Oscilloscopes to stay away from? (spec: Tek 2337 question) - Page 1
Forum section: electronics / beginners

author: Jschool
author_rank: Contributor
timestamp: May 22, 2011, 11:25:01 pm
content: Dave suggests you buy an old analog oscilloscope off of eBay, sticking with the major brands. Easy enough.But I've noticed some of the ones I find more desirable, like the Tektronix 2337, that upon reading some experiences from users it seems they're more difficult to work on or repair because they used a lot of custom parts. And that the 475 and similar models used standardized parts. Is there anything to this?I really like the 2337 for its size and features, but I don't want to sink a lot of money into a beginner scope that can't be easily fixed either.

author: Fraser
author_rank: Super Contributor
timestamp: May 23, 2011, 06:45:12 am
content: Peronally I don't recommend a Tektronix CRO for beginners unless it's very cheap. Don't get me wrong, they are superb scopes and are mostly reliable. The problem is many cheap ones are now 20+ years old and the odd failure is to be expected. In terms of repair the Tektronix oscilloscopes are a significant challenge as some of the custom hybrids and other parts are both rare and expensive. EHT modules are not an uncommon failure and can be hard to repair. More sophisticated Tektronix scopes are gorgeous but what do you do when a custom Hybrid or CCD dies ? Such failures are not uncommon amongst ebay auction units and that is often why they are sold on. Some fault symptoms can be hard to spot unless you really know your stuff, such as CCD failures....yes some use Charge Coupled Devices in their designs and not as camerasFor the beginner or someone who wants a relatively easily repaired oscilloscope with good manufacturer support, I would recommend HAMEG CRO's. Not necessarily the latest models though. As a beginners CRO with 20MHz BW you won't go far wrong with one of the following:HM203-x Beginner/basic functionalityHM204-x Intermediate functionality inc delayed sweepHM205-x Storage CROThe 30 x and 50x ranges are more pricey and the most recent models can have reliability issues with their EHT and focus circuits. HAMEG are now owned by R&S.Many of the HAMEG range contained a nice component tester that works and isn't a gimmick.The components used are nice and easy to find so repair will be possible for some time to come. Obviously tube failure would be a bummer but is usually rare except for drop damage. You can download the manuals and schematics for free from the Hameg site.Do not pay too much for a HAMEG.... GBP50 will usually secure a decent one and many HM203 models sell for much less (~GBP20) or even free if you find someone having a clearout.Oh, and for transparency.....I used to sell these when I was a student :-) Great customer support from Germany

author: DaveW
author_rank: Frequent Contributor
timestamp: May 23, 2011, 09:37:15 am
content: Quote from: Mechatrommer on May 23, 2011, 07:24:24 amThere are points where you need high amounts of bandwidth for debugging FPGA applications. However, most of the time you're looking at high speed data signals so a high speed logic analyser is the correct tool for the job. Similarly for radio, there are few times that you actually need to look at the signal output. Most of the time you are looking at the mixer inputs and output at the IF, so for most radio uses a 50MHz scope is plenty and 20MHz is enough for most applications.It seems to be mostly a matter of finding the right age scope. Not so old that it's coming up to failure, and not so new that it's unrepairable! At least with the older Tektronix stuff there's a large online community that can help with fixing. Although as you say the Hameg support is excellent, always happy to provide service manuals...

