What to do with my VXL-30?

[Munchkin]

My 500 works absolutely fine after recap and a new PSU. My VXL-30 works fine as well, the problem is that the RAM-32 doesn't.

One or a few of the 20 pin DIP's are fauly which causes crashes when those memory addresses are accessed. The VXL-30 is more or less worthless without 32-bit ram, it's barely faster than the stock 500, so it really needs working RAM to be fully useful. As it is now it has 2MB, 16 256kx4 DIP's. Ideally I would love to find 16 1Mx4 DIP's but I can't even find the 256k ones to replace the one's that are faulty. I don't even know an easy way to find out which one(s) are faulty.

So, what are my options, besides ordering a Vampire which I prefer not to? Since the 50MHz 68030 on the board as well as the 68882 FPU are, as far as I know, in good working order the best option would be to find som kind of board that I can move them over to, preferably something with more than 2MB RAM but some is better than none. I've seen the terriblefire but it doesn't seem to be avaliable anymore.

Ideas are welcome. Of course I can go back to a stock 500 but that's not as fun.

[dalek]

See here for a list of part numbers for 1Mx4 DIP DRAM - you can find them on eBay/aliexpress/ etc.  Though your luck from China may vary as there are a lot of fake non/working chips about.

http://www.amiga-stuff.com/hardware/1mx4-dram.html

I would find a plain old 512KB trapdoor expansion that takes your DIP RAM and use that to test the chips without the accelerator to work out which ones are good/bad.

If you can solder SMD then there are DIP -> SOJ adaptors available.  You can find old SIMMs with the SOJ variants of the DRAM and solder them to DIP adaptors.
  example: https://www.ebay.com/itm/New-4x-Adapters-for-SOJ20-DIP20-Memory-CHIP-RAM-Amiga-500-2000-549/122327379622

You've got a good accelerator, fixing the RAM would be the best way forward IMO.

[Munchkin]

I know it's a great card, that's why I prefer to keep it but finding the DIP's isn't that easy.

I know about the SOJ adapters. Problem is the DIP sockets are to close, they won't fit, unless I make different length on the legs of course. It won't look pretty but I guess it's doable. My soldering experience is good enough to replace caps but soldering SOJ's are a bit more than I dare to venture into though.

I know about the risks in buying chips from ebay and such, it's not fun to spend a lot of money only to find they're fake. Have tried to find some kind of reliable source but haven't found any. Since the board requires either 60 or 80ns, I don't know for sure if this is extremely important or not but the instructions says so, it's a bit harder to find as well since the few I've found have been 70ns.

Tricky bit this. It would be wonderful to find 16 1Mx4 DIP's  but I guess the SOJ route is a better one, if I can find someone that can solder them for me.

[hirschma]

I could make populated adapters that would fit, if there was enough demand. And if someone could get me the datasheets for the DIP memory, and the SMT chips that would be compatible.

I run a PCB assembly shop

[Oldsmobile_Mike]

Hi, just popped in and saw this thread.  I might still have a tube of the chips needed to bring it up to 2MB.  Can't recall if I got rid of those or not.  Will try to take a look around later.  I upgraded mine from 2MB to 8MB years ago, since I also had 8MB 16-bit fast in a GVP sidecar and 2MB chip, having an 18MB A500 was pretty nice.     Worked for years but I think my ram board finally crapped out, the past year or so It's crashed when I tried to activate the ram on it.  Oh well, maybe I shouldn't have overclocked it.

Should probably send it off to someone with more experience fixing these sort of things, but just haven't had any time for Amiga stuff the past year or so.  Will take a look around for that RAM, anyway....

[Motormouth]

Like you said.  the VXL-30 is mostly useless without a the RAM32.  I made a mistake by buying one back when they came out and could not get the ram32.  It took me forever to find one and it was overpriced.

Back to the ram.  Sometimes the ram comes up on Fleabay.  20 pin dips were fairly popular back in the day.  But Alas the 256kx4 come up more often than the 1Mx4s.  Also usually, at least with my experiences, the 1Mx4s are usually 80 ns not the 60s.  The 256kx4 in 60ns seemed to be easier to find, again in my experiences.

I personally would rather have 8 meg of 80ns ram than 2 megs of 60 ns.

[Motormouth]

Hi, just popped in and saw this thread.  I might still have a tube of the chips needed to bring it up to 2MB.  Can't recall if I got rid of those or not.  Will try to take a look around later.  I upgraded mine from 2MB to 8MB years ago, since I also had 8MB 16-bit fast in a GVP sidecar and 2MB chip, having an 18MB A500 was pretty nice.     Worked for years but I think my ram board finally crapped out, the past year or so It's crashed when I tried to activate the ram on it.  Oh well, maybe I shouldn't have overclocked it.

Should probably send it off to someone with more experience fixing these sort of things, but just haven't had any time for Amiga stuff the past year or so.  Will take a look around for that RAM, anyway....

Funny my configuration is very much like your's, Oldsmobile_Mike, ie the GVP sidecar and a VXl-30 with the ram32.

