TAL2 powerpack

[squeaky]

I've upped (and cropped) that first image. It's really hard to tell what the "bits" are...

But it does look as though someone has done a mod and if my guesses are right they've tried for half wave rectification and a smoothing capacitor. Can't think of any other reason why so many "bits" should be in there otherwise.

IF those guesses are right - then they must have gone for DC...?

Are there any data plates on your motors?

[AndyH]

Have a look at the back/flat of the mount motor. There may be a sticker on it giving it's ratings. I have one on mine. дсм 0.2 ухл 4.2 50гц 12V =revs per min with gearbox?/??/frequency/voltage

If it's(edit:yours is) not an AC motor I'll eat my hat.

If anything it's my transformer that's been altered. The wiring in mine is not Russian-esque and the components have all got 'made in England', stamped on.

[AndyH]

Just off the top of my head.

I wonder if OVL stopped importing the driven mounts(back in the mid 2000's) as they didn't want the hassle/expense of converting the transformers to UK standard.

All Russian wired stuff I've seen can be freaky and very un colour co-ordinated.

Andy

[Psychobilly]

can you gives us any markings of the components please

Peter..

[jerryTheC]

Had a look at the pictures again. I think the 'diode' bits may just be insulated mounting points - since they look as though they're attached to the base. which, if the white lumps are just knots in the wires, would make the 'capacitor' the only extra component.

My current guess is that it's NOT a rectifier - for a start, everything's on the high voltage side BEFORE the transformer, and I assume the thicker low voltage red wires go straight to the 12V output. (and anything trying to make DC would likely have a much bigger capacitor, and be on the low voltage side). At a wild guess, I'd say the orange/brown 'capacitor' is more likely to be some sort of choke to reduce interference, or maybe more likely, some sort of thermal fuse.

And given that there's an earth connection on the box, I'd assume it's a metal box, and would probably be much safer with a 3-core mains lead with the earth connected. At the moment, it looks as though it's just hoping nothing live touches the case...

[Psychobilly]

Thats pretty much my thoughts on the internals as well...

Peter...

[AndyH]

So would you guys recommend a rebuild of Jason's interior, similar to the way mine is wired up?

240vAC to 12vAC bolt on transformers seem to be readily available(at not great cost), as are the switch & fuses(I had a look through http://uk.farnell.com/ ).

Andy.

[jamespels]

And given that there's an earth connection on the box, I'd assume it's a metal box, and would probably be much safer with a 3-core mains lead with the earth connected. At the moment, it looks as though it's just hoping nothing live touches the case...

Scarily, I only noticed the earth conection on the case yesterday when I was replying to this... Don't know why, but it never occurred to me that there would be an issue with the live mains not being earthed! Will head down Maplins later and pick up some bits to fit a standard UK kettle lead, I think.

If you reckon the bits are not a rectifier circuit, you could well be right that this is an older USSR standard mount and the ones that Andy and I have were built by OVL. As Andy points out, the UK spec wiring and "Made in England" stamps are a bit odd otherwise.

jason.p: on the plywood coffin the scope came packed in (the one that gave you a hernia when you tried to lift it), there should be a date / serial number stamp: can you see when your scope was built? For reference, mine is number 1459, built in 1999. If yours is much earlier, this could be the reason.

[AndyH]

Regarding earthing.

On my pic(page 1), it's earthed to the box, with a split earth wire running to the optional 'out of box' earth terminal. Jason's seems earthed. Note the light blue wire, but with no noticable earth running to the terminal.

Are neither safe?

Just trying to get my non electrical brain round all this.

Andy.

ps: In another 2M thread, Jason mentioned that there isn't any stamp mark or plate with the year. Richard also has this early Tal 2M, can't remember if he mentioned the age of his. If I were to guess, I'd say early 90's.

[jamespels]

OK, panic over. Andy, the green / yellow wire that comes from the mains cable and is bolted to the case is the earth, and a quick continuity check of mine shows there is a connection from the wall-plug's earth pin to the power supply case. I guess the light blue wire in jason.p's does exactly the same thing. Not sure what the external earth connection is for, in that case.

Also, have just checked the markings on my motor - they are essentially identical to Andy's. Jason: note everything in the label Andy quoted other than the numbers is in Cyrillic (Russian) script: if yours has the same, it is a pretty fair bet it is the original Russian motor, though it is worth checking the numbers to make sure the supply spec is the same. Best guess of the meaning is:

дсм 0.2: current Edit: not sure - the 2A outlet fuse on the tranny suggests 0.2 is much too low, though the 0.2 - 4.2 could be the operating range?

ухл 4.2: not sure

50гц: AC frequency

12V: voltage

Will check on things the 4.2 could relate to and edit if necessary.

J.

[AndyH]

James - regarding a simple(the APM version is a more complex variable frequency type) 12vDC(ie:battery) to 12vAC convertor like Richards.

I don't think you can get a simple transformer/convertor, hence the complex(to me) build guides about, like here.... http://www.die-talianer.de/html/ezb_1.html

Whilst I don't know if Richard has had a peek inside his black box, I'd guess there may be a similar board inside.

I prefer the stuff in a box like Richards version, to the clutter inside the mounts housing. I have to periodically alter the clutch so, I wouldn't like that big board in the way.

