PDA

View Full Version : Amiga 4000D Capacitor Restoration (worklog)



d0pefish
13th October 2010, 23:10
So, today I took delivery of a full set of capacitors for my Amiga 4000D.

Months ago I spent time with a spreadsheet and a vernier gauge, measuring every capacitor inside the PSU and and motherboard for width, lead pitch (how far the apart the legs are) and of course farad rating and max voltage.

Why do we change electrolytic capacitors? They wear out, and they do so quicker than many other components. They can also leak corrosive electrolyte onto your precious motherboard. Even if they still work, after 18 years, they will be degraded and not doing their job as well as they used to. Capacitors are there as a "buffer" for the electricity that supplies your machine, and filter out noise, small surges/spikes and other electrical anomalies that would harm sensitive electronics - and computers can be very sensitive. They are present in every power supply, and your PSU is very important - it provides the lifeblood of your machine(s).

When a capacitor ages, it may have lost some electrolyte through leaking and evaporation, (how ever slow), and therefore its ability to perform its task. Power supplies are hot places (hence fans on pretty much all of them these days) and capacitors can dry out quite nicely in there.

So, having noticed some noise in the audio output of my Amiga, I figured now would be a good time to get them all serviced. Unlike some people who have decided to bin their power supplies in favour of modern ATX units, I decided to give my original Skynet power supply a good service and keep my Amiga original. Apart from that, I like the manufacturer's name. :)

My other reasons for servicing the original PSU is that there are many cheap, crap PSUs out there for PCs. New certainly does not mean good. I have seen many modern PSUs fail, because they were made with cheap or even counterfeit(!) components, plus I'd rather keep the original chassis/casing intact, and not have to do any modification. This Amiga power supply is still working fine to this day, even fully loaded with my CyberStormPPC, G-Rex and PCI cards, big and power-hungry SCSI hard disk, and other accessories - a testament to its build quality.

Skynet themselves were actually very helpful (they are still a big name in OEM PSU manufacturing) and kindly searched their archives for a complete schematic and Bill of Materials for the model used in the Amiga 4000, which they provided me with. I can now use it to identify any problems in future and find the correct components for any further servicing.

So let's start with the power supply; I've talked about it enough already. :)

Here is my PSU, the Skynet COM-915C-02. You can clearly see the two large NIPPON CHEMI-CON* reservoir capacitors in one corner, which smooth out the incoming rectified AC current. Also present are several brown capacitors that filter out the final 5v and 12v stages of the power supply. You can also see two large white box-shaped capacitors, which are film types. These don't tend to go bad like the electrolytics, but I replaced them anyway. :)

http://lh5.ggpht.com/_kRG1wB80tiI/TLYXzKemq2I/AAAAAAAAAZI/AHfuuDG3V8Y/s400/CIMG0034.JPG (http://picasaweb.google.com/lh/photo/2eLKG5RhdvbY7Bawq4jZ7A?feat=directlink)http://lh6.ggpht.com/_kRG1wB80tiI/TLYXzmFZWDI/AAAAAAAAAZM/BYnro_LbyJs/s400/CIMG0035.JPG (http://picasaweb.google.com/lh/photo/9uYrJFpo1ktR_TmxvkEPng?feat=directlink)http://lh5.ggpht.com/_kRG1wB80tiI/TLYX0BGebuI/AAAAAAAAAZQ/8xIuFklb3Zc/s400/CIMG0036.JPG (http://picasaweb.google.com/lh/photo/9akZsSzBxzSmvLCN1P_eLQ?feat=directlink)

Here's my lineup of brand new capacitors on the left, and the old ones on the right.
http://lh4.ggpht.com/_kRG1wB80tiI/TLYX1ueX1rI/AAAAAAAAAZY/eatuL8QoZlE/s400/CIMG0038.JPG (http://picasaweb.google.com/lh/photo/6GFogb8SZDe1lhA__gS2SA?feat=directlink)http://lh6.ggpht.com/_kRG1wB80tiI/TLYZi-b4lSI/AAAAAAAAAZk/nAGqOY1WH7I/s400/CIMG0039.JPG (http://picasaweb.google.com/lh/photo/js38kphFCI6js9Qq0ErIsQ?feat=directlink)

These are no ordinary replacements, and theyre certainly not your average tat from Maplin. These are Panasonic capacitors which I ordered from Digikey in the USA. The pretty gold ones are FM series, which are VERY high-quality capacitors with low ESR, a high temperature rating and a long life.

