Bought a used Oscilloscope.. but no probes.. what do I do?  - Page 1
Forum section: electronics / general

author: Crush
author_rank: Contributor
timestamp: July 24, 2012, 04:21:34 am
content: Hi,I'm a noob and was advised to get a used, dual channel Oscilloscope of at least 50mhz.I got this model with built in multi meter option:http://www.ebay.ca/itm/Agilent-HP-1742A-Oscilloscope-100MHz-/220749453229?pt=BI_Oscilloscopes&hash=item3365b157ad#ht_6071wt_857The only problem is it has no probes for either the scope or multimeter functions.I found the manual here and it talks about the probes.. I can't copy and past the text because it's PDF.. the lingo is confusing and I don't understand it.http://www.k7jrl.com/pub/manuals/hp/174xa_techdata/174xAtd..pdfI was hoping someone could give me some advice on the probes I should buy from ebay or what would be compatible. I can not find any info on the multimeter that's included with it.Any help would be greatly, greatly appreciated!

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2012, 04:48:59 am
content: I can't see much of the probe input section in the picture but it looks like a typical BNC probe.You can get probes from deal extreme for $10 or so.http://s.dealextreme.com/search/scope+probeebay will probably be faster to arrive though, dx can be very slow.I think that scope might have selectable input impedance, either 50 ohms or 1 megaohm.You want it set to 1meg for a typical probe.

author: slateraptor
author_rank: Frequent Contributor
timestamp: July 24, 2012, 04:53:52 am
content: Quote from: Crush on July 24, 2012, 04:21:34 amFor future reference, used scopes purchased on eBay typically don't come w/ probes.I recall one of our senior forum members posting a nice writeup on some cheap Chinese passive probes found on eBay w/ acceptable response...can't recall if it was saturation, ejeffrey, amspire or someone else. Do a search.EDIT: Found it:https://www.eevblog.com/forum/product-reviews-photos-and-discussion/cheap-oscope-probe-quality/msg31749/#msg31749saturation and alm steer discussion.

author: David_AVD
author_rank: Super Contributor
timestamp: July 24, 2012, 05:04:57 am
content: I have some cheap UNI-T ones on the way (from eBay) that were only $20 delivered for a pair. Supposedly rated for 100MHz but good enough for lower frequency work I reckon.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 24, 2012, 10:21:21 am
content: Welcome bacK!Oscilloscope probes are fairly standard,although some have higher frequency capabilities and/or voltage ratings than others.I started to write a long rambling discussion on these devices,but I thought it would be better to point you to w2aew's video on 'scope probes at:https://www.youtube.com/user/w2aew/videos?sort=dd&view=0&page=2It's about 2/3 the way down the page.He has produced a lot of videos on Oscilloscopes,so it is well worth browsing through the other ones.He mostly deals with Tektronix 'scopes,but HP are similar.The DMM sockets are on the side of the unit,so I Googled for some pictures.Most of them are fairly lousy,but it looks like it uses the standard shrouded leads used with most modern units.If you have a handheld DMM,or can borrow one,why not try the leads off that one,to see if they fit?

author: flano
author_rank: Contributor
timestamp: July 24, 2012, 10:27:47 am
content: Hi,I recently purchased a PMK PMT221A and have been very happy with it. It cost $65 AU from RS Components and came with a good assortment of accessories.The tips are very sharp and are spring loaded so work quite well for probing small pins. They have a 250MHz bandwidth and are 10:1 / 1:1 switchable.I'm using it on a Tek 2235 purchased of eBay.They seem to be a bit better quality then the cheap eBay ones and the ones I got with my Rigol 1102E.Hope this helps.Regards Mike

author: Unknown
author_rank: Unknown
timestamp: July 24, 2012, 02:07:07 pm
content: One thing to watch is compensation range. High bandwidth probes may not be able to compensate with older scopes, which usually have a higher input capacitance.More info on this topic:Choosing A Probe.

author: M. András
author_rank: Super Contributor
timestamp: July 24, 2012, 02:16:40 pm
content: did i really see over a thousand dollar for that scope?

author: Crush
author_rank: Contributor
timestamp: July 26, 2012, 09:51:31 pm
content: Well I got sent an HP 1741A instead of the 1742A which I'm super upset about because it doesn't have a multimeter on the top like in the ad.I researched and I found that the scopes above both come with this probe as included items:http://www.ebay.com/itm/HP-AGILENT-10041A-100MHz-10X-Mini-Scope-Probe-/350273714311?pt=LH_DefaultDomain_0&hash=item518df0b887#ht_818wt_857I looked at after-market probes, and they do not match the specification of the probe above. The closes I could find that matched was the 'typical' 100mhz ebay probe below. A comparison is below. Any help would be greatly appreciated at this point.HP 10041a probe:Bandwidth of 100MHzDivision ration is 10:1Input Resistance of 1MohmShunt capacitance of 12pFCompensates oscilloscopes input of 20 to 26pFMax. DC Volts of 300Ebay replacement probe:Two Oscilloscope Scope Clip Probe 100MHzBandwidthDC-6MHzDC-100MHzAttenuation Ration1:10Input Resistance1M?:10M?Input Capacitance1X:85pF-115pF10X:14.5pF-17.5pFCompensation Range15pF-35pFRise Time<3.5nsWorking Voltage10X:<200vDC+ACPeak --> ?? What does that mean?

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 26, 2012, 11:38:31 pm
content: Quote from: Crush on July 24, 2012, 04:21:34 amQuoteQuote from: M. András on July 24, 2012, 02:16:40 pmi dont know who's advising, but i think he has been scammed?

author: KTP
author_rank: Frequent Contributor
timestamp: July 27, 2012, 12:14:47 am
content: I am hoping that the OP didn't mean he bought that particular unit in that auction for $1000 but instead was just linking a similar oscope.

author: slateraptor
author_rank: Frequent Contributor
timestamp: July 27, 2012, 12:38:18 am
content: Quote from: KTP on July 27, 2012, 12:14:47 amEvidently not, considering how the ridiculously priced scope is still up for grabs...and will necessarily remain so indefinitely.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 27, 2012, 12:53:46 am
content: i think he did, except not sure at what price since the auction still open and has "offer" button. maybe he got from different or earlier order/item number. here's his evidence.Quote from: Crush on July 26, 2012, 09:51:31 pmhe got different/lower model instead of ads. so he is "super scammed". here another quote from the auction...Quoteso watch out with this kind of service lip/hypnotism. you have to think whats its "implicit" meaning. and the surplus got it from hosp/uni. probably they got it for free... easy money!

author: w2aew
author_rank: Super Contributor
timestamp: July 27, 2012, 01:01:12 am
content: Crush - you may want to review my video that describes the basics of 1X and 10X probes. It should clear some things up for you...

author: vk6zgo
author_rank: Super Contributor
timestamp: July 27, 2012, 01:25:07 am
content: Quote from: Crush on July 26, 2012, 09:51:31 pmWhy don't you try for a part refund,as you have been put to the extra inconvenience & cost of now needing to buy a standalone DMM to do what the built in one would have done?That said,the 1741 is still a very capable instrument.With the probes,both advertisers are pretty much mangling the specifications.They keep referring to 1Mohm in both ads.That,in fact is the input impedance of the 'scope itself,or with a 1X probe,a 10X probe lifts the impedance,(as far as the circuit you are probing is concerned) to 10 Mohm.The second probe is switchable from 1X to 10X.A drawback to these,is that the switch gives trouble after a while in many cases.The voltage rating on that one is a bit strange.I think they may be trying to refer to a DC voltage with a fairly high value of AC signal superimposed on it,as often is the case in the higher power stages of tube audio amplifiers,or CRT type TV deflection circuits.Both probes seem to have similar compensation ranges,so they would probably both be OK.The HP one would be my preference,but is probably more costly.Occasionally,you will see these genuine HP,Tektronix,Philips,etc probes available,but they are of course,either used,or old stock in many cases.

author: grumpydoc
author_rank: Super Contributor
timestamp: July 27, 2012, 12:34:16 pm
content: QuoteAs capable as the 1741 is the auction was for a 1742 and that's what the OP should receive, or he should ask for a full refund, even ebay should support him in this given that it's obviously not as described.To the OP - hope you didn't pay close to $1000!!

author: T4P
author_rank: Super Contributor
timestamp: July 27, 2012, 02:16:28 pm
content: Well he did say 'this model'not necessarily this auction

author: Crush
author_rank: Contributor
timestamp: July 27, 2012, 10:47:08 pm
content: Quote from: DaveXRT on July 27, 2012, 02:16:28 pmYes DaveXRT is right.