zuldan wrote on 2025-04-17, 12:03:

feipoa wrote on 2025-04-16, 12:49:

It's been a few months. How did the new chips work out for

The stick I made didn’t work at all unfortunately. I suspect I need to use different memory chips. I did manage to find an original coast module and the motherboard detects it but nothing uses the cache PCChips M919 Cache Stick not being used [FIXED]

Have you re-tested that one you made since you finally got the 256k one to work? Or, best not touch it anymore? 😀

bertrammatrix wrote on 2025-05-09, 20:48:

zuldan wrote on 2025-04-17, 12:03:

feipoa wrote on 2025-04-16, 12:49:

It's been a few months. How did the new chips work out for

The stick I made didn’t work at all unfortunately. I suspect I need to use different memory chips. I did manage to find an original coast module and the motherboard detects it but nothing uses the cache PCChips M919 Cache Stick not being used [FIXED]

Have you re-tested that one you made since you finally got the 256k one to work? Or, best not touch it anymore? 😀

I’m not going to touch the stick that’s in their now 😉 It wouldn’t be worth testing the stick I made since the motherboard didn’t detect it at all. Either I missed soldering 1 leg on memory chip or the memory chips I used aren’t compatible.

For anyone wanting to make their own stick I highly recommend using a soldering hot plate and solder paste. It’s a lot quicker and you probably have a much better chance of getting all the legs of each memory chip to make contact with the PCB. Soldering the stick together is a b***h.

Yesturday, I assembled another one of these M919 modules, using JLCPCB with 2U gold. I used 8 ns TSOP chips, which barely fits the solder pads. Plugged in the module, but it didn't work. A had my solder paste in the cooler, so I couldn't use it until it thawed, thus, I hand soldered the chips. Problem with TSOP and hand soldering for the M919 is that the iron tip cannot make direct contact with the PCB pads (TSOP leads are too long). To hand solder, I used flux and had to press down firmly on the TSOP lead so that it would also transfer heat to the pad at the same time. It took the solder just fine. I measured each pin to ensure they were making contact.

Why did the module not work?

Some analysis revealed that there's only 86 ohms between Vcc and GND, so either an SRAM IC is bad, a capacitor is bad, or some solder/lead is pushing through the solder mask somewhere. Looking for a small variation in the VCC to GND resistance should reveal the culprit as I probe around with the DMM. As one side of the cache stick gets much warmer than the other, I already have an idea where to look. My guess is that one of the SRAM chips is bad, either from the factory, or having to heat it too long with an iron tip.

Something else I noticed: this batch of gold PCBs has a thickness of only 1.55 mm to 1.56 mm, whereas my last batch was 1.61 mm to 1.62 mm. Measurement was taken off the gold contacts. That's a 70 um variation, which is more than I hoped it would be. The cache module fits looser in the slot and the slot pins don't make as much of a mark on the module's contacts. I don't know how much of a factor PCB thickness is in module performance, but of the 7 or so modules I've assembled, the best performers were of the thicker variety.

I looked on the JLCPCB website and was stated that they allow for +-10% tolerance on PCB thickness, or 140 um. I was wondering if we should be ordering these with the thicker 2 oz copper option for the outer copper weight? Their website mentions that the thicker copper adds 35 um to the height. Multiply that by two sides, and it is 70 um. Maybe this is how we can force a slightly thicker PCB? On the down side, this option increases the cost by $30, that is, for 10 units, the price goes from approx $62 to $92 USD.

feipoa wrote on 2025-05-10, 01:17:

Yesturday, I assembled another one of these M919 modules, using JLCPCB with 2U gold. I used 8 ns TSOP chips, which barely fits t […]
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Yesturday, I assembled another one of these M919 modules, using JLCPCB with 2U gold. I used 8 ns TSOP chips, which barely fits the solder pads. Plugged in the module, but it didn't work. A had my solder paste in the cooler, so I couldn't use it until it thawed, thus, I hand soldered the chips. Problem with TSOP and hand soldering for the M919 is that the iron tip cannot make direct contact with the PCB pads (TSOP leads are too long). To hand solder, I used flux and had to press down firmly on the TSOP lead so that it would also transfer heat to the pad at the same time. It took the solder just fine. I measured each pin to ensure they were making contact.

Why did the module not work?

Some analysis revealed that there's only 86 ohms between Vcc and GND, so either an SRAM IC is bad, a capacitor is bad, or some solder/lead is pushing through the solder mask somewhere. Looking for a small variation in the VCC to GND resistance should reveal the culprit as I probe around with the DMM. As one side of the cache stick gets much warmer than the other, I already have an idea where to look. My guess is that one of the SRAM chips is bad, either from the factory, or having to heat it too long with an iron tip.

Something else I noticed: this batch of gold PCBs has a thickness of only 1.55 mm to 1.56 mm, whereas my last batch was 1.61 mm to 1.62 mm. Measurement was taken off the gold contacts. That's a 70 um variation, which is more than I hoped it would be. The cache module fits looser in the slot and the slot pins don't make as much of a mark on the module's contacts. I don't know how much of a factor PCB thickness is in module performance, but of the 7 or so modules I've assembled, the best performers were of the thicker variety.

I looked on the JLCPCB website and was stated that they allow for +-10% tolerance on PCB thickness, or 140 um. I was wondering if we should be ordering these with the thicker 2 oz copper option for the outer copper weight? Their website mentions that the thicker copper adds 35 um to the height. Multiply that by two sides, and it is 70 um. Maybe this is how we can force a slightly thicker PCB? On the down side, this option increases the cost by $30, that is, for 10 units, the price goes from approx $62 to $92 USD.

I finally got that memory module, so tested and sent a message.

Long story short, it's starting to look more like the 12ns chips on my 1mb module just cant cope with faster timings at 60mhz 😒

Some can, some can't.
I have one 12 ns module that works fine at 60 MHz and 2-1-2, and another module which does not like this speed.
I have one 8 ns module that works fine at 60 Mhz and 2-1-2, and another module which does not like this speed.
I have one 10 ns module that works fine at 60 Mhz and 2-1-2, and two other modules which does not like this speed.

I guess socketing the IC's on module would make it too big?