Amiga 4000 SIMM sockets quick, cheap repair.

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    I recently purchased a defective A4000. This had the famous battery leakage damage. After using Amiga Explorer I located the bad traces and made many jumpers to repair the MB.

    I also found U891 74F245 buss transceiver was bad as it became very HOT as compared with U892 and U893. I lifted pin 20 (+5v) and was able to boot from CHIP ram. My A4000 has two bad SIMM sockets. I had a choice, to replace the sockets using a desoldering station and unsoldering 144 pins or replacing all 5 SIMMS 40-degree sockets with new metal clips for a total of 360 pins. Another option is the purchase the Big Ram Plus module from icomp store for 135,16, plus VAT, shipping and anything else Jens wants to charge you for, but you will need to KEEP the CHIP SIMM module and remove the FAST ram SIMMs. Or use my cheap fix for less than a $1. I used 2 red round hole crimp connectors and a piece of insulated stranded wire to stretch across the SIMMs. First remove the red plastic on the connectors solder the one end of the wire to the connector. Attach the wire to the 2 ground screws as shown, measure the length to stretch across the SIMMS and solder the connector. Placed some hard rubber 3mm weatherstripping on the loose SIMMS to take up slack (do NOT use foam weatherstripping as it will lose its shape!). There should be a slight deflection of the SIMMs when pressed with your finger. There is a reason the sockets fail is, age of the sockets, using the wrong thickness of the SIMM modules. It is imponent to use the thinnest modules of 1.26mm, I measured modules of 1.32mm these are wrong ones as they will not lock in place and WILL put additional load on the clips if they do. Please note, the SIMMs I used are examples, I have new two 4meg SIMMs on order, the A4000 came with two 4meg SIMMs. This mod may also work on other Amigas or boards that use SIMMs modules.

    Thanks!


    There's an even easier solution: Two of the four fastmem sockets support 8MByte modules, so one 8M module can replace two 4M modules. This can of course be combined with your hack, and it might improve stability, as the number of SIMMs to hold down will be less.


    Jens

    Jens

    You are correct in your suggestion of 8meg SIMMS I was not aware of using 8meg SIMMs, but the only SIMMs I have are double sided and are thicker 1.32mm and they won't work they MUST be single sided for clearance of the chip SIMM which is double sided. The 4000 had the original SIMMs which I measured at 1.26mm so I am ordering the same as what the 4000 came with. As to why you called my method for a cheap repair a HACK! it is a proven method of saving the user of unsoldering 72pinns for each socket and a chance of causing damage to the MB to get their Amiga in working order, a method that anyone can do.

    I ordered and received my Buddha Plus One adapter, for my 2nd A3000T and want to complain about the high shipping charges of 38,51E you MUST give the customer a choice of UPS or Speed Pack or other less expensive options. I purchased 4 buddhas I spent 154,404E on shipping alone.

    I ordered a Ripple IDE adapter for $83.50 with shipping and will evaluate it when arrives it has 2 IDE ports like the buddha IDE.

    Referring to the Big Ram Plus module that you sell I am in no way putting it down, it is a great upgrade to the Amigas. Tell me what programs / games can exceed the standard memory of 16mb to need the Big Ram Plus, GIVE ME A LIST? I have in one of my A3000T a Phase 5 68060-50 card with 64mb (expandable to 128mb) and 16mb on board ram plus the buddha plus one that has 1mb for a total of 81mb of FAST ram.

    Edited 2 times, last by Jens: Private information in attachments deleted - this doesn't belong in a public forum. ().

    Quote from A3000T

    they MUST be single sided for clearance of the chip SIMM which is double sided.

    Right - this can be considered an oversight by Commodore, as 8M SIMMs are only supported in the first and third SIMM socket. They *should* have wired the second and fourth socket that way.


    I wasn't aware of those slight differences of SIMM thickness. 0.06mm are such a small difference that this can safely be called "tolerance", maybe even measurement error.

    Quote from A3000T

    I ordered and received my Buddha Plus One adapter, for my 2nd A3000T and want to complain about the high shipping charges of 38,51E you MUST give the customer a choice of UPS or Speed Pack or other less expensive options.