[Oldsmobile_Mike]

Funny my configuration is very much like your's, Oldsmobile_Mike, ie the GVP sidecar and a VXl-30 with the ram32.

Nice.    One of these days I need to get it squared away why mine stopped working.  System freezes as soon as I try to activate the RAM on the card, now.  #shrug

Hey OP, I found a tube full of the 256k chips.  You interested?  My PM box is full but I can try to clear a little space.  Let me know.

[Munchkin]

Funny my configuration is very much like your's, Oldsmobile_Mike, ie the GVP sidecar and a VXl-30 with the ram32.

Nice.    One of these days I need to get it squared away why mine stopped working.  System freezes as soon as I try to activate the RAM on the card, now.  #shrug

Hey OP, I found a tube full of the 256k chips.  You interested?  My PM box is full but I can try to clear a little space.  Let me know.

Well, a full working 2MB is better than it is now so I'm defenately interested, even if I'd prefer to find the 1M ones. I'll send you a PM.

[Munchkin]

I could make populated adapters that would fit, if there was enough demand. And if someone could get me the datasheets for the DIP memory, and the SMT chips that would be compatible.

I run a PCB assembly shop

Sounds good. I guess it all depends on where in the world you are.

As I said, since the sockets are so tightly placed they have to have two different lenghts to the legs to fit since the adapters are so much wider than the chips.

[Motormouth]

Just FYI,

There are many, many 256kx4 20-pin dips on Fleabay
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=514256&_sacat=0

I know you want the 1Mx4 eventually.

I am shocked how few 1Mx4 there seem to be in dip packages on Fleabay.  Most are in SOJ or ZIP packages.
Zips seemed liked they were very are to get a hold of back in the day, just my experiences, (ie I have two A3000s) particularly the static column versions, Now they are all over Fleabay.
It might be a good time to fully populate all those A3000s and A2386s out there with memory.

But as you are alluding to making SOJ or ZIP to dip adapter should be possible.

[Motormouth]

Perhaps this would work for you??

You would need to make sure the SOJ-to-dip pins are the same and the dimensions are correct.

https://www.ebay.com/itm/New-4x-Adapters-for-SOJ20-DIP20-Memory-CHIP-RAM-Amiga-500-2000-549/123209561358?hash=item1cafdcb50e:g:bg4AAOSwA3dYihC8:rk:7:pf:0

Disclaimer:  I don't know if these would work, Anyone attempting using these would have to do some homework to make sure they are correct

[Munchkin]

That's what I've seen myself. Plenty of SOJ and ZIP but no DIP at all, at least not right now. I've looked everywhere.

There's plenty of the 256k ones as you say but I'm not really that keen on those, don't want to spend all that much money on just fixing a few memory errors. If I'm gonna spend a bit more money I want the 1M ones.

I've seen those adapters, those are the ones I'm talking about. They are to wide to fit on the RAM-32 board without having different lenght of the legs and I don't know if that can cause other problems.

If I had the knowhow I would have designed a replacement board for SOJ chips but I just don't know anything about that and perhaps the cost wouldn't justify it for just one board.

[hirschma]

I could make populated adapters that would fit, if there was enough demand. And if someone could get me the datasheets for the DIP memory, and the SMT chips that would be compatible.

I run a PCB assembly shop

Sounds good. I guess it all depends on where in the world you are.

As I said, since the sockets are so tightly placed they have to have two different lenghts to the legs to fit since the adapters are so much wider than the chips.

I'm located in Brooklyn, NY.

Depending upon the dimensions of the original DIPs (really, the sockets), it may be possible to design adapters that use surface mounted pins on the bottom (likely negating the width issue). There could be slight increased height - not for the leads, but for the overall "package". Won't know until I start designing.

So, if someone can get me the pertinent data (data sheets for the original DIPs, for suitable replacements), and dimensional data for the sockets (row/column pitch), I can design such adapters and assemble a batch for testing.

Happy to take on a project, but ideally it'd fill a general need for DIP memory replacement. This is obviously not a profit-making project, but I'd also prefer not to lose a lot of money being helpful.

So: does the Amiga (and/or retro computing) need a DIP memory clone? And does anyone have the information that would be required?

[Munchkin]

I don't know how big the interest in this might be, not very I'd guess. I fully understand that this could be a costly project.

I gather some of the info you need are in the link posted early in the thread. http://www.amiga-stuff.com/hardware/1mx4-dram.html

Here's the datasheet for the correct chips from Toshiba

http://doc.chipfind.ru/pdf/toshiba/tc514400ap60.pdf

I don't know the size of the sockets, I can't measure them right now since I had to stow away my 500 for a while because I'll be moving in the next few months. Here's a link to a picture of how it looks though. http://amiga.resource.cx/photos/photo2.pl?id=vxl30&pg=2&res=hi&lang=en

The adapters have been linked to earlier in the thread as well so you know what they look like.

I live in Stockholm, Sweden myself. Not that shipping is all that expensive and so on.