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Great thread, really interesting to see that come together. I'm a bit envious of your electronics diagnostic skills!
Nice work.
Nice work.
Amiga 4000 restoration
- Thread starter Elerion
- Start date
- Replies 61
- Views 31088
Thanx.
I'll take a vecation next week, and have more time to complete the work.
BTW I spent some time drooling over your great photos of old computers. Since you are a photographer, in case you want to know, most photos in this post (the better ones) were taken by my wife.
She was not so happy with the result, because she needs "a different kind of lens for this type of photography".
Anyway they are good enough for me. Thanx honney.
Thoughts on leaked caps
Thoughts on leaked caps
On this board I found two types of damage from leaked battery/caps.
1) Burned via.
2) burned trace very close next to via or a pad. (joints were copper was not protected by either lacquer or solder)
Both types of damage cannot be detected by visual examination (even using strong magnifier glass). You just have to test if each suspect trace is closing the circuit.
When you detect that solder next to a cap is not shiny, you can be sure surrounding copper traces already started to corrode. Then it's just a matter of time before the board starts showing serious problems.
What bothers me the most at this point is the fact that even cleaned and repaired, this board could contain more traces just about to get broken. Kind of “timed bombs”. And that a simply by bending a board or just after a few years’ time these “bombs” will go off.
I just hope I cleaned all the leaked electrolyte good enough.
BTW
Did you know that caps leaking problem is isolated to Taiwanese caps produced before approx. 2007.
The story is that some Taiwanese caps manufacturers have stolen a beta version of electrolyte formula that produced a hydrogen gas within a cap container that will depending on conditions blow up the cap to the point corrosive electrolyte starts leaking.
Japanese caps (that were more expensive at the time) did not produce this problem. They may lose their properties over time, but they are not leaking "time bombs".
So... If you have not replaced caps in your Amigas yet, do it ASAP.
Be sure to use Japanese brands or caps as fresh as you can get.
Because it may already be too late.
Thoughts on leaked caps
On this board I found two types of damage from leaked battery/caps.
1) Burned via.
2) burned trace very close next to via or a pad. (joints were copper was not protected by either lacquer or solder)
Both types of damage cannot be detected by visual examination (even using strong magnifier glass). You just have to test if each suspect trace is closing the circuit.
When you detect that solder next to a cap is not shiny, you can be sure surrounding copper traces already started to corrode. Then it's just a matter of time before the board starts showing serious problems.
What bothers me the most at this point is the fact that even cleaned and repaired, this board could contain more traces just about to get broken. Kind of “timed bombs”. And that a simply by bending a board or just after a few years’ time these “bombs” will go off.
I just hope I cleaned all the leaked electrolyte good enough.
BTW
Did you know that caps leaking problem is isolated to Taiwanese caps produced before approx. 2007.
The story is that some Taiwanese caps manufacturers have stolen a beta version of electrolyte formula that produced a hydrogen gas within a cap container that will depending on conditions blow up the cap to the point corrosive electrolyte starts leaking.
Japanese caps (that were more expensive at the time) did not produce this problem. They may lose their properties over time, but they are not leaking "time bombs".
So... If you have not replaced caps in your Amigas yet, do it ASAP.
Be sure to use Japanese brands or caps as fresh as you can get.
Because it may already be too late.
From what I read trough the years, they bought some capacitors, extracted the electrolyte from inside and tossed in a gas mass spectrometer, then re-create the formula without taking care of the small particles showed (the stabilizers!).
Repairing EGS Spectrum and A3640
Repairing EGS Spectrum and A3640
Well I wish I had more time during the holidays to complete repairs of this Amiga, but most of the time I had was spent in shopping malls, restaurants and other similar expensive places chosen by my wife.
However, I managed to put aside a few hours to pamper this beautiful Miggy.
Yesterday I repaired burned tantalum cap on EGS card:
and octal transceiver on A3640 accelerator:
Both EGS and A3640 are working great. After 4 hours of stress there were no crashes. This 18 years old lady is performing as fine as on the day she left the factory. (Well except for RTC, but I'll fix that soon.)
While I was examining these pictures, and admiring the quality of Nikkor optics, beside the dust that under magnification looks like dog hair, I noticed nasty looking whitish substance inside the vias of the accelerator board.
You can see that on the picture just right next to transceiver chip.
What's this? Is it corrosion from caps electrolyte spill :wooha:, or just a mix of solder flux and isopropyl alcohol?
Repairing EGS Spectrum and A3640
Well I wish I had more time during the holidays to complete repairs of this Amiga, but most of the time I had was spent in shopping malls, restaurants and other similar expensive places chosen by my wife.
However, I managed to put aside a few hours to pamper this beautiful Miggy.
Yesterday I repaired burned tantalum cap on EGS card:
and octal transceiver on A3640 accelerator:
Both EGS and A3640 are working great. After 4 hours of stress there were no crashes. This 18 years old lady is performing as fine as on the day she left the factory. (Well except for RTC, but I'll fix that soon.)
While I was examining these pictures, and admiring the quality of Nikkor optics, beside the dust that under magnification looks like dog hair, I noticed nasty looking whitish substance inside the vias of the accelerator board.
You can see that on the picture just right next to transceiver chip.
What's this? Is it corrosion from caps electrolyte spill :wooha:, or just a mix of solder flux and isopropyl alcohol?