    I have stopped working with cheap parcel services, and the reasons have been discussed extensively in this thread. I even announced that I'd be doing test-shipments for customers who are interested in a cheaper shipping method there, but so far, not a single customer volunteered to be the guinea pig. I guess that the majority of people like to pay for faster shipping. Or nobody saw it - people complain, then forget about it.


    Quote from A3000T

    As to why you called my method for a cheap repair a HACK!

    This was not meant to be negatice - not even remotely! We probably use the term "life hack" differently in Europe. Anything that solves a problem in an unconventional way is considered to be a "hack", and using mounting screws that are originally designed to be holding down the motherboard only surely qualifies for that classification.

    Quote from A3000T

    Tell me what programs / games can exceed the standard memory of 16mb to need the Big Ram Plus, GIVE ME A LIST?

    If you compile large C projects or render large 3D scenes, you can easily cross the 100MB RAM requirement barrier. When we introduced the "ZorRAM" with 128MBytes some ten years ago, we did have requests for larger units and numerous customers who were filling up their Z3 slots with these cards, so there must be more than one application. However, I'd consider them to be "power user apps", as I have a hard time exceeding the limits of my 128MByte accelerators, so I've had an even harder time to justify the 256MBytes that go on the ACA1240/1260. However, since that card is considered to be "for power users" anyway, I figured it's better to go big.


    Jens

    Shipping:

    I have used SpeedPak for parts and products with no issues! It takes a little longer though, but the price is worth the wait, for me. Give the customer a choice.


    Big Ram Plus:

    Good point, I and 95% users don't need the Big Ram Plus but the 5% would be happy that it's available, also great if you have bad ram sockets and don't want to replace them or use my super cheap fix.


    SIMM Sockets:

    Apparently, you don't have a A4000 to try inserting the thicker SIMMs, you would see what I'm talking about. My Phase 5 68060-50 in my A3000T has metal clip sockets, and it too does not accept the thicker SIMMs. JUST use SIMMS that require little force to lock in place and the sockets will be happy. Your choice.


    eSATAp

    I have installed the A4000 IDE adapter board to have up to 4 IDE devices. I ordered the SATA to eSATAp and IDE2SATA boards (free shipping using SpeedPak) so it too will have and external eSATAp to connect any SATA devices.


    Next Project:

    I am getting rid of the GVP SCSI HD and keeping the GVP RAM card to keep 8mb of FAST RAM, I added the 2mb CHIP ram adapter in my A2000 and converting it to IDE using the Ripple or Buddha IDE adapter, to add an internal IDE/SATA HD and CD drive, also adding the eSATAp so it to can be software upgradeable without dissembling it. I'm not sure if this modification will work on the A2000. The issue I see is KS/OS compatibility for all A2000, A1200, A3000, A4000 and some use buddhascsi.device, buddha.device, 2nd.buddha.device, lide.device, file systems, PFS, FFS, FFS International. If I just make a partition with just plain FFS they should all see it using the proper device driver and unit #. I will see!


    Too Many Amigas

    I don't need 3 A3000Ts so I will be selling 2 of them, I hope to find them a good home.

    Quote from A3000T

    I have used SpeedPak for parts and products with no issues! It takes a little longer though, but the price is worth the wait, for me. Give the customer a choice.

    To my knowledge, they ship _to_ western countries using local delivery services, but you can only book a shipment with them if you're in far east. That type of service is exactly the one I described in the thread I've linked to (kind-of-a-ride-share).


    Jens

    Jens

    I'm still around, I have been busy during the summer and now I spend my time indoors.

    I been having problems locating two 8 meg SIMMs for banks 1 & 2 that properly latch. Can you suggest any SIMMs.

    A photo of the correct SIMMs would help, I haven't been to locate any with clarity.

    Thanks

    To my knowledge, all you're looking for is single-sided SIMMs.


    Can't take any pics, as my A4000 uses 4x4MB SIMMs.


