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Old 16th Oct 2010, 1:31 pm   #1
Dekatron
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Default Calibration instructions for Taylor 45D & 45D2, do they exist?

Hi everyone,

As I am the lucky owner of three damaged Taylor 45Ds, and I am looking for calibration instructions for these. They where bought as spare parts or "fully working", but as usual did not turn up as that (except the one bought as parts, which funny enough was the most well packaged of the three!), one was also shipping damages due to almost no packing protection!

I have the operating instruction manuals and also the valve data manual for these so I have been able to make one working out of the three, but I am very interrested in obtaining a copy of any service/calibration manual if such a manual exists.

The selenium rectifiers used has quite a whopping forward voltage drop and I am guessing they are not working as good as they once did. The voltage drop is up to 8 volts when in use in the circuit, and from the datasheets I have found it should be much lower than that, but I feel a bit unsure here.

If there is anyone who has a Taylor 45D and who is willing to make some measurements for me to compare with I'd be very happy.

I have made a combined Operating Instructions manual for the Taylor 45D & 45D2 as they do not differ more than in a few points about the gm measurments, all differences are marked and in some places dual paragraphs on separate pages are incrorporated as well as dual component lists.

I have also run the Valve Data Manual 2nd edition through my OCR software and made a completely new manual from that with two pages of valve data printed on each page, but still very readable.

If anyone is interrested in those I can email them. The operating instructsions is roughly 37MB and the Valve data manual is roughly 15MB, both print very well on paper, better than most you can buy copies of.

Kind regards,
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Old 20th Oct 2010, 7:27 am   #2
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

I have now read that there is supposed to have existed a "Test Jig" for the Taylor Valve testers, atleast for the Taylor 45D.

Does anyone have any service information, as PDF files, for any of the earlier Taylor 45B or 45C that you can email to me or direct me to where I can download them?

Has anyone heard of this "Test Jig" for calibrating any of the earlier models, or the Taylor 45D/D2?
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Old 31st Oct 2010, 12:49 pm   #3
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

I was sent two scanned images from a "Test Specification for Taylor 45D Valve Tester" by Stephen at http://valve-testers-tubes.com . I have run those pages through my OCR software and cleaned them and I let Euan MacKenzie have a look at them for proofreading. I also decided to make new cover pages based on the Taylor 45D manuals and added those to the document.

I would just like to remind you that this document is NOT a Calibration manual, although you can use it as such in some parts but not all. Also the information regarding the "Test Jig" and the "Test Gear" is absent, my guess is that those two are a modified (extended with load resistors and also calibrated) Taylor 45D Valve Tester and an AVO 8 or similar instrument.

I am currently making a new document that will focus more on the calibration and inner workings of these fine valve testers.

If anyone has a clue to who "D. Winsor" who was working in the "Test Room" at the time the document was written I am interrested in more information, and I am of course interrested in knowing more about the "Test Jig" and the "Test Gear"!

I have included the document as a PDF-file here, please leave feedback and comments if you think there is something that needs to be changed or corrected.
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Old 11th Mar 2016, 10:43 pm   #4
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

Hi Dekatron
I'm wondering if you've completed the calibration procedure & if you can make it available to me & others. From what I see in its schematic, it looks like it's based on the AVO Mk.1 Two panels tube tester & Jac (from JacMusic) says that there's no calibration!
I'm about to get a 45D2 very soon from an eBay purchase from the UK. It does come w/ the measurement manual & tube data setup. It's probably the same as for the AVO's, but not to 400vdc as the AVO's. I've an AVO VCM Mk.3 which I calibrated, but it needed a new meter, because it requires 31.7uA for the full scale of 30 uA. I can get by by shifting the 0 mechanically - it's linear from 10uA & up. Thus, it gives me the 30uA @ full scale. In fact I already have a Yokogawa 30uA meter which I wanted to fit in the AVO's case w/ its faceplate. I'll also be installing 2 Digital Meters of 5 digits for Va & Vg.
HOWEVER, there was a break-in in our house & the thief jolted the AVO, thereby making it non operative - it's up to the insurance to deal with it.
I've other North American tube testers.
Thank you, Dany, Toronto, Canada
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Old 12th Mar 2016, 12:15 pm   #5
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

Hi Dany,

I didn't get any more information than those sheets which I made the document from.

