Hameg HM-304 Mini Review /Teardown

[Felicitus]

The Hameg HM-304 is a 35 MHz digitally controlled analog oscilloscope made around 1995. I was lucky to get this for 85€, and I really like it! Every setting (with some minor exceptions) can be stored in 6 preset slots and it can also be controlled via RS232. It is NOT a digital storage oscilloscope. With about 5.6kg, It is very light, and I was curious what's inside.

Here's an image of what it looks like (not my unit, mine is way cleaner ):


Bottom View: Main Board, shielded input section (haven't taken that one apart because it's soldered) and calibration/component tester section in the upper left region. On the bottom right, you can spot the switching PSU.



Mainboard "close up". Sorry for the blurred picture, I don't have my digital camera at hand right now. If you want a hi-res photo of this, please let me know, and I'll do a better pic once my new lab is set up. I was surprised to find SMD components almost completely, which is IMHO surprising for a 1995 vintage scope. There's also an Altera device, probably a CPLD.



Board beneath the PSU, not sure what it does:



Top view of the case. As you can see, there's barely anything in here. The board on the right-hand side is the
control panel. You can also see the input section, which I haven't torn apart.



Rear side behind the tube. They even went through the trouble and designed a plastic cover for the high voltage part. The white thing below seems to be a ceramic hybrid resistor of some kind.

[Analogdevice]

Nice machine. I was serviced a month ago HM605. I like the probe calibrator, wich have switchable calibration frequency between 1kHz and 1MHz.
In my piece there was bad BD199 and BF440 transistor in Z-amp. After replacement the scope was fully-functionable. Great to service, there was a lot of space to do measurements on it, for example in tesla there aren´t a lot of space to do measurements, so when I want to test anything, I must clear the PCB´s...

[Hydrawerk]

No readouts or cursors??

[Felicitus]

No readouts or cursors??

It's an analog scope with digital control, so no cursors or readouts.

[Hydrawerk]

This was a successor. But production was stopped in 2012.

[mos6502]

No readouts or cursors??

It's an analog scope with digital control, so no cursors or readouts.

Great - combining the disadvantages of both analog and digital scopes.

[Felicitus]

Great - combining the disadvantages of both analog and digital scopes.

Great - combining the advantages of both analog and digital scopes:

- Recall/Store/Autoset capability
- Analog display (okay, you can get intensity grading with modern digital scopes as well)
- Remote control
- Fairly cheap price

It depends on how one works, and I like it very much so far.

[Patent.STM]

nice to see the hm304 internal view.

I had a hameg oscilloscope in garage for years, and I'm surprised to find it a well-built machine.

hameg models whichever has a built-in rs-232 follows the same operation command, some of them comes with vendor supplied drivers like Matlab and NI Labview,, it worth a try since yours has rs232 too.

by the way , do you konw what kind of connector is suitable for the CT and Calibration plug?

[Felicitus]

by the way , do you konw what kind of connector is suitable for the CT and Calibration plug?

You mean the 0.2Vpp and 2Vpp? Just use your probe without the hook. The other two are 4mm standard plugs.

[Gunb]

Bought the HM407 Analog  Digital Scope at the end of the 90s which combined the advantages of both worlds. It's still on my desk and will remain there forever!

At this time most low/mid price scopes did not have much memory and A/D converters' sample rate were low - so for analog signals I've used the analog part, for non-periodic
signals the digital one.

As a student I was very proud to own such a lovely device!

I like these old Hameg scopes, they remember me on the good times in the past at university ;-)


Rgds
Gunb


P.S.: usually you can download old schematics for these scopes at Hameg site. If not separately available often the schematics are part of the manual.

[oldway]

In my opinion, the best HAMEG analog scope should be the HM1005 but it has no component tester.
For this reason, my preferred HAMEG analog scope is the HM605.

[Patent.STM]

by the way , do you konw what kind of connector is suitable for the CT and Calibration plug?

You mean the 0.2Vpp and 2Vpp? Just use your probe without the hook. The other two are 4mm standard plugs.

thx for that information, 
I'd get a banana plug to check out the octopus function.