Italian CRT monitor

[jncoleman]

I wonder if anyone could please help with information about a vintage computer monitor. My Nascom computer system is about 40 years old, and was supplied with an Italian-made monitor, which is shown in the attached picture. I have two of these monitors, both of which have failed electronics, although the CRTs themselves seem to be OK. Of course, I could use any sort of replacement, but the system was designed to match the monitor styling, and doesn't have the right look and feel with any other one. It's a 12-inch monochrome unit, very high resolution for the time, with a sticker showing the name 'Phoenix'. I don't know if that's the manufacturer's name or just a brand label, but there are no other markings apart from 'Made in Italy'. Unfortunately the repair people can't do much without a schematic diagram for it, so I would like to find out who this company is, and if they're still going, see if they still have one. Does anyone please know anything about this make of monitors? Alternatively, would it be possible to do a wholesale replacement of the electronics, whilst keeping the original tubes, or is that too way out? My own expertise is in the microprocessor side of things and I've got very little knowledge of CRT units, so I'm stuck myself. Any information would be really appreciated. I want to keep the system in its original condition because I'm pretty sure it's one of the last complete ones still in existence.

[nigelr2000]

It has an idesit look to the case and coincidentally they used to be an italian company. Maybe a modified version of their B&W portable

Have a look at this one https://1drv.ms/u/s!AkQ1RbHk79qhzAt6M9RBVA5DYv6l

[Welsh Anorak]

If you take the back off we can have a look and see if we recognise it. Hantarex were a big manufacturer of monitors and it could be one of theirs.
Very often the fault is fairly straighforward as matching more modern electronics to the CRT woulkd be a daunting prospect.

[jncoleman]

Thank you very much indeed Nigel and Glyn for this information. I'd never noticed it before but there is a punch-out at the top of the case that is obviously intended to accommodate an aerial, confirming that it is indeed a modified portable TV. It does look very similar to the Indesit one, but when I looked these up, I found a reference to their having been produced 'for' Indesit, suggesting that they were actually made by someone else. Could this have been Hantarex? (There seems to be both a British and an Italian one, the Italian one now being part of the GDS group). I attach pictures of the interior. If anyone recognises this, it would be really helpful.

[Red to black]

It has a certain resemblance to a Seleco/Zanussi portable with the tuner and IF section missing from the left hand side, I cannot recall the exact model/chassis sorry, but then again it looks typically like many of its contemporaries of the time also looked like, again not much help I am afraid.

[SiriusHardware]

One bit of advice which often comes up in cases like this is to Google any part numbers you may find on the line-output transformer - if you are lucky you will find something which tells you some makes and models that LOPT was used in, and may lead you to a schematic, perhaps for the same chassis badged by a different manufacturer.

[Maarten]

Sometimes, the manufacturer can be identified from markings on the pcb.

[TonyDuell]

The monitor that I got with my Gemini Galaxy (somewhat related to the Nascom), and which I believe to have been used with that machine from new, was a Hantarex unit, but looks nothing like the one in this thread.

[Maarten]

I think (but never say never) Hantarex mostly made monitors from scratch, not using a TV set as a basic design.

[SiriusHardware]

Can you read the numbers off any ICs you see in the chassis? Units like this often used 'building block' ICs for various purposes so the circuit surrounding such ICs is very often not so different for the application diagrams found in the manufacturer's data sheets for the ICs. If nothing else this will show where to look for power supply voltages, etc.

What are the faults on your monitors? If you provide a bit more info regarding symptoms the very knowledgeable people here may be able to suggest some checks.

[G6ONEDave]

Possibly Iskra or Indesit, although I don't have any circuits for those that have that frame output chip. All my circuits are transistor or TBA800 outputs other than some early valve types.
Dave

[Welsh Anorak]

Like everyone else says, it looks vaguely familiar. Indesit used a 'pump' power supply, whereas I think there is a mains transformer in the bottom of the cabinet which might rule them out. Also it looks unlike any Hantarex I've seen. It does have an Iskra look about it, but I thought those were made in Eastern Europe.
Assuming we don't know who made it and can't get any information, the big question is what's wrong with it? It looks a pretty basic chassis so we might bew able to help. We like a challenge!

[G6ONEDave]

That white paper label on the chassis just might be a chassis type, as opposed to a serial number. Could you respond with the number on it please, as I can't quite read it from the photo.
Dave

[jncoleman]

Thank you all very much for your help with this. I have two of these monitors, one with green phosphors and one yellow. The number on the label on the yellow one is '121485 C'. Unfortunately these isn't a corresponding label on the green one, otherwise I suppose we'd have known straight away whether it was a serial number or a chassis number. Would you please know, Dave? On the copper side of both PCBs there is also 'PR20-12', but I'm guessing that's just the manufacturer's assembly number. Other than that, all I can see are the usual silk-screened component numbers on the other side.