Also, these capacitors - whilst being pretty much the same size - are often a higher voltage rating than the older ones. All this means is that they're even more above specification. Happy days. :)

And now they're installed:
http://lh5.ggpht.com/_kRG1wB80tiI/TLYZjoO8jSI/AAAAAAAAAZo/O8qaGoInTz0/s400/CIMG0040.JPG (http://picasaweb.google.com/lh/photo/WvlGGqD-8AovjtxSegNqaw?feat=directlink)

Looks much nicer, no? Noteworthy is that when desoldering the old capacitors, there was a horrible smell of rotten fish - a clue to rotten caps :)

Now for a quick hookup and test on the meter. Amiga powers up normally, and the +5 and +12v rails are healthy and strong with all peripherals attached:
http://lh5.ggpht.com/_kRG1wB80tiI/TLYZknTA-bI/AAAAAAAAAZs/jv5iW5N07iI/s400/CIMG0043.JPG (http://picasaweb.google.com/lh/photo/qNes0rNFkEc-7Xq8-OLHdw?feat=directlink)http://lh5.ggpht.com/_kRG1wB80tiI/TLYZlJVuXJI/AAAAAAAAAZw/mKleWDlKyZw/s400/CIMG0047.JPG (http://picasaweb.google.com/lh/photo/BTr7AYJ-X-vIgj09crruPg?feat=directlink)
http://lh6.ggpht.com/_kRG1wB80tiI/TLYZlk1Ne7I/AAAAAAAAAZ0/W3A5iuUjBnI/s400/CIMG0045.JPG (http://picasaweb.google.com/lh/photo/ltywBzFelKV-MWWSO0zJkg?feat=directlink)

Coming up next, the motherboard, with some surface mount fun.
Oh yes, in Dale's house of pain, we use SMD components to replace.. erm.. SMD components. :thumbsup:

hikey
13th October 2010, 23:57
theyre certainly not your average tat from Maplin.

I seem to remember you moaning about Maplin when you visited me to collect those [unfortunately faulty] SID chips from me :p

d0pefish
14th October 2010, 00:11
theyre certainly not your average tat from Maplin.

I seem to remember you moaning about Maplin when you visited me to collect those [unfortunately faulty] SID chips from me :p

Ah yes :D

I seem to moan about Maplin a lot - sorry :p

tokyoracer
25th October 2010, 15:57
theyre certainly not your average tat from Maplin.I seem to remember you moaning about Maplin when you visited me to collect those [unfortunately faulty] SID chips from me :p

Ah yes :D

I seem to moan about Maplin a lot - sorry :p
I have to agree with Craplin, I mean Maplin products.

Thats a great peice of work, the neatest cap replacement I have ever come across. :thumbsup:

Elerion
5th December 2010, 10:41
Wow! Neat. I see a lot of love involved! :inlove:

I did similar thing to my A4k on this thread: http://www.amibay.com/showthread.php?t=10993
But I was not that picky when buying caps.

Can you measure AC component voltage of power outputs for comparation with my results?

imnogeek
5th December 2010, 11:06
Skynet themselves were actually very helpful (they are still a big name in OEM PSU manufacturing) and kindly searched their archives for a complete schematic and Bill of Materials for the model used in the Amiga 4000, which they provided me with. I can now use it to identify any problems in future and find the correct components for any further servicing.



Is there any chance you could post the schematics in the thread for others to refer to in th future?

Tajmaster
5th December 2010, 11:21
Another fantastic job Dopefish! If you dont mind me asking, how do you get the "insert disk" screen to display 3.5 ROM? I thought the last ROMs you could buy are 3.1s?

jvdbossc
5th December 2010, 11:26
Nice piece of work :thumbsup: - I am doing the same still waiting for the large ones to arrive.

Kin Hell
5th December 2010, 12:03
Just sheer class. What else can be said?.....

Awesome work d0pefish. I like your style. :thumbsup:

Kin

d0pefish
6th December 2010, 00:44
Wow, I almost forgot about this thread - I need to upload the pictures of the motherboard work! :oops:


Wow! Neat. I see a lot of love involved! :inlove:

I did similar thing to my A4k on this thread: http://www.amibay.com/showthread.php?t=10993
But I was not that picky when buying caps.

Can you measure AC component voltage of power outputs for comparation with my results?
Thankyou Elerion - I must say your work on your own A4000 is truly awesome, congratulations on getting so far already :D I look forward to you finishing the job :thumbsup:

I'd be glad to measure the AC for you, it would be an interesting comparison - but I am away for a week while I look after a friend's house and cats while they're on holiday. I'll try to remember to do this this coming weekend mate :)


Is there any chance you could post the schematics in the thread for others to refer to in th future?

Of course! I've added them to my Google Docs account. Here are the schematics:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=1cDIQxiods_OiHDF0qdnpnkavwFg8-aHhWdWtOuHQWHBsgZeJ_GIKpLn_OoS_&hl=en&authkey=CLqVnPsM

This is the Bill of Materials:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=1G3ewf7P9IL8KwGSkqUfjibqk5tuJfONG5pARVd1QdTaAP6_c4dnk7W4vFBIf&hl=en&authkey=COSc2OEM


Another fantastic job Dopefish! If you dont mind me asking, how do you get the "insert disk" screen to display 3.5 ROM? I thought the last ROMs you could buy are 3.1s?

