All righty. Here's a bundle of updates as I fell behind.
A couple of packages arrived at the end of last week.
Carb rebuild kit for the Rover.
Also the last couple of bits I'd been waiting on for the head gasket job on the Renault are now here. The timing belt kit is already in the boot. So I *think* I now have everything I need for that.
It meant this was time to get stuck into cleaning up the Rover's carb. Ten minutes later...
One extracted carb.
My suspicion that the innards were likely to be as grubby as the float bowl was pretty quickly proven to be correct.
That's about a third of what I dug out of there before it was dumped into the ultrasonic cleaner then left it to stew for half an hour.
I also discovered that the diaphragm was shot. I couldn't see any actual cracks all the way through, but it was definitely perished and had basically turned to plastic. Hard to see the perishing in the photo, but it was definitely there.
Beyond this point I was covered in carb cleaner etc so no further photos. However it basically consisted of removing all of the major parts of the carb and then putting it together again. I decided not to disturb the throttle shaft at this point, nor replace the needle/seat. My logic here was simple: That until the cold start control physically stuck and resulted in me likely pulling a load of crud out the bottom of the tank, it was running the engine absolutely fine. Visual examination of the needle showed no visible wear or damage at all. There is a tiny bit of play in the throttle shaft, so long term I will probably change it. Right now however I'm not throwing more variables into the mix. I know with the carb clean, it should go back to being fine. I might go back in and finish the rebuild at a later date - when I'm not in a situation where I have only 2/5 cars working!
A little disappointingly the carb to manifold gasket supplied with the kit from SU isn't correct as it lacks the cutout for the slow running air passage. Luckily I still had one in stock from when I bought the head gasket kit.
With everything back together I set about trying to dial things in. For what felt like forever. I just couldn't get the engine to idle smoothly no matter what I did with the mixture adjustment. It would clear up around 1000rpm or so, but below that would just get really stumbly. Until I took about 10 degrees of timing out. At which point she immediately returned to a more or less smooth idle. Not quite as smooth as it used to be, but I was clearly in the right ball park.
I'm not sure if the distributor had crept out of adjustment (the clamp wasn't massively tight) or what had happened there, as I'd not touched the timing in a long while.
Anyhow, with that set more sensibly I set about trying to find tune things a bit. While working largely by ear, I figured I may as well use the equipment I had to help see what I was doing.
That seemed to be where she was happiest. Not entirely sure that gauge reads accurately with modern fuels, but it was at least a help in terms of making sure I was adjusting things in the direction I thought I was.
Still waiting for the point where connecting things up this way around stops feeling really odd.
I had a helper for a good portion of the tuning process.
Must have been a good 15 or 20 minutes they stuck around.
The wiring on the nearside of the engine bay had shed a fair chunk of the outer cloth loom covering at one point and it was blowing around ridiculously in the airflow from the fan. So I set about tidying that up a bit.
Bit tidier at least.
On a similar note I noticed that the wiring loom down to the generator was rubbing against the brake servo at higher revs due to the airflow from the fan making it flap around at one spot so secured that in place so it no longer moves around.
A test run revealed things to be pretty close to back to normal. The throttle linkage needed a slight tweak as it was hanging up a little. I didn't realise you needed to preload it slightly because of how several springs act against each other.
The only thing I hadn't refitted prior to the test run was the intake silencer. Now I can fully appreciate why Rover fitted it, but equally I kind of wish they hadn't. Without it the car is plenty quiet and refined under most circumstances, but there is a truly gorgeous howl anywhere above about 3/4 throttle at any real revs.
I would like to get a paper element fuel filter installed between the sediment bowl and the carb, just to capture the smaller particles which can (evidently) get through the strainer. Though I'll need to acquire some fittings to do that as it's an armoured nylon line with crimped on fittings, so not just a matter of splicing in a bit of hose as on many cars.
Over the last few days I've been using the car quite a bit and am pleased to report that it seems to be back to its usual self. Don't think the idle is *quite* as smooth as it was, but it's close. I'll read the plugs again once we've got a couple of hundred miles covered.
TPA was out and about for yesterday's errands.
A decision I was quite thankful for given that I got stuck in an absolute stinker of a traffic jam on the way home. Which would have been way more tiresome in any of my other cars.
The only thing I did today was to tame my inner hooligan and refit the intake silencer on the Rover.
Which is of course absolute concrete insurance that I'm going to want to get to something that it's in the way of within the next 48 hours.
I did pick up a distraction a couple of days ago from a neighbour.
This is a 1942 era short wave radio receiver made by National, including the power supply and a full set of tuning coils.
This was otherwise going to be destined for the recycling bin...so suffice to say I wasn't going to turn it down. It looks to be in decent shape at least at first glance
Will obviously need all the wax paper caps like this one replaced though.
