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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 16th Mar 2021, 2:10 pm   #41
SiriusHardware
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Default Re: The Transam Triton Personal Computer

I don't think 8.5V will have been so unusual actually, since this need, to feed a 5V regulator with an input voltage not too much higher than the regulated output voltage would have been quite common at one time. The transformer in the PSU for my MK14 came from an old EPROM programmer and that too has 8V (ish) AC output for the same reason.
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Old 16th Mar 2021, 3:48 pm   #42
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Default Re: The Transam Triton Personal Computer

Interesting looking at electronic parts catalogue from that time (Watford Electronics and Cricklewood Electronics ) can not find any 8v transformers.

Watford Electronics is no more but Cricklewood Electronics is still in the same place doing mainly CCTV.

Takes me back looking at these old catalogues, Watford Electronics was suppling kits at that time one was the Superboard II computer based on the 6502 cpu with 4k ram 2k rom monitor and 8k basic for 149 , they were also doing a EPROM programer and MPU development system (SOFTY) in kit form for 100.

Superboard II looks quite good for it time and a Softy might be handy but had no experience of them.

Maybe another project here.
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Old 16th Mar 2021, 7:47 pm   #43
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Default Re: The Transam Triton Personal Computer

Has any one got the L5 Monitor and Tiny Basic ROM images for the Triton ? I see the Basic has a user definable extensions in a look up table, I would like to have a play with that.

I have also posted the VDU chip data sheet at ( https://github.com/woo-j/triton ) the SFC 96364.
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Old 16th Mar 2021, 8:50 pm   #44
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Default Re: The Transam Triton Personal Computer

I think the chance of getting an original unbuilt PCB is close to zero - the only difference mine has is in the RAM chips and a subtle change to allow the decode. Otherwise it is identical - the ETI article does not actually have the full PCB layout so only the recreated ones exist - in fact only the slightly further adapted one from Ian (to do with video out, a regulator rather than zener etc) and he only makes them in small batches when enough people want them.
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Old 16th Mar 2021, 8:51 pm   #45
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Default Re: The Transam Triton Personal Computer

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Originally Posted by GeraldSommariva View Post
Has any one got the L5 Monitor and Tiny Basic ROM images for the Triton ? I see the Basic has a user definable extensions in a look up table, I would like to have a play with that.

I have also posted the VDU chip data sheet at ( https://github.com/woo-j/triton ) the SFC 96364.

The data sheet for SFC 96364 VDU chip in the Triton is at (https://sites.google.com/view/transa...on/data-sheets)

Triton Emulator is at ( https://github.com/woo-j/triton )
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Old 16th Mar 2021, 9:01 pm   #46
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Default Re: The Transam Triton Personal Computer

You will find a softy thread in this section and there is a board now available to build...

That price on the 2111 is not bad as even utsource are listing AM9111 at $4.59 each in quantities above 20.
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Old 16th Mar 2021, 11:07 pm   #47
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Default Re: The Transam Triton Personal Computer

I could order a set of 2111 from the canadian supplier if you let me know who it was. Shipping to uk + customs handling charge for goods above 15 might add too much to make it worthwhile.

Last set of 10 AM9111 that I ordered from utsource were used. USD 2.40 each. 1 out of the three tested so far is faulty.
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Old 16th Mar 2021, 11:58 pm   #48
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I could order a set of 2111 from the canadian supplier if you let me know who it was. Shipping to uk + customs handling charge for goods above 15 might add too much to make it worthwhile.

Last set of 10 AM9111 that I ordered from utsource were used. USD 2.40 each. 1 out of the three tested so far is faulty.
It was these guys abra-electronics.com but having check the site again they are either 2111 or 2111-1 not 2111-2 from the data sheet looks like the difference is the access time.

