On 25 January 2011 20:18, Tony Duell <ard at p850ug1.demon.co.uk> wrote: Yup, the machine has a TV-out as well as the standard monitor. The PAL board is marked as such and has a colour modulator on it. 5.25". I've only ever heard talk of the 8" Yup, hence me raiding my store of Cumanas :) I remembered the internal layout from school. This machine has a perspex top cover so it's been dismantled and visually checked for damaged components, looks ok. I guessed that, there's 2 ribbon cables that come out of the PSU as well as the separate feed for the floppy drives. I should be able to get a Megger at work. The reason I mention the caps is because the last 3 or 4 machines I've had in have all blown the mains filters. Watch this space! Cheers, -- adrian/witchy Owner of Binary Dinosaurs, the UK's biggest home computer collection? www.binarydinosaurs.co.uk

Tony Duell wrote: Looking at photos of my system (physical hardware is in storage), it has 6 boards: 32K CPU/ROM/RAM, FDC/serial, 32K RAM, VDU #1 (keyboard, modulator, composite out, 1KB RAM), VDU #2 (composite out, 16KB RAM, 26-way header) Bus terminator ... plus an "RGB board" mounted on the back panel, which has RGBS BNC outputs and hooks to the 26-way header on VDU #2. VDU #1 and VDU #2 are connected together via 16-way DIL headers on the boards. I *think* what I've labelled as "VDU #1" is the standard 40-column board (1KB RAM isn't enough to do 80x25 text), and "VDU #2" is a hi-res board. From memory, there's not a lot on the little rear-panel RGB output board; just a few passives and transistors - I certainly don't remember it having a modulator, so I don't think my machine does hi-res PAL output (if it does it'd have to be via the UM1111 modulator on VDU #1) Sadly, I've seen one at Bletchley in a very poor state, which I think had a black bezel around the drives. I do know of one other person who has an 8" setup in private hands; IIRC that has an aluminium bezel around the drives (although the case tops and sides are still "380Z black"). Are we talking X/Y-class filters here, or primary smoothing caps just downstream of the bridge rectifier? I've had many ones of the former fail, but I can't think of a single machine I've worked on where I've needed to replace the latter. I've *seen* older equipment - 60s and early 70s - where they've been replaced, but it's not something I've had to do on the age of machine I normally work on. I seem to recall a small tantalum capacitor somewhere in the PSUs of one of the 380Zs that I've had letting go after a short while of use after being in storage - big bang and a lot of smoke. That's the only time I've had that happen to me, but it was a bit unnerving at the time :-) Yes... and if there's a chance of damp, it's probably worth stripping the whole system and checking for corroded connectors, IC legs etc. and then testing the PSU under a dummy load anyway. cheers Jules

Is this a normal sized board in one of the card guides? As Jules said, the RGB output board isn't, it's a little board an an L-brackt fixed ot the rear panel. I assume you also havea modulator on the text video board (VDU #1). The TV output socket cable is connected to that if you don't have the PAL board. Incidnetlaly, I've just rememberd I ahve a somwaht odd RML380Z board soemwhere. It's got a bit off address deocding logic on it, interconnected by PCB tracks. And 3 (I think) Z80-PIOs and a Z80-CTC in wire-wrap sockets. The Z80 bus linesare are connected to the 380Z bus connector, etc. the port lines and the counter/timer signals go nowhere. There's also a little prototyping area on the board and space to fit some header plugs. The idea is that you make your own custom interfce by adding the logic you need and wire-wrapping it to the PIO and CTC pins. Ans wire-wrap it to a header plug to connect a cable to the peripheral. I would love to find some of the other board too. There was rumoured to be an GPIB board. And an Econet interface. Oh, and a scheamtic of the cassette control box would be intreresting. Fuses generally blow for a reason. I asusme this is a mains fuse (in series with the live side of the mains), in which case the problem could be a short on the primary side (e.g. a filter capacitor, if they're after the fuse), or a short on the seondary side (redtifer diode, smoothing capacitor, etc0. I really would try the series light bulb trick in this case. Start with all the secoadary wires disconnected from teh trransfoerm, and power up wit ha ligth bulb in series with the mains live wire. It should be dark. If it glos, there's a short somwhwere. Power-down, reconnect the secondary wiring, but have the PSU unplugged from the rest of the machine. Power up a gain with the bulb in series. It will probabyl flash at power-on as the smoothing capacitors charge, and it may stay glowing, but dimly. If it's bright, I think you have a shorted rectifier or smoothing capacitor or similar. Of course findign a 100W bulb these days is a problem :-( -tony

