L3-3 Schematics

Brand name believed to be KALIBR.

Re: L3-3 Schematics

Postby g.ciccio » Fri Jun 19, 2015 1:37 pm

Hello,Jac,
I have two schematic diagram of 1973-76 and of 1983 you have requested,but the files are two heavy for your program.Give to me another
adress for normal e-mail.I am available for the community,I appreciate your website(but not for the software for generating test cards,completely
wrong),but I am very disappointed for your unkindness,because you have not answered my many requests for buying new meter scale and tube tester
calibration set!
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Re: L3-3 Schematics

Postby g.ciccio » Fri Jun 19, 2015 6:48 pm

The files are too heavy for your program,that reject them.
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Re: L3-3 Schematics

Postby Andreas » Fri Jul 03, 2015 7:30 pm

It would be very nice if you can upload this schematics to a file server and post the link.

I'm working at a '75 L3-3 with the R43 meter correction potentiometer next to R92. So there is no R100 & R101 in my tester available. Next to the meter at the backside is a R177 soldered.

The double R85 for the mains correction is splitted to the big R85 and a R178.
I'll change this R178 to a 500k/2watts mil spec potentiometer, so this adjustment can be done very easy and quick in the future.

But schematics for the meter circuit would be very nice.
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Re: L3-3 Schematics

Postby Andreas » Wed Sep 02, 2015 7:19 am

In the end I got some bad schematic copies/photos of my L3-3 tester with the R43 meter correction potentiometer.
I re-draw the schematics by hand and dyed the tube socket lines to make an assignment easier.

This is a first version, so it may contain errors, missing parts or bad connections. Be careful using this schematics.
Reported errors will be corrected soon. Please let me know if you find mistakes.

Sorry guys, current lettering is German. I'll make an English version once the schematic is verified.
This is a 300dpi low resolution sample to keep file size small.

---- at this place was my L3-3 schematics, which contains a few errors. I'll upload an updated version soon. ----
Last edited by Andreas on Mon Sep 07, 2015 7:56 pm, edited 1 time in total.
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Re: L3-3 Schematics

Postby Admin19 » Sun Sep 06, 2015 10:30 pm

Hello Andreas,

thank you for this beautiful made schematic! Fantastic work :)

There are some small variations of the L3-3, but i have no overview of that. Perhaps you can add the series number to it.

Also look at this one, perhaps you can extract some more information from it.

http://jacmusic.com/Tube-testers/L3/Sch ... m-L3-3.jpg

Best regards,
Jac
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Re: L3-3 Schematics

Postby Andreas » Mon Sep 07, 2015 7:48 pm

Hi Jac,

I found a few mistakes and will correct them soon.
But it is impossible for me to verify every single connection by measuring them in the L3-3. You have to unpick each connection to measure them with a true result.
And you know the compact construction of the L3-3...

As far as I know, there are 4 or 5 variations of the L3-3 at the market. Only 2 versions are really different in many components or component groups (this should be the ones with 3 or 4 levels at the isolation rotary switch).
Within this 2 versions are slight changes available (e.g. the R43 position in the meter circuit or the quantity of diodes at the -100V group).
At least it seems to be, that there is a hermaphrodite between L1-3 and L3-3 available. Virtually a "L2-3"... It still uses some rectifier tubes but in other circuits are already diodes.

My L3-3 is serial 3931 made in 1975. This one should be your missing schematic.

I'll replace German lettering with the English version, so everybody could use the schematic and make a new higher resolution PDF.
I know marcs schematics and his very useful hints regarding the module functions. But I'm not going to implement these in my schematics.
The function groups are identical to each other, so everybody can compare it quick and simple. Marc made a real good job at his schematics.

I can add some informations for the general calibration: mains, frequency, amplitude, meter and µA/S.
You simply have to replace the smaller R85 (or R178 in my schematics) with a 500k/2W potentiometer.
So first you can adjust the mains power voltage of the "newer" European 230V AC with the mains rotary switch (6,3V AC for the internal tubes, mains rotary switch should now been at "2" or "3").
With the new potentiometer it is now possible to bring back the needle to the calibration mark when pressing "mains". This is essential for the correct working of the L3-3.
Without this you can forget all the other calibrations, as the result will drift by time and input voltage very fast.
At mains rotary switch position "7", 230V input voltage and corresponding calibration mark the tubes will be heated by 6,8~7V. Not very good. Also the transformer will be noisy at this operating mode.
Alternatively you can use a variac at the input to set the originally 220V mains voltage. Many of them were been sold as "Stelltrafo" in the DDR.

Next you can adjust the internal 250V/100V. Measuring point is 39/II and 38/II.
Recently you should adjust the generator using pin 4/I. All you need is a voltmeter with AC & frequency range. AC voltage should be 450mV and frequency 1400Hz.

In the end this calibration made my L3-3 very stable after heating up approx half an hour.
Additional I do not "read" the meter to adjust the tube voltages. Instead I'm using 3-4 voltmeters and 2mm Banana plugs at the pin panel to get exact values.