I'm expecting this to be relatively simple though, these were pretty well made units so new set of caps and it will likely wake back up as though it was put away yesterday. Should be interesting anyway.
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There are three things which need doing (that I know of!) in the immediate future for the Renault. The head gasket is an obvious enough one and assuming that no absolute horrors are found when the head is removed should be relatively straightforward. Just keeping my fingers crossed the head hasn't gone porous or anything maddening like that. Second is a bit of welding in two spots. One is to repair some rust around an area that was damaged clearly some time ago by improper jacking, and some more on the inner wings where the seam sealer has clearly failed and trapped water. I think I've managed to find someone to do that now. Third is something which has been on the to do list since day one, and that's that it still needs a set of drop links. I'm still as unable to track down a set as I have been since day one. The issue here is that there are three different types which were used on the 25. One on the V6 (which is readily available) and some sources say the automatic, one for the lower power version of the 2.0 engine (which I have found one or two of in Germany), and one for this variant. Which appears to be completely extinct. The part I need is 7700766869. Which most websites tell you is compatible with 7700781498 - the V6 version. They're not...they're completely different. The latter part is a good 20mm longer and has the two ends pointing in totally different directions to the correct part. It doesn't help that when you try to search for part numbers for anything on Google etc now about the first 300 results are just repeats of Autodoc trading under about a thousand different names - which gets really old after about the first ten times you've clicked on results to find the same page saying no stock with a slightly different header at the top of the page. Alternatives are RTS 97-90477 or Imperium 31561. Searching for the latter of those is further frustrated as that's a valid Febi part number for something completely different so that saturates the search results. I'm sure there were probably a dozen other smaller companies who made third party parts that were compatible back in the 90s, and equally I'm sure someone somewhere still has a bunch of them sitting on a shelf somewhere. I've been digging on and off since December last year for them though without any luck. It's such a stupid, simple consumable to have turned into such a long term headache.
This is the thing I'm after.
screenshot.jpg
So the solution is most likely going to involve having to try to extract the existing bushes sufficiently intact to ascertain their correct dimensions and then obtaining new ones from
here and re-stuffing the existing links. I'm just extremely thankful that they're bushed on both ends rather than having a ball joint on one or both ends as with a lot of cars as if that were the case I'd probably be well out of luck short of trying to put something together using rose joints and adjustable linkages from a racing supplier most likely.
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Back to the technolgical necromancy.
After having rebuilt yet another iteration of the T1600 power supply only to have it explode more violently than any I've come across before, I've run out of patience with that approach. Without a schematic, even a block diagram or a working example to compare to I've not a hope in hell of getting one of these things working.
So this happened to one of the parts boards.
This has now been relegated to a cable termination platform and something to which I will secure the replacement power supply to (assuming it will fit, otherwise it will go in the expansion slot). Helpfully it also has most of the doubled up pins tied together right at the connector which saves me some hassle. With all of the components removed (I suspect I'll be finding SMD resistors around my desk for months) it's basically just an inert slab of board now.
A not insignificant amount of peering at the manual and very awkward pin tracing occupied a fair chunk of my afternoon.
I've said it before and I will again. The whole flex-PCB backplane the T1600 is built around is really good for keeping to overall volume of the system down, but it really does make working on the thing awkward.
The manual helpfully gives a nice detailed pinout of every connector in the system. Except for the one on the power supply board! Thanks guys.
We need the following.
+5V. Which basically the whole actual computer runs on, unsurprisingly given the era it's from.
+12V. Used for the display backlight and hard drive motor.
Ground. Obviously.
+9V. Only used by the modem, which isn't fitted. So we're ignoring that.
-22V. Bias voltage for the display panel.
That one has proven slightly tricky to trace. The manual clearly shows it as being on pin 14 of the display connector.
However there's no continuity from there through to any of the pins on the power supply. I suspect this may well end up needing some more time spent on it and possibly a dedicated line routed for it.
The absence of that rail though shouldn't stop the rest of the system from working...so time for some really messy prototyping to happen.
This mess is obviously only for testing to see if the idea works. The end result will be rather less messy and more robust.
Given the history with this machine I was kind of expecting smoke despite having been careful to ensure things were going where they should be.
No smoke. No fireworks. No actual display as expected, but the backlight is working and responding correctly to the brightness control. Even better, we get a POST beep, and the system is responding to the keyboard. However I obviously can't see what I'm doing.
Next step will obviously be to try to figure out something for the -22V rail or to have a dig around to see if I can find a CGA to VGA adapter in the giant box of cables.
I'm curious to see if hooking up -12V to the -22V rail would get us any sort of display at least for testing.
Longer term, I do have one of those little Pico ATX supplies floating around somewhere, which may well actually work well for most of what we need.
Still work to be done, but it feels like we're a lot closer to a working system than we were yesterday.
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Toshiba are now on My List for crimes against service technicians.