Well, I've not got a digital camera yet :-). I wonder if I could convince an HPCC member to photograph it for me at a meeting. Of course this means finding the darn board... IIRC, at least one of the serial port boards was a disk cotnroller/serial board with the former circuitry not fitted. There was also an 'intellegent' disk cotnroller/serial board which had a Z80 on it, I think that was used, with different ROMs, as the controller in the 480Z disk unit (which had a synchronous RS232 interface to the host). What I have never seen are any of the currnet loop serial options which were supposed to exist. IIRC most, if not all, of the 380Zhs have rear panel cutouts for the GPIB connecotr and the 'system controller enable/disable' switch. Whether the board ever made it into production I don't know. I haev never seen it, but 'The Econet Micro Guide' by C. Dawkins says : 'Econet hardware has been impleemnted for the Apple ][, the Nascoms 1 and 2, the Research Machins 380Z and 480Z, S100 bus machines and all Acorn computers, but only the last 4 are commecially available.' A little later it says 'The 380Z/480Z/S100 interfaces have the same driver, receiver, collision and idle detect circuiry as the BBC -- which at least ensures electrical compatibility -- but the ADLC functions are performed by the SIO chip. Only aobut half the hardware on the 380Z board is required for the Econet ; the rest is a 64K RAM expansion and a ROM socket, with the necessary decoding for the RAM to be paged as required. One important use for this paged RAM is when the 380Z is acting as a fileserver -- the RAM on the Econet board then provides cache memory which considerably speeds up opeeration.' The 'ADLC' is the 6854 of course, the 'SIO' is a Z80-SIO chip. Does a short on a power rail in a 380Z blow the mains fuse? It'll cause the apporopraite regulator to fold back and limit the output current, but that current may well not be enough to blow the mains fuse. My first guess is that the fuse blows whenre there's a major fault in the PSU (rectifiers or smoothing capacitors, possibly). Indeed they are. The advnatage of a normal light bulb is the positive temprature coefficient of the filament, and the fact that it will get hot enoguh for that to make a different. I am not sure if that applies to heat bulbs, though. It should apply to tungsten-halogen bulbs, and AFAIK those hve not been banned. I also believe the ban only applies to using bubls for domestic lighting, so it's quite legal to use one as a current limiter -- if you can get one. -tony

Tony Duell wrote: That'd be great if you could at some point (or find someone with a scanner - even a potentially-blurry scan is more interesting than nothing :-) This thread's rather making me want to try to put together some form of guide to RML bits and bobs and perhaps build up a better picture of what's what. Yes, that's true - I've got one of the 480Z disk units and it very much looks like a 380Z board, with PCB traces / pads for a 380Z bus connector (although the connector and associated bus logic/buffers aren't fitted). It has ROM, RAM (2KB SRAM), Z80 CPU, Z80 CTC, Z80 SIO and an 8877 FDC on board. (oh, further point that I forgot to mention elsewhere - the network board in my 380Z server was a mostly-blank 380Z board with a 480Z-style network interface grafted onto it. I'm not sure if they were all like that, or if there were earlier boards - prior to the 480Z's existence - which didn't share any hardware) True, they do. I'd forgotten that GPIB is the same as IEEE-488 (all the 380Zs I recall have the port labelled on the back as the latter). Wow, thanks for quoting that - interesting. I wonder if it was "commercially available" for long... I think companies had to licence the use of Econet technology from Acorn, and I've never seen mention on the Acorn side of RML doing that. Doesn't mean that it didn't happen, but I'm surprised it's not more known about, or that there isn't any apparent surviving hardware perhaps schools were either with RML or with Acorn, but rarely both) It's frustrating - I've not seen many 'good' CFLs; they all have nasty colour-cast, take ages to come on to full brightness, and never seem to achieve nearly what the manufacturer claims in output or longevity. They won't work outdoors here (too cold in winter), and are complicated (and hence "costly") to manufacture and dispose of. Energy savings are even a bit dubious for where I live - we run the heating for 6 months of the year, much of it via resistive electric heat, so anything that incandescents lose as heat is still doing useful work. Someone, somewhere, decided that they tick a nice little 'green' box and will save the world, though. Grumble! :-) cheers Jules

It's the left-most card next to the floppies. It has a colour modulator on it which goes direct to tv-out on the back panel, also composite which goes to the monitor connector. Nope. No modulator on VDU #1. It was. Fan action too. It didn't. The power light stayed on and the fan kept spinning - it's a 240v fan. This encouraged me to refit CPU, VDU#1 and the 80 column board. Both CPU and 80col need power and the 80col is permanently wired to VDU#1. However, while the power light stay on and the fan keeps running I get no display on my Hitachi 9" monitor (the one you remember from school). I know the monitor works because it came with my homebrew NASCOMII which is fine. What I don't have (gah) is a multimeter to check the voltages on the floppy connectors....I left it at work. More tomorrow! -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?

