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Another Hameg HM605: has anybody dug up full service manual in English?

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jtu:
I just opened this beauty for a quick inspection of the internals. You can look at the pics, not high quality, just iPhone camera under non-perfect lighting. But size wise well over the forum limit, so check the link to my GD at the end of the post.

A few observations.

First, caps look very good for the age. Not a tiniest bit of bulging nor any thermal stress signs that I could notice.

2nd, inside is very dusty. Especially top board. Which is timebase board as far as I understand. Might do some air dusting of the insides of the scope. Any advice on dusting an old scope?

3rd, I did not notice any thermal stress on any components except for the big green box named HV-cascade on Z-board at the rear and a few components around it. I don't know what it is, will read.

4th, I was a bit surprised first when I noticed that CRT tube (rear end) connections are not soldered. Wires leading to pins have kind of inserts instead. On a second thought, I remembered that I haven't seen any tube soldered actually (my father was very into restoring of old tube radios, I have his collection of 20+ mid 20th century ones and a heap of parts on my hands now and don't know what to do with it...). Quite logical not to do quick thermal things to big glass thingy empty with vacuum :D I moved the inserts up/down a bit (bad contacts thinking).

That's it regarding inspection.

I put the case back on, turned it up and it seems that state of things has changed...

Problem has not disappeared, but symptoms has changed a bit. Not that it makes things more clear to me.

First signs of the problem appeared later than previously. Previously it took 10-15 minutes, now I waited for almost 30 minutes before it happened. Tapping does not help anymore, even more than gentle tapping does not. I tried messing with controls while it did the thing, not that I could notice any correlation. Problem appears for much shorter periods now, goes away quite quickly itself. After ~ one hour it seems gone. Scope is running for more than a second hour now and I have not noticed the problem since approximately during the second half an hour of operation.

I'm still thinking-hoping that it's a contacts/pots problem. How do you address a pot problem btw, replace the pot?

I took a few ~30 sec videos while the problem manifested itself. It seem that this forum does not support video attachments (and why should it?) so I uploaded to Youtube. Check the following links if you want to see and comment. I'm not a Youtuber, so let me know it links does not work.
https://youtu.be/sm4o18oqQRw
https://youtu.be/JJOuPvmr738
https://youtu.be/KoutXDdCfQk

Link to pics: https://goo.gl/photos/tArA5ZYK5fR3d52R6

jtu:
during the third hour of operation problem appeared again but very briefly, ~ for half a second for three times quickly in a row with pauses of few seconds

btw, temperature of the case at back end is ~43 Celsius now at the beginning of 4th hour of operation

jtu:
I checked headings in the hm604 manual, thanks MK14!

It seem very similar indeed, testing and servicing chapter headings are almost identical, except for Triggerempfindlichkeit (something about trigger sensitivity) heading and the corresponding text missing from the English version of HM604. So, by no means identical. But in case I'll end up translating the service chapter, this will be very helpful. But I'll wait a bit before I go into translating, kind of hoping somebody might come up with a translation like oldway did with the testing chapter. Or email Hameg.

tronde:
The green HV-cascade is the high voltage "generator" for the anode voltage of the CRT.
https://en.wikipedia.org/wiki/Voltage_multiplier

It will most likely attract dust or small particles from the air. This will make it look dirty or sometimes burnt. In this scope you will have about 15kV anode voltage, so take care. It is well insulated, but don't touch it when powered up. The CRT will act as a capacitor, so the high voltage can remain for some time after power off.

I would take a closer look on all solder joints. It can be very difficult to find weak joints so be patient. You can tap directly on the solder side of the PCB, but not as hard as you tapped the metal case. Weak solder joints can be very sensitive to thermal change, and when it has been subject to some kind of movement it can be more or less sensitive.

You should also operate all switches and other controls on the front panel. If you use some kind of chemical contact cleaner, you should be careful and not drown everything, especially the input stages are sensitive to changes in electrical properties of the insulating materials. Too much cleaner can make trouble for the high frequency properties of the scope.

It seems like the horizontal sweep stops. That is a strong indication for the time base board or any switch connected to it.

I have seen many older Hameg scopes with weak solder joints. All single-sided PCBs form that era suffers from weak joints.

Try to remove as much dust as you can. A soft brush and a vacuum cleaner will be useful.

Be patient, take care, and you will end up with a very good scope.

oldway:

--- Quote from: jtu on August 25, 2016, 06:58:24 pm ---
--- Quote from: oldway on August 24, 2016, 08:05:10 pm ---I think this is what you are looking for:

--- End quote ---

oldway, perfect, now we have equipment testing chapter in a language I can use! big thanks!

I'm still in a hunt for the service chapter, anybody?

--- End quote ---
There is no service chapter in the manual in english.
Here are the last pages of the manual in english:
Scan quality is bad, use the german manual for schematics.

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