For 10+ the unit price is $2.73 but your price is good provided the rest work.
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Old 17th Mar 2021, 12:32 am   #49
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Default Re: The Transam Triton Personal Computer

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Originally Posted by GeraldSommariva View Post
>>
>>

From the catalogue ( https://sites.google.com/view/transam-triton/transam ) the transformer only cost 7.00 I wonder how much it would be to have one made today given its unusual 8.5 volts secondary winding.
Quite a while ago, in 1996/7 Catalogue Maplin used to sell DIY mains-transformer kits with ready-wound primaries: 20VA @ 9, 50VA @ 11 & 100VA @ 14. So were useful to make your own custom-secondary one.
But they'd dropped these by 2005 catalogue, in their phasing-out of stocking much in way of Electronics parts, before eventual collapse years later.

Although maybe others still do these, otherwise it's probably a case of using 2 different ones or a small DC-DC converter to generate lower power rails from the main DC supply.

I once bought a 20VA kit as 1.5V 1A? transformer on old Gas fire / back-boiler for Glow-plug igniters was NLA from the appliance manufacturer / couldn't find any other ones elsewhere.
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Old 17th Mar 2021, 2:37 am   #50
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Default Re: The Transam Triton Personal Computer

[QUOTE=ortek_service;1354233]
Quote:
Originally Posted by GeraldSommariva View Post
Quite a while ago, in 1996/7 Catalogue Maplin used to sell DIY mains-transformer kits with ready-wound primaries: 20VA @ £9, 50VA @ £11 & 100VA @ £14. So were useful to make your own custom-secondary one.
But they'd dropped these by 2005 catalogue, in their phasing-out of stocking much in way of Electronics parts, before eventual collapse years later.
Yes I forgot about Maplin they were good for a lot of different stuff , I supposed they phased out stocking electronics parts as more people started ordering online including myself.

Its a shame they collapse it was good to pop in a have a look round and normally end up getting something.

I fired up my external power supply for my Triton project tonight and its dead, its a switch mode type that should produce +5 +12 and -12 there is no voltage on any of the three outputs. I have not worked on these types before so were to start fixing it is a good question and I don't have a circuit diagram either.

May its time to either rebuild the original Triton linear power supply, get a new switch mode supply or maybe use a PC power supply.
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Old 17th Mar 2021, 10:33 am   #51
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Default Re: The Transam Triton Personal Computer

For your dead switch-mode, here's something you can try. (Carefully) take it apart far enough so you can get to the pins of the high voltage electrolytics on the mains side, or if it is possible to do so to the + and - pins of the mains-side rectifier.

Either way, see what the DC voltage on the high voltage capacitors / output of the bridge is and if you still have a very high (300VDC + ) voltage sitting there a long time after the mains was last applied, that would point to a problem in the start-up chain, narrowing things down quite a bit.

If you do find this to be the case then needless to say you should use a suitable resistor, held in insulated pliers, to discharge the capacitors before looking around for the cause.

Typically there is a chain of 2-3 identical high value resistors in series on the high voltage side, one of those often goes open circuit. Also look for small electrolytics which were placed too close to heatsinks, high frequency transformers or other hot-running components. These usually end up being baked dry.
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Old 17th Mar 2021, 2:52 pm   #52
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Default Re: The Transam Triton Personal Computer

The small electrolytic capacitor near the transformer is also a likely suspect.

YouTube user diodegonewild has made some good videos showing the operation of power supplies.
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Old 17th Mar 2021, 7:36 pm   #53
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Default Re: The Transam Triton Personal Computer

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Originally Posted by SiriusHardware View Post
For your dead switch-mode, here's something you can try. (Carefully) take it apart far enough so you can get to the pins of the high voltage electrolytics on the mains side, or if it is possible to do so to the + and - pins of the mains-side rectifier.

Either way, see what the DC voltage on the high voltage capacitors / output of the bridge is and if you still have a very high (300VDC + ) voltage sitting there a long time after the mains was last applied, that would point to a problem in the start-up chain, narrowing things down quite a bit.

If you do find this to be the case then needless to say you should use a suitable resistor, held in insulated pliers, to discharge the capacitors before looking around for the cause.