There is only one potentiometer inside and that is a long slider that works as a meter series resistor for adjusting the meter circuit. The only other way of "calibrating" the tester is by using good known valves to check the tester with those and if necessary loosen the grub screw on the grid volts potentiometer knob, or the nut holding the grid volts potentiometer and turning either of them until they show correctly on the grid volts scale compared to the measured values. This of course requires that all internal components have the correct value.

I have seen some of these where the shunts have been adjusted to show correct readings, but that is of course not the correct way of doing the "calibration" and I have also seen two where the grid volts potentiometer had been replaced with the wrong resistance to "calibrate" it.

You can replace the gradient potentiometer with a 10-turn potentiometer as it sometimes works poorly at the spot where the resistance change, just use a 10-turn potentiometer with 2k resistance and at least 3W power rating.
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Old 14th Mar 2016, 9:08 am   #6
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

A word of caution, don't fiddle with the grid volts control unless you really need to, as it is very hard to get it back to the same position as it was in previously, moving the knob or rotating the potentiometer is not as easy as it sounds/looks.
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Old 27th Apr 2016, 4:24 pm   #7
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

Hi again Martin.

Do you have by any chance a pictorial diagram of the printed circuit board relating to the numbered/value resistors in the schematic for the Taylor 45D2? I tried to test an EM81 and smoke started. At the same time I'll change the "Rat's Nest" components.

I just got the PB for the "test" PB. Still waiting for the 2K 10 turn pot, which will do in the mean time. I think a 5K will be better, because it'll allow me for less turns(but still multi turn) to zero the FS.

Another question: -Vg in the Taylor doesn't follow its Pot markings (although its span is correct) when measuring on the Grid. In the similar cct/setup of my AVO VCM Mk.3 this pot follows the Vg voltage when measured on any grid!?

Thank you, Dany.
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Old 3rd May 2016, 4:08 am   #8
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

Hello Martin
Obviously you don't have any more info on this Taylor, but I'll question you some more:
After getting rid of the "rats nest" that I've found, testing the resistors, installing proper value ones in place of some out of % values, proper 1N4004 silicons & some other parts that had kind of cold solder joints / kind of torn(!), I've the following remark / question:
A diagram I've found on the net shows R15 = 550 ohm / 6 watts / 5% & R16 = 110 ohm / 6 watts / 5%. Installed proper values, but readings were totally out!
Originally, I found R15 to be 2 parallel .5 watts, 62(10%) & 91(5%) ohms & not knowing the value of R16, because it smoked to death!
The instruction manual's diagram shows R15 the same 62 & 91 .5 watts, but 2% ea. R16 = 360 parallel to 390 ohm, .5 watts % 2% ea. I increase the wattage(as my AVO VCM Mk.3 shows way higher wattage for the Load resistor - these being Load resistors) & have hand picked combinations of +/- .5 / .6 %.
So, are these the right values?
Thanks, Dany
Because of R15
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Old 10th May 2016, 1:50 am   #9
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Default Re: Calibration instructions for Taylor 45D & 45D2, do they exist?

Hello again
Now that I'm done w/ my 45D2(until further notice) & here are some more repairs & conclusions:
- R15(36.9) & R16(187.2), each in parallel are the correct values. I achieved 36.72 & 187.4 ohms w/ 5w & < resistors in series(R15) & parallel(R16).
- The 2K 10 turn pot(A) is not adequate @ 0 for some tubes. I'm waiting for an attachment for geared turning for each turn - very cheap on eBay w/ another 10 turn pot. After this fine turning, perhaps I'll change the 2K to 5K or 10K, so I won't have to turn so much - the pot has only 2 connections.
- Once my AVO VCM Mk3 returns from Germany w/ its Bogey tubes(from the break-in, so it's covered by insurance), I'll be able to compare the 2.
Dany, Toronto
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