Recapping a PAL Amiga 1000

 Hi Again,

Since I suspected I had issues with reliable and stable power, I took the plunge to recap my PAL Amiga 1000 (no piggyback), and pleased to say it was a great success!

CLK (Pin 15) Before Recapping
Max 3.48V
Mean 1.64V

CLK (Pin 15) After Recapping
Max now 3.6V (+0.12V)
Mean 1.72V (+0.08V)

Interesting there appears to also be a small speed bump from 7.042MHz to the correct 7.09MHz, and a Period speed up of 1ns - although this is more likely to be nothing to really note, maybe just coincidence.

ECLK (Pin 20) before recapping
Mean 1.92V
Max 5.28V

 

ECLK (Pin 20) AFTER recapping
Mean now 2V (+0.08V)
Max now 5.52V (+0.24V)

I started with a purchase of an Amiga 1000 cap kit from Retro Rewind which I later found was really for an NTSC Amiga 1000 with piggyback.  The only difference was that I needed to purchase an extra 220uF electrolytic capacitor, which I purchased from Mouser.

16YXM220MEFR8X11.5
Rubycon Aluminum Electrolytic Capacitors  

The Retro Rewind Cap Kit says it comes with:

Cap   -  Value - Rating - Type

C48   -  22uf  -  16v   - Radial (my order came with 25V)

C49   -  22uf  -  16v   - Radial (my order came with 25V)

C50   -  22uf  -  16v   - Radial (my order came with 25V)

C63   -  22uf  -  16v   - Radial (my order came with 25V)

C64   -  22uf  -  16v   - Radial (my order came with 25V)

C65   -  22uf  -  16v   - Radial (my order came with 25V)

C66   -  22uf  -  16v   - Radial (my order came with 25V)

C78   -  100uf -  16v   - Radial (my order came with 25V)

C79   -  100uf -  16v   - Radial (my order came with 25V)

C80   -  100uf -  16v   - Radial (my order came with 25V)

C175  -  100uf -  16v   - Radial (my order came with 25V)

C93   -  220uf -  16v   - Radial

C95   -  470uf -  16v   - Radial

(Daughterboard)

C10   -  100uf -  16v   - Radial (my order came with 25V)

C11   -  100uf -  16v   - Radial (my order came with 25V)

There was a delay with the Retro Rewind order, and when I enquired about the difference in Cap values between my mainboard and from the caps supplied, I never received a reply.  Also note the caps provided by Retro Rewind were mostly 25V rather than the 16V on the original board - but this won't really matter and is a safe replacement.

OK on to the replacing...

I started with the 470uF cap - the biggest one on the board, and using a desoldering gun made the job very easy.  I use a Micron T2065 which I picked up from eBay for $240AUD in 2023.  I am really happy with, it does everything I need and I no longer lift solder pads as much as I used too.

So, starting with he 470uF cap, the ESR on my 470uF should be below 0.18 (adjusted for 16V as the meter uses 25V for everything), and was showing .27 - the meter said good if below 330uF...hmmm, found a cap out of spec, excellent!!

uh oh, should be below 0.18, this cap is not good!

Yippee!  First cap in!

The 22uF caps were really easy to remove and replace, but the 100uF and 220uF caps were absolute mongrels to remove!!  The 100 and 220's I tried adding solder, lots of flux, solder wick, hot air gun, back to the desolder gun, and finally managed to wiggle them out with he ordering iron held on one side!  However two of the caps I ended up snipping from the top side (very carefully) and then using long nose pliers and the soldering iron, managed to eventually pull the lead through...phew!  That was 8 hours in total that I don't really want to repeat anytime soon!

22uF caps all removed

Using LOTS of flux to remove the 100uF caps 

New caps in!

OK, could have used blu-tack to keep the 22uF caps  flush with the board, but sticking up a little bit is OK

100uF caps in, phew!  That was 4+ hours I will never get back :)

The 220uF caps were proving near impossible, I would not recommend this - but I snipe the legs as high to the cap as I could, and then added heat to the component side of the board which allowed me to pull the lead out quite easily with long-nose pliers.  Im sure there is a more professional way to do this!

220uF caps gone!  Holes ready for the new caps.

It took me so long to get these suckers out, her sis mother pic from the side :)

It is a thing of beauty!  All new caps - note the new caps are physically much smaller.  Proof technology continues to improve in the last 37 years!

Another photo of all the caps in, from the top.   It was easy, but  be patient!

White marks are from the Clea-up, they won't hurt the board.

 

After using so much flux and cleaning the board with LOTS of Isopropyl, I was almost ready to put everything back together.  The Isopropyl also reacted a little with the PCB protector covering the board, creating white residue on the board.

After cleaning the board 3 times with a lot more Isopropyl, I was able to use a can of compressed air to blow away as much of the white residue that I could, there was a still. little around component solder points, but it won't hurt or degrade the board over time as far as I could tell and read across the net, so I left tit to thoroughly dry for about 2 hours and then plugged it all back in!

I was worried It was going to blow up after a recent power supply re-capping fail :). But my Amiga 1000 came back to life first time, perfect and has been playing mods for the past 2 hours without a hiccup, yay!!

Catch you again soon!  Thanks for reading!