These came from a swapmeet a week back. They were on a big silent key stall. I asked about one, which was prominently on display on top of other units, and was told it was tested and it worked, so they wanted £5 for it. I bought it. I'll call that one New, although they appear to be around the same revision. There was another one, which I'll call Old. It was grubby and buried under other things. It had an obviously loose cover. I was wandering round with New and a couple of people recognised it and said how good the 7045 was. So I returned to the silent key stall and offered £2 for Old, which they accepted. A part of the reason was I didn't have much confidence in the seller's assurance that New was the Real Deal and a parts mule might be useful. There was another 7045 on another stall. This was in its case with a section for probes. I was told £30 was asked for that. I wasn't tempted. It was still there when I left.
On trying them out, Old, with its "patina" and loose case appeared to work well. New showed all segments of the 7 segment display lit very dimly. Inputs didn't change the display. So much for sellers' assurances. Well they may have mixed up New and Old, and equipment over 40 years old can fail without warning. These are later models as they have a 7805 regulator rather than a ciurcuit using discrete transistors. Even so, the manual documenting that is dated 1978.
So to investigate New. A fairly good copy of the operating/service manual is available on line. The first place to start is with the power supply voltage and ripple. They are +5V, +12V and -12V. These DMMs have a battery holder which accepts an optional four NiCd D cells. They have a charger/inverter board to charge the batteries, and produce the necessary voltages when the units are operated disconnected from the mains. In both cases the batteries appear to be useless
but had not leaked. The battery holder and inverter board had to be removed to access the test points for the + and - 12 Volt lines conveniently. The +12 Volt line was right, the -12 Volt line was at -6V, the +5 Volt was right. The -12 Volt line supplies op amps and other low demand circuitry.
The -12 Volt line is produced from a TO92 7912 regulator. The input voltage was at about -20V and the other line was at about +20V, so that seemed right. Either the 7912 was defective or something was dragging down the -12V line. Three terminal regulators don't fail often. There was an electrolytic capacitor on the -12V line. I changed that. There was no difference. It could have been something else such as an op amp. I searched through the collection and found a single TO92 7912, so I wouldn't have to order one, or bodge it with a TO220 7912. With the 7912 replaced, the DVM worked. I also replaced the reservoir capacitors on the + and -12V lines because it was easy.
They were powered up and left on. After a couple of hours I tweaked the zero offset, then checked them against a voltage reference board based on a MAX584. They were in agreement to within a digit or two as is a Brymen 867s. The resistance and current ranges also appear to be accurate. I haven't tried AC voltage. They were left running overnight measuring the voltage of PP3 battery, which is past its best. In the morning they still agreed to within a digit or two. For units last calibrated in 1999, I find this remarkable. New has a 7 segment dispay with a dim segment. It's still useable, but slightly irritating.
My general conclusion is the Solartron 7045 is a nice autoranging 4½ digit bench multimeter. LEDs have advantages over LCDs for bench DMMs. The NiCd cells were a thing of the era. These were well enclosed but hadn't made a mess. They don't have shrouded sockets. The case isn't ventilated and gets warm around where the mains transformer is placed. The weak spot is the case, which in both units have problems caused by the plastic pillars which are damaged or have sections missing. It should be possible to replace them with a section of plastic rawlplug. For what they cost, £7 the pair, it seems reasonable to use something like an elastic band or a cable tie, to secure the top of the case.
Top cover removed.
Both DMMs after being left on overnight.
I seem to come by a lot of this stuff in pairs.
Two Solartron 7045 bench multimeters.
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Two Solartron 7045 bench multimeters.
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Specmaster
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Re: Two Solartron 7045 bench multimeters.
Pretty good haul you got there for sure. I' think you have plenty of room on the right panel and in the case where the input sockets are located, to allow you to swap them over for shrouded ones, I once had 2 of the 7150+ models which had the inputs beneath the input selectors, it was tight but I managed to swap them over OK.
Who let Murphy in?
Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Advance-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi-Heathkit-Duratool
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Re: Two Solartron 7045 bench multimeters.
It's crossed my mind to fit shrouded inputs to the two 7150+ I have. Mainly I find the unshrouded inputs are a nuisance, because you can't use modern meter probes without cutting the shrouds off, which I don't want to do. Unshrouded meter probes are a rarity, and the ones I have are ancient, crude by modern standards, and the insulation is becoming stiff. However, I bought some unshrouded to shrouded adapters from Aliexpress. They are not Pomona quality, if Pomona do such things, but they work and are not too bad. They are rated for 30V, so they are the real deal.
Re: Two Solartron 7045 bench multimeters.
The only place I normally use shrouded probes is with my Fluke 25 or Metrix MX67 handheld DMMs. That's because I might be measuring high voltages, or I want to noodle around with the probes looking for something odd.
Otherwise I want to clip a bench meter (HP34410/K2015/etc) to a board etc, and/or have several leads attached to the meter[1], for not-very-high voltages. In those cases shrouded leads offer no advantages and make life difficult.
Have you considered taking a shrouded lead, cutting the banana plug off, and attaching a non-shrouded 4mm plug?
[1] as in your pictures
Otherwise I want to clip a bench meter (HP34410/K2015/etc) to a board etc, and/or have several leads attached to the meter[1], for not-very-high voltages. In those cases shrouded leads offer no advantages and make life difficult.
Have you considered taking a shrouded lead, cutting the banana plug off, and attaching a non-shrouded 4mm plug?
[1] as in your pictures
Re: Two Solartron 7045 bench multimeters.
I've cut the shrouds off old shrouded meter probes with a craft knife to use with unshrouded inputs, such as on my Micronta FET multimeter. I have three modern handheld DMMs and three sets of nice silicone rubber meter leads, which I have no intention of messing with, and certainly not fitting new plugs. They are what I normally reach for, and prefer to use for anything like dangerous voltages, where you are seldom interested in great accuracy anyway. For anything that might be really dangerous, I try to use hands off technique.
The bench multimeters are interesting and useful for specific things, or those occasions when you leave a meter on for a long time, and don't want it turning itself off and chewing through batteries. Some of them offer things like GPIB, so they could be used in an ATE setup. I haven't had to do that so far. The LED displays are easy to read.
The adapters make life a little easier. They have 30 V marked on them, but they have fairly substantial plastic bodies, and I'd guess they would be good for much more than 30V.
I've thought about fitting shrouded inputs to various things. They are surprisingly expensive, there may be hassles fitting them, and I haven't really seen the need.
The bench multimeters are interesting and useful for specific things, or those occasions when you leave a meter on for a long time, and don't want it turning itself off and chewing through batteries. Some of them offer things like GPIB, so they could be used in an ATE setup. I haven't had to do that so far. The LED displays are easy to read.
The adapters make life a little easier. They have 30 V marked on them, but they have fairly substantial plastic bodies, and I'd guess they would be good for much more than 30V.
I've thought about fitting shrouded inputs to various things. They are surprisingly expensive, there may be hassles fitting them, and I haven't really seen the need.