A package arrived this afternoon containing goodies for the P6.
Full new set of valves and a replacement for the broken spring.
Which meant that I got to spend several hours hunched up in a really awkward position lapping valves in - A job which with a workbench would simply have been tedious rather than tedious and exceptionally uncomfortable.
Nevertheless, we got there in the end.
Couple of darker spots on a couple of the seats (which the camera really seems to have made look worse), but they're all nice and smooth with no pitting I can detect.
Valves have now all been safely bagged up ready to be refitted, I just had them laid out there for the photo.
Next up was the first pass at cleaning things.
Any suggestions as to the best way to get shot of this - what I assume is utterly baked on residue of a previous head gasket (but not the one I just took off!)?
I'm obviously not in a hurry to go to town with a scraper given how easy it would be to scratch the head with it being aluminium and I'd rather not make myself more problems to deal with. You can't actually feel this with a fingertip, but it looks to me like it really should be removed, even if whoever put the last set of head gaskets in apparently didn't think so. Pretty much every head I've had off myself before has been cast iron, so I'm probably being a little paranoid about damaging the mating surfaces on these.
If I had a local machine shop I had a working relationship with the best solution probably would be to get them to just re-face the heads, but I don't - and last time I wanted to get something like this done I got a gruff "We don't do car stuff" from the two I did try speaking to.
Looking a lot better than they were though.
If I could just get that crud to shift from the head surfaces I could start looking at getting things ready to go back together. Weather however put paid to any plans for getting anything else done today as it's started raining, and I was pretty much out of time anyway.
In other news, it's been quite a journey but would you look at this?
Yes, that is a working Toshiba T1600, working entirely on internal power with only the original 12V input being used.
We've got a Pico ATX power supply doing most of the heavy lifting, giving us the +5V and +12V supply rails, and a separate DC-DC module providing the -22V rail for the display bias. Getting hold of that module turned out to be a pain in itself as it seems that it's a market that's rife with mis-labelled parts. Given that this was being used for a negative rail, I needed a supply that was isolated - plus I also needed it to be a boost converter as we were putting 12V in and looking for 22V out. It took me six attempts to get one which was actually as described. Shame it's not 24V, as I could have easily got a sealed PCB-mount module from RS etc to do that, however I needed something adjustable on account of this not being a commonly used value.
If it survives a couple of overnight soak tests I'll look at tidying up the installation. You're not getting to see it as it stands as it's seriously ugly in a few areas as proof-of-concept prototypes tend to be!
This system will be coming apart again anyway as it's disgustingly filthy in a few areas so wants a good deep clean - plus apparently we have an issue with the video memory on this motherboard. It's absolutely fine in text mode, but we have some issues when running in certain EGA graphics modes.
Odd that it's only in very specific modes it does that, others it's absolutely fine.
This isn't a huge surprise given that the VRAM is directly underneath the power supply board and was showered with the corrosive goo when the caps leaked. I do have a few spare motherboards though, most of which look less crusty than this one. Given I was mucking around with the power supply I was more inclined to risk trying a somewhat suspect board than one I expected to be fine. Contrary to modern laptops, completely stripping this down to having *everything* out of the case is about 15 or 20 minutes work. In all honesty, 99.99998% of the things I'm likely to use this for will be in pure text mode anyway so that video artefact issue really isn't an issue as it doesn't seem to happen in any text modes.
Now we have a working machine though rather than a large beige door stop I'm inclined to actually tidy up my work and get all the best bits of case together to give us a nice tidy machine.
No battery power available, but I'm not too precious about that. The original battery packs would need to be re-stuffed anyway, and that's not something I'm interested in delving into at the moment.
I really don't want to try to figure out how many hours it's taken to get to this stage! It's definitely been the most obstinate retro tech project I've got myself into in a long, long while.
I will - at some point in the future - investigate how much work would be involved in doing a similar mod for a T1200 as they very commonly have identical issues with dead power supplies. Nice to be getting towards a point where this project can actually be labelled as properly finished.