On 31 January 2011 21:24, Tony Duell <ard at p850ug1.demon.co.uk> wrote: If I get a voltage from the floppy connector I'l reassemble the whole machine as was when I photographed it. Ah. I kept it in when I reassembled the basic machine, should've realised. Will take it out tomorrow, If for nothing else I'd like my bedroom light back :) I have 2 multimeters, but one of them has a dead battery. I can borrow a scope from work if needs be. I also have a logic probe and pulse generator that I'm teaching myself to use (slowly) with a working and non-working PET2001... Cheers! -- adrian/witchy Owner of Binary Dinosaurs, the UK's biggest home computer collection? www.binarydinosaurs.co.uk

On 31/01/2011 21:24, "Tony Duell" <ard at p850ug1.demon.co.uk> wrote: OK, I've removed the bulb and checked the voltages on the floppy connector, seems like the death of the 12V circuit is what caused the mains fuse to go. +5V is reading +6.2 and +12V is dead. Looks like I'll finally have to remove the PSU from the case which will be fun as the earthing screws on the rear of the case have corroded quite badly. Anyone got a schematic for the PSU? Cheers folks, -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?

Adrian Graham wrote: I don't remember it being too complex - i.e. "traceable in ten minutes" level of complexity. If the screws are just for earthed terminals via wires, worst-case you could always cut them close to the terminal end and re-solder them afterwards, I expect. I've never seen the schematic in any of the RML manuals. +6.2V on the +5V rail is worrying - hopefully just an unloaded reading; if it really is that much it may have caused a mess (although I managed to accidentally stick +9V into an Atom that was expecting +5V once and incredibly it survived) +12V is used by many of the boards (as is -12V, although usually not directly, but via 7905 regulators to get -5V), so you're not going to get anything without +12V running. cheers Jules

I am a little puzzled. AFAIK you can make a minimal system with no bus cable or termiantor atall -- just the CPU board linked ot the 40 column VDU. Video output comes from the VDU card. Do you have any idea waht sort of components could be fitted on the terminator bord? Are there spaces for (DIL) ICs, or jsut discretes? The 16 wire cable is part of the hi-res system, and the machine can't run properly without it. I wonder if the OP was refering to the RGB output module -- it's quite possible to have a hi-res machine without that fitted. I am pretty sure my 380Z (and all the ones I used at school) has the voltage reguatlors mounted internally (on the metal cover over the PSU area) and a fan. There are at least 2 versions ofthe 5.25" machine. One has a pair offull-heigfht drives fitted horizotnally, the otehr has a pair of 2/3 height (!) drives mounted vertically. The latter seems more common. I am pretty sure the PSU will draw less than 750mA with no load. I don't know about the switch-on surge though a 750mA anti-surge fuse would probably be OL< a quick blow one may not be. -tony

Indeed.. I have an idea you can make a cassette-based system that way. Hmm.. I would want to trce this out. The 18 pin ICs don't sound like resistor networks (strange number of pins), but perhaps theyr'e active termiantors or something like that. I can't think of any other 18 pin IC that would be used on a termiantor. I wonder if the modualtor section is to add UHF outptu to the hi-res board. In other words you loop the composite output from the hi-res board throug hthe modualtor board and then to the composite output on the back, and the board picks off the signal and feeds it to the modualtor. Maybe third-party? Not that I know of. The 80 column one doenst' ahve a modulator AFAIK, but then 80 column text ona TV is likely to be unreadable anyway. My guess is that it's for the hi-res output. No. We had 380Z when I was at school, and they all had hi-res, mono monitors (litlte 9" Hitachi ones) and no RGB boards. I remeber in my final year at school converting the school's Barco monitor to have RGB inputs and fitting the RGB output board in one of the 380Zs. The 380Z I picked up at a radio rally had the RGB board in it. I have no real data. Only that at school we had 4 machines (IIRC), 3 had the vertical drives ,the other had horizontal drives. The one I got at the rally has vertical drives. I have no real idea how many of each were made, or how many survive. That sounds like RML :-) -tony