Very nice! Time for a disk drive.
This one gets a 2/3 rack next
MY other machines have those fancy disk drives and dectapes etc…
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HI all,
Refurbish and racking has stalled. Today I started the system to try a program that I had written. Within seconds of startup the mains fuse on the PC05 blew. The power supply has two fuses between the rectified and filtered secondary and the regulator inputs. On removing those fuses then mains transformer hums loudly fuse still blows.
The most likely failure is the rectifier pack as the large filter capacitors rarely go low resistance.
It seems to me that often such old equipment gives the restorer a glimpse of success before the strained components fail. In a funny way it is like a teaser of success to make sure you stay on task and fully restore it.
I just replaced a failed diode bridge in a PDP-8/I power supply. I imagine that you have some shorted diodes in one of your diode bridges.
Yes. The DEC rectifier is a little odd as it has two spade lugs on the positive and also two on the negative. I will need a few of those odd spade lug doublers so that I don’t need to hack the cabling.
My RetroChallenge 2023: I had a bit if a setback with my high speed punch/reader blowing fuses. With the primary suspect clearly in my mind I went on a hunt through my shed for a genuine replacement. Second hand of course.
Once again I am perplexed! On doing the exact same operation this video did not embed but created a link. I need to stick to old computing it is far more predictable 
Here’s the culprit
It is not your usual bridge rectifier with 6 tabs. Each leg of the bridge is separate so that they can be utilised separately with a center tapped transformer to provide full wave rectified output with only two diodes.
After some testing I discovered that one diode in the bridge was shorted and one was open. I suspect that while the machine was working the transformer was humming louder than it would normally do because it was already on the way out.
With the new rectifier pack in the transformer is completely silent. Yay!
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My RetroChallenge 2023: This next clip is an annotated video of the end to end process from power on through to running and saving a basic program with the PC05 high speed punch/reader.
There is only 5 days left so I am uncertain if I can get it all into a rack in time. I may just settle for the refurbishing of the power control and distribution module. The old versions have a huge glass bulb half filled with mercury so one needs to take care once again.
MY RetroChallenge 2023: My final say.
How efficient and useful could a computer system be if it’s only method of storing/loading both program and data was paper tape and printouts.
Watch this to find out…
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Kerry - This is excellent work indeed.
Congratulations on the work and thank you for such a detailed and exhaustive approach. This will certainly inspire and help generations to come!
Thanks for that. I have found that getting involved with like minded people has been very motivating. It has been quite a revealing exercise for me identifying my poor camera skills, awkward ad-hoc talking, repeating myself and slowly improving edit skills. I hope that when things calm down on the personal level that I can do a lot more restoration work and hone my presentation skills.
This is actively why we have got involved with the Retrochallenge - the real challenge is usually not doing the work - but sharing your efforts, findings and skills with others - which is what the ACMS membership is all about - particularly locally in Australia which does not have the density of skills as some other countries.