Buying quite old but good scope - Lecroy 9314 - Page 1
Forum section: electronics / testgear

author: degleve
author_rank: Contributor
timestamp: June 07, 2025, 10:37:53 am
content: Hey all,I have a possibility to buy a Lecroy9314 at 150$.1) Do you think it's worth it VS buying a new modern scope ? especially considering its a 20+ years scope. However, it's a good brand, 300MHz, 4channels, so to get the same spec for a modern scope would be more expensive.2) Also, I am confortable into servicing it if a problem would occur (using my other shitty scope!) but I wonder if scope are easily repairable (never get inside one). What I mean is I can change discrete part but I wonder concerning IC and MCU, I guess if these fails I won't be able to find replacement or reprogram an MCUThanks !

author: temperance
author_rank: Super Contributor
timestamp: June 07, 2025, 10:55:00 am
content: That's a 100 MS/s scope. I would not buy such a scope.

author: degleve
author_rank: Contributor
timestamp: June 07, 2025, 11:10:04 am
content: oh stupid me I've forgot it was a digital scope (it looks so vintage..)Of course with that I won't enjoy the front 300Mhz spec...Thanks !

author: Aldo22
author_rank: Super Contributor
timestamp: June 07, 2025, 11:15:23 am
content: And you always have to think about size and weight with these old scopes.This thing weighs 12.5kg and the depth is 41cm.You first have to think about where you can place it.

author: tggzzz
author_rank: Super Contributor
timestamp: June 07, 2025, 11:17:59 am
content: Quote from: degleve on June 07, 2025, 11:10:04 amIn a past life I enjoyed a 1GHz HP scope with a 40MS/s.I currently have couple of ~4GHz scopes with <1MS/s. Approximately since they specify the risetime (100ps and 200ps), not the bandwidth. One is delightful but only has a single purpose. The other is more general purpose with more front panel controls that young people could understand, and BC107s (fT300MHz) in the main signal path.Having said that, $150 seems much too high, and other scopes (modern or old) would be better value.In general it is rare that an amateur needs a >300MHz real time sampling scope. Almost always it is sufficient to use equivalent time sampling to see risetimes and eye patterns to ensure signal integrity. After that is ensured, flip to much cheaper digital domain tools such as protocol analysers, logic analysers, and printf.

author: nctnico
author_rank: Super Contributor
timestamp: June 07, 2025, 12:21:53 pm
content: Quote from: degleve on June 07, 2025, 10:37:53 amSave a bit more money and buy something decent. Even the cheap Fnirsi scopes are better nowadays because technology has progressed so much. Would you buy a model-T Ford? Also keep in mind that these old Lecroys make noise like a jet-engine.

author: temperance
author_rank: Super Contributor
timestamp: June 07, 2025, 01:19:17 pm
content: QuoteHow does the front end reach anything above a few 100 MHz with BC107's in a TO-18 package in the signal path?

author: dietert1
author_rank: Super Contributor
timestamp: June 07, 2025, 01:56:33 pm
content: I have been using our 9314A recently. And we also have a 9354AL that still works. Both scopes got their switching power supplies recapped.They are heavy yet portable, though one has to watch out as handle and case become brittle after so many years. It can stand on the floor to not occupy the workbench. Another thing to observe is the clock battery. It's a rechargeable coin cell on the CPU board and it may be empty after one or two years without using the scope. So it takes some time after turning it on until the battery reaches a minimum voltage level. Only then the CPU will start operation and one should set the clock.The price of the scope may depend a little on what software options are enabled, but one can find the fix on the web.Those scopes have gray scale displays, but the 9354AL sends color screen dumps via GPIB.Of course the modern Chinese color scopes with 12 bit digitizer and 100 Megasample memory are a lot more fancy.Regards, Dieter

author: temperance
author_rank: Super Contributor
timestamp: June 07, 2025, 03:58:06 pm
content: QuoteThat's not only fancy. Any low cost 8bit 1GS/s scope will beat this old 40 MS/s scope for looking at non repetitive signals.

author: tggzzz
author_rank: Super Contributor
timestamp: June 07, 2025, 04:11:15 pm
content: Quote from: temperance on June 07, 2025, 01:19:17 pmSkill and understanding means the BC107s don't have to. Standard old skool stuff from 1970. Five years later I saw my university tutor use similar techniques to plot MHz waves on an XY pen plotter.The trigger circuit has 2GHz FETs in it.FFI search for Philips PM3400

author: dietert1
author_rank: Super Contributor
timestamp: June 07, 2025, 04:52:56 pm
content: Quote from: temperance on June 07, 2025, 03:58:06 pmPlease remember that only a very small fraction of analog scopes had storage tubes in order to capture in single shot mode. Most people were quite satisfied to trigger and look at repetitive signals.Of course nowadays you may want to capture an I2C transaction and check it. But then again, we have a Rigol scope that fails to decode I2C properly, without any chance to ever get that fixed.I still think one of the most interesting used scopes is a WaveRunner 204xi if you can afford it (2 GHz bandwidth).Regards, Dieter

author: nctnico
author_rank: Super Contributor
timestamp: June 07, 2025, 05:19:12 pm
content: Quote from: dietert1 on June 07, 2025, 04:52:56 pmThere are other relatively low cost brands like MicSig who deliver equipment which works as promised. When on a budget, one of the Fnirsi (or similar) scopes to look at the signal and a cheap logic analyser for decoding is a very budget friendly option. But you'd need to check the reviews to see which model is worth buying. This looks promising for example:https://www.eevblog.com/forum/testgear/new-oscilloscope-from-fnirsi-dpos350p/Ofcourse it doesn't do the same a test equipment costing thousands of dollars but it is better than nothing.

author: temperance
author_rank: Super Contributor
timestamp: June 07, 2025, 05:29:43 pm
content: QuoteI see, first sample then process.

author: tggzzz
author_rank: Super Contributor
timestamp: June 07, 2025, 05:44:24 pm
content: Quote from: temperance on June 07, 2025, 05:29:43 pmYup. Effective and high performance using whatever technology is available at a given time.The astounding progress in ADCs and DACs has been one of the few revolutionary changes in the past 30 years. I'm ignoring incremental smaller faster cheaper, of course.

author: degleve
author_rank: Contributor
timestamp: June 07, 2025, 08:33:25 pm
content: Thanks all for the replies, really helpful:)