Those tables of connector pinouts, the sneaky sods haven't used consistent labelling! On the display I/O connector the -22V pin is labelled "M22V(-22V)."
That label however it turns out is suspiciously absent from anywhere else. Hence my wondering for a while if the voltage might actually be generated on the motherboard somewhere - with it being such a low power (0.22W) rail that wouldn't necessarily have been unreasonable - but I couldn't see anything which looked like a likely candidate, and the display obviously wasn't working.
It turns out that on the 100-pin connector to the "backplane" there is one pin however which is labelled "LCDV" which piqued my curiosity. Helpfully again, no further mention of that anywhere else in the manual.
Time to add another wire to my prototype. Which I also added a bit of hot glue to stabilise things having already pulled one wire off already.
Then followed a bit of experimentation. I don't have an easy way to generate -22V right now, but I did have a -12V rail from the ATX supply I'm currently hooked up to on hand. Figured it would maybe do something different (with a resistor in series initially to hopefully reduce the odds of me potentially blowing anything up) to give us some idea of whether I was on the right track.
It looks like we are! See that white border around the display? That's a clear sign of the panel is actually starting to try to work now. Essentially it's still an overloaded "white" screen as we've only got half the intended bias voltage, but it's a pretty clear sign I'm on the right track I think.
This is the power supply connector pin out as far as I'm currently aware. Which is the one table missing in the manual.
Key to acronyms:
ELV - Display EL Backlight supply.
RAMV - Memory board power supply.
LCDV - LCD Panel bias voltage.
VCC - Main motherboard 5V supply.
HDLV - Hard drive low voltage supply.
HDHV - Hard drive high voltage supply.
HDMV - Hard drive spindle motor supply.
GND - Ground, as I'm sure you figured out.
P12V - Expansion card slot 12V supply.
The currently greyed out pins are what appear to be data lines. Reverse engineering what those are up to is way, way, way, waaaaaay beyond my ken. As such they are essentially being ignored for now. There is a definite element of crossing my fingers that those lines are only used for communication regarding power management and then potentially being floating (I've no idea if the termination would be at the motherboard or PSU end) isn't potentially going to cause other issues - but at this stage I'm crossing my fingers. If we wind up having to add a bunch of pull up/down resistors later so be it.
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Had a dig around this afternoon and found the little Pico ATX supply I was thinking of.
If it works as hoped I'll figure out a way to directly secure this to the underside of the original supply PCB. The idea here is to keep everything I'm modifying attached to that PCB, so if I ever come across a proper original board again it can just be plugged in.
Having a bit of a ponder about the -22V rail, I was thinking about buying in a little DC-DC converter for the job, but given it's such a low current application I might actually see if I can cobble together a simple voltage doubler circuit to do the job. Seems worth a try. All I need is a 555, handful of caps and a few diodes if I remember the designs I learned back at college right...big if!
The Rover got a small tweak made to the windscreen wipers yesterday to address the issue with the driver's side wiper hitting the top of the screen surround. This was a very high tech solution.
Yes, I just attacked the end of the blade with a pair of scissors. Problem solved.
This has improved the performance of the wipers from "it's actually worse with them turned on than off" to "pretty poor."
Turns out that the spring in the arm isn't applying enough pressure to keep the whole blade in contact with the screen. However I've noted that there's a lot of play in the bush where the spindle comes through the scuttle, so that needs to be investigated - when it's not actively raining.
I noted today that there is one visible point of water ingress while driving in the rain.
Not really surprising given that you can see daylight through gaps in the seal between the centre and left hand glass panel up towards the top. Sure a couple of blobs of sealant can sort that.
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Finally got around to actually extracting these today.
Fun fact: Things held in place by snap rings come apart a lot easier once you've found and removed said snap ring.
I definitely didn't spend about half an hour staring at this thing and trying to figure out how on earth it came apart.
Also don't punch anti-roll bars. They're harder than your knuckles.
I've been given a tip off that the links used on VW T4 Transporters are very similar. They're a centimetre or two shorter, but I don't think that's likely to be a huge issue - provided they match both sides I don't imagine a little extra pre-load on the ARB being a huge issue.
More importantly the diameters of the bushed parts look to be right - top one accepts an M10 bolt (identical), and the lower bush inner diameter is 23mm.
Hard to see in the photo, but that looks like it's a match.
The inner portion of that bush is actually fine - however it's a very loose fit in the body of the link, which ties in with where I was seeing movement with it on the car. The rubber of the lower bush looks distinctly newer than the top one, so I do wonder if someone in the past has attempted to replace the bush but picked one with slightly too small an outer diameter.
They're really cheap so I'll grab a pair and see if they fit. Watch this space.
Edit:
Also ticked off a to do list item on TPA which has been pending for uuh...about four years today.
Replaced the missing valve cap on the front wheel. Riveting stuff, I know!
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Which I believe brings us up to date.
I'm liking these updates.
