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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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13th Aug 2022, 1:20 pm | #21 |
Tetrode
Join Date: Jul 2009
Location: Zwolle (Netherlands)
Posts: 74
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Re: Mullard E7600/4 tube tester card database
Last open question... Does anyone have some close up pictures of the big transformer from the E7600/4?
It seems someone has been soldering on the transformer and there is also one loose wire. So I would like to compare my wiring with a known good tester. Thanks in advance! |
13th Aug 2022, 5:36 pm | #22 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Mullard E7600/4 tube tester card database
I did not find a blind 'go/no go' tester of much use as the test conditions are unknown and the 'replace' threshold has been set by the valve manufacturers who have a vested interest.
I will one day get around to fixing the Javascript emulator as I find it invaluable and still run it on an old version of Internet Explorer. Javascript is still supported but for security reasons the method I have used to access html objects is no longer supported. The emulator takes the card hole information and calculates all of the test conditions and will be more accurate than the tolerance of a tester. As well as giving the anode current for the go/no go threshold it also calculates the values for the centre bar and top of the screen and as the deflection is fairly linear it is easy to extrapolate an approximate value for any deflection. GMB provided an early copy of the card hole database which allows the card holes to be setup from the card number but they can also be entered by simply clicking on the hole in the card image on screen. The card database from GMB is no doubt out of date but the emulator is not designed to be a source of card information, it is intended to make the tester more useful by providing quantitative results. |
13th Aug 2022, 6:55 pm | #23 | |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: Mullard E7600/4 tube tester card database
Quote:
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13th Aug 2022, 8:07 pm | #24 |
Hexode
Join Date: Jul 2008
Location: Gateshead, Tyne & Wear, UK.
Posts: 336
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Re: Mullard E7600/4 tube tester card database
Hello Roland
Please find attached a Photo of the mains transformer on my Mullard E7600/4 HSVT. From your photo I think you are referring to the Brown wire and the vacant terminal number 7. It may be wise to do a continuity check on the Brown wire, by clipping one lead of your ohmmeter to the unconnected end. Then following the path the wire takes through the wiring harness to where it is terminated, then using the other lead of your ohmmeter, check that you have continuity and then checking the diagram for the E7600/4 to ensure the wire is connected to terminal 7 on the transformer. I have also attached two PDF copies of the Mullard Test Card Index. The first PDF is of the front cover and the second is an alpha numeric index of the valves and card numbers. The list was compiled in 2010 in Excel and converted to a PDF file, this index includes some of the more modern valves not included in the 1966 list. The front cover should be printed full size in Landscape and in Colour and the list should be printed, 2 pages per sheet also in Landscape and double sided Black and White. When bound up as a flip chart it will resemble the original Mullard index. With Reference to PDF copies of the tester cards, I Scanned all my cards and other cards supplied by other form members around 2009/10. The whole data base is available in the Library on the following link. Caution the file is over 70Mb and may have to be down loaded in sections or just the cards you need. https://www.radios-tv.co.uk/ I hope this information will be of some use to you. Regards Stan.
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14th Aug 2022, 10:45 am | #25 |
Tetrode
Join Date: Jul 2009
Location: Zwolle (Netherlands)
Posts: 74
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Re: Mullard E7600/4 tube tester card database
@pjl
I agree on the go/no go part. For me the Mullard is an addition to my vcm 163 which I have for a quite long time now. That tester was a mess and incomplete once I got it. I got it litteraly in bits and pieces. Missing one meter, missing knobs, missing oscillator transformer etc... But I love these projects. And I could not resist the poor mullard for a decent price. I hope the mullard speeds up my testing for boxes loaded with unknown state tubes. The vcm is a lot of work to setup for a different tube each time. But you can see it testing the EL37 from the Mullard tester. @stan Thanks for the documents and transformer picture. I think I can get some theps further now. Regards, Roland |
18th Aug 2022, 7:43 pm | #26 |
Tetrode
Join Date: Jul 2009
Location: Zwolle (Netherlands)
Posts: 74
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Re: Mullard E7600/4 tube tester card database
I've slowly been powering up the Mullard, and the last two capacitors for the CRT supply are definitely bad too. I wanted to test some basic things like the protections.
When you pull down the lever without a card the tester should switch off immediately. This to prevent a shortage when all pins connect to each other. This is done by a microswitch on the lever. This switch turns on the tester to heat up the tubes. When you place a card, the microswitch underneath the card closes and keeps the tester switched on while pulling the lever down. So far so good... But when I pulled down the lever without a card, the tester switches off and when it is half way I got a shortage! My series lamp turned just on bright! I didn't understand it in the first place. Both microswitches were working great. But a short with the lever halfway got me wondering if there was something connecting trough the spring contacts. So I took an ohm meter and connected it across the microswitch on the lever. Pushed down the lever and indeed, 0 ohm without a card. So I started to pull back the contacts to see if it was one of these. And there were two outside the card range. Pulling back one of them immediately solved the short. Looking in the documentation, it seems there is a piece of insulation placed between the contacts when there is no card in the tester. So there are actually three protections in the tester. Guess what, I found the broken piece also in the tester! Now I have to figure out how to fix it It seems the small microswitch is not mentioned in the doc and it looks a bit new to me. Is this original/modification or added later? The wiring is strapped in the harness, so initially I thought it was original... Last edited by Roland Huisman; 18th Aug 2022 at 8:08 pm. |
20th Aug 2022, 5:23 pm | #27 |
Tetrode
Join Date: Jul 2009
Location: Zwolle (Netherlands)
Posts: 74
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Re: Mullard E7600/4 tube tester card database
Baby steps... I still have to fix the safety lever, but I got the CRT from peter. Since I didn't got the mounting clips I had to make something myself. Replaced the capacitors for the CRT power and there is a bit of life in the tester
Regards, Roland |