TDS 540 problem III

[vaualbus]

This posts continue my TDS540 repair adventure and sega .
Now the scope is turning on but now every time it fails acquisition and sometime acq/processor interface (when the scope is working for a whil it don't fail).
It show waveform to all of the channel but there is some imperfaction. I show those in one picture.
I will post the image regarding the error I get in the log. Every time it fails the signal path test.
For what I can figure out, There is memory curraption.

Despite that, anyone know which memory chip we could use to replace the current acq memory?
And anyone have a memory map for the TDS540.
I have understood that the memory error refer to channel 4(adress 0x73xxx) but what chips give the two error (adresses 0x73c0046 and 0x79c00c6)?
And this errors means: 
- Insufficient differential response DigA gain cal,
- Call means clipped at max dig output , Ch2 balance call of attenuator
- Calibration failed trigger (ERROR 2260)

Anyone can help me to figurate what is not working?
This is the link for the images: https://dl.dropboxusercontent.com/u/89622982/TDS540%20Images.zip

[AlfBaz]

I haven't been following your repair posts so maybe it already been suggested, have you tried downloading the service manual to see if it gives you any hints regarding the errors it showing?

[vaualbus]

Ya, no info in fact I have to buy the manual from artekmanual (the TDS540 is different from the TDS540A), and it have only the second volume called  "component level dignostic and repair manual volume 1" that have only the repair digram for find the probelem and the schematic. It even not have the component list and the cricruit description! (sometime on this diagram, it said to look volume 1!)
Pheraps in the first volume there is all the info I need (but artekmanual haven't got them). If any body have this ducument please send me the file.
I also searching for the calibration software called adjustement software for the TDS540.
I not found any place where each error is describe.
Now I wish somebody give me some hint.

[nctnico]

IMHO you need to clean the boards thouroughly, replace all the capacitors, resolder oxidised joints (add flux and fresh tin) and check for shorts. You can download the TDS520B component level service manual from Tektronix. These scopes (TDS500, 600, 700 and 800 series) are all based on the same design.

[vaualbus]

And you are wrong the think you said is faild but the B is a new revision and it have a lot of more hybrid integration even in the psu they use a custom transistor that have inside a pwn control!
So the manual are the same if I have a TDS540B but I have TDS540.

Ya, but in my unit all the capicitaor has been arleady changed before I get it and the board is cleaned.
Now I have to figure out what cause error on ch4 acq memory.

[nctnico]

If there are pieces of the signal missing then it seems like one of the address lines are shorted. I'd look for a drop of solder where it doesn't belong.

[vaualbus]

Now I've removed all the 68 caps from the acq board but it is strange because I've measured the resistence and according to the manua the resistence of the -5.1V is only 17.9ohm, for me is a semi short circuit. I'm right?