Need repair advice for C15 on an A500

[Franko]

In the meantime you might like to look through this online Service Manual for the A500+, If I recall correctly though I don't think it contains a part list...

A500+ Service Manual...

[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!

[Franko]

Found it unfortunately It's the A500Plus service manual I have too...

I couldn't say therefore if C15 is different from the original A500's C15 Capacitor but the only details given in this service manual are...

C15 = MLC AXIAL Z5U .01uf

(If I recall correctly the Z5U means that this capacitor has a 50v rating)

However as you have said that your one is 0.1uf then it looks like C15 in an A500 and C15 in an A500plus are two entirely different sized components...

If the capacitor is the Un-Polarosed type then these generally have a minimum rating of 50v (usually a lot higher), hopefully someone else can supply you with the appropriate details... sorry...

[guest7146]

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!

Okay, so we're talking about a through-hole 100nF ceramic capcitor, then.

You don't need to concern yourself with voltage ratings.  The IC in question is on a 5V supply rail and all ceramic capacitors are going to have a larger voltage rating than that.

In fact, you can pretty much just shove any 0.1uF (100nF) ceramic capacitor in there and it's going to work fine.  The only reason I asked for a picture was so that I could try and find you one that looked similar.  If you don't care about it looking similar, you can put any decent 0.1uF capacitor in there you like.

What about this one - it'll do the job nicely: http://uk.farnell.com/vishay-bc-components/a104k15x7rf5taa/capacitor-0-1uf-50v-x7r/dp/1612199

Or if you don't want the hassle of buying one then just find yourself a piece of junk electronic item and nab one out of there - it's pretty much a dead cert that it'll have a 0.1uF ceramic capacitor in there somewhere.  You'll need to choose a relatively old piece of junk electronics though because most modern stuff is surface mount only.

Hope this helps.

AH

[JimS]

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.

[JimS]

Ooooh... dunno about that, here's a wee pic of one I had to replace in an old Hi Fi about 3 weeks ago... (very rarely do I come across one's that aren't polarised)...

Interesting.... I can't recall coming across an electrolytic capacitor smaller than 1uf...

[Franko]

Interesting.... I can't recall coming across an electrolytic capacitor smaller than 1uf...

I've got bags full of em 0.33uf, 0.47uf etc...

It's the opposite for me I very rarely come across the UnPolarised type...

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"...

[smerf]

Found it unfortunately It's the A500Plus service manual I have too...

I couldn't say therefore if C15 is different from the original A500's C15 Capacitor but the only details given in this service manual are...

C15 = MLC AXIAL Z5U .01uf

(If I recall correctly the Z5U means that this capacitor has a 50v rating)

However as you have said that your one is 0.1uf then it looks like C15 in an A500 and C15 in an A500plus are two entirely different sized components...

If the capacitor is the Un-Polarosed type then these generally have a minimum rating of 50v (usually a lot higher), hopefully someone else can supply you with the appropriate details... sorry...

Hi,

Only Amiga, come on lets all sing it together.

smerf

[Franko]

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

[guest7146]

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...

There was a time when you could walk into a Maplins store and discuss your latest project with the guy (or girl... but I never saw any girls back then) and get some advice/share some tips etc.  Also they always had a huge range of components in stock.  The people behind the counter actually knew what they were talking about.

These days the majority of Maplin staff haven't got the faintest idea about electronics.  If you give them a part number they can find it in their part bins, but that's about the extent of it.  They keep only a small range of components in stock, and even then it's basically ones and twos of things.  Pretty poor.
There used to be a Maplin electronics magazine too.  That stopped years ago.

If you want disco equipment or flashing LEDs for your car or ICE - Maplins is the place to go.
If you want some component for an electronic design, forget it.

Shame though!

AH

[guest7146]

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.

I agree.  In practice it's not going to make any difference whether the OP fits a 0.1uF or 0.33uF capacitor in there.

As Franko has said we don't have many decent electronics component shops here in the UK any more, but if there's one local to you Michael then I'd recommend you take a drive down there and ask them for a 0.1uF axial ceramic capacitor.  We're only talking about a decoupling capacitor so the exact type of ceramic capacitor is not particularly important.  Just get one that will physically fit onto the board.

AH

[guest7146]

Best place these days to get components and the like is CPC/Farnell but they are only mail order...

Yeah and there's a £30 minimum order for non-account (residential) customers.  Which is a pain if all you want is a 0.1uF capacitor that costs 4p ;-)

AH

[Franko]

@ AppleHammer

I avoid Maplins at all costs these days, the trained monkeys they employ sometimes can't even work the till let alone have a scooby doo about what your looking for. It's a far cry from years ago when they had to compete with Tandy and the staff were knowledgeable & friendly back then...

CPC's minimum charge these days is now £45 for free delivery, I used to have a business account with them that avoided that but these days I only have a customer account and end up ordering stuff I don't need at the time just to get a few components that cost pennies...

I miss Tandy and all the little private Component shops that used to be around, but as the manager of my local Maplins explained to me a number of years ago, there is no longer the market for electronic hobbyists and almost everything these days is of a "throw away value" as it's often cheaper to buy something new than to have it repaired...

Doesn't help those of us in Amigaland or who still like to repair things or build our own circuits but then that's the way of the world these days not many can be bothered learning how things work let alone repairing them and the electronics hobbyist market is like the Amiga market, fading into obscurity...

[JimS]

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 ...

Well, Michael's in Tennessee, so there ought to be a Shack around somewhere that still has components... usually wedged into the back corner as you Brit's would say inside a disused lavatory with a sign saying "Beware of the Leopard". ;-)

Point taken about the hobby market not being what it once was.... we used to have maybe a dozen hobbyist magazines, now it's down to maybe 2 or 3 and one of those is an import from the EU.

[TheBilgeRat]

Doesn't help those of us in Amigaland or who still like to repair things or build our own circuits but then that's the way of the world these days not many can be bothered learning how things work let alone repairing them and the electronics hobbyist market is like the Amiga market, fading into obscurity...

It's not that you aren't consuming, just that you aren't consuming ENOUGH and of the "CORRECT" things!  Planned obsolescence, roll-over, 400% margins for Steve Jobs and the CFO of Dell!  M$ licenses!  You, sir, are a communist if you don't recycle your old electronics after a year!  You are denying jobs to third world countries!  There are people relying on your greed and avarice..er..I mean consumer savvy... so they can melt down your cast-offs in their back yard and feed their families before they die of heavy metal poisoning!

CONSUME!  CONSUME! CONSUME!

OK.  rant done.