The faults are these. The yellow one works fine for about half an hour, then the internal fuse always blows. The repair company had some suspicion that it may be the LOPT, but they really needed the schematic to get any further. The green one just produces the pattern shown in the picture below. Does this please look familiar to anyone?

These units do have mains transformers. Glyn, do you have any more information the charge pump supplies please? Were these for use in battery operated models? Tony, I think the reason we have different monitors may be this. The original Gemini Galaxy series had steel cases, cream top and black front, which were matched by the monitors like mine. However, the range was subsequently revamped, with grey plastic enclosures I think, and issued with a new range of matching monitors. I guessing that you have one of these later systems.

From an article I found on radiomuseum.org, Indesit had a subsidiary called Eurovideo that produced CRTs for Indesit TV sets. Eurovideo also made yellow and green CRTs for computer monitors, which were presumably also built by Indesit. Nascom monitors are housed in what is almost certainly a modified portable TV case, very similar in styling to known Indesit ones, and Nascom monitors also have a yellow or green display. While this all suggests that they are in fact Indesit units, the tube in the one pictured above is labelled 'Fivre', whom Indesit would presumably not have been using if they had had their own production facility. So who else it could be is still a mystery.

[TonyDuell]

No, my Gemini Galaxy is in a metal case, as is its keyboard.

As others have suggested, many 'classic' (pre- PC VGA) monitors used very standard circuitry. I guess they were made in small quantities so it wasn't worth having custom ICs made. European models often use a TDA1170 in the vertical deflection with (slightly less common) a TDA1180 as the horizontal oscillator. Looking at the circuits of portable TVs can often give some clues.

Some monitors even used standard Philips line output transformers, for which data sheets were published.

Incidentally, if this site produced a DVD of 'classic' monitor service manuals I'd buy it in a nanosecond...

[Maarten]

PR20-12 should theoretically be enough to match it to a brand name, given similar numbers on known PCB's, but you'd have to find service manuals or pictures that match up.

You could have a look at http://obsoletetellyemuseum.blogspot.com/ for pictures of many Italian models.

[Welsh Anorak]

To answer your question in post #14, the Indesit T12 series didn't use a mains transformer but instead had (from memory) a series chopper circuit. This enabled the TV to be lighter and look quite stylish - well, it was Italian!

Let's consider your faults.
A fuse that blows without warning after it works perfectly for a while is puzzling. If it is the LOPT then it would be the EHT diode failing. Is this separate or potted? I can't see because of the metal shroud. There are ways round this.
The green one appears to have low HT. It might be being dragged down or possibly an HT regulator fault.
Now the questions! Do you have a multimeter and how confident are you in fault finding yourself? The good news is you have two so you can measure, say, the HT on the working orange one (while it is working!) and see if I'm right about low HT on the green one.

[ben]

Some photos of Hantarex monitors from this era:
https://retroinvaders.com/es/100942/...-fosforo-verde

[G6ONEDave]

Having just done some internet searching, Italian electronics manufacturers seem thin on the ground. I have found 3 possibilities: Ducati Energia, Indesit and Zanussi. There are quite a few aerospace companies and is possible that one them could have been involved with this monitor. Iskra appears to be a Russian company. Of course we can't rule out the possibilty that the parent company could be someone in another country that may have their own factory in Italy, or maybe sub-contracted to an Italian company. At present, I think the most likely candidate is Indesit.

PR20-12 does suggest a model number or chassis type, although internet searches don't find it.

Apart from checking out the power supply in the green screen monitor, I would also check the electrolytic capacitors around the frame output stage. From the chassis photo, that looks like the single inline chip with the heatsink (top centre).

What does the screen display with an input signal? A picture of that could be helpful.

Re the amber screen, switch it on for around ten to fifteen minutes and then turn it off before it blows the fuse. With the power removed carefully check the temperature of components on the chassis. Hopefully something will be hotter than it should be. This will hopefully help to narrow down the problem area.

Also check for electrolytic capacitors with swollen ends or any chemical leakage at their connections.
Dave

[Maarten]

Originally Posted by G6ONEDave

Having just done some internet searching, Italian electronics manufacturers seem thin on the ground. I have found 3 possibilities: Ducati Energia, Indesit and Zanussi. There are quite a few aerospace companies and is possible that one them could have been involved with this monitor. Iskra appears to be a Russian company. Of course we can't rule out the possibilty that the parent company could be someone in another country that may have their own factory in Italy, or maybe sub-contracted to an Italian company. At present, I think the most likely candidate is Indesit.

I'm not sure whether Ducati made TV sets. Apart from Seleco/Zanussi and Indesit there would have been at least a dozen other TV manufacturers in Italy at the time. Iskra was from Yugoslavia, I forgot which part. Probably Serbia if they use Russian looking text.