Hameg HM1008 help/manual - Page 1
Forum section: electronics / repair

author: fra.gherard
author_rank: Contributor
timestamp: March 13, 2016, 02:47:13 pm
content: HiAt work we have an Hameg HM1008. A nice multipurpose digital/analog oscilloscope 100MHz 1Gsa, used daily.From 1 year, the regulation of X-position both channel A and B doesn't work fine, also the trigger X and Y have the same problem.The intensity, V/div and time/div knobs work good.I tried to switch the intensity encoder with X-position, but didn't change anything.I contacted Hameg, but they didn't have the service manual, and they said me to ask Rohde & Schwarz. I wrote Rohde & Schwarz, but also them didn't have the service manual, and they send me the contact of the official support. I wrote to them, but the can't send me the service manual, because is only for internal use.This is a video of the problem:Anyone have the service manual of HM1008 or HM1008-2, or any idea of the problem?Thanks

author: Fraser
author_rank: Super Contributor
timestamp: March 13, 2016, 03:14:55 pm
content: Sorry to hear this.I have the older HM1005 model but that is very different to your unit.Hameg have always been very helpful on the schematics front but since being taken over by R&S there may have been some changes in policy. If you ask for a schematic rather than a service manual, you stand more chance of help as Hameg always used to include the schematic in the user manual. That stopped when R&S took over.In your case it sounds like the HM1008 is an outsourced model made by neither Hameg nor R&S. That does complicate mattersI have some more modern Hameg test kit that has not been as reliable as the older equipment. Mainly intermittent push button contacts and rotary encoder issues, but also failed electrolytic caps. Hameg had difficulty supplying schematics for these units so I suspect they are also outsourced to another company.Sorry I cannot help more. You are back to basics carrying out voltage and waveform checks on the various stages involved with the area that is showing failure. Power supply rails are the place to start.Fraser

author: bktemp
author_rank: Super Contributor
timestamp: March 13, 2016, 06:56:09 pm
content: The HM1008 was designed and manufactured by Hameg. They should have both the service manual and the schematic, but they are probably not allowed to send them to you.I don't think the service manual would help much because it does not contain a schematic and the troubleshooting guide covers only the analogue path.For your problem it only says replace front board.Does it work in digital mode?There seems to be a dedicated microcontroller for the control inputs. That contoller seems to read the encoders using some multiplexers or analogue switches. Maybe all non working encoders are connected to the same multiplexer?

author: fra.gherard
author_rank: Contributor
timestamp: March 13, 2016, 07:20:36 pm
content: This is the Hameg replay at my mailQuoteIn digital mode i don't remember if it works, tomorrow i'll try.All the four non working encoders are connected to a shift register. I already replaced it, but still not working

author: Fraser
author_rank: Super Contributor
timestamp: March 13, 2016, 07:36:10 pm
content: Ah, now I understand, the ever helpful Hameg service department has goneI used to sell Hameg kit and have always liked it. I still have lots of Hameg test kit that is used regularly.Fraser

author: fra.gherard
author_rank: Contributor
timestamp: March 13, 2016, 07:51:51 pm
content: Also the website hameg has gone. I wrote them a mail the 26/01/2016 and the website was online, i searched the contact on it. Now all hameg results redirect to rohde-schwarz.just now i sent an email to rohde-schwarz italy for ask if the schematic are available, but i am not very confident about a positive reply....

author: bktemp
author_rank: Super Contributor
timestamp: March 13, 2016, 08:58:37 pm
content: Quote from: fra.gherard on March 13, 2016, 07:20:36 pmIf you already know where all four encoders are connected to, it should be easy to verify all signals going into the shift register and the data going to the microcontroller.My guess is, one signal looks strange or is missing and therefore the encoder signals are not sampled correctly by the shift register.I have a HM1508 and it has occasionally a similar problem. But it seems to be a sofware bug, because cycling power always solves the problem. But it happens rarely, so I don't care.

author: fra.gherard
author_rank: Contributor
timestamp: March 13, 2016, 09:32:24 pm
content: Do you have the schematics of HM1508?

author: bktemp
author_rank: Super Contributor
timestamp: March 13, 2016, 09:45:06 pm
content: No, unfortunately not. I only have the adjustment guide. If anything is wrong it tells you to replace the whole board. It is completely useless for component level repair.

author: fra.gherard
author_rank: Contributor
timestamp: March 13, 2016, 10:01:02 pm
content: The official support said me to change board, but the oscilloscope is not mine, so i don't decide I.

author: fra.gherard
author_rank: Contributor
timestamp: March 14, 2016, 07:14:39 pm
content: Rohde & Schwarz italy replied at my mail, but said the headquarters in germany does not send the documentation of instruments out of production from few yearsmaybe you, bktemp, can you try to ask Rohde & Schwarz if send you the manual, you are german and Rohde & Schwarz also...

author: Fraser
author_rank: Super Contributor
timestamp: March 14, 2016, 07:25:08 pm
content: Try the support address that you were given again. This time state that both Hameg CS and R&S Italy wanted to help and all you want is the schematic for the front panel PCB of this old and obsolete unit. Also state that it is for your own personal use and will not be shared.I have often managed to negotiate schematics out of companies that normally do not provide such. It' is all about the approach taken and perseveranceFraser

author: bktemp
author_rank: Super Contributor
timestamp: March 15, 2016, 12:02:51 pm
content: It shouldn't be difficult to reverse engineer the section. The design looks rather simple:4 encoders are connected to a 8bit shift register. This register is read by a microcontroller. Maybe there is an additional mux somewhere to select between both shift registers (there are 8 rotary encoders -> 2 signals per encoder -> 16signals -> 2 8bit shift registers). Or they are connected in series or parallel.Since you already have identified the shift register ic, did you check all the signals? There should be a shift clock and a latch clock. Maybe the latch or shift clock is missing or has a bad solder connection or a broken via somewhere.

author: fra.gherard
author_rank: Contributor
timestamp: March 15, 2016, 06:40:29 pm
content: Today i spoke with Rohde & Schwarz support. After some mail they sent me the service manual of HM1008-2, but there aren't the schematics. I requested it, but they haven't them.So, my boss said that is not convenient send the instrument to repair, and without schematics in quite impossible to repair it.In the next days during lunch break i will try to take some measurement with another oscilloscope