Need repair advice for C15 on an A500

[BosonMichael]

While trying to remove a faulty U15 chip in my Amiga 500, I damaged C15. According to the A500 service manual, it looks like C15 is a 0.1uF capacitor. Does that sound right? I don't know much about component repair... can I use any 0.1uF capacitor, or is there a certain type I should try to get?

[BosonMichael]

If it's a 0.1uf Capacitor and the voltage rating on it is say for example 16v then you can easily replace it with any other 0.1uf capacitor as long as the voltage rating is at least 16v...

Well, that's the problem... I don't know what the voltage rating is.

[BosonMichael]

I only have a copy of the A500+ manual but in there C15 is a 0.01uF (10nF) capacitor, non polarised (please re-check your manual and advise if yours says different. From here on I will assume C15 is the same in your machine as the A500+). As JimS has already said, it's a decoupling capacitor and is not critical to the operation of U15. You could probably get away without fitting a replacement, although obviously this isn't ideal.
 
I checked the parts list and it looks like we're talking about a through-hole axial component, right?
 
Please see my info attached.
 


 
The capacitor is described as a Z5U device in the parts list. That means it's designed to operate between +10 to +85 degrees C and has a tolerance of -56% to +22%.
 
Get yourself a replacement ceramic capacitor (MLC means Multi-Layer Ceramic) that matches those specs (easy peasy) and you'll be just fine!
 
If you want further help choosing a capacitor let me know and I'll suggest some replacements from Farnell for you. In this case please photograph the component for me so that I can suggest one that will match the footprint of the original component. I'd dig out my A500+ and find it myself but I've just moved and my A500 machines are both still at my old house!
 
Cheers!
 
AH

I don't have a manual, but I dug up one from the Internet. Here's the relevant pic - it shows a 0.1uF capacitor:
 

 
Note the bottom corner that indicates an A500. Perhaps they improved processes by the time the A500+ came out that required only a 0.01uF cap?
 
Unfortunately, I no longer have the component. I split the little piece in two and could not read the markings on the outside. I do recall that it looked similar to some of the ceramic axial capacitors I've seen in pics on the Web... but there are a lot of pics online that don't look the same. It was encased in a little plastic "shell", and the leads came out each end. It looked like the ceramic (inside the plastic) had little rings around it, but I didn't remove the rest of the plastic to investigate further - I just desoldered it and threw it out. I figured it'd be easy to find the specs online! Live and learn...
 
I could potentially take a pic of C13 or C33, both also marked as .1uF. They might be similar... but I'm not certain. I can try to take pics this weekend...
 
So... what would happen if I put a 0.01uF cap in a spot that should have a 0.1uF cap, or vice versa? And is there a particular voltage rating I'd need to look for?

[BosonMichael]

Thanks for all your help on this, everyone. I greatly appreciate the help in getting this A500 back on its feet after nearly 20 years of sitting on the shelf!

[BosonMichael]

OK, here's something else to stir the pot.... I just looked in my 500 schematics, which cover the rev5 and 6/7 motherboards. On the 6/7 boards, they changed the decoupling capacitors - including c15 to .33uF.
In any case, you should be able to find something that works at the local Radio Shack.

Thanks, Jim! I'll be sure to check the revision number when I crack my case open. I should be able to get some markings off the other assorted decoupling caps.
 
No pics yet... the weekend was way too busy. Will shoot for Tuesday night (the busy work continues tonight). Thanks for the continued help!

[BosonMichael]

On the subject of Radio Shack...
 
You'd have a hard job doing doing that here...
 
They shut down all the Radio Shack stores (TANDY) in the UK back in the late 90's ...
 
Loved going into those little treasure troves shops, now all we have left is Maplins and even though the stores are bigger components & electrical DIY are only a tiny part of them these days as they are more like PC/Gadget stores these days...
 
Best place these days to get components and the like is CPC/Farnell but they are only mail order...
 
I miss being able to wander round them stores and buying components I didn't really need just because I thought "those look interesting wonder what circuit I can build with some of those"...

Fortunately, I'm in the States. Unfortunately, Radio Shack has lost much of the charm it once had... components are harder to find, particularly in newer Radio Shacks.

[BosonMichael]

Hi Smerf...
 
Yup, how many folks would go to all this bother to fix a PC !!!
 
Not many I guess, they'd just pop down the nearest discount store or ASDA/WallMart and buy a new one...
 
Where's the fun in that...
 
Cheers
 
Franko

Actually, it was a PC problem that finally compelled me to get off my backside and learn how to solder. I have a six-year-old Dell Inspiron 5160 laptop that developed a loose power jack. I was reluctant to spend money on a new laptop, so I figured I'd first try to repair it myself. And as an added bonus, I'd be able to repair my beloved Amiga as well!
 
The Amiga repair was first... and didn't go as smoothly as the PC repair. The laptop jack is solid... so I'm guessing I did a good job on soldering U15 - with the exception of the C15 destruction. Hopefully that fixes the joyport problem I was experiencing... we shall see, as soon as I get C15 fixed up. Compared to U15, it should be a piece of cake!

[BosonMichael]

Hi Michael,

Did you get your problem sorted out? I would be interested to hear if she's up and running.

AH.

Nine years later, and I'm just getting around to this. Kids were young then... now they're in high school.

Ordering some axial caps as we speak. Thanks for your help, everyone.