Test Equipment Anonymous

I I bought a second 2019 for £70 at MK last year, assured that it was fine, apart from a LED not working. It works after a fashion but the frequency is nothing like expected and a LCD digit segment is dark when it shouldn't be. I had this with my 2019, it was the level shifting CMOS chips used to d...

Some PCB assemblies refuse to be repaired, sometimes this is because they've absorbed something that makes them conductive or that has dissolved vias. I had the former with a Marconi 2019A that I'd bought for £100, it mostly seemed fine except it couldn't manage to tune over its full range. The osci...

I also have a RACAL 1992, the red power button fell off a few years ago and I never found it - perhaps the vacuum cleaner did. I like the 1992 but I found that, a bit like the HP 3314A, the computer tended to do strange things if left powered on for too long. It's probably a thermal issue in the RAC...

Haha! Or should I say something much worse?

I have not fixed it.

Yes, it has rebooted itself. I guess I'm going to be changing the non-volatile RAM. All the nvram presets that I'd stored had been replaced by defaults.

Is the LeCroy 9400 a dodgy number, likely to overheat or something? I wouldn't hesitate to leave either Siglent set up to catch something like that. Not really, it's an early high performance DSO so it turns a fair amount of power into heat, it's also about 40 years old. It has never given the slig...

A magnificent effort! CMOS pathology has driven good men to drink. Circuits that ought to work but are stubbornly dysfunctional until an oscilloscope probe is put somewhere that ought to be irrelevent, and then they spring to life. The probing of the defective CMOS hex inverter was like this, I use...

Several years ago I succumbed to the Easter egg demo on this function generator at the Milton Keynes radio rally, when it was still at the Irish centre. I don't recall how much I paid but it might've been £60. I've never used it as much as I wanted to because it had a very bad habit of rebooting its...

You are in luck with a dodgy connector on the 8714ES. Unlike most HPAK analysers the connector is not part of a bridge assembly. It's just a N to SMA adaptor. You can even order one from Keysight 08711-60038 . Before you do that, pull the front panel and check the SMA connectors are tight including...

AWGs don't appeal, even though I do have a couple of instruments that implement a very early form of it - the "join the dots" approach used in HP's 3325B modulation generator (that most people with a 3325B probably never use) and 3314A (which uses the feature to achieve polyphony with a si...

This is a Philips pulse generator from the late 1970s. No GPIB, so I shouldn't have bought it really, but it's very compact relative to the HP 8007B that I bought earlier this year. I was expecting this to be a repair for the £15 price, but it works, albeit with the expected slightly scratchy vernie...

This was a fiver bargain buy at the Flight Refuelling rally but it needed a wash and brush up as well as a new cap for the mains power switch. Who was I kidding? As soon as the cleaning was complete I tried out the now easy-to-press power switch a few times. And you know what is coming. It stopped p...

Away from test equipment the display problem was worse because equipment was being thrown away because of bad displays, even when those displays were generic. I was one of the first people to spot generic LCDs in quite expensive electronic music modules could be replaced by inexpensive and much bett...

My plan to work on the HP 8405A changed and I had a closer look at the Tek 468's cursor control today. I've identified the fault as the RC4151 V-F converter that turns the resistance change in the 10kΩ potentiometer into fine cursor movement. It's a form of A/D converter. I have found two sources of...

This Tektronix 468 with both service manual volumes and the operator's manual was unavoidable, at the rally. I was told that it had a bad timebase but what I wasn't told was that the person who reassembled it after deciding they couldn't fix the timebase had mangled one of the internal coaxial conne...

The attenuator switch decks on the 465B, as well as other 400 series, can be problematic with general wear and dirty contacts. 100% IPA will help, but months down the road you'll have to do it again. This has reminded me of the other action I took, one of the contacts was not aligned above the cont...

IIRC the DM44s have an interesting filter, just an opamp and capacitor on the input and output. Guaranteed not to add an offset Have fun. Have had a lot of fun, the next step will be to do some proper performance verification but it's too hot for that at the moment. I need to do this for the 335, t...

I was given a rather nice Tektronix 465B with DM44 multimeter, manuals and service manuals. It had been a standby scope, bought secondhand 35 years ago, but had been stored in a garage for some of those years. After cleaning off rather a lot of mould I decided it could enter the house and I could in...

I'm lost for words, a shame that ChatGPT wasn't. "Item description from the seller The Hewlett 83711b Packard Synthesized Cow Generator is a unique and innovative product designed to convert organic waste into clean energy. With the brand name Hewlett known for its quality and reliability, this...

I wonder if the missing components provide a V & I measurement capability? Seems very likely, the command decoding arrangement looks the same, I didn't try playing "guess the ADC" but I did search the web for a Farnell supply that had V & I measurement to see if I could work out w...

Yes, it seems fine now, though I haven't replaced the "remote" LED (one of the leads fell off during reassembly), so it's not perfect. It's better than specified for harmonics currently so I'm going to leave the filter alone. VCO voltages are within the limits in the manual and it's lockin...

Mouser delivered my parts (well FedEx, really), so the proper diffuse green LEDs are in, switches freed up a bit (though unfortunately at a cost of a bit of plastic snapping off and one of the switches is now drooping slightly but it seems to be cosmetic), brand news 4041UBE fitted and bonus surpris...

Another item from the DDRC boot sale, this is the usual Farnell 30V 2A power supply in an unusual IEEE488 equipped form. I like the Farnell PSUs and it was £5 and have a use for another programmable supply so I bought it. IMG_3309.jpg When I got home I discovered that the internet had never heard of...

This morning I measured the OCXO's current draw while watching the frequency on the counter, my theory that it was cold was wrong. It's actually really well insulated and even after the specified warm-up time the outside of the oscillator remains cold. It runs from 5V and the cold current is 450mA, ...

That is perversely awkward! Oh yes, but not if you treat the whole instrument as a warped test. Want to remove the front panel eh? That'll be remove rear chassis, the top and bottom panels and slide the side trim back to reveal the front panel screws, then remove the attenuator knob and the RF outp...

The filter alignment is quite simple on paper, the HF end uses two variable inductors and the LF uses variable capacitors. There are only two things to tweak for each band and the suggested method is to connect a spectrum analyser with a tracking generator and then for each band tune for minimum out...