ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I'll bet even Leslie doesn't have one of these. Rebadged no doubt.
Real B&O.Not rebadged.
Part of B&Os extensive series of laboratory and repairshop instruments. You would find many of themin authorized B&O repairshops and other places.Some service manuals refer to certain models of these instruments.
There was several series of these instruments, a previous series had raw alumininum fronts like this ST5
but the "blue" series is by far the most common (if you can speak of them being common).I use a good collection of them in my own humble little repairshop, mainly the blue series.
I'm sure that, sitting with far more experience in matters B&O, Leslie will be able to tell you much more and probably provide better photos.
Martin
I have two of the blue ones and my father has a RV7 - They do come up for sale from time to time here in Denmark.
Dillen:I'm sure that, sitting with far more experience in matters B&O, Leslie will be able to tell you much more and probably provide better photos.
And excuse me, but are comments like this really necessary?
- Dennis
Dennis: Dillen:I'm sure that, sitting with far more experience in matters B&O, Leslie will be able to tell you much more and probably provide better photos. And excuse me, but are comments like this really necessary? - Dennis
Well, he IS far more experienced than I. He started working with B&O when I was only at the age of seven and theinstrument series is, as you mention yourself, not THAT uncommon. They were also used by repairshops inother countries, I've found some in Holland myself, so I'm sure Leslie will have seen many and know a lotmore about them.
If that turns out not to be the case, I will be happy to chime in with what little knowledge and info I have, shouldthere be interest.
BTW that RT12 variac is one of the best on the market.Without a doubt, the single piece of B&O I have used the most.I have two in my repairshop; One to power the item undergoing tests, the other to power f.e. my oscilloscopeif measuring in valve things. Don't want to put any stray live mains onto the valve chassis, you know.
What is this all about? Are you talking about me or is there another one with that name
Brengen & Ophalen
AFAIK, there's only one Leslie. In any event this is turning into a 'Flash your B&O Test Equipment' thread. Long overdue.
You almost tempted me to buy this instrument Bob, but then (just on time) I realised that this must be a 110Vac US type (I guess).
For $50 I almost bought it. Then my sanity came back. I sent an email to him re: voltage.
Leslie: You almost tempted me to buy this instrument Bob, but then (just on time) I realised that this must be a 110Vac US type (I guess).
Most likely. A few models have the rotary voltage selector at the back but this one obviously doesn't.All B&O instruments, I've bought in the states were 110V so I had to replace the transformer in the ones, I was going to use.Their power supply circuits and constructions are generally fairly basic and most components are common typesso usually quite easy to work on.
@Dillen/Martin
I just saw it as adding fuel to the fire with the hopefully passed conflict in mind.
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I found an article from 2008 about a year or so ago regarding these blue instruments, but as the Nåsåers would say: "Oh ***, it's på danish" (Only Danes will understand )
I've translated the article the best I could:
B&O measure instruments are still being produced, and new ones are also developed. But the original wide range has been reduced a bit.
Written by Jørgen Jensen
It's uncertain when B&O entered the market with the well known light and dark blue measuring instruments. But Ib Lundgaard, owner of Electric Instruments in Struer, remembers the instruments from his apprenticeship on the B&O factory in the early sixties where they were used internally in the development and production department.
B&O were using the instruments when there were seminars, and that's probably one of the reasons why they entered the market. There were several power supplies in the range; the simple SN14 and the double SN16, the signal generators TG7 and TG8, the vacuum tube voltmeter RV7 , the variacs RT11, RT12 and RT15, the wow and flutter meter WM1, the diode probe for measurement of high voltage in televisions and the audio effect monitor AM1.
Bought rump and stump
The B&O instruments were sturdy, easy to operate and very used in Radio & TV repair shops in the industry. But in the late eighties when Anders Knutzen took over the leadership of the electronics group and began to outsource to focus on the company's core competencies; audio-, TV- and video-equipment, there was no longer space for the instruments. "- I knew the manager of the department where the instruments were manufactured, and when he told me, that they wanted to get rid of all of it, I went for it and bought all of the stock, components, semi-finished products and the seller index" Ib Lungaard tells.
That was in 1988. Ib Lundgaard continued producing in new premises in Struer and he also began to develop. "-The power supply SN19 with 0-30V and 0-10A was the first I finished. There was a need on the market, among other at the former Dancall, that couldn't use switch-mode power supplies because of the noise" Ib Lundgaard explains.
