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Old 21st Feb 2021, 2:17 pm   #1
martinreid
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Default Help with Scopex 4D10A

Need some advice on mains transformer wiring on my Scopex 4D10A. UK model but I took it to the US and used it there in the 80s. I must have rewired the mains transformer for 110/120v AC at some point but didn't keep a record of the original configuration. Does anyone know what the correct transformer wiring should be for 240v mains?
Many thanks!
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Old 21st Feb 2021, 2:36 pm   #2
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Default Re: Help with Scopex 4D10A

Hard to tell from the pic but in a nutshell you probably have two primary windings which would be wired in series for 240/250v and in parallel for 120v, so first you need to ID the two primary wndg's with a DMM after cutting off the links, they'll both measure the same resistance, 46 ohms say, they then need to be wired in series in phase, the easiest way to tell if they're wrong is by using a lamp limiter, it'll glow bright if wrong.

It could be though that there's one primary with taps, but it's unlikely, check with your meter.

Andy.
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Old 21st Feb 2021, 2:37 pm   #3
orbanp1
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Default Re: Help with Scopex 4D10A

There is a service manual for your scope here:
https://elektrotanya.com/scopex_4d10...wnload.html#dl

The schematics there, and the specs, show a mains transformer for a single mains voltage.
The picture of your transformer also suggests that possibly the whole transformer was replaced with a 110V unit.

The suggestion is to feed the scope with 110V temporarily, and with a DMM check out the various taps and connection points of the transformer if there is another "110V section" there that could be wired in series with the connection used for the US 110V wiring.
You can get 110V if you have a mains transformer that can be wired to 110V/220V, and use the 110V tap.

Regards, Peter
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Old 21st Feb 2021, 3:17 pm   #4
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Default Re: Help with Scopex 4D10A

Hello Martin,

The final page of the Scopex 4D10 manual available here:

https://usermanual.wiki/Document/Sco...eOM.1286895535

shows how to configure the mains transformer to a number of voltage options. Your photo shows that the mains transformer primary arrangement of the 4D10A is the same as on the 4D10.

Paula
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Old 21st Feb 2021, 6:39 pm   #5
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Default Re: Help with Scopex 4D10A

Unless there is another similar label on the other side of that transformer, it shouts to me that it is US mains only, and cannot be set for UK mains. You need to either get a UK transformer off a scrapper scope, or run it off an auto transformer or simple 230:110v transformer.
You must have changed the transformer yourself if you are certain you used it in the UK previously.
Les.
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Old 21st Feb 2021, 6:50 pm   #6
Michael Maurice
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Default Re: Help with Scopex 4D10A

It looks like that there might be two primary windings with the tappings for each on the label in the middle, the easiest was is to remove the links and measure the windings, if they are the same, then it should be easy to configure it.
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Old 21st Feb 2021, 7:00 pm   #7
martinreid
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Default Re: Help with Scopex 4D10A

Thanks very much to everyone for the info, this has been super helpful. I think we have a way forward to get the 'scope up and running, and when I do I will probably put it up for sale as I really don't use it anymore and I'd like it to go someone who will. Anybody interested?

All the best, Martin
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Old 21st Feb 2021, 9:36 pm   #8
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Default Re: Help with Scopex 4D10A

I agree with Michael Maurice re. the primary configuration.

Judging by the wire links between the tags on each side of the windings, it has two similar tapped primaries of 0-105-115-125, currently connected in parallel for a 115V input. For nominal 240V mains (which I assume it is more likely to be at your location, whilst being aware of the "230V" harmonisation kludge), remove those two bare wire links, connect one of the original mains wires to ONE "0" tag. Connect a linking wire between the "125" tag of the same winding and the OTHER "0" tag, and the other original mains wire goes to the "115" tag of this second winding, i.e. 125 +115 giving 240V input.

The two tags at the top look like "parking" tags for the mains wires, so as to avoid mashing them up with voltage changes. Leave that short link between one of them and "0" in place, also leave the green link between the other and "115" in place, the rest of the change is as above.

Good luck with it, keep us posted, Colin.
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Old 21st Feb 2021, 10:59 pm   #9
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Default Re: Help with Scopex 4D10A

Quote:
Originally Posted by martinreid View Post
Thanks very much to everyone for the info, this has been super helpful. I think we have a way forward to get the 'scope up and running, and when I do I will probably put it up for sale as I really don't use it anymore and I'd like it to go someone who will. Anybody interested?

All the best, Martin
Hi Martin
If you do decide to put it up for sale it's best to start a fresh thread in the Sets, Parts and service information offered section.

Cheers

Mike T
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Old 22nd Feb 2021, 8:59 am   #10
martinreid
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Default Re: Help with Scopex 4D10A

Thanks again everyone and to Paula and Colin. It does look very much like there are two primaries and the links do appear to be newer solder joints. I'll run it up to 120v anyway as I have a step down transformer to run the (imported from the US) garage door opener – don't ask! – and take some voltage measurements.

Best, Martin
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Old 24th Mar 2021, 5:57 pm   #11
martinreid
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Default Re: Help with Scopex 4D10A

Hi all

Back on the case. So the most likely scenario is that the green sleeved link is original, the two bare wire links were added, and the '125' tabs have never been soldered. This kind of makes sense with the mains wiring schematics from the 4D10 user manual - the only difference being that I have two extra tabs labelled T1/AMk7 and one is linked to the '0' tab on one side, the other is linked to '115'.

So I'm proposing to remove the bare wire links as suggested, and link '0' to '115' as on the diagram at right for 230v which was probably the way it was originally.

Does this make sense?
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Old 4th Apr 2021, 11:31 pm   #12
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Default Re: Help with Scopex 4D10A

Hi!

Yes that wiring is correct for 230V!

However, it is my experience over many years that mains voltages, both in the UK and elsewhere, tend to be on the high side of the nominal "230V", so I recommend you connect the incoming mains N (0V) to the first "0V" tag, link "115" on the first side to "0" on the second side, then connect the incoming mains L (230/240V) to the second "125" tag, hence wiring the transformer for "240V", which will prolong the life of the transformer, CRT and other components!

Chris Williams
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Old 6th Apr 2021, 2:01 pm   #13
martinreid
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Default Re: Help with Scopex 4D10A

Hi Chris

Many thanks, that does make absolute sense. I never figured out what the extra terminals are there for as they just appear to link to the '0V' of the windings. Maybe the T1/AMk7 refers to a part number of the transformer. I will fire it up and report back.

Best, Martin
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