For some, it is like solving crossword puzzles: fixing defective test equipment. - Page 1
Forum section: electronics / testgear

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 29, 2015, 03:21:31 am
content: "Quality. Arguably, and except for new digital signal-fast scope stuff, the instruments build in the late 80s and early 90s might be the best ever build. Most of them have specs and typical performance far above what most regular quality can provide nowadays. The reason is simple, in the 80s, these rigs were build for the military and related agencies as the key target market. Nowadays, for consumer electronics, consumer communications… One exemple: the HP 8566B spectrum analyzer. Not sure about the price of such equipment nowadays, if build new – certainly 6 digits. On xbay, they go for about few cents per USD list 1985 list price… and be assured, no big deal to get them working in-spec."-Pretty much of the same opinion for hp, Tek and other high quality test gear from that era.Interesting blog on test gear repair adventures.http://www.simonsdialogs.com/?cat=101

author: G0HZU
author_rank: Super Contributor
timestamp: April 29, 2015, 11:18:41 pm
content: I think the last of the HP8566B analysers sold (new) for about $85,000 each in the mid 1990s. To make one today would be staggeringly expensive even for just the RF unit. The display unit would be replaced by modern DSP etc but the RF unit is very special.Not many of the younger engineers will understand just how special this type of spectrum analyser was back in the late 1980s. I now own the company HP8568B that was donated to us on a defence project about 25 years ago and it gives me a special feeling to use this very analyser as I can remember how it was treated as royalty back in 1990 by all the engineers at work. I can remember how thrilled I was to be able to use it every day as a design tool back thenQuoteI think the HP8568 and the HP8566 were also popular as ATE machines in the 1980s so these analysers also made financial sense to buy for high volume production companies making high end RF equipment. That's why there are so many of these analysers available today.One additional bonus of owning test gear from this era is that the service manuals were very comprehensive with full schematics and BOMs and faultfinding/alignment procedures.

author: PaulAm
author_rank: Frequent Contributor
timestamp: April 30, 2015, 02:05:56 am
content: You can learn quite a bit puzzling out problems in gear of that era. Most of the manuals have theory of operation, which helps quite a bit.And, well, it's fun. One of these days I should total up the list price of all the equipment I've fixed or in the queue.The gear with MCUs can be a bit of a challenge. Some of them suffer ROMrot and HP used a proprietary controller in a number of instruments that has very limited documentation available. That situation improved when they went to the 6800.I think this link was posted before, but it's a nice collection:http://emperoroftestequipment.weebly.com/

author: Rick Law
author_rank: Super Contributor
timestamp: April 30, 2015, 05:04:45 am
content: While fixing item like the one in the OP is way out of my league, but even as a hobbyist with limited skill, I do enjoy the satisfaction of finding the fault that cause the failure, fixing it, and getting something working again. It is indeed very rewarding.Recently, I was so pleased with correctly identifying the faults with my cheap PSU (B3603) which caused the LED display to be dead. I was even close to being proud of myself fixing it (replacing the pair of shift registers). Very rewarding experience when it comes back to life.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 30, 2015, 07:15:53 am
content: Of all the spectrum analyzers used over the years, that 8566B was special. This is one of those instruments that gets basically burned into your memory of how special and nice it is to use. Such a joy in may ways. The construction of the RF section lives as an example of what hewlett packard was during it's peak and what that company and group who created and produced that series of SA were allowed to do and achieve.After looking for quite a while now, Im about to take delivery of a 8566B that was used in a military ATE test system. It appears to be in excellent condition, well cared for and local which should limit the possible shipping damage. I'm really looking forward to this treat.BerniceQuote from: G0HZU on April 29, 2015, 11:18:41 pm

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 30, 2015, 07:40:16 am
content: Most of the hp & Tek items and many of the other brands of test gear has been part of my history in some way or another. Over the decades of this stuff, the selection process has become rather stringent and selective of what stays and what goes off to a new home and what will never be. The sheer volume and concentration of test gear to be found in Silly Valley is staggering. There are storage buildings and warehouses FULL of used surplus and stuff from start-up companies that died young. That is just test gear, multiply that by 10 to >100 X for components, cables, connectors and a LOT more related stuff.There is SO much that can be learned from repairing vintage test gear, yet it is not often appreciated. There are more than a few lesser known test gear companies and instruments that are absolutely excellent and have extremely low resale value due to lack of market recognition. hp did excellent most of the time, hp & Tek did produce more than a few instruments that were lacking and did fit with the companies reputation.BerniceQuote from: PaulAm on April 30, 2015, 02:05:56 am

author: tautech
author_rank: Super Contributor
timestamp: April 30, 2015, 09:22:14 am
content: Quote from: Rupunzell on April 30, 2015, 07:40:16 amAnd your favorite models are?Reasons please?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 30, 2015, 11:26:05 am
content: Quote from: Rupunzell on April 30, 2015, 07:40:16 amAnd yet most of the surplus shops still charge an arm and a leg for even very basic old kit in questionable condition. At least that's what I found the last time I was there, and what I often see when they do offer their wares on ebay.

