Kalibr L3-3 Mains cable (with special chassis connector)

Brand name believed to be KALIBR.
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SeveBC
Posts: 2
Joined: Mon Oct 28, 2013 3:16 pm

Kalibr L3-3 Mains cable (with special chassis connector)

Post by SeveBC »

I have just received a purportedly NOS Kalibr L3-3 from a Ukraine evilbay seller (with 100% feedback). On initial inspection the interior is clean and free of white oxide from damp. Two sockets have been replaced and replaced parts included. However the supplied Kalibr L3-3 Mains cable lacks the special chassis ground connector. It is a standard two core euro plug. The unit I received is essentially identical to one the seller currently has listed on ebay (photos) with copy docs (identical serial number) http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1315053350 The unit I thought I was buying appeared to have all original documents, 5 replacement valves http://www.ebay.co.uk/itm/281132693292 Notice however that both mains leads lack the special chassis ground connector. Is the special chassis ground connector mains lead a 3 core cable with externalised ground? Is it required for 240v operation (I am in the UK). Essentially what do I need to chase the seller for?

I received the stuff included in the photos shown http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1315053350 and attached photo including 287 cards cables 4 replacement valves and a screwdriver.

Advice regarding powering up would also be appreciated. I have a variac so could trickle charge the capacitors using the variac to ensure reformation of the oxide layer. however, this reduced voltage would risk damaging the valves unless I pulled them and progressively reinstalled them in following stages.

All help advice and recommendations gratefully received.

jimmy74
Posts: 43
Joined: Fri Feb 22, 2013 7:02 pm

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by jimmy74 »

I've had really nasty experiences with an L3-3 that I bought on evilbay so I'm with you about this. I would definitely ask the seller for any original parts he has forgotten to put in but if the mains plug has been replaced with a modern 3 prong connector, be very careful as to what connections he did underneath the bonnet. I am no great expert about this unit, but from what I understood, grounding this unit can lead to having mains voltage running through the whole control panel... that's why the original mains plug and cable have the option ground lug. I would invite some of the experts to explain this fact in a more precise way and please forgive me if I'm mistaken.

As for some instructions, there's this link that can be useful:

http://www.vacuum-tube.eu/wp/?p=393

anton
Posts: 19
Joined: Tue Feb 26, 2013 11:47 am
Location: Hazerswoude, The Netherlands

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by anton »

Hello SeveBC
The original power cord does not have a ground connection, it is a 2-core cable with a strange (Russian?) connector.
As stated in the manual, the unit must be carefully grounded by connecting the 4 m/m banana jack labelled with the earth symbol to a proper ground point, usually only available in lab environment or medical examination rooms.
In general, you have to use the ground connection of the wall outlet.
As equipment goes older, the insulation resistance will be lower and leakage current increases, special in case of high voltage equipment. So it can lift the front panel and case of the unit to a dangerous potential. Or at least to a very unpleasant feeling when touching it. ;)
For that reason and for your own safety you have to ground the unit, it can be done on different ways: by removing the weird Russian connector and fit a modern so called euro mains entry and standard cable.
Or, if you didn’t want to modify the unit, by replacing the original 2 conductor cable for a 3 conductor cable with fanned out ground connection, for details see here: http://jacmusic.com/Tube-testers/L3/Imp ... unding.jpg
When powering up the unit after a long period of storage you best use a variac, I’ve never seen this reduced voltage would damaging tubes, there is only a risk of cathode stripping when you will draw a high current from underheated tubes. But of course you can pull them out. Before you start: note their position and put them back to their original positions, especially the tube for the tube voltmeter VL18.
best regards,
Anton

jimmy74
Posts: 43
Joined: Fri Feb 22, 2013 7:02 pm

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by jimmy74 »

Anton PM sent to you

tomix
Posts: 3
Joined: Sun Nov 24, 2013 1:34 pm

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by tomix »

Hello Anton,

I have just received Kalibr L3-3 from a Poland seller. Unfortunatelly there is no power cord included. Do you know where I can find original (or replacement) power cord?
I can do 3 conductor cable with ground myself but I don't know where I can find power connector.
Appreciate your help on this.