Regards,
Andreas
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Re: L3-3 Schematics

Postby Andreas » Mon Sep 14, 2015 11:54 am

Updated schematics revision 2a.

format A3 - normal quality 600dpi, rev2a, german:
http://fs1.directupload.net/images/150914/rwgtc94m.pdf

For private use. Non commercial use.
Free to share without changes.

Please let me know if you find any errors, so I can correct them.

Thank you,
Andreas
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Re: L3-3 Schematics + CALIBRATION

Postby Admin19 » Tue Sep 15, 2015 10:48 pm

Thanks for those professional schematics.

One remark, for the calibration. A very important one is the mains calibration of course. So the "^" mark for the mains voltage. I remember from some of the actions by Marc Michalzik, that calibration of the internal resistor R85 was totally wrong in his tester. Also it was wrong in mine. For myself put a pot meter in there is not so ideal, because these can be the beginning of later problems, with contact errors. So I prefer a fixed resistor, as the value is set once and for all. There is some misconcept with tube testers, that the internal tubes have to work nicely and exactly at 6.3 Volts, because "that is so". It may as well be not so, and I find they run tubes at too high heater voltage often in L3-3. That may have reasons that are not documented. Perhaps they wanted the tubes to work better, and do not care about faster wear out. Or, these are +/-10% types, and they made the transformers for 6.9 Volt. It's legitimate for such tubes, and if they are made for +10% and still +5000 hours. Also Perhaps they wanted the tubes to be at minimum 105% heater, at full plate current load, and full heater current load. So then whem you test them without all thet load it is above 105% of course. So you see whatever their considerations were, we may not know. I think it's best to do as they say in the book. Whatever that is, do not do it another way, because this tester has virtually no design errors. Here is a link to it: http://www.jacmusic.com/Tube-testers/L3 ... -index.htm.

Andreas, if you want, better upload the schematics here. "directupload" will delete them later, and then we end up with a dead link. Thanks again for the perfect work :))
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Re: L3-3 Schematics

Postby Andreas » Wed Sep 16, 2015 10:28 am

Hi Jac,

I tried to upload the file, but unfortunately .pdf extensions are not allowed in this board.
Maybe you can save it at your webspace and replace your "needed schematic". So it is preserved :)

My first opinion was to try a variac to set the mains voltage external fix to 220VAC. In other words: doing a time travel to the old mains voltage.
At this tests the L3-3 worked as described. Mains rotary switch at "6-7", tubes heater voltage 6,3~ and meter at "^" .
So everything is perfect with the L3-3 design.

But since 1987 the European mains voltage increased from 220V +-22V to 230V +-23V.
This was not considered in the L3-3 design. At my home I can measure 228-234VAC. And this 6 volts will affect the meter triangle mark with a fixed R85 resistor value.
Once calibrated at "2" and "^" the next day the meter wouldn't meet the "^" any more because the mains voltage fluctuation.
That's why I use a 500k pot instead of the smaller R85 (resp. R178 in my schematics). Of course you should use a sealed mil spec pot to avoid temperature drift, dust/dirt inside and voltage leakage by time.
This is only one more option if you have to calibrate the mains voltage often. Makes things easier. Anyways, the R85/R178 should be replaced in every L3-3 with a customized value.

The higher heater voltage in many L1-3/L3-3 is the result of the higher mains voltage. Comparing the tube datasheets most tubes allow the highest heater voltage of 7V. So 6,9V with 230V mains voltage are borderline.
The only benefit I could see is the shorter heat up time to generate the 450mV/1,4kHz signal. Disadvantage in this case is the faster drift, so you have to calibrate "S" much often than usual.
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Re: L3-3 Schematics

Postby Admin19 » Thu Sep 24, 2015 10:57 pm

Hello Andreas,

this forum software is so unnecesairy difficult, I have NO IDEA how to allow pdf. It probably has to do with pdf being from Adobe, and anything from Adobe is to my opinion a safety risk anyway.

So we do it like this: http://www.jacmusic.com/Tube-testers/L3 ... s/L3-3.pdf

For the calibration, I don't understand your issue. You need no Variac! Inside the tester is already an auto transformer. You operate it with the switch "CETb". This tester can do all mains voltages. All you need to do, set the mains mark with the switch "CETb" before you begin, and that's it. If you find the internal voltages are wrong, you need to adjust R58 and that is once only, it's no user adjustment, rather when the tester is born. People think they need to adjust this such that the internal tubes run on 6.3V. but that is wrong. That voltage is higher than 6.3V. It says nowhere in the books you must set 6.3V as a reference. So the internal heater voltage in above 6.3V with the tester in idle. I don't know how much. If you want to re-calibrate the mains mark, you need to make sure you know what you want. There is the full procedure in the book. Also you should read the document by Mark M. about this, you find a copy on the jacmusic site. Personally I think the mains mark is set for too high internal voltages, and I set mine a little bit lower. Though it may be completely right when you put full load on every voltage source. They may have used higher internal heater voltage for a pupose, we just don't know. Still Mark M. changed his R58 also a little bit. I think with mine it was only two clicks of the switch "CETb" and the transformer was nut humming so loud any more. Which was why I did it. The test results of course do not change by this, as the whole tester is stabilized anyway.
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