Problem with the X axis on analog oscilloscope (PM3232)

[luc.aas_]

Hello everyone I just buy an oscilloscope but it's totally out of calibration but it's okay I'll read the manual to calibrate it and all! The most annoying problem is that the X axis is not used at all. I don't really know how to explain myself but it's really tiny it moves on 5 mm so I don't know if it's a problem with the CRT screen, calibration, components errors... If someone can help I would really be thankful! Thanks for your attention

I attached some pics to describe the problem (Look at the screen)

[Specmaster]

I think that you will find that the problem is that your scope is missing a few parts, like the level control for instance, just to the right of the time/cm control. Those three controls in that top section to the right of the screen are to do with the X axis, the X POSITION, TIME/cm and LEVEL all form part of the controls for the scope. I'm guessing this your first scope and that you're a beginner, would that be a fair assumption to make?

[luc.aas_]

Yeah It's my first oscilloscope but I just them at school so I know the basic like how to read it how to set it and all but the thing is that I tried every combinaison and I think that the horizontal coil of the crt hasn't much current or they are some problems with the calibration of even some dead transistors I don't really know I tried to read the manual but I couldn't find something that solve the problem :/

[Specmaster]

The CRT looks fine to me, does the display move across the screen at all? I can't help it but I think that you have been taken advantage of because that is one sick scope that requires a fair amount of TLC before it will work IMO. Did you get from eBay?, was it advertised as working? If, so I'd personally be asking for a refund right now if that was mine.

[luc.aas_]

I get it for 20€ from eBay mmh so I think it's okay! But yeah it moves a little bit on the X axis, like a middle of cm.

[Specmaster]

Sorry, but I fail to see how you can think that is OK. You say that you have used them at school but you failed to notice that a very important control on the front panel, and one that affects the X axis is actually missing and yet you still bought it? I would raise a claim against the seller if they in any way at all lead you to think that it was fine and working scope. In all seriousness, a scope is not  really a fit project for a newbie / beginner in electronics. There are some pretty lethal voltages in there that a beginner should never be tackling with. As I said before, I fear that you have been taken advantage off by an unscrupulous ebay seller and you ought to be returning it for a refund and looking for a better one that is actually working.

EDIT:

My bad, I see that the level control is not missing at all, its just the angle of the photograph, make it appear as if the shaft is missing, but I see now that it is just the cap of the control knob that is missing.

However, if the display is not moving from left to right across the screen then it shows that there is a fault with the timebase section of the scope. What happens if you alter the TIME/cm control and the LEVEL control?

[luc.aas_]

Yeah I think I will do that dang I feel bad now haha, no really I know the X parameters it's just that it doesn't work. The guy on eBay refuses refund so I think I'm stuck with that thing. Yeah I know the danger of high voltage I stay safe use gloves when opened I'm really careful ! Anyway thanks for helping me

[Specmaster]

When did you buy it on ebay? How was the advert worded on ebay, was it sold for spares/repair or as untested or what? If you have only just brought it, raise a claim via ebay resolution service and ebay will take it with the seller and will normally find in your favour and give you a full refund. That however does depend on when you purchased it and just how did the seller list it. 

Gloves may not protect you if you go anywhere near the CRT as there could be anything there from 1500V to 5000V or more.

[luc.aas_]

I bought it a week ago. And the guy said(in pm) it turns on but he didn't test it 100% so I don't know if I can ask a refund
Yeah the CRT is 1.8kv but all the connection are on the back not on the main PCB.

[Specmaster]

Yeah OK, as far as a refund is concerned, I think that you can forget about what he said in a pm, it what he actually said about in his eBay listing that really counts. I'd be inclined to raise a dispute through eBay buyer protection program and see what happens, you have nothing to lose by it even if does piss the seller off, you're hardly likely to buy from him again anyway. There are plenty of good scopes on eBay for not a lot of money, granted they will be old and of very low bandwidth but that is what most people start off with, like cars, start at the bottom and work your way up.