author: eas
author_rank: Frequent Contributor
timestamp: April 30, 2015, 07:28:05 pm
content: Quote from: Wuerstchenhund on April 30, 2015, 11:26:05 amSV real estate is *expensive*!

author: woodchips
author_rank: Frequent Contributor
timestamp: April 30, 2015, 09:00:07 pm
content: I would add the 60's, 70's and early 80's as well. Fixing a Tek scope using the ceramic strips is some experience.Fixing an 8566/68 is no big deal! I would disagree to some extent. The display is ridiculously complicated. Also get irritated by every different signal generator having a different method of synthesizing the frequency, doesn't help. Look at the way the 436 does its ADC, mad.Perhaps this equipment was never intended for ordinary users, the repair bills matched the buying cost?Not just Tek and HP, I am currently trying to use some B&K audio test equipment, crap, rubbish, heading fast for the junk pile. Why? No manuals, no possible way to test the boards due to too short internal cables and complete inability to get at some boards without a total dismantling job. Crap.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 30, 2015, 09:07:57 pm
content: Quote from: eas on April 30, 2015, 07:28:05 pmI know. Which makes the fact that they seem to rather sit on their stuff for years while its value declines even further than selling now for a sensible price even more lunatic.

author: woodchips
author_rank: Frequent Contributor
timestamp: April 30, 2015, 09:13:32 pm
content: Forgot to say. The processor in the A version of the 8566/68 is the same as that used in the HP 9845 computer, for any information look on hp9845.net. No floating point chip though.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 01, 2015, 06:02:03 am
content: Let's try this way, I'll post some brand & model numbers and reply with why these particular instruments are significant.Boonton71A250AEH Research pulse generators, 122A, 139B and others.EIP 500 series counters.Krohn Hite 2200, 2400 and related generators.Gigatronics 900Hewlett Packard:200CD250B400 Voltmeter428, A/B_Applied Physics Systems 428C/D435340034032402A52108644866586408566358535803562850448004815357785058510and....Keithley610Mincom 8300ATektronix:7904A7104793478547A137A147A227A267A247A197A297S117T115471A41A51A7A1S15194852467P6042P6046P6015P6021P6022CT-1and more...Type 109Wiltron6649, 6659, 6669560A97_50Enough for now.BerniceQuote from: tautech on April 30, 2015, 09:22:14 am

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2015, 06:05:05 am
content: Wow, more than enough.....Who'd have thought so many had turned you head.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 01, 2015, 06:09:07 am
content: Like Halted Specialties?http://www.halted.comThey do have plenty of old boat anchors that are well past their usefulness at prices that will never move them. Some have sat on the bottom shelf for years.. and are likely going to stay there until a purple moon occurs and a possible buyer makes them an offer. On the flip side, they do get bunches of interesting test gear every so often and when priced properly, the good stuff is gone within a day or less.That is not the place to get test gear in SV, the swap is the place to get good and interesting deals which often happen on the back of a truck. Other places are visit one of the many ebay sellers in SV, some of these sellers have immense warehouses full of stuff. Do the tour when visiting, bring cash, have a sharp eye and shop smart when an interesting item appears.BerniceQuote from: Wuerstchenhund on April 30, 2015, 11:26:05 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 01, 2015, 06:12:00 am
content: The really FUN part is knowing why these are significant items of instrumentation..BerniceQuote from: tautech on May 01, 2015, 06:05:05 am

author: mzzj
author_rank: Super Contributor
timestamp: May 01, 2015, 06:35:21 am
content: Quote from: PaulAm on April 30, 2015, 02:05:56 amI also enjoy fixing and doing detective work with broken equipment. Except when I would actually need the damn instrument for getting a work done and it turns out to be broken!Waiting for new CPU to my HP 33120A func. gen. Bizarre looking problem with power supply power-good signal leads to cpu with busted input pin. That bugger was still partly operating with crystal running so it was not my first suspect.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 01, 2015, 06:41:27 am
content: For work, have more than one spare.. if that instrument dies, there is a alternative.Question is, how did that pin get "busted"?BerniceQuote from: mzzj on May 01, 2015, 06:35:21 am