author: tekfan
author_rank: Frequent Contributor
timestamp: May 23, 2011, 03:09:23 pm
content: Well the Tek 2300 series are great if they work. Small and very rugged. The ones that still work probably will keep on going for a long time. This series has specially high performance power FETs selected for the vertical amplifier. If they fail and you replaced them with a similar one, the max bandwidth would be seriously degraded. The low frequency signals would be unaffected. But I think if you looked hard enough you could find the correct FETs. They have a slightly reduced CRT (not the standard 10x8cm type)The 400 series is probably the most well known for it's reliability, ruggedness (all metal case), etc.465a/b - 100MHz, dual trace466 - 100MHz, analog storage, dual trace468 - 100MHz, digital storage, dual trace, RS-232 output475 - 200MHz, dual trace, 2mV/div sensitivity485 - 350MHz, dual trace, internal 50ohm termination (quite a beast but still somewhat portable)All the models have delayed time basesYou can't get anything wrong with buying anyone of these. They are very easy to repair, have linear supplies (none of that noisy switching stuff). The 465 now almost holds a legendary statusamong Tek scopes. It's been the world's standard delayed sweep dual trace scope for nearly 30 years.2200 series are a bit more flimsy than the 400 series since their front panel is plastic (same as the 2300 series)2212 - 60MHz combined analog/digital storage scope2230 - 100MHz, same as above2232 - 100MHz, same as above but a bit more advanced with softkeys2235 - 100MHz, analog, general porpouse, basically a revised and lightweight 4652236 - 100MHz, same as 2235 but with added frequency counter, timer, multimeterAll of them have 2mV/div sensitivity, delayed time base, all the units weigh as little as 8 kilosA couple of years ago I bought the 2236 on American ebay. I live in Europe so the shipping and customs cost almost as much as the scope. But it was worth every single penny. The really nice feature of the scope is the counter. Press a button and you get a 8 digit readout of the frequency. It also does period and time difference measurments, gated frequency or period measurments of short bursts. The scope even succesfuly triggerers on signals at almost 150MHz.If you want to measure the voltage of channel 1 just select CH1 volts and set the coupling switch to DC or AC, whichever you would like to measure. The AC range is even true RMS and works to about 200KHz. On the side of the scope are two jacks for standard shrouded multimeter probes. With the press of a button you can measure again DC or AC (autoranging 5000 count), or you can measure ohms to 2 Gohms. No milliamp range but what else do you want for a 30 year old scope!This isn't a review but I just want to help people to decide which scope to buy.Repair of the 2300 series scopes is also not a problem. Most of the ICs are standard off the shelf parts apart for some of the EPROMS. Even the time base switch was originally used in ham radios. All the electronics are found on a couple of big boards. The design philosophy was to put all the circuitry on a single board and get rid of the unreliable connectors and ribbon cables.Probably the only thing that can go wrong in one of these is the switching power supply. Again standard parts and easily repairable.The CRT is probably one of the more reliable parts of any scope (that is if you don't throw it down the stairs).A bit more on the Hameg scopesWe have a lot of HM303s (35MHz). Sadly they haven't stood the test of time. They were bought new somewhere in the 90's. One third of them developed problems. Either reduced bandwidth, bad attenuator contacts, weird oscillations of the time base.The 205 series is much better. We've never had any problems with these. They are nice scopes but are higher in price on the second hand market. The only drawback is the low bandwidth.

author: Fraser
author_rank: Super Contributor
timestamp: May 23, 2011, 03:38:25 pm
content: Mechatrommer,Regret FPGA's etc are well away from my area of experience and I agree that a 20MHz CRO would not suffice for the high frequency stuff.....but then what bandwidth CRO would ? With 500MHz square waves on my PC's bus I would need one heck of an expensive CRO to cope with that .....I don't think CRO's are the best tool at those higher frequenciesNow as for RF at 400MHz...you are now talking my languageI carry out repair and development work up to 1.7 GHz and some ISM band 2.4GHz and K/Ku SHF stuff now and again. When carrying out diagnostics at the full operating frequency, I would not be looking for any form of oscilloscope as my primary tool. If accurate level measurement is needed, I use a True RMS RF Millivoltmeter or Power meter. If frequency is important, I use a UHF or SHF frequency counter with GPS disciplined oscillator reference. And finaly, for linearity and filtering tests I would reach for my Advantest R4131D 3.5GHz spectrum anlayser and hunt for the tell tales of distortion spurii, harmonics and filter leakage. I would only use an analogue CRO when looking at the lower frequencies in the IF stages of the RX or TX and even then a spectrum analyser can be more useful. For reciever testing and repair it is often possible to work at the lower IF frequencies in order to diagnose issues in preceeding RF stages. You are effectively using the receivers own RF downconversion for diagnostic purposes so a CRO would be usable.The bad news is that the cost of a DS1052E pales into insignificance when looking to buy RF test kit capable of 3GHz working. My Advantest R4131D originally cost GBP15,000 and, 10 years later, now costs around GBP2,000 t0 GBP3,000 on the used market. I can see why you would like to use the DS1052E for the role at 400MHz but considering it's limited bandwidth, sampling rate and the fact that it is a budget DSO, regret that it is definitely not the tool for the job.