SN19 works after the good old linear principle, therefore noise is not a problem. If you place a transistor radio directly on top of the supply you will only be able to notice very little noise on the scale from the rectifier bridge.
Much is in stock - No waiting time
The old RT12 variac is also available in a new version, RT12A. One of the reasons to that was that the two "soft iron indicators" from a Japanese manufacturer gradually went so nonlinear, that they couldn't be accepted. They have now been replaced by a real RMS-detector and ordinary moving coil instruments. Besides that has the old C-core transformer been replaced by a modern toroidal transformer and the circuit breaker is now electric.
Only the old wow and flutter meter and the vacuum tube voltmeters RV11 and MM2 have been discontinued. "-I either have the rest of the range in stock or am able to produce them within a short amount of time. Power supplies, variacs and high voltage testers are always in stock, but the demand isn't what it has been. Maybe the reason is, that I never have taken me the time to visit customers, there has always been enough to do with developing and producing.
Transportable high voltage tester
Since Ib Lundgaard took the blue B&Os on board twenty years ago, has it become mandatory at many places to safety test equipment with high voltage after repairs. The authorized B&O workshops must perform high voltage tests on flatscreens, when they are serviced at the consumer. "This way there occurred a need for a little transportable high voltage tester, that was easy to take with you in the car. There is a a stationary tester in the range, but it provides from 0 to 5kV AC, and that gives problems with the flatscreen because of the great capacity over the mains input. The transportable tester is therefore running with DC in the range from 0 to 5kV.
Right now Ib Lundgaard is modifying the RT12A to make a bigger model. It is going to be named RT20, and will be able to provide 1,6 kV and is needed when servicing and testing big plasma screens.
Would love to repair
And should there be someone out there in the electronic industry, that needs help to get an old (blue) B&O instrument repaired, then Ib Lundgaard will solve the job quickly. "I've never had a faulty B&O instrument I wasn't able to repair, and I don't think that's going to happen either" Ib Lundgaard ends.
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I hope there aren't to many non understandable sentences - There are many technical terms to keep track of . The original article and a few pictures can be found here. I love these blue instrument btw. - I am hoping to ad at least 2-3 more of them to my little repair corner. Maybe I should find out if Ib is still in business - Could be interesting to visit him in Struer and have a chat with him!
Dennis: @Dillen/Martin I just saw it as adding fuel to the fire with the hopefully passed conflict in mind.
Already forgotten, but you're a nice bloke Dennis.
I can tease Martin as well!
I was given an RV7 by a friend who had three of them - a very nice tool...
Vinyl records, cassettes, open reel, valve amplifiers and film photography.
Dennis,
Yes, indeed!
See if you can get his contact details! This is a super piece of information.
Menahem
I have two SN14, one SN16 and a RT12. I have manuals and schematics for the RT12 and SN16, but I cannot find a manual or schematic for the SN14. I need to repair and refurbish the two that I have. Does anyone have an SN14 manual? The SN14 is 20V 2A, using the obsolete MC1466L Motorola floating voltage and current regulator IC. I have a manual and schematic for the SN15, which used the same regulator IC, but is 50V 1A, so the circuit values will be different.
You don't really need it! The SN15 service manual and an MC1466L datasheet/app note should more than suffice.
There will be only minor differences in the output transistors and the MC1466-external current/voltage regulation resistors and you can easily figure them out by studying the MC1466 datasheet.
If the MC1466L is busted you could try a fake chip from China (readily available via ebay) or if you don't trust them Chinese, why not just build your own! <see here> It looks simple enough!
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Just by accident I came across this site, which you might find helpful: <SN14 repair> (If your Dutch is a bit rusty, Google Translate does a fairly good job!)
Apparently early versions of the SN14 did not use the MC1466 (no surprise, coz the chip probably didn't exist before the early seventies!) and if you have one of those models the SN16 manual is probably best as a guide. If you do have the MC1466 version, the SN15 manual will help, but based on the description of the original poster in that link above, the design might be more different than I thought.Anyways, looking at the innards of the beast, I'd say it should be easy to trace the tracks and components and draw up the actual schematic that will help troubleshoot the unit.