Electronics > Repair
Hameg HM8118 repair
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TRN:

--- Quote from: Hamelec on November 22, 2023, 10:31:02 pm ---have a look into the comments of
Maybe Michel.Waleczek (at) gmail.com can help you out with a manual...

--- End quote ---
Hamelec,

Thanks for this info, and I have contacted Michel, who responded that he is currently enjoying his vacation
I will contact him again once he is back home
TRN:

--- Quote from: jchw4 on November 23, 2023, 09:36:42 am ---
--- Quote from: Hamelec on November 23, 2023, 08:38:01 am ---cant believe that it is a failure of the display themselfes, more of the flexboard/connector or driver unit

--- End quote ---
Exactly.

The flex bonding looks very suspicious:
(Attachment Link)

Does it normally fold the flex cable back behind the display? I would try pressing the bond with pencil eraser and see whether it helps.

My personal experience with trying to heat up and re-bond the flex cables under stress has been negative so far. It works until you fold the cable in place and then detaches again.
You may be able to fold a piece of sheet metal to make a clip and attach it to the top to hold the flex cable. It worked for me once...

--- End quote ---

Your hunch about the suspect flex bonding was correct.👍

With the lcd installed in the unit, I flexed the cable in different positions, while booting the unit, and it booted once with a beautiful full working display.
I then removed the lcd, put some light pressure on the bonding area, and reinstalled the lcd
Unfortunately after this no more luck, so I must have screwed something up👎
Anyway this proved that the lcd matrix and 2 controlers are ok.
Does anybody know any company (preferably in Europe) which repairs flex bondings, and if so, what would be the estimate repair cost?
TRN:

--- Quote from: coromonadalix on November 26, 2023, 02:29:43 am ---the last resort would be to snif out the communication protocols with an logic analyser and figure out wich controller by chance they are using and finally finding the right lcd ??

--- End quote ---

Sniffing out the communication protocol, is probably doable, but trying to find the controller type will be a hard nut to crack
coromonadalix:
well i checked the video   since some comments are in french (im native french)

there was a substitution with an LCM 219  with a different bootloader  for this lcd ....   and this one too is a tough one to get


R&S  get  bad points here for repairability, and for sure they know it

it would mean to trace down  lcd pinout on the main board and try to figure out the data lines etc ...  i would be able  if i have this lcr  ... wich i dont


look like a 40x8 characters lcd for sure .... if i count them in their user manual images  ....  i dont think its a graphical one ??
CJay:

--- Quote from: coromonadalix on November 26, 2023, 02:06:53 pm ---

look like a 40x8 characters lcd for sure .... if i count them in their user manual images  ....  i dont think its a graphical one ??

--- End quote ---

I'm pretty convinced it's a graphical LCD, the third picture has an uninterrupted line of pixels down the display, character LCDs generally have 'gaps' between rows of characters.

Looking at the includes and source files in the video linked give the impression it's a graphic one too, LCDDRAW.C and LCDTEXT.C, plus the Epson.c might indicate it could an Epson (compatible?) controller?

The pictures are nearly good enough to count the pixels, I think it's almost definitely 64V just by counting but obvs counting pixels that aren't visible on the RH side makes it tricky, maybe 128H making it a  128x64 (maybe 138 which would mean custom?).

There's 2 chips mounted on the glass and the flat flex looks as though there's a bunch of vias so they're 'in parallel' for the data and probably most control lines so there'll be a 'chip select' line somewhere.

It might be useful to know the physical dimensions of the display.

****Also might be interesting to see a little more of the CPU and memory, if it's got external program memory or there have been firmware updates it might give some clues to examine the contents?****

Interesting, uses a PSD chip so it's 8052 based, firmware update is likely encrypted though :(



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