Measurement on memory with multimeter

[GGMM]

Hello,
I continue my tests on my DL1640 after changing 2 memories

https://www.alldatasheet.com/datasheet-pdf/pdf/6963/NEC/UPD45128163G5-A75-9JF.html

If you look at the datasheet you will see that there are actually VSSQ, VSS, VCC, VCCQ.
VSSQ and VSS appear to be interconnected on the PCB like VCC and VCCQ.
Given the implementation is done so it should work.
One thing that intrigues me is the multimeter measurement of the DQ outputs of one of the changed memories.
If I have the same result on the DQ pins, only the DQ2 seems inverted in the measure.
ex: To the digital multimeter 70Kohm/ ground and 0.6 Mohm if I reverse the wires. But on DQ2 I have the same result in the other direction of the wires.
In addition, I have an old analog multimeter that is more than 40 years old, and gives it the same result on all DQ.
I changed two of the four memories.
The other one’s good on all the DQs.
Other intricate, on the new memories the value is 70Kohm, while on the original on PCB  66Kohm. Other fabrication? Tolérance?
At the multimeter the VCC+VCCQ and VSS+VSSQ seem interconnected, but this may be internal memory connection. (??)
Unless a new memory is just out?. I always wondered why they deliver in batches of 5.  LOL
NB: if we could find the internal electrical diagram of this memory?

NB: Since the change I have a SNAP memory error on the memory test which can prove the anomaly and that I am actually making wrong road on the acquisition memory error.
I’m thinking of making bridges to be on connections for testing

After that, you can’t measure memory with a multimeter that can cause damage?

thank's for your answers
cdt

[GGMM]

No more answers, by it's solved.
In fact, the 4 memory pads for channels 1 and 2, and the other 4 for channels 3 and 4 of oscilloscope Yokogawa DL1640, must match the memory test SNAP memory. (In fact image or record storage)
As I tried to change 2 memories, I ended up with this concern. (Memory error acquisition, I thought it came from there)
It turns out, there was a 49 leg VCCQ connection that had to be defectful.
Doing this power bridge resolves the error.
Well, I find myself at the same point as the beginning, but at least I know what the test corresponds to.
For more, see my post on the Yokogawa DL1640 oscilloscope

see picture: now error memory snap resolved. in fact, it was a bad road in diagnostic.
I think the memory error is on this specific flat.
The welds being below, I will try the method of resolution as on the PS2, that is to heat to redo the welds. The hot air station is insufficient, so I will use a thermal decanter. I’ve already helped shrinks like that and I should have started with that.
Especially since the failure seems to have occurred after a long teps of non-use.
wait and see.

cdt

cdt

[Haenk]

(honestly, what's the point in a completely blurred ultra-hires picture of "something"?)

[GGMM]

Hello Haenk,

Sorry for the picture

Here the description of the chip  WINGAD. It's the chip on the picture
https://www.yokogawa.com/fr/library/resources/yokogawa-technical-reports/dl1640-dl1640l-digital-oscilloscopes/

I’m not an expert in English.
What I want to know is where the acquisition memory is.
Is it in this WINGAD box or elsewhere?
I’ve listed all the chips on this acquisition card, except 45128163 A75, no other memory chips.
I tried to reflow the WINGAD, the problem is still there.
If not, do we have to change the other 2 memories, at least the block of 4 will have been done? No documentation or schematic

cdt

[shakalnokturn]

Keep it going, I'm enjoying these topics.
My bets on your error codes would have been the AQP or acquisition memory. (Or maybe even somewhere between them considering the AQP is a large BGA... Tried applying pressure by hand to that see if it clears the self test errors?
You're not giving up are you...? I hope you get some answers one day.

[GGMM]

Hello, Shakalnokturn.

Thank you for your encouragements.
Yeah, for now, I’m not giving up.
I tried on the AQP to "heat it up" as I already did on Sony consoles. No more result, but I didn’t try to press it. I’ll do the test because visible on the bottom.
What I want to know is where the physical acquisition memory is. On this card, the only ones I saw are 45128163 G5 A75 9JF.
There are 2AQP and 2* 4 memoires on this card. (1 AQP + 4 memoires for channels 1-2 and idem for 3-4)
The question is: Whether these 4 memories, the SNAP processing and the acquisition
or just SNAP treatment?
I ask this question because by changing 2 memories I had a memory error "Snap" because of a bad connection. Now solved.
I can also do a test by isolating a DQ output from the 2 unmet memories to see if the Snap error reappears or not.
I list all the main components on this card, but no other memory a priori if you are interested.
4053BF, AG089LG,C319G,CY2305,152,4558,3771,DS90L,Quick logic 507,74HC04,F02SL,AABD,HEL11,LCX04,Y31S,313,MAX9691,31CC,LCX14,152,151.
There’s some left on the preamp part.
As a reminder, if you put a triangular signal for example, you see the shape of the signal, but it is like "filled", between the shape of the signal and the anointed grond, I think you know what I mean.
Some ideas
cdt

[Haenk]

If you check Figure 2, "Acquisition Memory", "Display Memory", "Data Processing Memory" and "CPU Memory" is shown as external (not integrated into AQP or WINGAD").
The Acquisition Memory has to be pretty close to the AQP. If you can provide a readable picture of the PCB, one might be able to find it...
(I assume it's some kind of two port SRAM, rather small in capacity.)

[GGMM]

Hi,
itry to list copoment on this board. no other memory than those already seen: 45128163 A75


C319G = Comparator
CY2305 =  3,3 V zero delay buffer
HEL11=Fan out buffer
LCX04=hex inverter
LT1097 = low cost op precision
LCX04= hex inverter
LCX14= hex inverter
4558=Dual OP amplifier
F02SL= serial input PPL synthetizer
3771= Power supply monitor
4053= Multiplexer  analogiq
74HC04 = hex inverter
Max9691 = single ultra fast output comparator
152 = 3,3 V linear voltage regulator
Y31S = Régulateur 3.v??
DS90LV=3V 400mbps quad differential line receiver
HV507PG 64 bits SRL // 3
unkrown  marked = 151, 152? AABD, Y31S...

+ specific chip AG089LG  and the 2 big A6289LG

cdt

[GGMM]

Hi,
in fact when i read here:
https://www.electronicdesign.com/home/article/21199767/understanding-long-memory-in-a-dso
https://www.testandmeasurementtips.com/making-best-use-acquisition-memory-digital-storage-oscilloscopes/

and the the presentation of DL1640 and 1640L
https://www.yokogawa.com/fr/library/resources/yokogawa-technical-reports/dl1640-dl1640l-digital-oscilloscopes/

The memory to change is there on picture.
2 chips  already changed, I change the other 2 at least we will know.
I think I’ve covered the problem. It may or may not work. At some point we have to decide.
cdt

[shakalnokturn]

I agree with whoever hinted that you're not helping yourself by starting a different topic on a question that is very closely related to the original one.

Without schematic it can be worth taking some time to gather better understanding of the equipment.

On CPU board I'd say that:
U401 is the display processing circuit with U403 as  display memory and (6 bit? R-2R) RGB output DACs built around U404, 405, 408, 409.
I'm not sure what SRAM U402 is for, possibly printer dedicated.
U502 would be the data processing memory.
U201, 202 the CPU memory.

So on ACQ/FE board the RAM would be dedicated solely to acquisition that needs plenty of bandwidth anyway.
However when replacing RAM if bad solder or short was on a line shared with another device (data processing memory?) that could cause your new SNAP error.

If you have access to a working oscilloscope try probing / comparing acquisition RAM lines for at least a quick signal integrity check. If your hands are steady enough you could even try feeding the same input on CH1+CH3 with exact same gain and offset settings and do simultaneous comparisons between RAMs for 1+2 and 3+4 it may make differences more obvious.
But not really knowing how the self test routine works to detect the RAM errors it could be an idea to start by comparing ADC outputs as they are few compared to acq. RAM.


Interesting to note that the amount of acquisition RAM physically available is 32kB per chanel even on a non "L" model meaning that the "L" memory could be unlocked either by a jumper software code or firmware revision

[GGMM]

Thank you for your answer Shakalokturn

I agree with you about the CPU card and its memories. They have to match with a dedicated feature.
For example, you can control an internal printer.
There are a priori other similar memories U203 to U213 that probably pilot other things (port serie, ...)
You may have documentation I couldn’t find (manual service??)
Regarding the acquisition card what is important to understand both operation and failure, is to know where the acquisition memory is.
 
1) Can you confirm that it is part of the block of 4 memoires U911 to U914.
Ram made of 4 circuits 45128163 A75 .?

2)Does this memory manage both the acquisition and the Snap?

Indeed I had a bad weld on the U913 DQ8 after the change of U913 and 914 hence the SNAP error and always the acquisition error.
After welding correction, re-test and still only acquisition error.
That day, I did another test, I unsoldered the U911 memory, and without reassembling one, I started the test. Result: the same acquisition error.
So I’m wondering if the acquisition part is on U911 or U912.
So I’m going to replace U911 and test it. That will make 3 of 4 memories changed.
Will remain at worst to change U912, in this case the 4 will be new.
NB: it is not possible to watch the signals on the RAM, the cpu board is above.
+ it became very easy to remove memory them with my pliers to cut each leg. LOL
Thank you for your answers

[shakalnokturn]

No service manual unfortunately.

Yes the acquisition RAM is the parts you have been changing. I'm no expert on the question but as previously said I doubt they have anything to do with "SNAP".

This is a lot of guessing but to me "SNAP" would be the data processing memory, if you want to be certain desolder a data or address line to U502 and see the error that returns. You could also trace back testing continuity from U913 -DQ8
 to see if that shares a common bus (there could be a latch between) with U502 on CPU board.

Because you're in the dark without schematic or probing replacing the Acq. RAM is "sort of" the thing to do as they're the only non-custom suspicious parts. I would have gone about it cross testing by swapping RAM one by one from side 1+2 <-> 3+4.
It's worth the try even if in the end you may find out you have a bad AQP.

[GGMM]

Hi, Sakalnokturn,

I don’t touch the 3-4 channelsl side RAM that work.
Besides, I can’t make the exchange because it’s a hell of a hassle to undress if you want to keep memory pins intact.
I anticipated the change in the channel side 1-2.
So I received a lot of memoires (5) with the same references, already changed 2, so I have 3 for the last 2, including one already disassembled.
I’m changing them tomorrow
So I remain hopeful that it will come from there.

NB:Yes it is difficult to find the documentation. Only advertising for this model

Cdt