First oscilloscope dilemma - Page 1
Forum section: electronics / beginners

author: picofarad
author_rank: Regular Contributor
timestamp: September 15, 2013, 06:37:59 pm
content: Hello there,I need an oscilloscope, but since I'm a beginner and due to the economic crisis, I don't want to spend much money.So, following Dave's advices I started searching around for analog scopes and I found two in my area:- the first one is an old italian scope made in the '70s. Single channel, 10 MHz. Fully operational. The seller would give me all the schematics and complete manual. Price: 50€;- the second one is an Hung Chang 5502. Dual channel, 20 MHz. The scope shows a small linear trace in the center of the display, but the seller said that he doesn't know how to use it, so he sells it as not working. Seems to be hard to find the manual and schematics. Price: 50€;The dilemma is: if I get the first one, I would have a working scope with manual and schematics, but it's nearly 40 years old and it's single channel, that for the moment it's enough to me;if I get the second one, it could be both working and not working, but it's dual channel and 20 MHz. Besides, if the second one is not working it could be both a broken cap (so I might probably fix it) and something else (I'm not too good in troubleshooting).What do you recommend to do?P.S. As always, sorry for my english.

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 15, 2013, 07:39:25 pm
content: Hung Chang 5502 is also Protek 5502.Not exactly the same model number, but I bet it's close.http://www.eserviceinfo.com/equipment_mfg/Protek_35.html

author: picofarad
author_rank: Regular Contributor
timestamp: September 15, 2013, 07:56:46 pm
content: Thanks for the info.The italian one is a Unaohm type G49.Here there are some pics and info.http://www.radiomuseum.org/r/unaohm_oscilloscopio_g_49.html?language_id=2

author: Stonent
author_rank: Super Contributor
timestamp: September 15, 2013, 08:34:47 pm
content: Honestly, I'd take a chance with the second one. Lets say for instance one channel is completely dead. You still end up with a 1 channel scope with 2x the bandwidth of the other scope.Second, you know the screen is good, so you can eliminate that as being an issue. It comes on so the power supply is at least functioning to a degree.The old 70s scope could potentially have parts inside it that don't exist any more.Also the Hung Chang / pro tek scopes are all over the place rebadged by other companies such as BK, Tenma, I think even LG may rebadged it as well.

author: picofarad
author_rank: Regular Contributor
timestamp: September 15, 2013, 09:02:14 pm
content: Mmmmm, so I should have a chance with the Hung Chang.The problem is that I'm a beginner and I don't have so much experience in troubleshooting (only repaired few pc monitors and TVs, I prefer to make my own projects).That's an image of the Hung Chang:As you see, there's only a small trace on the screen. The scope seems to have all the pots and switches. I thought that the strange vertical position of the trace can be due some rotation of the vertical position pot made by the seller trying to understand if it works, but I have no idea about the width of the trace.

author: sync
author_rank: Frequent Contributor
timestamp: September 15, 2013, 10:24:39 pm
content: Unfortunately you didn't set your country. So i don't know where you live.The Hung Chang is broken. It probably can be fixed. But to repair an oscilloscope often a second, working oscilloscope is needed. Also often needed are the schematic/ service manual, a (function) generator and experience in repairing. 50€ is too much for this one. IMHO even for a full working one 50€ is a bit expensive.Regarding the other scope. Don't buy a single channel one. It's not enough.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 10:18:54 am
content: I'm from Italy (now I setted the country).How do you know it's broken?As I said, I can fix it only if the repair is easy (caps, resistors, inductors, maybe transistors).Regarding the price, maybe I can ask the seller a lower price (30€ ?), since I don't know if it's working.

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 16, 2013, 10:40:34 am
content: I agree the Hung Chang is probably broken, and probably a complete waste of money. The other scope is a recurrent sweep type. You should at least get a triggered sweep type. Stay patient and keep looking. Neither of these two scopes are for you.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 10:52:08 am
content: Thanks for all the replies. I'll keep looking.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2013, 11:10:24 am
content: Yep, I agree, keep looking, one will turn up.Do you have any local classifieds like the equivalent of craigs list?Set up ebay serachs so you get alerted when a new scope pops up.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2013, 11:12:45 am
content: How about this?http://www.ebay.it/itm/oscilloscopio-HP-1222A-tarato-hp-1222a-oscilloscope-15Mhz-2ch-/271277725564or make an offer:http://www.ebay.it/itm/OSCILLOSCOPIO-KENWOOD-CS-1025-20MHZ-/130989769954

author: M0BSW
author_rank: Frequent Contributor
timestamp: September 16, 2013, 11:59:41 am
content: You should ask the colleges around or near you to, I know this works as I just got a Tek 2465 from a college, for £200. UK, and they were going to bin it, its perfect and in perfect working condition, so ask, they can only say no.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 12:24:22 pm
content: Thanks for the reply, Dave.The HP oscilloscope seems very good. Only some glitches an jitters on some horizontal and vertical scales combinations. The seller says also that at very high frequencies, the waveform is distorted horizontally. It seems to be manufactured on late '70s: would it be hard to find replacement parts, like the old italian mentioned in my first post?The other one, Kenwood CS-1025, it's good but the auction begins from 95 €, the price can raise too much.My school still keeps all the broken scopes. They prefer to have a full room of non-working gear rather than give it away. I guess that this condition is due to the messy burocracy in my country.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2013, 12:41:49 pm
content: Quote from: picofarad on September 16, 2013, 12:24:22 pmLikely just some dicky switches that need a clean, as I showed in the Hameg video.QuoteSorry, don't know the model off-hand.QuoteAh, I didn't see "starting price".

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 01:16:13 pm
content: Now I'm focused on the HP 1222a. Anyone has any info about it? I found that actually is from early '80 (the schematic says 1982).

author: PA4TIM
author_rank: Super Contributor
timestamp: September 16, 2013, 01:29:46 pm
content: For an old scope, the 70's is a good periode. Most low frequency scopes were build with just transistors and some opamps. Later they started using special ICs for things like readout, cursors. Most scopes from the 50's to end 70's are rather easy to repair but most times you need a second working scope to repair a broken scope.I would go for the HP. They are good. I have a HP122AR (got it for free) from the 50's, this is never repaired and still perfect. Only had to clean the switches and reform the caps. I had a HP-1740A (100 MHz including probes I bought it for 100 euro including transport), that worked but got a problem. Somebody had repaired it before me and forgot some screws so the pushbuttons wobbeled the whole mount and killed a solderjoint. A while later the floodgun got problems, burned a resistor, this was caused by a bad cap. I gave it to a friend 2 years ago and it still works perfect. I bought a 200 MHz 7704 and a 100 MHz 7603, both working scopes with plugins for a total of 125 euro. A 150 MHz 2445B working for 125 euro, A Tek miniscope for 40 euro, but all my other analog scopes I got for free (around six Tek 5XX models, a 453, two 1 GHz Philips samplescopes, a 75 MHz Philips, a 100 MHz fairchild, a few very old 50's Philips scopes (from the top of my head, and I'm not searcing, in fact, I never look on ebay or other sites, only looking if people ask advise, like the links given here by Dave.So again, just be patient.But just be patient, there are lots of cheap or even free scopes, but most times not on that legal gambling site were you do not buy but win scopes, and like with most gambling, you often pay more then you win ,

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 04:22:58 pm
content: Quote from: PA4TIM on September 16, 2013, 01:29:46 pmNice collection, you're very lucky!

author: Sigmoid
author_rank: Frequent Contributor
timestamp: September 16, 2013, 04:34:09 pm
content: I entertained the idea of getting an old HP storage scope, those are awesome, with that oldskool heavyweight cold war feel to them... XDBut unfortunately in the end reality won, as the thing is about the size of my entire workbench.So I went with a Rigol. How uncool.

author: edavid
author_rank: Super Contributor
timestamp: September 16, 2013, 04:43:56 pm
content: Quote from: picofarad on September 16, 2013, 01:16:13 pmThat was a low end model, which has particularly bad switches and pots. So, I wouldn't count on getting them working perfectly. Also, it's pretty darn slow. On the other hand, it's fanless, which is very nice if you need to use it in your living room.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 04:55:49 pm
content: Quote from: edavid on September 16, 2013, 04:43:56 pmWhat do you mean?EDIT: just discovered that the seller is the user ddavidebor in the forum!!!

author: van-c
author_rank: Regular Contributor
timestamp: September 16, 2013, 05:09:52 pm
content: The suggestions from Dave and others about being patient are the best advice you could get. Remember, as happy as you might be once you finally buy that first scope, the person selling it is probably equally happy, if not happier, to have finally sold it. And there are lots of sellers out there.I would also offer this advice: Don't be afraid to ask the seller if there is anything about the scope that you should know before buying it. Ask if, to the seller's knowledge, any parts inside the scope been removed, scavenged or replaced. Often a used scope becomes a parts donor and known faulty parts are put back in after working parts are removed. Of course the seller may not be honest enough to tell you if you ask, but he is much more likely to tell you if you ask than if you don't ask.Good luck.--Van

author: edavid
author_rank: Super Contributor
timestamp: September 16, 2013, 05:18:55 pm
content: Quote from: picofarad on September 16, 2013, 04:55:49 pmOnly 15MHz spec, and don't expect better than that.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 06:38:14 pm
content: Quote from: edavid on September 16, 2013, 05:18:55 pmI mostly work with audio stuff. I think that 15MHz it's enough for what I have to do.

author: picofarad
author_rank: Regular Contributor
timestamp: September 16, 2013, 09:15:45 pm
content: And what about a Tektronix type 454? The auction starts from 25€.

author: Msusec
author_rank: Newbie
timestamp: September 17, 2013, 02:03:42 am
content: Hello!The same question, but another person!So i would like to buy my self a new oscilloscope.i can chose between :- Hameg HM400( because i love analog scopes )- Rigol DS1102E- Tektronix TBS 1152because they all are in range of 460€ max.so which one should i buy?thanks for Helping me.

author: edavid
author_rank: Super Contributor
timestamp: September 17, 2013, 02:14:37 am
content: Quote from: picofarad on September 16, 2013, 09:15:45 pmIs it a 454 or 454A? 454 has 6x10 screen (cramped) and nuvistors. 454A has 8x10 screen and JFETs, very nice sharp trace, but is very old...

author: EEVblog
author_rank: Unknown
timestamp: September 17, 2013, 03:44:35 am
content: Quote from: Msusec on September 17, 2013, 02:03:42 amThe official Rigol price is only 320€http://www.eu.rigolna.com/products/digital-oscilloscopes/ds1000e/ds1102e/The Tek TBS series is old crap, don't bother.Don't bother with the analog if can afford a modern digital.Of those 3, hands down, the Rigol.The new Rigol 1072Z is only 450€http://www.eu.rigolna.com/products/digital-oscilloscopes/ds1000Z/ds1074z/Awesome value!

author: Paul Moir
author_rank: Frequent Contributor
timestamp: September 17, 2013, 03:48:49 am
content: Quote from: picofarad on September 16, 2013, 06:38:14 pmw2aew makes a compelling argument on why you might need more:

author: picofarad
author_rank: Regular Contributor
timestamp: September 17, 2013, 10:44:13 am
content: Quote from: edavid on September 17, 2013, 02:14:37 amIt's a 454. However, the seller want to be paid with a check, no Paypal. I prefer to focus on the HP scope.I watched the w2aew's video. Very interesting.

author: picofarad
author_rank: Regular Contributor
timestamp: September 17, 2013, 06:24:21 pm
content: I just found a working HP 1707A on Ebay starting from 50€. Same glitches when changing timebase and volt/div as the other HP scope. The auction ends thursday.Any advice?The 1222A has a 8x10 screen, but it has lower bandwidth and the controls looks 'cheapy'.The 1707A has a smaller screen (6x10) but it's a 35 MHz and it seems to have more features.

author: Stonent
author_rank: Super Contributor
timestamp: September 17, 2013, 10:56:13 pm
content: Glitches when turning a knob are likely dirty contacts and that can be cleaned.

author: picofarad
author_rank: Regular Contributor
timestamp: September 18, 2013, 12:18:12 pm
content: Quote from: Stonent on September 17, 2013, 10:56:13 pmYes, I know.However, anybody has a HP 1707 or ever used one? Does it worth 50€?

author: Crazy Ape
author_rank: Regular Contributor
timestamp: September 18, 2013, 07:04:09 pm
content: Have you seen this one in your searches?HP 54502A DIGITIZING OSCILLOSCOPE 400MHZ w/HP-IB 250 €http://usato-computer.vivastreet.it/usato-computer-informatica+tezze-sul-brenta/hp-54502a-digitizing-oscilloscope-400mhz-w-hp-ib----/66294366There are others at the same site, but the one above caught my eye.

author: picofarad
author_rank: Regular Contributor
timestamp: September 18, 2013, 08:01:37 pm
content: 250€ is too much. If I had enough money I would buy a Rigol DS1052E, since I use one at school. I can spend a maximum of 80-90€, if it really worth I can raise to 100€.

author: Crazy Ape
author_rank: Regular Contributor
timestamp: September 19, 2013, 03:13:42 am
content: These guys have an ancient HP 1220A for €80,00http://www.radiosurplus.it/StrumentazioneUsata/STRrevisionati.htmThe trace does look very dim though (intensity knob on full), I didn't notice it before posting.

author: picofarad
author_rank: Regular Contributor
timestamp: September 19, 2013, 12:16:40 pm
content: Quote from: Crazy Ape on September 19, 2013, 03:13:42 amYep, it seems that there's a missing piece on the screen (maybe a dimming plastic to increase trace contrast).Again, nobody has any info about the HP 1707?

author: sync
author_rank: Frequent Contributor
timestamp: September 19, 2013, 12:43:04 pm
content: Yes, the contrast filter and the safety plate is missing. Without them and at full intensity the trace should be very bright. It looks that this oscilloscope is too dim.

author: chibiace
author_rank: Regular Contributor
timestamp: September 19, 2013, 01:02:13 pm
content: try the make offer feature on ebay. i recently got a hitachi v660 for 40 dollars and another 40 dollars for shipping by sea to new zealand. took 6 weeks to get here but works perfectly

author: picofarad
author_rank: Regular Contributor
timestamp: September 19, 2013, 01:49:41 pm
content: Just won the auction for the HP 1707A! Got it for 71€ plus 10€ for shipment.Thanks for all the advices, tips & tricks!

author: Ecklar
author_rank: Regular Contributor
timestamp: December 12, 2014, 04:06:40 am
content: Quote from: EEVblog on September 17, 2013, 03:44:35 am

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: December 13, 2014, 12:43:42 am
content: Quote from: Ecklar on December 12, 2014, 04:06:40 amI guess Dave is referring to the pathetic specs of this scope. The sample memory is ridiculously small (2.5kpts), the screen is piss-poor, functionality-wise it's absolutely primitive (lacking even basic stuff like intensity grading). In short, it's a perfectly fine entry level scope if the year was 1999. In 2014 selling such a scope at that price is just an embarrassment.Also, claims of 100% better quality are simply preposterous, but I guess that's one area where Tek might convince some technically challenged corporate buyer to go for their products instead of one of the modern-day alternatives.Dave says these scopes are crap. I'd go as far to say that everyone who seriously considers to buy one at the price they're asking for it needs to have his head examined.

author: Ecklar
author_rank: Regular Contributor
timestamp: December 13, 2014, 02:35:06 pm
content: Thanks WuerstchenhundCrap did sum it up quickly, but as a beginner I wasn't fully understanding the reasoning. Your expansion gives me not only an explanation but also a better reference as why the modern Rigols and such are so much more liked. I guess what caught my attention was that I saw some of these Tek TBS scopes offer in new warranted condition for $600 US so thought at that price it was worth exploring.However, now I can see the capabilities are really lacking compared to the latest stuff on the market.