author: cs.dk
author_rank: Unknown
timestamp: May 23, 2011, 07:48:47 pm
content: Quote from: tekfan on May 23, 2011, 03:09:23 pmGreat post!!I'm also looking for something to begin with..What can you tell about the 24xx-series?

author: tekfan
author_rank: Frequent Contributor
timestamp: May 24, 2011, 03:01:25 pm
content: The 2400 are large format portable scopes. All of them have dual delayed time bases all the analog ones have 4 channels. 2 have standard attenuators in 1-2-5 sequence. Sensitivity is from 5V/div down to 2mV/div. The other two channels are selectable 100mV/div and 5mV/div (probably the most usefull ranges). These are excluded in the digital scopes. All of the scopes feature (unlesso therwise noted) readouts, cursor functions and various options are (were) available including integrated frequency counter/timer, GPIB, setting storageA few notes about repairing these:These all use switching power supplies. Usually the only problem is sometimes the capacitors in the supply start to have high ESR which usually leads to noisy supply lines or the scope not even turning on. This is easy to repair.The other thing is these scopes use hybrid ICs which can develop corroded contacts. These can also be cleaned and the problem goes away. A sign of corroded contacts of the ICs are failed self tests. Yes these scopes have a self test facility which aids in identifying which part of the scope needs repair. It is a very small chance of them failing but if one of them does they can regularly be seen on ebay. Going from anywhere from 10-50 EUR. A small price to pay for such an advanced scope.No doubt these are one of the most advanced analog scopes ever built. Only surpassed by the Tek 11000 series analog scopes (much much much bigger but still worth every penny).On with the list:The large format portable scopes actually start from the high end 2200 series:2245 - 100MHz, 4 channel, analog, basic large format scope, no cursors, no setting storage2246 - 100MHz, 4 channel, analog, advanced triggering (TV line and field trig)2247 - 100MHz, 4 channel, analog, advanced triggering (TV line and field trig), added function with high resolution counter/timer2430 - 150MHz, 100MS/s, 2 channel, digital storage, only limited trigger functionality2440 - 300MHz, 0.5GS/s, 2 channel, digital storage, other same as 24302445 - 150MHz, 4 channel, analog, internal 50 ohm termination, available high resolution counter/timer, optional TV(line, field) trigger2465 - 300MHz, otherwise same as 24452465A - 350MHz, otherwise same as 24452465B - 400MHz, otherwise same as 24452465 DMS - 400MHz, added multimeter on top of scope, otherwise same as 24452465 CTS - 400MHz, high resolution counter/timer as standard, otherwise same as 24452465 DVS - probably the same thing as the 2465 DMSIn a class of it's own:2467B - 400MHz, otherwise same as 2445 plus MCP (microchannel plate) inside the CRT which allows a single 1ns pulse to be viewed in normal roomlight2467 BHD - 400MHz, specially designed for development and work on high definition broadcast and television, TV trigger standard of course, otherwise same as 2467B, optional triggering from logic probe (no logic analyzer functions), otherwise same as 2467BLike most Tek products, the bandwidth ratings are very conservative. Most scopes will almost have double the rated bandwidth (amazing, I know).To prove it, here is a picture of a fast pulse viewed by a 2445A 150MHz scope, the rise time is 1.24ns which equates to a bandwidth of more than 270MHzI have a suspicion this is the Jim Williams avalanche pulse generator that's being fed into the scopeAnyway, whichever scope you buy from this series surely won't let you down.I don't currently own one from this list as there is not enough space at my bench.

