LPL 7700 transformer issues

ozphoto

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I contacted Akira Nakata: akira-nakata@lpl-web.co.jp

This is their contact page (Google Translate style):
https://translate.google.com/translate?hl=en&tab=wT&authuser=0&sl=auto&tl=en&u=http://www.lpl-web.co.jp

Scroll down to "Product Enquiry".
 
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ozphoto

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They are *the* most useless supplier in Australia within the photo scene.

I ended up purchasing $10k of Bowens gear 15 years ago direct from Bowens simply because A) they sent used gear to my local store as "new" and B) when called out, basically said: "Take it or leave it, we won't reduce the price and aren't going to be importing what you're after anytime soon."

I've actually been darn tempted top approach the companies they deal with and ask what it would take to take over their distribution, citing the c••p service their current distributor offers.
 

AgX

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Jerevan, I do not understand why you are looking for the LPL transfomer? Any 230/12 AC transformer of sufficient current will do.
And it is unlikely that yours already has to be declared dead yet. (Though it likely is a 220/12 volts version and thus supplying a too high voltage today.)

Be aware that at yours the terms "Primär" and "Sekundär" are mixed up. It must be the other way round.
 
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Jerevan

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AgX said:
Jerevan, I do not understand why you are looking for the LPL transfomer? / .../
Be aware that at yours the terms "Primär" and "Sekundär" are mixed up. It must be the other way round.
Click to expand...

I am just hedging my bets, looking for alternatives, just in case. I think the transformer might be good. Going off on Monday to find the fuses.

The 10 A fuse was placed in the slot named "Primär" (Primary) and the 2 A in the "Sekundär" (Secondary) slot. Why would it be the other way around? In that case the 2A would burn out first, and then, the 10A. Since my knowledge of electronics is limited, I can't see why only 10A (as it is in the original transformer according to the manual) then wouldn't be enough.

As a curiosity, someone paid 1750 DM for the transformer (it says "Funkshop DM 1750" on a small sticker on the case).
 
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Jerevan

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Jerevan

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As it stands now, I have figured out what fuses I need and ordering a new lamp.

I have also gotten in contact with a few companies and sourced alternative transformers (for example the Tufvasson one that is used for the enlargers supplied to the swedish market), in the unlikely case that the one I have is done for.

I'll report back when I have more developments in the matter. Thank you all for your help!
 
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AgX

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You did not get my point.

By definition the "primary" circuit at a transformer is the one driving the transformer, the "secondary" the one that serves the outlet.
In your case the primary one is 220V/2A.

The guy making your transformer likely got the terms wrong, but the Amps right...

(If you would turn that transformer into a mains substitute, by hanging it at a 12V battery and oscillator, the fuses would stay where they are, but the designations had to be changed around. [And a female mains connector had to be installed too.])
 
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Jerevan

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Aha - then I understand. Thank you - always learning something new every day.
 
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Jerevan

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I have gotten hold of some fuses (10A and 2A), put them in and turned on the power. No light, no smoke, no nothing. Not even the small bulbs for the controls turn on.

I am waiting for a new halogen bulb to see if that makes things a bit, ahem ... brighter.
 

voceumana

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This transformer might be a good replacement for that entire power supply: http://www.farnell.com/datasheets/1...6.1514283126.1564204428-1485376122.1564204428

Since the manufacturer is German, it might be easy to find a distributor near you. Price in the USA is quite reasonable.

The power supply in your photo looks like some person made their own, as there are some things about it that don't look like a production unit, particularly the cables going to and from the unit pass through holes without any protection from fraying or strain relief, and the use of fuses on both the primary and secondary side, which is honestly a waste of one fuse.
 
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Jerevan

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Yes, you are correct, it isn't a production unit; someone had it made in a shop. I am waiting to see if the halogen bulb makes any difference. If it lights up, then I'll use the transformer. The 10A fuse that sat in the transformer seemed blown (the small metal cap was loose and it was dark (as if burnt) so maybe something is really up with it.

By the way, does anyone know if the original connector from the head looks like this (see photo)?
 

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voceumana

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The 6x7 power supplies made by LPL and sold in the USA by Saunders and Omega used that type of connector.
 
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Jerevan

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The connector shown above in my earlier post is not the one from my enlarger head - it was just another one I found that seemed to be original. Of the small sample of machines I have seen, quite a few seems to have been altered in some way with other sorts of connectors, but I am not sure why. The ones on my enlarger looks like an IEC connector type that is used on the RH Designs Stopclock Pro timers, but I have no idea anymore what the technical designation is - possibly IEC C13, male/female connectors.
 

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Jerevan

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voceumana said:
The 6x7 power supplies made by LPL and sold in the USA by Saunders and Omega used that type of connector.
Click to expand...

Thanks, good to know that it might be an official type of connector.
 

AgX

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I have never seen a C13 connector applied to low voltage. I assume it is even against the rules as it basically allows to feed mains voltage into a low voltage circuit.

Maybe you mix it up with the one I linked to.
 

jim10219

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Grab a DMM and unplug the transformer. Connect each probe on the DMM to each of the wires coming off the primary tap (that plugs into the wall) to get a reading of the resistance (ohms) across the primary. It should read something other than infinity (or out of range). Do the same thing with the wires on the secondary. They too should read something other than infinity. Now connect one probe to a primary wire, and the other probe to a secondary wire (doesn't matter which). It SHOULD read infinity (or out of range) this time. If these aren't the readings you get, the transformer is dead.
 

AgX

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The transformer in question is no plain coil transformer but some solid state one. As there is that large heat sink and as the fuse currents relation is not apt for the primary and secondary side of a plain coil transformer.
 

voceumana

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Because of the very high current demands of the lamp, it seems "overkill" (that is, a design that has been over thought and is more complicated than it needs to be) to use a solid state power supply for the lamp voltage. LPL uses a simple transformer for the supply. Incandescent lamps have a very high inrush current until they warm up and this current can be up to 15 times the steady state current. Since the transformer is rated 100 VA, the steady state current is about 8 Amps, so the inrush can be up to 120 Amps as the lamp starts to glow. Although the inrush is very brief, it is probably enough to cause problems for the solid state supply. A transformer, however, won't react to this inrush current.

All the more reason to replace that supply with the type that LPL intended--a simple step-down power transformer.
 

AgX

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The power supply in question not necessarily was designed as feed for a plain incandescand bulb. But may have just been used for this. On fleamarkets I come across quite some selfmade supplies of unknown use.
 

jim10219

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If it's a solid state transformer, get rid of it. They're overly complex and unreliable (in this scenario). They have their uses, like when needing the change the frequency of the line voltage, needing to regulate voltage AND current, or needing to switch from a two phase to a three phase system. But I just can't see how it would be a good idea to use one in a situation such as this. The only reason I could see to use one is because the last owner blew the old power supply and had this one lying around with no other use, so he wanted to save a buck.

Trying to diagnose and repair a solid state transformer wouldn't be easy for an electronics novice, and wouldn't be worth the money to take to a pro.

I'd say if you can't find a proper used one at a decent price, build a new one yourself. It wouldn't be too hard if you have some electronics experience. If you don't feel comfortable with that, find someone who's good at electronics to build one for you. Or buy a proper one from another country and just use a compatible step down transformer to counter the input voltage mismatch.
 

AgX

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A transformer as linketd to aboved would fit perfectly: to my understanding you only need 12V AC, thus a plain coil transformer is sufficient and that model even has strenghtened isolation between both circuits.
 
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Jerevan

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@AgX , I am not going to dispute your comment about the useability of a C13 plug combination, but this is what I have on the other end of the transformer, going into the LPL ... (see photos) - I do think this is C13? But as said before I am not even close to being an electrician.
 

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