I just bought a big lot of Data Precision 8200 and some Analogic AN3200 DC Voltage/Current Calibrators with a bunch of hard to find (unobtainium) genuine parts (relays, switches, hardware, regulator and amp ICs, whole modules, transformers) that that I believe it’s the leftovers of a closed down repair shop.
That means I’ll have all the materials needed to service and upgrade Analogic / Data Precision 8200 that you are unlikely to be able to find elsewhere.
Data Precision 8200 is the official unit to field adjust TDS 500~800 series oscilloscopes as the automation software (GPIB) was hard-coded to this model. Nonetheless, I find it a reliable reference for verifying oscilloscope performance and adjusting my multimeters as well.
Call me at 949-682-8145 for a repair quote or if you are interested in buying a unit. GPIB and 1kV option can be ordered for extra, either with the unit or service upgrade.
I recently got a repair evaluation order that took me two intense weeks to nail the problem. It’s a MDO4104C that does not get past splash screen.
Worst of all, the unit failed right within 3 months right after the warranty expired. The unit didn’t show signs of heavy use. In fact, I nailed the problem so I can tell for sure the unit DIED OF NATURAL CAUSES. It’s not the first time I (and other people on forums like EEVblog) bitch about Tek designed their unit to last beyond the support/warranty period. This one takes the cake.
Basically everything in MDO4000C series happens in the main acq board. Anything that goes wrong there you might as well just buy another unit.
It runs embedded linux (uboot) and it’s slow to boot as I always expected from Tek (Keysight/Agilent use VxWorks for their modern embedded scopes and they boot fast).
There are no UART debug consoles anywhere and the only two test points with digital signals that idles high at 3.3V. The data pulses are quite long for the frame, and one of them looked more like clock bus in either SPI or I2C. So no UART. The firmware file mentioned BDI3000, which is a JTAG, which I suspect there’s a 10 pin IDC (ribbon) port on the right hand side of the main acq board, but this is as much as what I can get getting debug info.
There’s a RS-232 driver chip on the peripheral board, but it goes to the ID pin of the VGA port. I didn’t see any data traffic on it on boot.
Getting stuck at the splash screen practically tells you nothing about what’s wrong. The only thing you can infer from it is that the unit powers on and the display/keyboard is good. This is pure evil. HP/Agilent/Keysight designed their products to make it easy to service, and Tek has always been a pain to service, and the new ones are no exception.
They don’t even mark the grounds in test hook points. It’s just a bunch of TPXXXX numbers. Apparently they are there for testing the design, not repairing it.
It’s obvious from the way they designed their product to the service manual, Tektronix definitely don’t want any people to do board level repairs: ultimately they want you to blindly send it in for factory repair within the first 5 yr of production, and make you buy a new one if the model is discontinued.
Despite I hated it, Tek has a valid strategy. If a product is cheaply made, even at the cost that it only last long enough through their warranty period, the manufacturer doesn’t even need to bother with board level repairs because it’s cheap for them to just give you a new board/unit instead of figuring out what’s wrong with it.
Putting the frustrating to use UI designs aside, Tek works if you are a company buying the scope for a short 3 yr project. I wouldn’t recommend Tek at all if you plan to buy it for a long haul (because they are not designed to last given ones I’ve serviced), or plan to use it as a daily troubleshooting scope (because their user interface is slow and clumsy).
Tek has a huge following from the analog days when they did things right. Ever since the digital age, the learning curve for Tek’s UI was so steep that inevitably it turned into a customer lock-in where Stockholm syndrome kicks in.
Nonetheless, Tek was a little ahead of Agilent in terms of the MDO concept that correlates time domain measurement with the built-in spectrum analyzer. If that’s a feature that is important to you to the extent that you are willing to live with Tek’s clumsy UI and it might break down right after the warranty expires and it’s nearly impossible repair it yourself, it’s reasonable to go with Tektronix for this one given the lack of functional alternatives. Do NOT get MDO3000 series for this reason though, since the spectrum analyzer and oscilloscope are not time-correlated there’s no material innovation out there. MDO4000 series and up are time-correlated with the spectrum analyzer.
Again, I’m not saying Tek is bad. Tek is just mean towards their customers from a product design’s point of view, when you contrast them with how considerate (nicely thought-out) HP/Agilent/Keysight products are designed. Tek is still much better than the RCCC (Random Cheap Chinese Crap) in every way.
EDIT (2017-07-02): I just got a call this morning from somebody who bought a TDS 220 from me years ago. The BNC connectors broke off and he has found somebody selling a kit specifically to fix the problems in TDS 200 series. That’s pathetic. I knew the design was obviously flimsy back in the days, but I trusted the Tek engineers knew what they are doing given their brand reputation. Turns out common sense is right. A bad design cannot last even if they had solid parts/manufacturing.
From my experience opening up many Tek and HP/Agilent/Keysight units so I can compare their mindfulness, I can see that Tek is one of those high pressure companies that cut corners to get stuff out fast with low manufacturing costs. It’s not necessarily a bad thing from a business standpoint, it’s just Tek and HP/Agilent/Keysight operate with very different set trade-offs (or say, philosophy). Apparently Tek’s kind of trade-offs makes their used equipment a terrible choice unless it’s covered by their extra warranty.
Since I deal with old gears, I’m not impressed with the outcomes of used Tek products that I have/had. If I were to buy from Tek, I’d rather lease it since I don’t expect their products to last beyond their warranty period without multiple breakdowns that are costly to fix. My experience with used HP/Agilent/Keysight gears is that the problems are more predictable, limited to a small area and easy to reach and fix. For example, the caps in power section and CRT driver of TDS 500~700 series starts to fail, and the flyback transformer dies year after recapping the SMDs, and the units were just sitting there, not actively used. On the other hand, early 54600 series are almost always problem free other than an occasional cheap capacitor in the CRT driver drying up. This gave me a very bad impression about how Tek’s made their stuff.