author: mzzj
author_rank: Super Contributor
timestamp: May 01, 2015, 07:35:47 am
content: Quote from: Rupunzell on May 01, 2015, 06:41:27 amYea, having more than one of everything would be nice if not limited by budget and spaceCan't offer any reasonable explanation for the failed cpu. Cosmic rays, age related random failure of some sort. Long-term failure after assembly line ESD seems unlikely also since this is old HP and not your cheapest noname-chinese clunker.Nothing obviously stupid in the schematic and if this would be more common problem it should turn out on google.

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2015, 07:50:32 am
content: Quote from: Rupunzell on May 01, 2015, 06:12:00 amExactly....for me it is "documentation", probably why I have a soft spot for older TE, particularly Tek, with their wonderful Service manuals that usually contain the priceless chapter Theory/principles of operation".Had a Telequipment D83 that I quite liked, large crisp display, they must have been OK because Tek bought them out.Never warmed much to HP other than the 1740 that I've had a couple of, the SM being quite good.Back to todays gear, I can't/won't comment on other than Siglent who do a good job in assisting me if required, repair being like most modern stuff is replacement of assembly or PCB.

author: Unknown
author_rank: Unknown
timestamp: May 01, 2015, 03:11:14 pm
content: I worked for Hewlett Packard in the late 1970's and early 1980's. I can still spot many (if not most) of the instruments from those days from across the room and tell you the model number and basic specs. Can do the same with quite a few Tek models from that era.These days I just try to remember where I parked the car

author: G0HZU
author_rank: Super Contributor
timestamp: May 01, 2015, 07:16:29 pm
content: QuoteI bought an ex rental HP8566AB (A converted to B) about 4 years ago to give me a capability up to 22GHz as my other analysers only run to about 1800MHz.It's a very special beast but mine hasn't been totally reliable. However, the faults have been easy to fix and I managed to get the CRT really sharp by servicing and adjusting the Z circuits. See example screen shot below. The image looks a bit dull and gloomy but it's the only way my camera can capture just how sharp the CRT now isThere are a few downsides in terms of performance though. I think the 8566B is the only high end lab analyser that we didn't ever buy or rent at work. Cost was one obvious reason but also the first mixer IP3 and 2HI are quite weak on it when used on range 1 up to 2.5GHz. The phase noise performance (at 1kHz to 200kHz offsets) is 'good' but not good enough for the work we were doing back in those days.The HP8568B was better in these areas (up to its 1500MHz limit) and the 1980s built Advantest TR4172 outclassed them both in most of these areas. We upgraded to the TR4172 when the HP8568B couldn't quite deliver the SFDR or phase noise performance we needed back then. The TR4172 was insanely expensive in the late 1980s because of the strong japanese yen and we were again donated one by our customer (which was nice) as we couldn't afford to buy one ourselves. There were various rumours it cost £60k with its numerous options fitted.The internal build quality of the TR4172 is very impressive. At least as good as anything from HP from the same era.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 06, 2015, 07:16:38 am
content: The 8566B arrived by local motor vehicle courier a few days ago. It was very well packaged in close cell foam over sized double wall boxes. The driver unpacked the units, and was kind enough to take the packing material back for recycling or re-use.This is one clean 8566B. According to the serial numbers, the RF section was built 7th week of 1994, Display section 5th week of 1995 putting this system near the last years of production The CRT is sharp & bright with no burns or signs of abuse.. The RF section checks out good so far. I'll need to do a check and cal to verify its OK, but so far so good. Even the air filters are in very good shape with minimal mechanical lumps, bumps of scrapes. Last cal date was 2008. Previous owner was Loral Aerospace systems. It has the opt. 002 or "Turbo" speeded up processor and the demo program installed. hp Catalog price at that time (1994-95) was $78,350 USDFor the price of less than most "hobby" spectrum analyzers cost new including delivery, this was an absolute bargain.Display using a signal from the sweeper about 5 GHz (delta market set for a quick check), as delivered no adjustments or cleaning done.Feeling pretty luck and good about this 8566B.Now, I'm going to retire the other spectrum analyzer.BerniceQuote from: G0HZU on May 01, 2015, 07:16:29 pm