author: slburris
author_rank: Frequent Contributor
timestamp: May 24, 2011, 03:22:33 pm
content: Don't at least some of the 4XX series use tunnel diodes for their triggeringcircuits? TDs are unobtainium except from donor scopes, although I've heardof some success people have had with Russian TDs obtained on Ebay.Personally, I have the 2236, 2246, and 2465 scopes and love them all.No one has mentioned the 7000 series, which take plugin modules and atleast one can go up to 1Ghz, the 7104 I believe.There are some "fake" 2465 scopes out there, which are 2445's with some bandwidthlimiting parts clipped out. There was a discussion about this on the Yahoo tekscopes lista few months ago.Scott

author: tecman
author_rank: Frequent Contributor
timestamp: May 24, 2011, 06:58:36 pm
content: Quote from: Mechatrommer on May 23, 2011, 07:27:35 pmI was also searching. Eventually got a Tek 2714 for $ 600 on eBay, advertised as in good shape. It is designed for CATV, but you can menu out of the cable related menus and you have a 9 KHz to 1.8 GHz general purpose analyzer. After I received it, I found it would not respond to any key entries. Next challenge was opening it. It had been slightly dented in the corner of the case, but since the case is a glove tight fit, it would not slide off. After several hours of prying, pushing and pulling I finally got the case off. I downloaded the 2712 manual (sister of the 2714 except for the menus) from the Tek site. A bit of troubleshooting pointed to a 4538 dual cmos one-shot. Replaced the 4538 and all worked. I then carefully hammered the dent out of the cover. The last change I made was to change the input connector. The 2714 has a threaded front panel connector that mates with a CATV F connector and is 75 ohm input Z. Looking at the schematics, the input attenuator is a 50 ohm attenuator, and the input jack assembly has a series 25 ohm resister internally for the 75 ohm input. I ordered a new BNC bulkhead connector (they have an SMA on the back) which fit like the old one, just requiring a slight enlargement of the front panel opening. An amplitude recalibration to compensate for the 25 ohm loss in the old connector, and now it is a great general purpose 50 ohm analyzer.paul

author: Fraser
author_rank: Super Contributor
timestamp: May 24, 2011, 11:16:35 pm
content: Off topic but applicable...I have a Tektronix 2710 1.8GHz Spectrum Analyser languishing under my lab bench. It's a very nice piece of kit but sadly it started to have display text issues where it would fail to display some digit locations. A little later it's PSU went BANG ! and the main swtching transistor blew to pieces. All new low ESR capacitors, switching controller IC, switching transistor, switching drive transistor and inverter transistors fitted. I also replaced some SMD transistors that had been potentially stressed by the original failure. All tested Ok around the PSU with power off.Power was applied and BANG! goes another switching transistor and all associted components that were previously replaced. I am used the the foibles of SMPSU's but this one has tested my patience to date and I know there is still a fault in that PSU but damned if I can find it at the momentThe unit has been set aside until I have more time. I already have a staged diagnostic procedure in mind to isolate parts of the unit that could cause such a failure.The lesson....whilst TEK equipment is gorgeous it can be a pain to repair and even when I fix the PSU I know I have a problem with the display board that is very likely unrepairable from comments I have read regarding the likely failed component.Where beginners are concerned I firmly believe the KISS principle applies to test kit, to ensure it is maintainable.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 25, 2011, 11:24:33 am
content: The 2465A was probably the best general-purpose analogue scope ever made. The main issue is that they used some custom ICs that were unobtanium - they don't fail often but if they do it's Game Over. However the comments above from Tekfan suggest that now that analogue scopes are much less in demand and prices have dropped, there may now be enough recycled spares floating around at reasonable prices, but the supply will dwindle eventuallyThe moral is don't buy a dead one unless it's cheap enough to be a gamble - working ones seem to be available for around the price of a much lower-end digital scope these days.You need to pay for a DPO/invinivision type digital scope to get comparable performance to something like a 2465.

author: Teknotronix
author_rank: Regular Contributor
timestamp: June 03, 2011, 04:43:10 am
content: Quote from: mikeselectricstuff on May 25, 2011, 11:24:33 amHas anyone reverse engineered the IC's or have a block diagram?