Typically there is a chain of 2-3 identical high value resistors in series on the high voltage side, one of those often goes open circuit. Also look for small electrolytics which were placed too close to heatsinks, high frequency transformers or other hot-running components. These usually end up being baked dry.
Have now had a look as you have suggested , I do get DC voltage on the high side, I have check all the rectifier with a multi on diode check and they all look good.

The model is cherokee QB2G2 but have not found any information out there.

Some photos for the supply transam-triton repair-power-supply
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Old 17th Mar 2021, 9:08 pm   #54
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Default Re: The Transam Triton Personal Computer

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Originally Posted by julie_m View Post
The small electrolytic capacitor near the transformer is also a likely suspect.

YouTube user diodegonewild has made some good videos showing the operation of power supplies.
Thanks for the pointer on a good video especially the warning on HIGH VOLTAGE, having spent a bit more time investigating my power supply.
This supply uses the following two chips CA339 and TL494CN both have no supply voltage need to do a bit more circuit tracing.
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Old 17th Mar 2021, 10:17 pm   #55
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Default Re: The Transam Triton Personal Computer

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Yes I forgot about Maplin they were good for a lot of different stuff , I supposed they phased out stocking electronics parts as more people started ordering online including myself.

Its a shame they collapse it was good to pop in a have a look round and normally end up getting something.

I fired up my external power supply for my Triton project tonight and its dead, its a switch mode type that should produce +5 +12 and -12 there is no voltage on any of the three outputs. I have not worked on these types before so were to start fixing it is a good question and I don't have a circuit diagram either.

May its time to either rebuild the original Triton linear power supply, get a new switch mode supply or maybe use a PC power supply.
I thought Maplin had been going downhill for Electronic parts for quite a while before most people were buying parts online. Their shops had little stocks of their ever reducing range, and they seemed to have moved to trying to sell disco stuff and inflatable decorations etc. And had kind of become a version of Tandy's, that had been very overpriced due to lack of much competition.
They also frequently seemed to have more staff than customers in there.
I found Maplin wanted several pounds for a watch battery and no stores within 10miles actually had any stock. But got one posted 1st class for just over 1 inc. delivery from a UK online seller.
However, it seemed it was actually some venture capital company, who bought them and put the cost as debts on the business that brought it down.
So really lost its way from the family business it had originally been for many years and a sad end to what it many of us remembered it was originally.

Getting a circuit for your SMPSU will probably be tricky, but they mostly function the same way so can often fix without a full circuit when you know what normally fails - Mostly covered by subsequent posts.
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Old 17th Mar 2021, 10:45 pm   #56
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Default Re: The Transam Triton Personal Computer

Quote:
Originally Posted by GeraldSommariva View Post
Quote:
Originally Posted by julie_m View Post
The small electrolytic capacitor near the transformer is also a likely suspect.

YouTube user diodegonewild has made some good videos showing the operation of power supplies.
Thanks for the pointer on a good video especially the warning on HIGH VOLTAGE, having spent a bit more time investigating my power supply.
This supply uses the following two chips CA339 and TL494CN both have no supply voltage need to do a bit more circuit tracing.
These IC's are normally on the secondary-side of the main 'chopper' transformer. So if that isn't running, then all output side will be dead.
They will be part of the feedback circuit to control the output voltage, and usually drive an optocoupler to reduce the drive to the transformer when the output voltage start to go above what it should be.
The TL494 is a PWM-Controller IC, often used in these.

Note: Some SMPSU's (especially early PC ones) require a min. output load to work. Otherwise output voltage shoots up too high, and they shutdown. So you may have to put some load resistors on the outputs, to ensure this ins't happening.

I can't quite see all the transistors / IC's on the Primary-side, but it looks like there's a couple of regulators at least : 7812 (+12V) & 7912 (-12V) which is quite uncommon in these, but could check voltages around these.
I also see there's an output-side fuse (F2), which is also uncommon, and I presume you've checked it.
Looking at it, I think it may actually be two PSU's!, as it seem there are 2 transformers - the rusty one looks a bit too large for just a power-line filter inductor (common-mode choke).
So I'm wondering if there is a standby supply that is used to power the control circuitry for the main one.
And there could also be some external control switching required, although I assume it did once work OK?