    Jens

    Jens

    I have tried single-sided chips, but they won't Lock in, I had the same issue with my Phase5 68060-50 board. Do I use Apple/Mac SIMMS? I ordered Apple/Mac SIMMs but they wouldn't fit in banks 1 through 4, the seller said they were Apple/Mac SIMMs but now I don't believe they were. On bank 0 on the 4000 any 72pin SIMM will lock ok. But bank 1 through 4 the sockets are different. Do I get two 8MB Apple/Mac SIMMs for bank 1 & 2? I don't want to waste $ for the wrong SIMMs. On my other A4000 I need to replace all sockets because of battery leakage and broken sockets. I don't want to desoldering another 360 pins, once is enough. I may look at your Big Ram Zorro slot ram if I can't get this resolved. Th A4000 using my hack works fine with 16mb SIMMs but that's where I need the correct SIMMs.

    72-pin SIMMs aren't vendor-specific - at least they shouldn't be. It's a Jedec standard if I remember right. Only the organization of address muxing is different on larger modules (>32MByte), but that shouldn't be a concern here. So if you have an old PC lying around that uses 72-pin SIMMs, you should be able to harvest them and use on the A4000D.


    Jens

    Jens

    Explain these photos of the size difference of the SIMMs for the A4000 in sockets bank 1 through bank 4. Bank 0 is a standard EDO SIMM 1.3mm because it is a double-sided SIMM. Do NOT use 1.3mm SIMMs in banks 1 through 4, you will damage them. The ONLY way around using 1.2mm SIMMS is to change out the SIMM sockets the newer sockets that will accept the 1.3mm SIMMs. I have been looking for two 6mx32 1.2mm SIMMs to put then in bank1 and 2 to get 16megs and I can't find them. I have 2 A4000 motherboards one has good 1.2mm sockets, the other I had to remove the 1.2mm sockets due battery contamination. I will change all SIMM sockets the newer 1.3mm with METAL clips sockets!

    I wasn't even aware of the PCB thickness difference. Never made a product with SIMMs - only serviced somewhere between 10k and 15k Apollo acceleratrors in my life :-)


    Seriously, I have a hard time imagining that 0.1mm thickness can make such a difference, given that the spring path is easily 0.5mm. Best guess is that the material has lost it's elasticity over the decades. I just recently learned that steel on cars gets softer with the years: You may have seen that I've auctioned off my 23-year old Volvo. The buyer fixed a door closing issue by opening it, lifting, then at the same time leaning into it - closed perfectly on the first attempt! The same may apply to the tiny contacts of a SIMM socket.


    Note that I have no knowledge about this level of material science. This is purely anecdotal, reasoning by analogy rather than fundamental basics that I could point to.


    One thing from chemistry lessons is an obvious cause: All your SIMMs have gold contacts, while the sockets have tinned contacts. Gold is a precious metal, acting as a catalyst on the tinned contacts. By pure presence and proximity of the precious metal, the non-precious metal reacts with the air's oxygene way faster than it would without the gold near. As a result, you'll have to clean the SIMM contacts on a regular basis (probably once every six months). An old toothbruch (stiff-britled) and Isopropanol (short: IPA, should be available in any pharmacy) are the tools to go for. Never use contact sprays, as they often contain lubricants for potentiometers that you really don't want in a computer.


    Jens

    Jens

    That is why I have been looking for 4 4mx32 SIMMs that are 1.2mm to repair one of my 4000s. Ther other 4000 after I replace ALL SIMM sockets with ones that will take 1.3mm SIMMs and have metal clips I will not have this issue

    I tried 2 8mx32 SIMMs in banks 1 and 2 and only see 8mb not 16mb as you suggested, so I will install 4 4mx32 SIMMS to get 16mb.

    Apparently, you do not own or have access to a 4000 to verify my issue.

    If there anyone on the forum that has a 4000 and can verify the thickness of the SIMMs, please reply to this post, and use caution when removing the SIMM.

    I have been using AmiKit emulator on my windozzz 11 pc and it sems to work great! I do have AmigaForever so I have the ROM file, I do have OS3.2.2 CD ROM files as well. I am going to install whiteload and try some games now that I have a USB joystick.

    Frank

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.

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