LC575 64 MB SIMM memory issue

[LC_575]

I just recently bought a 64MB memory module to max out my LC 575. Bought from this page here:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160527757777&ssPageName=STRK:MEWNX:IT

It came in the mail today. Packaged fine, took it out, put it in the LC, and booted it up. About This Mac says that there's only 20,000K of built in memory. Recall that the LC has 4MB built in, so the module is only putting out 16MB.

Huh? That's odd. i figured that if something were wrong, there'd be all or nothing. Reboot, extensions off, and it's still only 16MB.

Take it out, put it into my Performa 6300, and it too says it's 16MB!

Unless the module is very defective, the 64MB module I paid for is only a 16MB module.

Who do I complain to first? eBay or the seller?

 

[Strimkind]

They could have easily shipped you the wrong RAM...talk to the seller first before going to ebay/paypal.

 

[Anonymous Freak]

Always try to fix with seller first. If it's an honest mistake, they'll make it right.

Also, look up the SIMM's model number online, and see what technology it is. It's possible that it is the full 64 MB, but just not compatible with your system. (Like certain 4 MB 30-pin SIMMs with 30-pin-taking Macs.)

 

[LC_575]

I contacted the seller and received this message in reply:

"

You bought the wrong memory for your Apple Macintosh computers. Both of them (LC 575 and a Performa 6300CD) can take a max of 32MB simm made of two memory banks. These 64MB simms we sold are 64MB made of a single memory bank. Each of your Apple Macintosh computers can read up to two memory banks at 16MB each. Therefore, it can only read 16MB out of the total 64MB simms.

"

Now I KNOW that the Performa can accept 64MB modules, and the LC should too. Or does he know something that I don't know?

 

[LC_575]

For those interested, the RAM chip's model num is:

SIEMENS

HYB3165400AT-60

9820

 

[LC_575]

According to this reference data sheet:

http://www.datasheetcatalog.com/datasheets_pdf/H/Y/B/3/HYB3164400AJ-60.shtml

Each chip is 64 Megabits, or 8MB. And there are 8 chips total, so 8*8=64MB

Well then it is a 64MB module! But why will only 16MB be detected?

 

[trag]

It shouldn't work at all. According to the datasheet the memory uses a 3.3V supply. Is there an additional component on the SIMM which could be a voltage regulator? Might have three pins or a little IC with eight to twelve?

Also, are you sure the chips are HYB3165400AT? Because you list the datasheet for the HYB3164400AT which also won't work, but the one datasheet covers both chips, so that's probably okay.

Anyway, eight 16M X 4 organized, 5V memory chips with 12 X 12 multiplexing should work in the LC575. IIRC, people have successfully used both 64MB and 128MB SIMMs in that machine. So a single bank 64MB SIMM would be fine.

Now if they had used HYB3164400 then the chips would have 13 X 11 multiplexing for the addressing and that would not work. but you'd see half the capacity, not 1/4.

Anyway, I think what you have there is a 3.3V EDO SIMM, which is odd. I'm not sure what ever used such a thing. But if there is a little voltage regulator on there, then it could run on a 5V system (I have a few SIMMs like that) in which case something is defective in the SIMM.

For compatible memory, look for something like an HP D4290 (64MB) or HP D4893 (128MB). There are also some Samsung part numbers for the same SIMMs (pretty sure Samsung manufactured them for HP). Ah, here's the Samsung number for the D4290, KMM53616000BK. I've seen nearly identical SIMMs from Kingston and IBM and the thing they all have in common is that they're made with KM44C16100 memory chips, which are 16M X 4, 5V, 12 X 12 chips. I'm not sure anyone else made 5V 16M X 4 chips. All the Micron chips I've seen in 16M X 4 are 3.3V and SIMMs made with them to run in 5V systems have a voltage regulator on board somewhere to make it work.

On thing I've learned with memory and hard drives. If the seller can't be bothered to post critical information like the operating voltage and speed rating for memory and the type of SCSI connector for SCSI drives, then it's usually not worth wasting your time trying to do business with them.