That german guide is way beyond my understanding sadly.

Andy.

[AndyH]

Poor Jason

Here's me gibbering away and all he wants is a working transformer box.

Sorry mate.

[jamespels]

Poor Jason

Here's me gibbering away and all he wants is a working transformer box.

Sorry mate.

You're right - it's just there aren't many TAL conversations on here so it is easy to end up adding your own interesting bits!!! Going off on another tangent, I have my OTA in bits at the moment - I'm hacking it fit the JMI mini Crayford focuser - I'll start a new thread with pics, etc.!

Jason, not sure where in West Wales you are, but if you are heading towards Stoke any time soon, drop me a PM and bring it over with you - happy to spend a couple of hours going over it with you and there is a Maplin nearby . Can give the mount head a service while we're at it.

J.

[jamespels]

On a different note - I can still fit in a TAL corner at PSP2012 if enough people are interested...

[AndyH]

Me again

James - do you only have 1 fuse? I've got 2. One for what seems like the switch(250mA), the other for the outlet(2A).

[jamespels]

Me again

James - do you only have 1 fuse? I've got 2. One for what seems like the switch(250mA), the other for the outlet(2A).

You're right - mine is identical. Two fuses, rated at 250mA in; 2A out.

J.

[AndyH]

..... Going off on another tangent, I have my OTA in bits at the moment - I'm hacking it fit the JMI mini Crayford focuser - I'll start a new thread with pics, etc.!

Pics, pics n more pics please !

On a different note - I can still fit in a TAL corner at PSP2012 if enough people are interested...

One day when I'm on my feet financially, I just have to go ! Once at Kielder, the closest to a Tal Corner we got was when SpookyKat pitched next to me with her 200K. Sadly the weather Gods didnt play ball, so we couldn't do a side by side and judge our collimation.

[jerryTheC]

Hah - apologies if I worried anyone on the earthing thing - both look fine. I was looking at the annotated pic of Jason's box and didn't notice the blue wire was connected to the case - the connector was hidden under one of the labels and I'd mistakenly assumed it was connected to the switch instead oops!

Went back to the original pic and it's all fine. As long as the case is earthed, and any metal bits going through the case make good electrical contact with it, you should be fine - if anything live shorts to the case/ metal bits then the current should flow from live to earth and blow the fuse in the plug, cutting power off. And hopefully proving a much easier path to earth than going through you, as well - although it's a good idea to use an RCCB/ELCB plug or adapter with outdoor mains stuff, just in case - they kill the power if the current going out on the live lead doesn't match that coming back down the neutral one (which happens if there's a fault and the live current is flowing to earth instead, possibly through someone.) just make sure the wires match up properly in the plug

[AndyH]

Hehe. Yes, the earth issue caused an extreme eyebrow raising moment from this electrically challanged user !!

For the first time ever, I had look inside the wall plug. It has a 13amp fuse. Is that too high? If so, what would be best to fit?

Whilst I use my russian made 'vega' frequency convertor on my mount, it would be nice to know the above.

Andy.

[squeaky]

At most a three amp mains fuse for your plug.

[AndyH]

Ta.

Thought it seemed a bit too high.

[jerryTheC]

Yes - definitely go for a lower rated fuse - 13A ones are for electric heaters and suchlike. 3A (up to 720w) or 1A(240w) if still available would be better, since you're only using 24w (12v x 2A). You also want a fuse that isn't more than the current rating of your mains lead - otherwise, if there was a sustained fault, there's a possibility that the lead could overheat without blowing the fuse.

( the main danger of overheating comes when you use a low rated extension lead with high power devices like heaters - a short will usually blow a fuse, so it's not normally critical whether you're using a 1A or 3A fuse - a solid short will blow either - and probably a 13A as well - but just overloading a low rated cable can leave a 13A fuse intact, while heating up the cable.) Lower rated fuses give you more protection against faults that aren't as obvious as a solid short - so for example, a 13A takes more than 4x the current that a 3A one will before it blows - so the 3A fuse is more likely to catch a partial short that might cause a fire than a 13A one would.

[jason.p]

Haven't been able to respond. Broadband drops out when it's wet. I'll read replies and get back if I get another"wind ow"

[jamespels]

Pic of the motor in case it helps...

[RichardL]

I don't think you can get a simple transformer/convertor, hence the complex build guides about, like here.... http://www.die-talianer.de/html/ezb_1.html

Whilst I don't know if Richard has had a peek inside his black box, I'd guess there may be a similar board inside.

Andy.

Thanks for this link Andy. You're right, I haven't looked inside, and I am unlikely to do so for the simple reason that at the moment it works! The circuit your link points to has a quartz crystal oscillator as the clock input to a programmable counter/divider which is wired so that it steps the frequency down to - you guessed it - 50Hz. The data sheet for the counter is at (for example) http://pdf1.alldatasheet.com/datasheet-pdf/view/31772/TOSHIBA/TC74HC7292AF.html The 50 Hz output is then fed to a pair of power op-amps which saturate in opposite senses, so you get an alternating current to the motor. I strongly suspect this is what I have - it seems to be of the same era. The crystal oscillator would ensure a very accurate 50Hz.