?

Do you have the URL for the debugging website? I can't seem to find it on obsolescence.dev? Attached below is a picture of the problem.

John

Preview attachment PXL_20251214_133424421.jpgPreview attachment PXL_20251214_133424421.jpg

PXL_20251214_133424421.jpg

3.2 MB

[John Stout]

Ah, think I've found the debugging site. Just installing KiCad to look at the file.

John

[John Stout]

No, I've just found (on hackaday.io) just the CAD files for the case.

Is there somewhere else I should be looking?

All the best.

John

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[Matthias Barthel]

John,

Here the Link tontge kicadfiles

https://obsolescence.dev/pidp1-sw/pidp1-final-kicad.zip

And the debugsite

https://obsolescence.dev/pidp-1-building-debugging.html

Matthias 

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[Matthias Barthel]

John,

I can not open your picture 🤷🏼‍♂️ 

Matthias 

[John Stout]

Thank you so much. Looking at the CAD files the centre pin is common so I'll try my solution (I'll check with Ivan/Oscar first).

I've just ordered a heated solder sucker (40W Vacuum Desoldering Iron Pump Solder Sucker | eBay UK) but that won't be here quickly.

John 

[John Stout]

Is that any better?

[Matthias Barthel]

Yeas, i can see the problem. With a solder sucker this is easy to fit... 

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[Matthias Barthel]

Try to get the solder out with a desoldering copperwire, that sould work fine...

After this you can check the lines if they ok or you must make a wire from another middlepin to the switch.

Matthias 

[Glenn Babecki]

If you opt to use solder wick, I would recommend adding a bit of flux to the wick to help pull the solder away from the site.  Start with applying the heat at the pad then drag the iron away down the wick to help move the solder away from the pad hole.

But you probably already knew this...😉

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[John Stout]

Thanks for the advice. 

As I said, my soldering technique isn't the best, so any and all advice is really welcome.

All the best.

John

[Unibus]

Hi,

I'd start with a solder sucker tool and move to Soder-wick if the tool doesn't fix the problem. If desperate, an alternative to Soder-wick is clean, multi-strand copper wire. From the photo I can only see a solder filled hole and cannot see any PCB damage. 

If you are not confident about removing the excess solder look for a company that does PCB repairs in your area. In my case there are companies that have repair technicians in their workshops. Catch is finding the right person with the right training and experience who is willing to help. If they work to Mil specs you won't find any better. Alternatively ask members of an amateur radio (Ham radio) club in your area to provide recommendations for PCB repair services.

If you damage a PCB the first step is to remove any excess solder from the hole{s) and/or track(s). Just in the area of the damage you may have to remove a solder mask from copper tracks by careful scraping off the surface layer.

If a straight section of track is damaged with a simple cut I have used a straightened piece of fine single strand of copper wire. Note I said straightened and not straight wire. Anchor one end of relatively fine copper wire in a vice and pull on the other end until you feel the copper 'give'. This will remove any kinks and should yield a section of straightened wire. Wire size is important, can't be too thin or too thick. Use a piece to bridge a PCB track gap.

For more complex repairs you can get sheets of stick on copper tracks to solder onto the PCB for track replacement.

Regards,

Garry

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[sunnyboy010101]

I have never had much success with solder wick. As mentioned above, probably lack of flux. For years I used a solder bulb to desolder (even used it on Saturday!) but what really saved me was a 26$ el-cheapo desoldering iron with integrated solder sucker. "Preciva 929D-V Electric Desoldering Iron Solder Sucker" (link: https://www.amazon.ca/dp/B09MZ16JBV?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1 ). It came with cleaning wire and spare tips, but I find an unbent paperclip works best for cleaning the nozzle. It has saved me from soldering disasters many times since last summer when I bought it. Cheap enough I don't worry about it compared to the $$$ desoldering stations.

-R

[John Stout]

Thanks Garry. I'm going to my local Hackspace today to see if they can either help or provide me with the tools I need.

I've never heard of the 'straightened wire' approach before. Very handy.

With a bit of luck I'll report back with a successful outcome.

John

[John Stout]

Thanks. I've ordered one of the integrated gadgets but I'm popping in to our local Hackspace to see if they've got one since the ordered one won't be here for a bit. 

I'll report back with any progress, or alternatively just solder up the controllers for something to do while I wait!

John