[luc.aas_]

Yes I will ask a refund because it says "partial use marks but fully operational". I hope it will be okay. Thanks a lot dude you help me a lot. I'll tell you if there's any news about it

[luc.aas_]

What I claimed

When I go on the description of the item, the seller has selected the option "used condition, wear trace but operational" but the oscilloscope is not operational, I asked an engineer friend and he says that the X axis is defective which makes the item totally unusable (I attached a picture, as you can see whatever settings I make, the signal stays only on the vertical axis and does not move at all on the horizontal axis).  That's why I ask for a feedback.  I was thinking of buying a second hand item but it works.  On top of that, it was totally destroyed during transport (broken stainless steel handle, disassembled screen, lost screws...).  Thank you very much for your attention.

[Specmaster]

Good job, keep us informed of the outcome, fingers crossed you will get a refund because he actually listed it as fully operational which it clearly is not.

[tggzzz]

It looks like specmaster is doing a good job of mentoring you

If something is damaged in transit, often because it is badly packed, that is grounds to reject it and get a refund. Basically the seller should pack something properly, but often they don't. If packaging looks inadequate, I take many photos as I unpack it.

With ebay the critical point is what it says in the "Condition:" box. If it says "Used"/"Refurbished" then it should work correctly to the original specification. If it says "Spares or repair" then it might or might not work. Those of us that sell test equipment on ebay really wish there was another category: "all functions work, but we cannot guarantee that it fully meets the original calibration". If I sell a multimeter I will be able to show that all the readings are sensible, but I will not be able to calibrate it to the full specification. If I marked it "refurbished" or "used", an unscrupulous buyer could use that to reclaim money from me. Hence I have to mark them "spares or repair"; shame.
FFI ebay>>help>>search for "condition" https://www.ebay.co.uk/help/selling/listings/creating-managing-listings/item-conditions-category?id=4765&st=3&pos=1&query=Item%20conditions%20by%20category&intent=condition&lucenceai=lucenceai

I will emphasise a couple of specmaster's points.

A beginner should not attempt to repair a broken scope, unless the damage is obvious, simple, and can be easily repaired.

There will be around 2kV, possibly 8kV inside the case, stored on capacitors that can spoil your day. Gloves wouldn't be sufficient. Be very sure of all the places those voltages exist before turning it on when it is outside its case. There are other places "near the power supply" where there are dangerous voltages, but gloves might or might not help.

Do use the ebay complaints procedure correctly. It is explained well in the help sections. Give the vendor the chance to put things right, but don't allow them to "run down the clock" so that complaints are no longer possible.

Sometimes things go wrong that are outside the vendor's control. I've just had somebody complain that something I sent didn't arrive, so they asked for a refund. I'm content that they aren't lying nor trying to cheat me, so I discussed the options with them. In the end I sent duplicate goods, and they have arrived. The buyer is happy, and I'm irritated but not unhappy.

BTW, ignore anybody that says you shouldn't buy an old analogue scope but must buy a digitising scope. You will learn a lot with a working scope, analogue or digitising, and analogue scopes are simpler for beginners to learn.

[luc.aas_]

Thanks a looot, I will! Without you I wouldn't do anything because I'm maybe "too sweet" haha

[luc.aas_]

Okay, there are strict rules about that, but at the same time it's good because it can protect us from misleading ads and stuff.

I'm gonna read up on eBay tomorrow morning, try to "win."

Yeaah don't I know how the CRT is made with really high voltages and all, I know where those dangerous place are but don't worry. I always disconnect and wait some seconds to let capacitor discharging before touching anything! When I received it the suction cup of the crt was removed because of the.. delivery? So when I started it first time it was like KRKRKRRKRRRRKRKRKKRKRR.. I was so scared.... anyway haha. I just stay safe with those dangerous component because they don't mind if there is meat or not.

And yeah! I personally love analog scop at least you do the math! It's not a computer that calculate everything so yeah it's better to learn electronic ^^

I'm sorry to hear that, I just hope it will not happen again!

[tggzzz]

Sometimes waiting seconds is completely inadequate. It all depends on the leakage paths. It is very much a case of RTFM!

You should also be aware of capacitor "soakage" or "dielectric absorption". That can make it look like a discharged capacitor " magically" regains charge/voltage.