But again, it could be a 5V SIMM if it is using a voltage regulator, and the seller might not realize that there's anything besides 5V 72 pin SIMMs.

 

[LC_575]

There appear to be three capacitors along the contact edge, but besides that nothing interesting.

See pic:



Uploaded with ImageShack.us

 

[Unknown_K]

How can you say you were conned? You paid for a 64MB SIMM and that is what you purchased. As a buyer you need to know what kind of RAM you need to buy for your specific application. If the seller stated it was 64MB SIMM for a LC-575 then you would have a reason to complain.

For example I got a spare Thinkpad T22 recently and needed RAM for it. I also wanted the biggest SODIMM I can get, which happens to be 256MB LOW DENSITY, 16 chips per module. There are plenty of 256Mb PC100 DIMMs on ebay, most are high density and will not work (but few will even mention density). So what I do is read the advertisements and double check the model number on the SODIMM to make sure it works. Luckily for me somebody was selling a Samsung SODIMM as working in a DELL laptop 128MB but I researched the model number (mostly because the SODIMM looked exactly like a 256MB module) and found out it was a 256MB SODIMM, lucky for me I got it for $6 shipped and it works fine.

Lowendmac.com and some other sites will tell you the limits on RAM and what to look for, it is not that hard to do some research before you get the paypal out and buy something.

 

[LC_575]

Look, I didn't know at the time. I know NOW that it's an actual 64MB module. If I could change the post title I would.

In fact, I will. Note to Mods: please change this topic's title to "LC 575 Memory Problem."

And I did do my research prior to buying. I thought this would have worked fine. It's not like the seller posted the chip numbers of the module itself on the ebay page.

 

[Unknown_K]

Well if you knew you needed a special RAM type and none were listed then taking a chance (if cheap enough) is no big deal, I have done it myself with good and bad results.

 

[LC_575]

That's exactly why I looked for something with free shipping.

 

[trag]

Well, you only showed me one side of the SIMM there. There could a voltage regulator on the other side, unless there is nothing on the other side except four more memory chips.

If there are just four more memory chips on the other side, then this is a 3.3V SIMM. Again, I don't know why you'd get 1/4 capacity out of it. I would expect it to not work at all. I'm also not so sure about there being 3.3V 72 pin SIMMs. But maybe there were.

 

[LC_575]

The other side is just memory chips.

 

[trag]

The other side is just memory chips.

Then that thar is a 3.3V SIMM. Still puzzled that you'd get 16MB of capacity reported from it, but electronics can be weird.

 

[LC_575]

Looks like it's time to ship it back. I'll ask the guy if he has modules that WILL work in a Performa 6300CD/LC 575.

Speaking of that, what specific type of mem is needed? Single banked, low density, etc?

 

[Dennis Nedry]

Those are not caps, they are diodes, and they are the voltage regulator. Connected in series, each has a small voltage drop. The advantage of using diodes in series is that the voltage drop is fairly immune to current fluctuation, as would be a serious issue with using series resistors. They are also cheaper than a real regulator.

 

[trag]

Those are not caps, they are diodes, and they are the voltage regulator. Connected in series, each has a small voltage drop. The advantage of using diodes in series is that the voltage drop is fairly immune to current fluctuation, as would be a serious issue with using series resistors. They are also cheaper than a real regulator.

Yep. What Dennis said. I didn't see that until he mentioned it. The positions are labeled Dn rather than Cn. If each diode causes a .6V drop, that will take 5V down to 3.2V. Or it could be .5V drop or .7V drop...

Still, the SIMM doesn't work.

Single bank, 16M X 32, 5V SIMM with 12 X 12 chips. Another way of saying the 12 X 12 part is 4K refresh.

Also, eight chips. Twelve is okay if it's a parity SIMM. But not 32 chips.

 

[LC_575]

Just got email from the seller. I asked about exchanging this module for one that WILL work in an LC, mentioning that it has to be single banked. He replied by in forming me that the one I received IS single-banked.

:?: