Yes the solder blob can be easily sucked with a litz wire and I'll be back in original state within a minute when needed 😀

UPDATE: there are 2 "T" structures, each on one side. Both contains 0-ohm resistor...

Sphere478 wrote on 2024-04-09, 17:11:

Never bypass pullups/pulldowns like that if what was done is what I think was done. There is an example of someone doing this in the tillamook thread, I had to fix the procedure for them 🤣. Anyway, following their method it sometimes blows up a resistor.

Ah, I'd wondered if there might be a problem using boards that actually used the REGE pin, relieved it's just blowing a resistor. Must be quite a low value resistor for it to blow?

Sphere478 wrote:

I would have to look at this circuit closer to see what exactly is going on, but snufkin, could a smd resistor replace that solder blob?

Maybe, but it'll start to matter what value is used. A quick recap: On my Micron stick then there's already a 10k pull up on the input to the inverter, so that if nothing drives REGE (pin 147) then the output from the inverter will be low, so the stick will be registered. I removed the inverter and used two pads provided nearby to bypass the inverter. That means the 10k pull up is connected to the LE pin on the register chip, putting it in transparent mode. If a motherboard tries to drive the pin high then nothing happens. If a motherboard tries to drive the pin low then a current of around .33mA will flow. So nothing should break, but does mean the stick operates back-to-front: if the board tries to set the stick to registered then the stick will be unregistered. So there's a good chance that the stick won't work in a board that actually supports switching from registered to unregistered.

So, if the inverter isn't removed then the problem becomes how to neatly have the input to the inverter be default low, but without becoming a risk to the motherboard. That can either be done by lifting one end of the existing 10k pull up and connecting it to a convenient GND (I think that's what I'd do now). Or add a pull down resistor to the input that's strong enough to overcome the 10k pull up so that the input is still read as low.

The datasheet for the register chip on the Micron stick says that for a 2.5V input then an input must be under 0.7V. So I'll aim for 0.5V on a 3.3V supply. That'd mean a 2.8V (3.3V - 0.5V) drop over the existing 10k resistor, which would be .28mA. So if a pull-down was 1.79k then the input voltage would be 0.5V ( 0.5V / .28mA = 1.786kohm ). Using a smaller resistor will pull the input closer to GND, but also increase the current to a few mA (~3mA) if REGE is ever driven high.

Short version... Adding a 1k resistor between the input pin and GND should make the stick default to unregistered and keep the stick working as expected if the motherboard tries to drive REGE either high or low. Still not guaranteed to work in a motherboard that supports registered because a motherboard might rely on the stick default being registered, so could just leave REGE floating and expect that to set the stick to registered.

RayeR wrote on 2024-04-09, 20:37:

UPDATE: there are 2 "T" structures, each on one side. Both contains 0-ohm resistor...

That sounds right. Rotating both 0-ohm resistors seems to pick 3 different settings, I think for clock phase, one of which will give you the best timings. Clock signal comes in on one link, through a via, I think to a loop on an internal layer, through a via to the other side of the stick, through the second link, and back to the clock feedback. I'm assuming each of the 3 positions has a different internal loop length.

snufkin wrote on 2024-04-10, 17:01:

Ah, I'd wondered if there might be a problem using boards that actually used the REGE pin, relieved it's just blowing a resistor […]
Show full quote

Sphere478 wrote on 2024-04-09, 17:11:

Never bypass pullups/pulldowns like that if what was done is what I think was done. There is an example of someone doing this in the tillamook thread, I had to fix the procedure for them 🤣. Anyway, following their method it sometimes blows up a resistor.

Ah, I'd wondered if there might be a problem using boards that actually used the REGE pin, relieved it's just blowing a resistor. Must be quite a low value resistor for it to blow?

Sphere478 wrote:

I would have to look at this circuit closer to see what exactly is going on, but snufkin, could a smd resistor replace that solder blob?

Maybe, but it'll start to matter what value is used. A quick recap: On my Micron stick then there's already a 10k pull up on the input to the inverter, so that if nothing drives REGE (pin 147) then the output from the inverter will be low, so the stick will be registered. I removed the inverter and used two pads provided nearby to bypass the inverter. That means the 10k pull up is connected to the LE pin on the register chip, putting it in transparent mode. If a motherboard tries to drive the pin high then nothing happens. If a motherboard tries to drive the pin low then a current of around .33mA will flow. So nothing should break, but does mean the stick operates back-to-front: if the board tries to set the stick to registered then the stick will be unregistered. So there's a good chance that the stick won't work in a board that actually supports switching from registered to unregistered.

So, if the inverter isn't removed then the problem becomes how to neatly have the input to the inverter be default low, but without becoming a risk to the motherboard. That can either be done by lifting one end of the existing 10k pull up and connecting it to a convenient GND (I think that's what I'd do now). Or add a pull down resistor to the input that's strong enough to overcome the 10k pull up so that the input is still read as low.

The datasheet for the register chip on the Micron stick says that for a 2.5V input then an input must be under 0.7V. So I'll aim for 0.5V on a 3.3V supply. That'd mean a 2.8V (3.3V - 0.5V) drop over the existing 10k resistor, which would be .28mA. So if a pull-down was 1.79k then the input voltage would be 0.5V ( 0.5V / .28mA = 1.786kohm ). Using a smaller resistor will pull the input closer to GND, but also increase the current to a few mA (~3mA) if REGE is ever driven high.

Short version... Adding a 1k resistor between the input pin and GND should make the stick default to unregistered and keep the stick working as expected if the motherboard tries to drive REGE either high or low. Still not guaranteed to work in a motherboard that supports registered because a motherboard might rely on the stick default being registered, so could just leave REGE floating and expect that to set the stick to registered.

RayeR wrote on 2024-04-09, 20:37:

UPDATE: there are 2 "T" structures, each on one side. Both contains 0-ohm resistor...

That sounds right. Rotating both 0-ohm resistors seems to pick 3 different settings, I think for clock phase, one of which will give you the best timings. Clock signal comes in on one link, through a via, I think to a loop on an internal layer, through a via to the other side of the stick, through the second link, and back to the clock feedback. I'm assuming each of the 3 positions has a different internal loop length.

In that case I was lucky that that’s all that happened. It’s a bad thing to 0 ohm that bridge. You need a value high enough that it can survive and make a voltage divider. Which is how those work usually basically. (On BF pins on cpus)

snufkin wrote on 2024-04-10, 17:01:

That sounds right. Rotating both 0-ohm resistors seems to pick 3 different settings, I think for clock phase, one of which will give you the best timings. Clock signal comes in on one link, through a via, I think to a loop on an internal layer, through a via to the other side of the stick, through the second link, and back to the clock feedback. I'm assuming each of the 3 positions has a different internal loop length.

Is it needed to run (stable) the modules at nominal 133MHz speed?
Currently I don't have usage for the modules at this speed as my 440BX MBs don't take 512MB modules anyway (I use 3x 256MB double-sided modules there).
And in GA-5AA they run probably at lower speed, I don't know exactly what FSB2SDRAM ratio that Ali chipset use but I guess no more than 100MHz. I tested both modules and they passed test in GM (it took ~5 hours total). Also this Ali chipset is a piece of f* crap, as I mentioned in other thread, when FSB is set higher than 66MHz (I tried 75, 83, and 95MHz) then memory transfer rate (and also overal system performance) significantly degrade compared to 66MHz FSB. There's no explicit option to set some FSB2SDRAM ratio in SETUP (EDIT: according to M1541/M1542 datasheet it seems SDRAM runs synchronously with FSB, max official supported speed is 100MHz, Gigabyte added some overclocking). So currently I don't need to do any speed tuning on the modules. Do you tried all options? What's the best?

RayeR wrote on 2024-04-10, 20:21:

Is it needed to run (stable) the modules at nominal 133MHz speed? Currently I don't have usage for the modules at this speed as […]
Show full quote

snufkin wrote on 2024-04-10, 17:01:

That sounds right. Rotating both 0-ohm resistors seems to pick 3 different settings, I think for clock phase, one of which will give you the best timings. Clock signal comes in on one link, through a via, I think to a loop on an internal layer, through a via to the other side of the stick, through the second link, and back to the clock feedback. I'm assuming each of the 3 positions has a different internal loop length.

Is it needed to run (stable) the modules at nominal 133MHz speed?
Currently I don't have usage for the modules at this speed as my 440BX MBs don't take 512MB modules anyway (I use 3x 256MB double-sided modules there).
And in GA-5AA they run probably at lower speed, I don't know exactly what FSB2SDRAM ratio that Ali chipset use but I guess no more than 100MHz. I tested both modules and they passed test in GM (it took ~5 hours total). Also this Ali chipset is a piece of f* crap, as I mentioned in other thread, when FSB is set higher than 66MHz (I tried 75, 83, and 95MHz) then memory transfer rate (and also overal system performance) significantly degrade compared to 66MHz FSB. There's no explicit option to set some FSB2SDRAM ratio in SETUP (EDIT: according to M1541/M1542 datasheet it seems SDRAM runs synchronously with FSB, max official supported speed is 100MHz, Gigabyte added some overclocking). So currently I don't need to do any speed tuning on the modules. Do you tried all options? What's the best?

I think I had problems getting 133 / CL3 stable in the initial position and it was then stable (24 hours memtest) after repositioning those links. I suspect that the best position will depend on too many small things (buffer propagation delay, bus capacitance, ...) for there to be one good position, otherwise why have option? With the buffer still in place then the added delay means the stick is never going to be as fast as an unbuffered stick. But if you're already at the limit of the motherboard then none of that really matters.

Just adding some photos...

Ahhh get rid of that blob! Use a resistor 🤣

Looks like the PCB is the same as mine, so there's the option of moving the current 10k pull-up resistor that's on the back, by soldering on to the vias. Either above pins 147&148, or just to the side of the original pads. Easy enough to undo, leaves the inverter in place, should look reasonably neat, doesn't mean finding a single tiny resistor, and doesn't leave the small chance that the shorted-to-ground version ever finds its way on to another board.

Assuming I can still find the inverters I took off of mine then I think that's what I'd be doing.

[edit: Don't use the vias by the pins. I was being dumb and didn't realise that the via above pin 147/REGE connects to the pins on the front of the stick. So just use the vias to the side of the original pads]

I'll add some 0201 resistors on future order... 😀