Motto I taught my daughter was "let's have fun, safely". We did several " dangerous" things together, with acceptable damage to ourselves.

[Specmaster]

Yes, just as tggzzz said capacitors can take a long time to discharge to completely safe level but even then they can recharge themselves to an extent, certainly enough to make your day less enjoyable. Those in the EHT side of things can be even worse, can retain their charge for far longer than those used within the power supply section do. Oscilloscopes of the CRT type or CRO's as they are sometimes called are not items that novices should ever contemplate working on. They need to build up their skill set a bit before attempting such a task.

Its like learning to drive, there is a reason why driving schools have small low powered cars and also why insurance companies won't generally insurance  a relatively new driver, regardless of their age, for a high performance car until they have a few years of experience of driving to build up their car craft / skills and become a safer driver.

I expect that you will hear back from eBay very quickly in your favour on this claim, I generally get an answer in hours rather than days when I have reason to complain about a seller.

[luc.aas_]

Wait when a capacitor is discharged it can recharge because of other? I didn't really get it

And yeah i remember when I was younger I made a desk power supply with an ATX power supply (I waited like 10 minutes) but the storage capacitors of the supply were still charged I almost get a really strong shock, since that I'm really careful.

At least you share something interesting with your daughter

[luc.aas_]

Yeah that's why I asked help here! I now changed my mind from "repair it" to "refund it". It's safer to not do anything for me!

It's a nice metaphor, starting with something complicated could "disgust" beginners.  I completely understand

And no the seller was really quick to my message but since I claimed a refund, no answer :/

[Specmaster]

Did you raise your claim with the seller or eBay? If the seller then you probably won't get a reply. If you followed the correct procedure with eBay then you will get a response.

[luc.aas_]

I raised the claim to the seller but I couldn't do anything else, it says "if the seller does not reply you will can ask help to us from June 17"

[tggzzz]

I raised the claim to the seller but I couldn't do anything else, it says "if the seller does not reply you will can ask help to us from June 17"

It is polite and sensible to ask the seller first. Sometimes that is all that is necessary to rectify a problem to both side's satisfaction.

If the response is unsatisfactory, then raise the issue formally with ebay by following the ebay procedures. Don't accept excuses which could "run down the clock" beyond the ebay deadlines. There are some actively bad sellers out there, but this one is probably incompetent rather than malicious.

It sounds as if you have been doing things sensibly. Good luck

[Specmaster]

Yeah I think I will do that dang I feel bad now haha, no really I know the X parameters it's just that it doesn't work. The guy on eBay refuses refund so I think I'm stuck with that thing. Yeah I know the danger of high voltage I stay safe use gloves when opened I'm really careful ! Anyway thanks for helping me

Seeing as the seller had already refused to refund you, you should have at that point raised it directly with eBay and to do that you need to go to your "Purchase History", then find the item that you want a refund on and follow these steps as shown in the attachments. Once that has been done, eBay will normally find in your favour very quickly, often with in hours, if they don't get a response from the seller, or if they are unhappy with the tone of the sellers response. It really is that simple.

It's always nice to give the seller a chance to respond first before you go to eBay to make a claim, you did and the seller refused. It is eBay's promise to buyers, is a full refund if something is wrong with your purchase, but you have to start that process quickly and leave it until the time is up.

[luc.aas_]

I raised the claim to the seller but I couldn't do anything else, it says "if the seller does not reply you will can ask help to us from June 17"

It is polite and sensible to ask the seller first. Sometimes that is all that is necessary to rectify a problem to both side's satisfaction.

If the response is unsatisfactory, then raise the issue formally with ebay by following the ebay procedures. Don't accept excuses which could "run down the clock" beyond the ebay deadlines. There are some actively bad sellers out there, but this one is probably incompetent rather than malicious.

It sounds as if you have been doing things sensibly. Good luck

Ooh it's my first refund claim so I didn't know I hope he will not be mad or something haha! Also, I think the seller isn't a scammer he just doesn't know what he sells. He claimed that "it turns on" that's all! Thanks!