Tag Archive: diy


While doing spring cleaning in my parts storage I found two old hard drives of mine, which had broken off SATA connectors. They were among broken hard drives and I wasn’t sure if they are still working. Apparently one of them had its’ port already soldered at some point and I didn’t remember why it didn’t stay that way:

Problem in it's glory!

Problem in it’s glory!

I tried soldering able to the pins, however that didn’t work out. Plan b it is!

Bend the signal pins out of the way

Bend the signal pins out of the way

Initially I only wanted to have pins on different levels so they wouldn’t stick to their neighbours. Turns out using one side for groun and other side for signail is best solution.

Than I flushed all the through holes on SATA port with solder to be able to attach signal cables.

Soldered straight to the board

Soldered straight to the board

It ain’t pretty, but it holds. Connecting ground wires after that was a breeze compared t it.

Looks much worse on the inside

Looks much worse on the inside.

I connected drive to the PC and it’s humming along nicely as it’s being backed up.

hard-drive-transfers

Transfer speeds are not so ghetto

Whith first drive working along nicely, I got on with second one. Finished much faster as I knew what I was doing and could prepare connection properly. Secret lies in pre-bending wire to desired shape.

With second one I knew what I am doing.

With second one I knew what I am doing.

Preparation equals results and… drum roll, here it is:

Looks much better

Looks much better

01. Zydec AMRAM-X Iss. 2

Although Amiga 500 was released with only 512kb of stock RAM it was very often bundled with memory expansion. For many users it was most important Amiga upgrade to buy and rightly so. as it not only made games look better (and in later years run at all) but allowed use of many productivity applications in a meaningful way.

A501 and it’s equivalent where so ubiquitous that Amiga 500 beefed up to 1Mb quickly became a standard, baseline that game programmers expected. There was variety of compatible memory upgrades that were following similar design principles. Like most of them Zydec’s Amram 500 included battery backed Real Time Clock.

Unfortunately, nickel batteries at the time weren’t designed to last 20 years and checking for battery damage should be your top priority whenever you buy or rescue Amiga. They have tendency to leak corrosive electrolyte which effects include damaged components, corroded PCB traces and even dead Amigas. They were used aplenty at the day and are very common circuit board wreckers. It’s easy enough to replace old battery with modern CR2032 at a budget.

As expected Workbench couldn’t read nor set date on the during the boor, so I removed the culprit from it’s trapdoor slot and started assessing the damage.

And we can admire fill extent of the leakage

Sure enough, whole area around battery was covered in electrolyte. It’s small blessing that A500 relied on external Real Time Clock due to budget constrains as it keeps corrosives away from motherboard.

Oh no! More electrolyte

It isn’t pretty sight, especially green stuff on IC pins, but upgrades can be tinkered with or exchanged while Amiga stays functional, albeit with only 512k of system memory. Use q-tips dampened interchangeably in isopropyl alcohol and white vinegar to clean affected area.

It looks much better after cleaning. Electrolyte burned thru vias and traces, but really critical damage is concentrated in small area battery’s negative connector.

First time recreating PCB traces, could be done much better.

It was my first time recreating PCB traces and hope to do much better next time. At this point I decided it’s time to see how I’ve done, so Amram back into trapdoor went.  Unfortunately as long as jumper was set to enable trapdoor memory, Amiga would greet me with sadness on her screen.

guru-meditation-small

Memory is much more important to me than real time clock, so I decided to convert my expansion into 500+ compatible model by removing IC clock and supporting circuitry. At that point I already downloaded expansion schematics, but they had such poor resolution they were barely readable. I found all the info I needed on Big Book of Amiga Hardware. After comparing pictures of both models I desoldered all unnecessary parts and added some headers, just in case I’ll change my mind about having RTC.

512k trapdoor expansion for Amiga in it’s most minimalistic form

I decided not to rely on corroded traces and used jumper cables to bypass them. Instead of connecting PIN 16 of  DRAM chip to jumper’s ON pin I connected it directly to PIN 32 on the connector and ran it to  middle jumper to have it always ON and to spre. Thanks to corrosion there was no metal for solder to sink into in jumper thru holes, so cables are soldered to pins themselves.

With Amram 500 stripped to bare minimum I tried booting Workbench disk again. It loaded without Guru Meditation this time, but it didn’t recognized upgrade.

Troubleshooting

  • Using multimeter I checked if expansion gets enough power from Amiga. Voltage between PIN 32 on trapdoor connector and ground (RF Shield or metal jacket on any of external ports) should be 5V.
  • Individually checked if ram DIPs are being fed current. Thanks to pinouts on Amiga Stuff website I knew to measure voltage between PIN1 and PIN 10 of each memory chip. All four were being fed enough current.
  • I checked continuity on all connections I resoldered earlier to find they are conducting as supposed.
  • Then I realised I ran one cable on the other side of PCB than originally, connecting it through depopulated battery solder point. And surprise, surprise, no continuity there.

Let’s hope it worked! Amram 500(+) sits nice and tight in trapdoor, time to boot Workbench and see if my efforts paid back.

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I don’t think there’s much more I can do without logic probe or oscilloscope, or is it? Would it help if I replaced decoupling caps and resistor banks? I guess if that wont work, it’s 1MB Chip Ram hack for me.

X500 Plus Prototype

I have to admit, I’m blown by Loriano Pagni’s project. Inspired by classic Amiga 500 form factor he spent last 7 years working on X500 Plus custom case. During this time he hand crafted 5 different prototypes as project evolved.

Designed mainly with AmigaNG and Classic hardware requirements in mind, X500 Plus is surprisingly versatile. If you’re planning retrocomputing project, crave PowerPC goodness in your desktop, need compact FPGA platform or just want to have unique PC to remind you of days long gone, X500 Plus is for you.

It is well thought out and carefully planned construction that goes far beyond novelty factor or nostalgia appeal. It offers more than enough expansion and customisation options to make your dream keyboard computer come true. Continue reading