author: EEVblog
author_rank: Unknown
timestamp: June 03, 2011, 06:30:08 am
content: Quote from: mikeselectricstuff on May 25, 2011, 11:24:33 amI'd concur with that. They are still highly sort after on ebay.Don't forget the 2225 is you are doing low level signal work. The 500uV/div sensitivity is pretty much unmatched by any other scope?http://republika.pl/rubi/oscyloskopy/tek/t.pdfDave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 03, 2011, 07:47:43 am
content: Quote from: SimRacer on June 03, 2011, 04:43:10 amAround 10-15 years ago, when 2465's were still fetching £2-3000 I did wonder why, with off-the-shelf semiconductors 20-odd years advanced from where they were when the scope as released, nobody had done PCBs to replace the hybrid modules. I do recall reading about 5 years later that someone was working on something, but by then digital scopes had caused the prices of analogue scopes to plummet, and a lot of the old 2465's with dead hybrids had probably been long since scrapped.Quote from: EEVblog on June 03, 2011, 06:30:08 amA quick look on ebay shows 2465A's with cal & warranty can be had between £300-500, which is amazing value for money. When I got my MSO6000, I considered selling my 2465A, but the prices they fetched just weren't worth it.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: August 11, 2013, 04:50:47 am
content: What's the say on Tek 2201s? I saw one with a seller warranty on eBay, but quite far from cheap for a 20Mhz scope.How complex are they from the inside (hybrids, etc.)? Is it likely to develop problems?

author: robrenz
author_rank: Super Contributor
timestamp: August 11, 2013, 03:10:29 pm
content: Quote from: EEVblog on June 03, 2011, 06:30:08 amExcept a 7000 series with a 7A22 differential amp plugin at 10µV/div

author: vk6zgo
author_rank: Super Contributor
timestamp: August 12, 2013, 04:18:18 am
content: Quote from: robrenz on August 11, 2013, 03:10:29 pmYeah,the 7000 series are nice old beasts--you can get such a range of plugins.I'm looking for a 7L12 or similar Spectrum Analyser plugin.Rotten thing is,I saw several on eBay Aust before I got the 7613,but nary a one,since!

author: Sigmoid
author_rank: Frequent Contributor
timestamp: August 12, 2013, 02:33:00 pm
content: I've been thinking about it for about a minute, but I dropped the idea. They are just too huge, and I'm a bit afraid of buying something this old that I cannot really use to its full capabilities.Currently I'm hesitating between a 2201 (seller refurbished, 30 days warranty, but seems expensive for $150), and a tested 2225 in really good shape (if I can score it)... I've been considering a Hameg given how I have a history with them, but those vernier pots (and all the mechanical wizardry with the front panel) seem really easy to break and hard to fix.

author: kfitch42
author_rank: Frequent Contributor
timestamp: August 12, 2013, 02:59:17 pm
content: I bought a 2336YA (nearly identical to the 2337) on epay a while back. $50 including shipping. The pics showed it displaying a flat line, turns out the coax going to the input bncs had fallen off. And it was missing a button (trigger view), a chop stick and some duck tape fixed that.After I got it (and fixed those two simple problems) I realized there was no freely available service manual. I spent $10 to get an electronic copy of one. So far I have liked it pretty well, though I haven't used it a ton. It is pretty far out of cal, but one day I will actually attempt to get it close-ish to calibrated now that I have the service manual.The good and bad is that the scope is small and portable. Good being portable. Bad being that things are a bit more packed in when trying to service it.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: August 12, 2013, 03:24:18 pm
content: Lol it's one of these military ones, right?Looks pretty cool, but I think I'll stay with the civilian models.Quote from: kfitch42 on August 12, 2013, 02:59:17 pm

author: GK
author_rank: Super Contributor
timestamp: August 12, 2013, 03:32:21 pm
content: Quote from: vk6zgo on August 12, 2013, 04:18:18 amMy much older 1A7 plug-in for 500 series scopes does 10uV/division with DC coupling. Parallel push-pull nuvistor input stage. DC drifts like fark though.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: August 12, 2013, 03:37:04 pm
content: By the way, does anyone know a good online reference with release dates, manufacturing history, specs and possibly some words about the major Tektronix models? (Like the differences between a 2336 and a 2337, etc.)

author: Unknown
author_rank: Unknown
timestamp: August 12, 2013, 03:37:47 pm
content: There's also a plugin for the Tek 5000 series and even a stand-alone TM-500 version (AM502) of this plugin. Probably all based on a very similar design (I know for a fact that the 7000/5000/TM500 were very similar). So while 500 uV/div is decent for a portable scope, it's definitely been matched and exceeded by lab scopes.

author: GK
author_rank: Super Contributor
timestamp: August 12, 2013, 03:39:47 pm
content: Quote from: Sigmoid on August 12, 2013, 03:37:04 pmhttp://w140.com/tekwiki/wiki/Main_Page

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 12, 2013, 04:01:48 pm
content: The 24xx list didn't mention the 2432/2432a DSO. which is inbetween the 2430 and 2440 in performance It's not a bad scope.The 468 had a GPIB option. The DSO section is only good to 10MHz though.On the 2465, U800 is the primary problem. There is a design with smd parts that's available that more or less is a drop in replacement. I don't know first hand anyone who's tried it though. Some people have had some success running it through a baking process. It comes up a lot on the Tekscopes list.

author: c4757p
author_rank: Super Contributor
timestamp: August 12, 2013, 04:07:43 pm
content: Quote from: PaulAm on August 12, 2013, 04:01:48 pmIndeed, there is!Damn you, I've already got too many projects piling up!I'd love to try to have a go at this and see if I can do something about the couple problems it supposedly has.Why the hell would he have blurred out the part numbers in the photo??They're all in the schematic...

author: w2aew
author_rank: Super Contributor
timestamp: August 12, 2013, 04:08:19 pm
content: Quote from: GK on August 12, 2013, 03:39:47 pmYou might also be interested in this archive of older Tek product catalogs - from 1962 to 1981:http://bitsavers.informatik.uni-stuttgart.de/pdf/tektronix/catalog/

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 12, 2013, 04:43:05 pm
content: Somebody mentioned the 5000 series. These are mostly low bandwidth scopes, but they were like the 7000 series with bunches of plugins. I think most of the mainframes were in the 15MHz BW range, although one went to 50MHz and there was one that had digitizing ability. I think these are most useful for either audio work or if you have a specific plugin (eg spectrum analyzer or curve tracer) that doesn't need a high bandwidth scope. Working with high speed logic we tend to forget that there are lots of applications for a low BW scope.

author: kfitch42
author_rank: Frequent Contributor
timestamp: August 12, 2013, 04:46:37 pm
content: Quote from: Sigmoid on August 12, 2013, 03:24:18 pmYup, got a navy sticker on it. I mainly went with it for the price. It was definitely treated like a bit of military gear, hence the coax falling of the bnc connectors.

author: kfitch42
author_rank: Frequent Contributor
timestamp: August 12, 2013, 04:48:21 pm
content: Quote from: Sigmoid on August 12, 2013, 03:37:04 pmHere is one that is specific to the 233x series:www.buy17.com/TEK/PDF/tek2336.pdf?

author: rf-loop
author_rank: Super Contributor
timestamp: August 12, 2013, 08:15:58 pm
content: Quote from: EEVblog on June 03, 2011, 06:30:08 amWith Tek2465 (and other 2400 models) there can use CH1 - CH2 cascading and get 200uV/divThere is CH2 output what give 20mV/div out. (20mV to 1M and 10mV/div to 50ohm. This can connect to CH1 and get 200uV or 400uV/div. (using 1M or internal 50 ohm impedance impedance )I have not seen data about cascaded BW/Risetime/noise and I have not measured it.But B model specs for 2mV/div is 350MHz and 5mV and more, 400MHz

author: Kennynva
author_rank: Newbie
timestamp: January 13, 2017, 04:52:52 am
content: Well I seen alot of Tek scopes on here..but not ONE mention of my Tek 2431L,,,,,Is this some kind of a weird scope, in between a 2430..??

author: edavid
author_rank: Super Contributor
timestamp: January 13, 2017, 06:03:29 am
content: Quote from: Kennynva on January 13, 2017, 04:52:52 amYou're right, it's not very common.It was a cost reduced version of the 2432A.

