Hardware Repairs / 2020-12-27 20:27:17

Most Amiga hardware has now more than 20 years... so, yes, it is getting wiser but also needs some repairs. Here are some repairs and tips.

PS. Follow these tips at your own risks! I cannot (and won't) be responsible for any damage that you may cause!

Installing an ACA1230 or ACA1233

The ACA1230 and ACA1233 are accelerators for the A1200 from Individual Computers. They are modern and clean-built accelerators, using surface mounted components. They are without mobile parts (no fans!) and therefore totally silent... They are also plug-and-play!

The are actually very easy to install: just open up the trap door under the Amiga and gently slide them in, starting with the side with the "small connector" and twisting them straight to connect them tight. Then, close the trap, fire the Amiga, and enjoy!

Changing an Amiga 1200 PSU for a Modern, Standard ATX PSU

There are now lots of ATX PSU for sale for cheap in second-hand stores, which are in perfect conditions. They can be bought for less than $CA10 and used to effectively replace the old Amiga PSU with more power (watts) to support more extensions. There are a few steps to follow to use a ATX PSU: 

1. Find a ATX PSU in good condition;
2. Use the paper-clip trick to get it to switch on:
   
   1. In the 20-pin block going out from the ATX PSU, find the green wire (there's only one);
   2. There are two black ground cables beside it, find one of them (no matter which one);
   3. Connect the green and black wires using a paper-clip, then isolate it using electric tape;
   4. Plug and switch on the ATX PSU (when on, its fan should turn, even if briefly);
3. Open the Amiga PSU and unsolder from the PSU the cable connecting to the Amiga;
4. Connect the unsoldered end of the Amiga cable to the 20-pin block from the ATX PSU as explained here or here or as follows:

5. Check carefully—twice!—the voltages between each pin of the Amiga connector, using a voltmeter. BEWARE of shortcuts!

6. Voilà ! You can now use your Amiga with a modern, standard—and powerful!—ATX PSU

Changing an Amiga 4000D PSU for a Modern, Standard ATX PSU

I'm lucky to have a A4000 that works (still) very well, even its original PSU... but this PSU is 220V only and thus requires a heavy-duty, cumbersome, and ugly 110V-220V converter... Meanwhile, Meanwell produces sleak PSUs, perfect for an Amiga 4000.

TUMO found the RPT-160B for me . This PSU takes anything between 90V to 240V and outputs +5V at 14A, +12V at 5A, and -12V at 1A. It also features a Power On Good signal. And it is (much) smaller than the original PSU so it fits perfectly in the original case .

Using some spare 18 gauge wires, 8 molex female pins, heat-shrink tubing, and 18-poles screw terminals, a soldering iron, and some patience, I desoldered the wires going in and out of the old PSU and reconnected them to the new Meanwell and it works very well!

On the original A4000D PSU, from the 6-pin, brown-redish, motherboard connector; the brown wire is the Power On Good signal:

On the Meanwell RPT-160B, with the writings horizontal, CN3 above CN2, both on the right, vertical:

In practice, this looks like:

Main Connector	Original PSU	Intermediate Wires
Output Wires	Fitted 1	Connected	Fitted 2

Fixing a A4000 Motherboard with Damage due to a Leaking Battery

I would not recommend trying to fix damage due to a leaking battery at home! Trust experts, like AmigaKit, even then find that difficult! In particular because the leak damaged "through holes" and connection under the memory sockets . Here are some pictures of the step to fix the damage, courtesy of AmigaKit:

Changing the Capacitors in the Amigs

The worst problem with Amigas, after a leaking battery, is malfunctioning capacitors... In old times, they used to use electrolytic capacitors, which are cheap(er) but have some limitations: they leak or they dry, at best loosing their properties, at worst damaging the motherboard. Fortunately, these capacitors can be replaced "easily" with modern, more expansive, but (very) long lasting cermaic capacitors. The differences between the too are too long to explain here and go waaay beyong my head anyways Suffice to say that they work well and do not fail!

Here is a list of the capacitors per Amiga models/revision:

In Canada, these capacitors can be bought from DigiKey! 

Connecting a Arananet and ENC28J60 module

The Vampire is an amazing card that really give a second life to the Amigas! It can be equipped with a combo Arananet + ENC28J60 module to provide an Ethernet port and access to the Internet using the SDNet driver . Usually, the Aranenet and the ENC28J60 module come separately, although I bought mine together from Relec (very nice and very fast!). So, the question can be: how should I plug these two neat pieces of hardware together? Thanks to XRay from Relec and guibrush from the ApolloTeam, here are some hints on how to answer that question!

Arananet Pins

My Arananet came with 12 pins and two soldered wires next to the 5V and GND pins. These two wires are not connected to the 5V and GND pins! I connected them to the 5V and GND pins (duh!) of my 12-pin ENC28J60 module. Now, there are two possible organisation of the pins. Trying one or the other should not damage anything. In my case, this organisation was correct:

5V   --   -- GND
     o1   2o INT
     o3   4o S0
SI   o5   6o SCK
CS   o7   8o 
3.3V o9  10o GND

ENC28J60 Module Pins

In theory, the pins of a ENC28J60 module are:

CLK  o1   2o INT
WOL  o3   4o S0
SI   o5   6o SCK
CS   o7   8o REST
VCC  o9  10o GND

BUT, on my ENC28J60 module, the pins are as follows because there are two models of modules: with 10 or 12 pins!

5V   o1   2o GND
INT  o3   4o CLK
S0   o5   6o WOL
SCK  o7   8o SI
RST  o9  10o CS
Q3   o11 12o GND

So, at first, I also connected the 5V and GND pins from the Arananet to those of the ENC28J60 module. However, the Ethernet module was very unstable, often "powering off" and leading the driver to freeze or go into an infinite loop. I received help from people on the Apollo forum, in particular Henryk who gave me the solution: the Vampire and Arananet module provide +3.3V (actually, +2.8V according to my measures) instead of the expected +5V to the
ENC28J60 module. So, really, I connected the ENC28J60 5V (o1) pin to the +5V (brown wire) of the floppy disk and, voilà!, it works perfecting. Henryk also advised not connecting +3.3V to Q3.

Connections

Here a table showing the correspondance (hence, the connections) between the two:

Note: GND 10o (even number) goes into GND 12o (also even number). The +5V must come from the floppy disk (brown wire) into the 5V (o1) pin of the ENC28J60 module. Thanks again XRay, guibrush, and Henryk!

Connections between Arananet and ENC28J60 module in pictures

Photo 1
Photo 2
Photo 3