Reagrds,
Tomasz

anton
Posts: 19
Joined: Tue Feb 26, 2013 11:47 am
Location: Hazerswoude, The Netherlands

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by anton »

Hello Tomasz
Like I wrote before, it’s a weird Russian connector and I don’t know where to buy.
For that reason I usually replace them with a so called Euro (IEC) connector.
Easy to get and plenty of cables available in almost every home or in your yunkbox .
Otherwise you find them on every flea market for "crappy" prices like € 0,50 or € 1,-
It’s not a direct replacement, you have to enlarge the dimensions of the hole, by file out or similar.
For picture (rear-side frontpanel) look here:
http://jacmusic.com/Tube-testers/L3/Ant ... entree.JPG
For the original connector, most likely to find one ……Ebay
Best regards,
Anton

SeveBC
Posts: 2
Joined: Mon Oct 28, 2013 3:16 pm

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by SeveBC »

Appologies for my lack of response. I have been ill with food poisoning gastroenteritis. Thanks for the reply and superb link Jimmy74 and for your advice Anton.

Sorry I wasn't clear. The unit was supplied with a 2 core 2 prong Russian Euro plug with L3-3 kettle type connector on the other end i.e. no ground. No apparent mods. I have some ground points in my house in the basement and also in the boiler cupboard so I'll temporarily connect to one of those until I make up a modded lead as per the photo.

Am I correct in thinking that the voltage selector fuse holder should be set at approx 10 o'clock and turned clockwise to 12 o'clock to lock in place for 220v? Have to get my head around the circuit diagram. If I remove the four large machine screws on the faceplate does that enable me to remove the whole unit from its case? Anything to watch out for? I'll remove the valves and inspect all the capacitors to check for any obvious signs of failure. I can then slowly reform the capacitors in the power supply although I need to purchase some low value fuses to protect the power transformer while reforming. I'll temporarily replace the usual 2 or 3 amp fuse with a very low value, such as 0.25 or 0.5A. The variac will prevent the switch-on surge that would normally blow this size fuse. I have a large value cement resistor 17W 33k Ohm made up in a discharge lead for ensuring the caps are discharged safely before I tinker - just to be sure I have a couple of Fluke 123 20 KHz Scopemeters so I can connect one across a resistor in the power supply and monitor the current increase.

I have a number of NOS Russian 6P14P-EV valves I can test once I get up and running. I'll use a residual current device RCD and the Variac to establish whether the device powers up stablises OK and Is working normally once I have ensured the capacitors are OK.

anton
Posts: 19
Joined: Tue Feb 26, 2013 11:47 am
Location: Hazerswoude, The Netherlands

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by anton »

When you want to have the unit from its case, you need to remove the four screws on the panel and one on the side off the unit, in the vicinity of the carrying handle.
Warning! Very high, lethal voltages (more than 900 Volts DC!!) can be appear on some components (o.a. electrolytic caps) and they can easily being touched when working on the open unit with mains voltage connected and unit switched on, see picture:
IMG_2127small.jpg
IMG_2127small.jpg (104.15 KiB) Viewed 18678 times
Not sure how to set the correct position for the voltage selector, but there is a simple way to find out if the unit is connected for 220 Volts, plug mains cable in the unit and put AC power plug into a digital multimeter (if its fit), make sure power switch is in the "on" position, set multimeter for Ω range and measures resistance between the two pins, the highest value is that for 220 V connection, usually about 2,3 – 2,4 Ω.
It is obvious that it once goes wrong, so I suggest to replace this voltage selctor with a normal fuse holder and insulate the wires for 127 V & 115 V/400 Hz.
Only connect the wire nr. 141, see picture.
IMG_2115small.jpg
IMG_2115small.jpg (68.01 KiB) Viewed 18678 times
To protect the transformer during the reforming process you can take a 100 W bulb in series with the variac, if something really goes wrong, the actual (primary) current will be limited to about a ½ amp or so.
Don’t forget to place a test card for a 6P14/EL84 or something like that, otherwise there is no connection between the transformer and the rectifiers.
Regards,
Anton

tomix
Posts: 3
Joined: Sun Nov 24, 2013 1:34 pm

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by tomix »

Hello Anton,

This weird Russian connector is really hard to find. I know the same power connectors were used in tube testers like Elpo P-512, P-507. I'm searching ebay for old russian devices so hopefully I will find something simillar soon. I would avoid changing power socket for IEC as I don't want to change anything. On the cover there is a sticker, which may indicate a revision in 2006.

Tomasz

aj4ks
Posts: 2
Joined: Fri Dec 19, 2014 11:23 am

Re: Kalibr L3-3 Mains cable (with special chassis connector)

Post by aj4ks »

I've fit a C6 connector to replace the soviet power connector. I found a flange panel mount that fits after elongating the holes to use the factory screws.

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