author: rstofer
author_rank: Super Contributor
timestamp: January 13, 2017, 06:48:48 am
content: Most of my FPGA projects run at 50 MHz or so. To see a decent square wave, I need at least 250 MHz to show the 5th harmonic and that's kind of a minimum if you want to see something resembling square. The 7th and 9th really help but the 9th requires a 450 MHz bandwidth.i bought a used Tek 485 about 12 years ago for about $200;. I got lucky and the scope still works well. I bought a Rigol DS1054Z for the measurement and decode features (plus 4 channels). But when the image requires bandwidth, the 485 is the scope to use.If my FPGA projects get up to 100 MHz or higherk I don't have enough bandwidth, even with the 485.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2017, 08:43:00 am
content: Quote from: Fraser on May 23, 2011, 06:45:12 amThey won't go right with such a tool. They are only suitable for audio and mechatronics applications. They are useless for digital circuits built using any technology since the mid-70s!When you have a problem with digital circuits there are three things you need to check:signal integrity: are the edges monotonic, are there overshoots/undershoots, is there ground bounce. The period is irrelevant. 100MHz is just about adequate for original TTL; modern TTL requires >=300MHzrunt pulses: especially near reset inputs and in asynchronous circuits. 100MHz is just about about adequate to spot 5ns runt pulsessetup/hold violations: a common source of problems. Look at the Tsuand Thspec of any logic family!And a scope is the wrong tool for RF applications, other than seeing if a signal is present. RF requires sensitivity and linearity; scopes fail both of those.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2017, 08:47:25 am
content: Quote from: rstofer on January 13, 2017, 06:48:48 amGood choicesThe 485 is fairly easy to repair; I've done two. In one a custom IC was faulty, but a little understanding allowed me to repair it with external resistorsThe only penalty was that the risetime was ~1.25ns rather than 0.9ns.

author: rstofer
author_rank: Super Contributor
timestamp: January 13, 2017, 05:01:06 pm
content: Quote from: tggzzz on January 13, 2017, 08:47:25 amLet's see, 12 years, $200 so about $17 per year. I think I got my money's worth!If it breaks, it goes to Electronic Waste Disposal. I'll just buy another. Maybe a 485, maybe something with a bunch more bandwidth. I clearly won't get another 12 years out of a scope (just turned 71) but something will work out.485's are all over eBay for prices between $200 and about $650 for a unit that is refurbished and calibrated. Maybe do a little dollar cost averaging to make the numbers look better. One $200 scope plus one $600 scope over 12 years plus, perhaps, 5 years so $800 over 17 years or around $50 per year ($4 per month). That makes sense! Can I cook the books, or what?The problem with used scopes is that you are buying a 'pig in a poke'. You have no idea whether the unit works properly or even if it can be fixed. Assuming you can afford to fix it. We had one fellow on the forum go down this path and he wound up with 2 defective scopes. He would have been money ahead to just buy the DS1054Z and be done with it. Shipping alone is enough to make me think twice. Given this attitude, it's a wonder I bought the 485 at all. I probably wouldn't have if the 1054 had been around at the time.There are some great scopes on the used market. I'm not going to recommend any of them. I'm out of the recommending 'used' anything business. Inevitably, it is a newcomer to the hobby with limited ability to repair a defective unit trying to get a scope for no money. It is almost guaranteed to end badly.

author: danmcb
author_rank: Regular Contributor
timestamp: January 13, 2017, 05:34:05 pm
content: I've had three old Tek's. I have a 475 which still works great, but I don't really use. Don't want to get rid of it though, because it's just such a beautifully made thing.I have a 2225 which is my workhorse - i do a lot of audio and it is great for that. But it had an intermittent fault which the seller hid. Turned out to be a transistor deep inside with a leg that was physically broken. It was attached to the metal can, so that was easy to repair - once I found it.I have also had a 5103 that I got for next to nothing with an HT fault. I was happy because it had a differential amp, amongst other things. But it turned out to be a dog to work on, and I got shot of it in the end.So like everything second hand, you can run into issues. Doesn't have to be Tek though - Hitachi, Hameg and Philips also made some great ones. They are cheap enough second hand, if you get a bad one, oh well, better luck next time.

author: j ferguson
author_rank: Contributor
timestamp: April 11, 2017, 03:36:42 pm
content: I replaced the dallas nvram on my 2445b. and the smd capacitors which had just started to leak, no trace penetrations. I was very careful in solder sucking but did disturb a trace running past one of the pins but it is still sound.Now I get flashing lights on control board when I turn it on, but it never gets to self-test. I tried replacing the dallas nvram but no joy.if i do the delta v- delta t slope button push, no effect.my garage has room, so I could buy another 2445b, or maybe i should go to a 2445 and get away from the smd problem.what would you do?

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: April 11, 2017, 03:55:28 pm
content: Quote from: Sigmoid on August 12, 2013, 03:37:04 pmhttp://w140.com/tekwiki/wiki/Main_PageOrhttp://barrytech.com/tektronix/tek.htmlAre both great resources for us Tek fans.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: April 11, 2017, 03:56:42 pm
content: Quote from: j ferguson on April 11, 2017, 03:36:42 pmJoin the TekScope yahoo group. Some of those guys are on here too, but they seem to know everything about old Tek gear and how to fix it.

author: j ferguson
author_rank: Contributor
timestamp: April 11, 2017, 11:36:52 pm
content: I do follow the tekscope list-serv. I suppose I could have asked the question more clearly. I have a problematic but otherwise very nice 2445b. But it doesn't work for reasons not clear. I could buy another 2445B and might find a deteriorating situation withe the A5 SMD caps AND get to do another NVRAM ....ORI could buy a used 2445 and avoid the SMD problems.is the 2445 a better bet as far a maintainability over the next ten years or so? Or is this a silly question?

author: edavid
author_rank: Super Contributor
timestamp: April 12, 2017, 12:25:42 am
content: Quote from: j ferguson on April 11, 2017, 11:36:52 pmSure, a 2445 (or 2465) has fewer things to go wrong. Not a huge difference though.Re: the 2445B, did you double check all the internal cables and make sure they were plugged in properly?

author: j ferguson
author_rank: Contributor
timestamp: April 12, 2017, 02:53:22 am
content: i only removed the A5 board to fix the smd caps and remove the dallas nvram, install a socket and the FRAM I replaced the Dallas with. When it didn't work I replaced the Dallas NVRAM but it didn't make any difference. it seems possible that one of the ribbon cables may have gone intermittent. there are also some shakey looking cables which are part of the GPIB option. I guess it would make sense to see if all of these have conitinuity and aren't sorted. the advantage of getting another 2445b in addition to all the parts is that if it is working now, i can use it to see if my A5 is actually ok.thanks for the idea.john

author: peter-h
author_rank: Super Contributor
timestamp: December 27, 2019, 11:49:13 am
content: Just a little update of an old thread, since the situation with these Tek scopes has changed a bit.The hybrid modules seem plentiful on Ebay, and quite cheap (tens of $) presumably due to plenty of scopes being parted out. A good 2465B may fail but isn't usually expensive to repair.A late-model 2465B will be mostly as good as new inside.At work, we spent 4k on a Le Croy 4Gsps digital scope which blew up (some BIOS error message) after 1.5 years. It was done in warranty but if/when it blows up again it will be cheaper to buy a 15 year old Tek digital scope which was 15-20k $ new!

author: JimS
author_rank: Contributor
timestamp: December 28, 2019, 09:40:15 am
content: QuoteI have not seen U800 be bad on any of the 2465B/2467B scopes I have worked on.I have replaced some U650 display sequencers because the bandwidth was around half of what it should be.Other than that, is leaking caps in the power supply and occasionally the scale lamps are burned out.Nice scopes as long as the CRT is not in too bad a shape.I prefer the 2467B for what I need a analog scope for.

author: peter-h
author_rank: Super Contributor
timestamp: January 02, 2020, 10:18:26 am
content: There are big changes in the quality of the components used in the latest 2465B etc models, compared to ones made say 15 years earlier.The last ones were made 1994-1996 or so.I have been in electronics design and production since 1978 and things had really improved in the 1990s, with really good quality SMT components, including the miniature electrolytics. I have many thousands of products out there with the same components and most of them are still working. The actual MTBF numbers we are seeing are of the order of 500+ years. With SMT, things improved a lot because the components had to withstand crazy soldering temperatures, so the chemicals had to be improved.When I read reports of the WIMA polyester film caps needing to be changed, I simply do not believe them. I have used those caps since the 1970s (they were the primary ways of getting a cap in the say 1000pF to 1uF range; nowadays one would use ceramics if possible) and never saw one fail.Old electrolytics do dry up and fail, certainly, and in these scopes these will be found mostly in the power areas. But again the most recent scopes should be ok for many more years.OTOH the very recent, say 1995, examples go for a lot more money. I have just bought a 2465DVS for GBP 250 and it is fully working and a superb scope, but that one will be from c. 1985.