If fibre was exposed to this extent, I don't think the board would be working.
I agree that wiring the holes would be a permanent solution, but there are just too many of them, and they are smaller then they appear on the photos. It would take ages to solder them all.
I’ll take the suggestion and fill those closest to leaking caps (especially close to inverted C107 that was leaking heavily) to prevent future problems.
easypreacher
Member
I'm still missing 3,5" front cover.
If you can help providing one, or have an idea on how to recreate one, please do.
I have one of these if you still need one. PM me with postage details and i will send it to you.
Awesome restoration skillz BTW
I'm still missing 3,5" front cover.
If you can help providing one, or have an idea on how to recreate one, please do.
I have one of these if you still need one. PM me with postage details and i will send it to you.
Awesome restoration skillz BTW
Fantastic! I love you! PM on the way!
RTC circuit repair
RTC circuit repair
Last stage of refurbishing this board is RTC circuit.
First, I removed all the chips and cleaned up the board under them:
I spent a few minutes testing traces. I was somewhat disappointed when I found out there are healthy. One would expect most damage from battery leak right here...
Anyway I resoldered the chips and fitted a socket for new Ricoh RTC chip:
And an ugly green barrel of imminent board destruction got a replacement. A coin battery fitted to holder modified with a diode:
Works like a charm!
This concludes the repairs to the board.
Time to light up a cigar and celebrate with some fine alcohol.
int:
Next year I'll do the cosmetics. Corrosion removing, retr0brighting and fitting all the parts together.
In the meantime, I congratulate all of you wonderful people on another successfully finished year, and all the best in the next one!
Cheers!
RTC circuit repair
Last stage of refurbishing this board is RTC circuit.
First, I removed all the chips and cleaned up the board under them:
I spent a few minutes testing traces. I was somewhat disappointed when I found out there are healthy. One would expect most damage from battery leak right here...
Anyway I resoldered the chips and fitted a socket for new Ricoh RTC chip:
And an ugly green barrel of imminent board destruction got a replacement. A coin battery fitted to holder modified with a diode:
Works like a charm!
This concludes the repairs to the board.
Time to light up a cigar and celebrate with some fine alcohol.
int:Next year I'll do the cosmetics. Corrosion removing, retr0brighting and fitting all the parts together.
In the meantime, I congratulate all of you wonderful people on another successfully finished year, and all the best in the next one!
Cheers!
Last edited:
Adix
New member
Hi Elerion, Great job with your A4000. I have to do the same job witch my 2 a4k. I saw your pic and Caps replacement before and after replacement. First cap 22uF before replacement have good polarity but after is solder with wrong polarity could u check it (first from bottom pic caps for audio)?
Cheers,
Adam
Cheers,
Adam
As requested, here are two piscs of A4000 running with on an oversized monitor. :roll:
I was using old 1084 monitor while testing repairs, but I decided to test the GVP 28/24 with this one, and used the oportunity to make some photos.
It tooked me a while before I figured out that OS3.9 Boing bag 2 patches exec.library in a way that CGX modes are not showing in ScreenMode Prefs.
Not so elegant solution was to skip exec.library patching in setpatch. Is there a better one? (Upgrading CGX4 to RC4, 5 and 6 didn't help.)
I was using old 1084 monitor while testing repairs, but I decided to test the GVP 28/24 with this one, and used the oportunity to make some photos.
It tooked me a while before I figured out that OS3.9 Boing bag 2 patches exec.library in a way that CGX modes are not showing in ScreenMode Prefs.
Not so elegant solution was to skip exec.library patching in setpatch. Is there a better one? (Upgrading CGX4 to RC4, 5 and 6 didn't help.)
Retr0bright time
Retr0bright time
Encouraged by Abraxxxious great success, It's time to try it myself:
I'm using cheap Muhler Blacklight lamp, 12% peroxide, some castor oil, and some Vanish oxy.
And here we go:
Let's sleep on this one...
Retr0bright time
Encouraged by Abraxxxious great success
, It's time to try it myself:I'm using cheap Muhler Blacklight lamp, 12% peroxide, some castor oil, and some Vanish oxy.
And here we go:
Let's sleep on this one...
Encouraged by Abraxxxious great success
I'm using cheap Muhler Blacklight lamp, 12% peroxide, some castor oil, and some Vanish oxy.
And here we go:
Let's sleep on this one...
Oh Snap! You didn't take the keyboard apart first? You're going to need to take it apart and make sure it's 100% dry in there before using it.
Of course I did. I have just placed top cover on the keys to save space. It seems the lamp is not strong enough to spread light over three parts of keyboard and A4000 front at once.
Anyway, after approx 7 hours of sunbathing, I've rinsed the parts.
It's not perfect, but there is definite improvement. (Especially on the "space key".) No damage on the plastic or metal parts.
I will take and post pictures at first opportunity.
What is noticeable right away, it seems that lamp is really too weak. Keyboard has been unevenly whitened. It's whiter on the center (closer to the lamp), and yellower on the sides.
It seems I need a better lamp for next attempt, but it's quite hard to buy a nice lamp here in Croatia. The closest match are overpriced medical lamps, and reptile ambient lamps...
What do you think of these?
http://www.exo-terra.com/en/products/compact_fluorescent_bulbs.php
It seems that Repti Glo 5.0 and 10.0 have a lot of light in UVA and UVB part of the spectrum, and are not so expensive.