Even if I could lease Tek products on other people’s budget, I still won’t consider until they radically changed their clumsy user interface and dumb autoscale mechanism that doesn’t even detect all channels and show you all relevant signals.
So far I haven’t see the kind of extra attention to detail in Tek products when I put it side by side with HP/Agilent/Keysight. This is how corporate culture reflects in their products: if you treat people well and trust them, they’ll get to all the nooks that managers and processes can’t reach and do it right. Tek just did enough that it will work as marketed, but whatever that’s cannot be objectively claimed in the advertisements, you are on your own.
I have spare parts to repair MDO4104C, MDO4054C, MDO4034C, MDO4024C
If you have an oscilloscope that you’d like to send it to me for repair evaluation (no fix, no fee), please call me at 949-682-8415 or email owner@humgar.com.
I recently sent a 1152A probe for calibration and was surprised to find out the data on the calibration report tells little about how the tests are done and under what settings. I searched the throughly and called tech support and they confirmed my observation the performance validation procedures are not mentioned anywhere in the published documents.
I called Keysight cal department and was able to reach a super-helpful tech, Markis, who did the calibration for my 1152A probe and he explained to me how the calibration process is done when I called.
HP/Agilent/Keysight probes using AutoProbe interfaces are powered by 1143A (that was intended for 54701A probes) through a N1022A adapter (the one used in 81600 Infiniium DCA) for Keysight’s calibration process, which measures uncompensatedprobe-only performance. I saw the calibration reports from 3rd party-labs, and probes are are calibrated inside the oscilloscope they are used in, and therefore it’s measuring a compensated system (scope+probe) performance.
There is a 30 minute warm up period.
The procedures resembles to what’s detailed in the old 1144A probe user/service manual, (page 10-14) with the exception that the ‘Gain Accuracy’ done there is ‘AC gain accuracy’ (at 1kHz, 1Vrms) instead of ‘DC Gain Accuracy’ claimed on the report. In fact, given that it’s simply measuring relative error (multimeter reading of the probe BNC output divided by the 5V Fluke Calibrator reference) at one voltage setting, I believe it should be called ‘DC measurement accuracy’. The number on the calibration report was divided by 10 times since 1152A is a 10:1 probe.
The bandwidth test for 1152A is simply looking at attenuation at the advertised bandwidth (2.5Ghz for 1152A) relative to 50Mhz (low frequency reference set at 0dBm).
Ever since I got my hands into assembling and troubleshooting PCs when I was a kid, both through my own experience and general consensus in the computer hobbyist community, CPU is almost the last thing to suspect at fault for a non-functioning computer, much less likely if:
There are no signs physical damages (mechanical or heat stress)
There were no shorts (burning electronic smells)
There weren’t any extreme overclocking (at least Vcore was pumped)
The computer used to boot, but has some random hangs
After 20+ years (and troubleshooted a few hundreds if not a couple of thousand PCs), today I encountered (actually zeroed-in that it’s the culprit) the first bad processor in my life. It was inside a M815G motherboard from a 54854A oscilloscope that I bought that wouldn’t boot into windows without random ‘file corrupted’ errors. Then after a few tries, the board wouldn’t even boot, not even any code on the POST card.
At first I suspected it’s an aging motherboard, since I checked the RAM and passes Memtest86+ on another board. It’d be either the motherboard or CPU, which I never considered it might be the CPU given how unlikely it is both by other people and myself.
I couldn’t be bothered to dig at the moment so I simply replaced the entire motherboard (with CPU and RAM installed) with another unit and confirmed that the 54854A I bought didn’t have any deeper problems. Then I put this ‘bad M815G motherboard’ on my back burner.
Today I was trying to revive a VP22 motherboard (which boots only if I apply pressure on certain areas of the PCB) that didn’t have the Fan+Heatsink+CPU+RAM. I happen to have a spare Pentium 3 and some PC-133 (SDRAM) lying around, but not the heatsink+fan, so I borrowed it from the M815G in the repair-if-I-feel-like-it pile.
The VP22 booted with pressure on the PCB (beeped, checked POST card) but I couldn’t see any display, so I thought of swapping-in the known-‘good’ CPU from the ‘faulty’ M815G to see if I had the wrong revision that the VP22 didn’t support. The VP22 used to get stuck in the boot process, but at least the POST card has a reading, this time after swapping in the CPU from the M815G, it has no POST code at all. No pulse.
I got suspicious and took the the CPU from the VP22 and put it in the ‘faulty’ M815G. Guess what? The M815G in question boots and runs fine!!! WTF! For all that time I thought my M815G has a difficult fault just because I had a marginally failing an then dead CPU, which I didn’t even consider the possibility given how unlikely the CPU is at fault.
And no, it’s not the thermal compound drying up, it’s freshly applied every time I move it to a different motherboard. The CPU was only used in M815G/VP22 which does not even have any means of overclocking. No burns or smells or physical damage, and the computer used to boot. The CPU just died of natural causes.
I fired up one of my 6632B stored for almost 10 years and smelled burned electronics, despite everything is functioning. I tested the unit immediately when I bought them a decade ago and it was working fine, so it’s an example where electronics can deteriorate by storing (even in temperature controlled, dry environment).
Since I see smoke, I turned everything off immediately and investigated. Turns out one of the tantalum capacitors in the processor/controller board gave in:
