My first osciloscope?

[Scootie]

Hey everyone,

I'm looking to buy my first osciloscope, more likely looks like im going to receive one unit from a far away relative who used to repair his own vintage gears.
The unit is a Hameg HM 604, sadly without scopes/probes. From what I found out the scope replacement part number is HZ32 but I cant seem to find it anywhere online.

Can I use some after market instead?

Also, the screen presents itselfs the following way:

Does this mean it has some problems? Maybe needs a maintanence?

Thank you.

[Zenith]

Of course you can use after market - third party - probes. There are loads of new Chinese 100MHz probes on ebay for about £12 a pair, which should be fine. There's no need to track down a specific Hameg probe, which probably hasn't been made for many years anyway.

It's hard to know what's going on by just looking at the screen with no other information, such as how the controls were set and what signal was input. It doesn't look healthy. You ought to be able to get it to display a straight line by making sure it isn't in XY mode and setting the triggering to auto.

Bear in mind these scopes are now around 40 years old and so will likely need contacts to be cleaned and control shafts freed and lubricated. The 1000µF 25V reservoir capacitors they used in most Hamegs will almost certainly need replacing and smaller electrolytics in the power supplies are also prone to fail. They can have other faults such as caused by soldered joints which have become bad. With the faults dealt with they are nice scopes.

If it has faults and this is your first scope, you may find fixing it hard.

[Scootie]

I may be able to provide another picture of the screen after it powered up.

I'm thinking it needs some time to warp up? Hence the multiple dots on the first screen?

My relative also has a HM408(original bag + probes) and a HM 203-6(probes only) and lets me choose to pick one of these 3 models.
If I go by model number I'd say the 604 is more advanced or should I pick another one?
Am I right about that?

[tatel]

Yeah, 604 is the more capable of the three candidates. However you should make sure the unit you get is fully working. If it needs some adjustement you could do it eventually. But if not all functions are basically working, you would have a rough time fixing it. Often you need an oscilloscope to repair an oscilloscope.

Even a working 203 would be better than a non-working 604. A working 203 with his 20 MHz bandwidth would be OK to learn and after your learning it will be still plenty useful to do audio work and power supply related work, better than almost any cheap modern handheld oscilloscope-multimeter combo. Of course, it will not be as portable.

I guess that relative of yours should be able to send a working unit to you. If that's not the case, I would guess he's unable to fix it. In that case I don't think you could be able to fix it right now, either. Ask your relative for a working unit and stick to it, no matter the bandwidth.

A working Hameg should be able to show at least an horizontal line in just seconds, assuming all the buttons are "not-pressed".  Hameg manuals are available online in most cases and you can see on them how things should go.

Should you go to ebay, often 203 and 604-605 go about the same price. Some people ask quite a few hundred bucks for one of these. To pay about 100 bucks for a 203 and about 150 for a 605 (which is about the same than a 604) would be about right in Europe, assuming they are in full working condition. But the problem is you don't know if the unit is really working. So, having the possibility to get one from a relative means you are quite lucky.

[Scootie]

Since im barely an amateur in electronics I was thinking of having the unit fixed(604) by a profesional.
It might cost some money but at least I'll have a good working unit for some time.

[tatel]

In that case probably a handheld modern oscilloscope-multimeter combo would be cheaper, but feel free to do it the way you like

[Aldo22]

Since im barely an amateur in electronics I was thinking of having the unit fixed(604) by a profesional.
It might cost some money but at least I'll have a good working unit for some time.

Tatel is right.

I don't know what “professionals” cost per hour in Romania, but here in Switzerland you can get a new DSO from China for the price that “professionals” charge for saying “hello”.

I would save the money for a DSO if the Hameg doesn't work "as-is".

[Zenith]

The second picture looks like the spot you see when the scope is in XY mode with no input signals, but it might be the scope has a timebase fault, or the timebase was set to a very slow setting when the photo was taken.

These scopes are normally able to show a stable display easily within about 20 seconds of being turned on. They don't need long warm up periods.

Generally I agree with tatel and Aldo22. Choosing the scope with the highest bandwidth is always tempting, but I don't believe you will need a scope with more than 20MHz bandwidth for some time. Much more important is having a scope which works with no problems. Ask your relative for one which works with no problems, and don't worry too much about the bandwidth and other features, or the probes.