Thankyou :) Ah yes, the "3.5" ROM - this version number is a result of a patch; Piru's Exec v44.1. I have rolled my own Kickstart with many patches and fixes, and these are available from switch-on thanks to the Algor PRO card and its flash ROM. The real Kickstart in my Amiga is indeed 3.1, but the Algor overrides it with my custom Kickstart. :) You can also see the Black-Border patch in action here; there's no border around the screen - just a preference of mine, but looks better on full screens and not the reduced size of the Kickstart screen :)

Many thanks jvdbossc and Kin Hell :D

dkedrowitsch
14th February 2011, 17:14
d0pefish: I'm about to recap an A4000/040 and would like to know if you wouldn't mind could you share your parts list for the replacement caps you used?

Thanks!

d0pefish
14th February 2011, 17:37
Hi - of course :)

Here's my collection of documents and lists:
Click here (https://docs.google.com/leaf?id=0B87O0bRBiC6fZGRjNzA5MmYtYmIxNy00MGIzLWE0NzItYjEwMzRkZTk1Mzdi&hl=en)

Please double check it against your board - my A4000 list is for a revision B - and as there could be errors in the list, you use it at your own risk :whistle: I appreciate your understanding!

Part numbers/DigiKey order numbers may be incorrect as I have since switched to Farnell and I keep separate baskets on my account in there.

But the cap values/sizes should be correct :)

I need to update my lists really, there are some old ones for example - my separate A1200 lists are old and the combined A600/A1200 one is the newest. This is why I haven't shared them previously as they were just for my own use.

Suggested bi-polar capacitors for the alleged problematic audio circuits are there, but I've not bothered when doing my orders, and just went for regular
ones as I'm not convinced that they have any shorter a lifespan than the other capacitors on the board.

Suggestions/amendments welcome :)

hooverphonique
23rd April 2012, 22:20
My A4000 has a "Taiwan Liton" PSU.. I've started putting together a capacitor parts list (the small ones on the daugtherboard are not on it (yet)).

list:
https://docs.google.com/a/bruder.dk/spreadsheet/ccc?key=0AusBZF1jG-b2dG5RcGI3ODF0MWZYTExKNjZEci1pdVE#gid=0

Paul_s
23rd April 2012, 22:36
Nice thread Dale, do you fancy doing some cap replacements on my 2000 PSU? It could probably do with an overhaul - must be 6 years older than your 4000 one! :unsure:

lostrego
30th April 2012, 18:12
Hi hooverphonique:


My A4000 has a "Taiwan Liton" PSU.. I've started putting together a capacitor parts list (the small ones on the daugtherboard are not on it (yet)).

list:
https://docs.google.com/a/bruder.dk/spreadsheet/ccc?key=0AusBZF1jG-b2dG5RcGI3ODF0MWZYTExKNjZEci1pdVE#gid=0

I've listed those also from my Liteon:

c40 - 1 uF , 450v through hole - electrolytic (that's missing on your list)

C1 - 0.68uF , 250VAC "x2 class" Polyester (PET)

daghuter:

all through hole - electrolytic

C44,C46 - 22uF , 16V each
C31,C38 - 22uF , 16V each
c56 - 10uF , 50v
C11 - 10uF , 50v
c10 - 2.2uF , 50V

Do they match to your Liteon ones ? as I've catch the values without desoldering them, so perhaps I'm wrong.

I'm also interested in recap mine. :)

paalrosen
27th December 2015, 10:35
can anyone confirm that these two are right type?

www.elfadistrelec.no

Art.-nr.11086296Serie (https://www.elfadistrelec.no/c/cat-614481?q=*&filter_productFamilyCode=cat-614481)
Kapasitans0.68 µF
DielektriskMetallisert polypropylenfilm

TypeECQUAAF684K
Merkespenning275 VAC
Bredde10 mm

Panasonic Automotive & Industrial Systems
Kapasitanstoleranse±10%
Høyde17 mm


Pitch22.5
Lengde26 mm






Temperaturområde-40...+110 °C
ø d0.8 mm





Art.-nr.11086287Serie (https://www.elfadistrelec.no/c/cat-614481?q=*&filter_productFamilyCode=cat-614481)
Kapasitans0.22 µF
DielektriskMetallisert polypropylenfilm

TypeECQUAAF224KA
Merkespenning275 VAC
Bredde7.5 mm

ProdusentPanasonic Automotive & Industrial Systems
Kapasitanstoleranse±10%
Høyde14 mm


Pitch15
Lengde17.5 mm





Temperaturområde-40...+110 °C
ø d0.6 mm

Deling
27th December 2015, 11:01
yes this caps are correct , but my ask sound , why are you replace X2 polypropylene capacitors ?
this caps are for long life never leak or other damage !! this kind of caps are not for replace

strange

paalrosen
27th December 2015, 11:20
yes this caps are correct , but my ask sound , why are you replace X2 polypropylene capacitors ?
this caps are for long life never leak or other damage !! this kind of caps are not for replace

strange

I came across this thread where they had been replaced, but if it is not necessary then it's no point
but thanks for the information

Deling
27th December 2015, 11:51
off course you can replace :-) your money your time , but really not necessary