Also note that the incoming mains supply is usually rectified to around 350-380V dc, and probably split across the two large (200V?) capacitors - Which should hopefully have equalising resistors across them, that will also discharge them a bit once power is removed - but may take quite a few seconds before safe to touch.
This nearly 400V (HT) voltage is actually + & - half that with respect to mains neutral (/ Earth), so touching either side can give you a shock.
And they also often connect heatsinks to the negative side, so touching one of these could give you a -180Vdc shock whilst on.
Plus makes taking measurements with non-isolated test equipment like many 'scopes were, a bit difficult.

I thought that RCA RUR-D1610 might be an IC, as they did sometime use TO-3 packages for some SMPSU ones, and I've not seen that one before. But I've found it's actually a dual 16A 100V rectifier diode:
http://radio-hobby.org/uploads/datas.../rur-d1610.pdf
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Old 18th Mar 2021, 1:51 am   #57
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Default Re: The Transam Triton Personal Computer

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These IC's are normally on the secondary-side of the main 'chopper' transformer. So if that isn't running, then all output side will be dead.
They will be part of the feedback circuit to control the output voltage, and usually drive an optocoupler to reduce the drive to the transformer when the output voltage start to go above what it should be.
The TL494 is a PWM-Controller IC, often used in these.
Thanks for the notes

I got it sort of working a 10uf 50v electrolytic capacitor on the 18v supply rail to the chopper and control circuit. when I checked the 7818 reg on the heat sink there was no output but +35V on the input pin which comes from the secondary winding on the black transformer.

Could not find any optocoupler on the pcb I think the mains isolation is provided by having the chopper drive transistors driven by transformers (T3 T4) it is an old supply from approx. 1982.

The supply should produce +5 +12v and -12v now the +5v is good and works under load the -12v is good but the +12 is +16v. both the 7812 and 7912 regs are being feed with +18v and -18v respectively.

For testing I have been powering the supply from a 300W 12V inverter purchased from Maplin and a 12V SLA battery to give we isolation from the mains so I can use my scope etc.... now need a new 7812 to try!
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Old 18th Mar 2021, 4:12 am   #58
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Default Re: The Transam Triton Personal Computer

It's probably not surprising that an electrolytic capacitor was causing the main fault, as they often do in these if it isn't high-value start-up resistors going even higher resistance due to high voltage on them (why they normally put a few in series, to try to prevent that)

I had thought that T3 / T4 might have been output filter inductors.
But from looking at the underside, it does seem these are across the isolation barrier gap and drive the 2N6672 transistors.

So it would appear that F1 & F2 are both mains-side fuses, and that there may actually be 2 switch-modes on the board, with a slave one producing a supply for the circuitry to control the master one.

And if you've got 16V coming out of the 7812, then it does look like this has gone a bit shorted - unless there's an issue with its ground pin reference connection.

Well done on the inverter DIY-alternative to a mains isolation transformer !
Luckily, most SMPSU's won't have an issue with the quasi-sine output from these.
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Old 18th Mar 2021, 8:33 pm   #59
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Default Re: The Transam Triton Personal Computer

Yes I was impressed with that isolation solution - especially as I have one here and have been looking into getting one for this sort of work. The few I have looked at when you scratch are Auto Transformers really.
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Old 18th Mar 2021, 9:07 pm   #60
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Default Re: The Transam Triton Personal Computer

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Well done on the inverter DIY-alternative to a mains isolation transformer !
Luckily, most SMPSU's won't have an issue with the quasi-sine output from these.
I came up with this to fix a RIELLO oil boiler control box again it turned out to be a electrolytic capacitor a few pennines ,new box was 80+.

Found a 7812 reg which I have now fitted and its giving me +11.82 volts, I connected it directly to the mains and the +5v and -12v are still good checked with scope nice and clean.

But the +12v is still low ?
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