As for getting it serviced by a professional, in the UK at least, it wouldn't be easy to find one these days. Companies offering calibration services or instrument dealers might do it. I'd guess the cost would make buying a new basic digital oscilloscope from Rigol an attractive alternative.

[Wallace Gasiewicz]

I am with Aldo on this one.  How much does it cost per hour to have someone service your car?   
A good electronics teck would probably cost as much.   
Now, I really LIKE CRT Scopes BUT:   
Perhaps 10 yrs ago I could fix a scope and make a bit of money to spend on my hobby, but not today. In USA at least there is very little market for these CRT scopes. Even if it is working it is not worth much.   I have seen working good 200 MHz scopes at Hamfests for less than $100 and they did not sell.
Read some of the posts about scopes here on the forum. You may gain some insight.   
About probes: I have purchased some inexpensively from China. I think they are actually better than my Agilent Probes ( also made in China), just make sure they match the capacitance of your inputs on the scope.   
The pictures are of concern, a scope should produce a line across the screen without any input at all, unless it is in X/Y mode, as Zenith said. Probably more than a simple fix.

[rstofer]

Post a picture of the front panel settings.  The first photo looks like some kind of 'dots' mode.

http://frankshospitalworkshop.com/equipment/documents/workshop_equipment/manuals/Hameg%20HM604%20Oscilloscope%20-%20User%20and%20service%20manual.pdf

[Refrigerator]

I'd immediately go for a new scope. I've been using a VDS1022 for over 7 years and it still works perfectly fine.
But it's an old scope, i think there are better options out there nowadays.
Would definitely cost less than having an old scope fixed and they have much better usability, because a scope is not worth much if it can't calculate anything.
Also being able to export screenshots from a scope helps alot when working.

Analog scopes have charm but they suck by modern standards, even digitized CRT scopes suck because they weigh as much as a boat anchor.

[Scootie]

Thanks for all the good inputs but before I go for a modern osciloscope I wanna see if I can get around this old one.

I was always fascinated by all the buttons on an osciloscope and wanted to know more about them but never got the chance.

Well get back as soon as I get it sometime next week.

[Refrigerator]

Trying to fix the scope yourself would serve as a great learning opportunity tho

[Zenith]

Trying to fix the scope yourself would serve as a great learning opportunity tho

Designing and building a spectrum analyser would be another great learning opportunity.......

The thing is that learning exercises need to be things you can do with a bit of effort, not things that are hopelessly difficult. Since the OP is not clear on what the controls on a scope do, the notion of him fixing one at this stage in his learning would seem overly ambitious.

[AussieBruce]

It may be worth just having an initial look inside to see of there's an obvious possible cause such as a leaky capacitor or clearly corroded joint. Plus spray some good electronic contact cleaner around the mechanical switches. But Zenith is spot on, you could easily burn a lot of time without any result at all - best to do the basic checks and then be prepared to walk away if that doesn't yield any improvement.

[perieanuo]

probes are cheap on olx site, like 10 euros, branded ones.
osciloscop usb hantek 6022 costs 80 euros.
repairing yours is only educational, imho no-go
if you want to learn electronics with scope, buy one at least 40 Mhz, you have OSCILOSCOP TEKTRONIX TDS 1012 digital pe doua canale 100 MHz 1 GS/s for 150 euros on olx.

[6gv5]

That scope is old, but quite good and more than capable for any analog work. I personally would never ever swap it for a cheap digital one; the reason being that I also use RF, and at high frequencies unless the sampling rate of the scope is *way* higher than the signal being shown, I mean at least 5 times, the waveform will be badly distorted and small details could be completely hidden; also 8 bit quantization on the screen in many cheap digital scopes doesn't help. Analog scopes are immune to all of that.
Cheap digital scopes are good at measuring things, but analog ones beat them at showing signals. Of course there are excellent digital scopes, but they do cost a lot more than a used analog.  As for the probes, just buy any 3rd party ones; they're standardized.

Here's some documentation from Tek about how to use oscilloscopes.
https://www.tek.com/en/documents/primer/xyzs-oscilloscopes-primer

[aliarifat794]

 The HM 604 has a bandwidth of 60 MHz. The probes you buy must match or exceed this bandwidth.

[Scootie]

So finally, I received today my osciloscope.

Sadly, it suffered a pretty serious damage while being shipped and im not sure its safe to power it on under the current situation.
Found inside this broken pin.


Most likely will have to take a part the osciloscope, remove the display somehow and fix that broken pin.
No other inside damage was noticed.

I also seem to be missing 5 push buttons(inside I found 2 rods) and their according rods and mechanism that reaches inside the push buttons.
I wonder if I can find replacement buttons somewhere cause no luck so far.

[Zenith]

It's hard to see what the pin is from the photos, but the missing buttons would make it hard to use. I doubt you would be able to find replacements apart from a scrap Hameg, but https://sky-messtechnik.de/ might be able to help.

Unfortunately, in my opinion, you've drawn a blank on this one. I believe fixing it is not something you should attempt and I'd class it as a parts mule.

If you lived five miles away, I'd be willing to swap it for a good worklng HM203, because I'm a sucker for old scopes, but you don't.

Put it to one side and more or less forget it. You might be able to swap it for something you want, or at a later stage come across another and be able to make a good one from the two.

[Scootie]

I will try your site out but first we have to see what DHL has to say about the shipment damage.

Meanwhile I took some more pictures about the broken leg.
Im not sure if the display is sitting well inside or not, seems to be as it is a little out of its place.

Im also wondering if the nuts on the last picture uploaded should be loose or not.

[Zenith]

I'm not familiar with the HM604, but I have worked on HM203-5, 203-6 and 203-7, HM605 and HM1005.

You need to download the service manual for the HM604. There are a couple of versions, so you will need to download the one for the version of HM604 you have. With Hameg manuals the German version usually has circuit diagrams and PCB layouts, other language versions may not.

This is one site where HM604 manuals are available, but there may be others, which may offer better copies.

https://sky-messtechnik.de/reparaturdienst-service/downloads

I'm not completely sure what exactly the wire with the detached pin is. It looks as if it's a pin which was soldered to the PCB and which had a wire soldered to it. You would need the service manual to know what it did and that you were putting it back in the right place. it looks as if it was soldered to a PCB track which has lifted from the PCB but that's odd, in that such pins are usually through hole. Repairing detached or burned copper tracks can be done in various ways, but usually a thin insulated wire replacing the track will do, but it's always messy.

Usually nuts on these things need to be comfortably tight, but no more. If they are loose they are not holding anything together and could work completely loose, with a chance of causing a short circuit.

Again, I'm not certain what the last photo represents, so this is largely guesswork. I suspect it's the final Y amplifier. The white discs with nuts are probably heat conductive, insulating spacers for transistors to be attached to heat sinks. There may have been a cover which is missing, which would have acted as an electrical screen and also as a heatsink for the transistors. The nuts would have secured the spacers and transistors to the cover. The cover would have access holes so that the trimpots and trimcaps could be adjusted.

[tatel]

Missing buttons make it look as a scavenged for parts unit. Are you sure it was on working condition? With some parts missing, even a technician could be unable to fix it, unless he has these parts. Not that they couldn't be printed/machined, or got from some other device, but they make to fix the device, much more difficult and expensive.

About shipment package, I would expect to see some dent in the device. If not, perhaps that pin/track damage is the result of some previous "fix"

You got bad luck, Sorry.  I hope you got it very cheap or free.

[jerryk1234]

Often you need an oscilloscope to repair an oscilloscope.

*** Yes, indeed.  My first scope was an ancient Heathkit that somebody had given me.  It had a problem where it showed an AC hum trace unless you shorted out the input.  No amount of power supply filter capacitance made any difference.  I beat my head against the wall until somebody lent me another scope.  Using that other scope, I discovered that there was AC voltage between one part of the chassis and another.

  It was Heathkit's use of aluminum chassis held together with steel sheet metal screws.  Dissimilar metal corrosion caused resistances.  AC currents passing through the chassis caused voltage drops across those resistances.

[Scootie]

The unit was working yes but due to the damaged it got during shipping I now consider it almost trash. The case got hit so hard that the welding broke almost completly on one side.

So even if i find parts for the pushbuttons who knows what else is wrong inside.
Well see how it goes with DHL to recoup shipping cost which werent much but still.

Meanwhile, I bought another 406. Hope I have more luck with that.