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Forums > CSDb Discussions > MOS 8580R5 incompatibility?
2018-01-24 00:43
Bago Zonde

Registered: Dec 2010
Posts: 28
MOS 8580R5 incompatibility?

Hi guys!

Is there any chance that MOS 8580R5 SID won't work on the newer version of C64? I used 8580R5 there, but CSG.

Recently I've bought a MOS 8580R5 but unfortunately it won't work with this motherboard:

PCB ASSY NO. 250469
PCB NO. 252311 REV.B

I hear a loud buzzy noise, and SID is warming up very very quickly.

So, I've bought another 2 SIDs, one CSG and one MOS. And, CSG works perfectly but another MOS behaves the same, buzzy noise, warming fast...

I tested it on two C64s (both are the same revisions), with two different power supplies. And, it's the same behaviour...

Any idea?

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www.commocore.com
2018-01-24 07:04
lft

Registered: Jul 2007
Posts: 352
Please stop destroying SID chips, it hurts.

The new sid chip requires 9 V at pin 28, the old sid chip wants 12 V. It seems that your motherboards are configured for 12 V.

You can modify the motherboards to accomodate the new sid chip instead. You will also have the change the filter capacitors. The procedure varies between motherboard revisions.

Or you could get a sidfx.
2018-01-24 11:36
Bago Zonde

Registered: Dec 2010
Posts: 28
Hi lft, I don't know if you understood me correctly.
In all cases I'm dealing with 8580R5. The only difference is that MOS doesn't work, and CGS works.

I have a SIDFX-3, although when I've put MOS into it, something started to... smell bad so I immediately turn off the machine.

I'm confused.

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www.commocore.com
2018-01-25 17:12
Mr Ammo

Registered: Oct 2002
Posts: 100
Are you sure the MOS 8580s you bought aren't faulty?
A very vast warming chip is usually a sign that it is broken.
2018-01-25 22:03
Bago Zonde

Registered: Dec 2010
Posts: 28
Well, this is the case I cannot be sure of. The first one I bought on eBay, so it could be that. So then, I bought two SIDs from poly.play, one CGS and one MOS. My assumption is that they wouldn't sell me a wrong chip. But, the MOS chip doesn't work as well. The same behaviour, with the only difference, that with this SID my C64 is able to boot, but with the first one it wasn't even booting.

Seems like there is some pattern, or I'm really unlucky... I've asked poly.play but they haven't answered yet.

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www.commocore.com
2018-01-25 23:42
lft

Registered: Jul 2007
Posts: 352
Hi!

Sorry if I jumped to the wrong conclusion. Perhaps there is more to this than meets the eye.

But could you measure the voltage on pin 28 in the (empty) sid socket?

If you first put the chip in a faulty motherboard, accidentally damaging it, then the broken chip might later behave badly (e.g. smell) in some other environment, like the sidfx.
2018-01-26 18:12
Mr Ammo

Registered: Oct 2002
Posts: 100
Quoting Bago Zonde
Well, this is the case I cannot be sure of. The first one I bought on eBay, so it could be that. So then, I bought two SIDs from poly.play, one CGS and one MOS. My assumption is that they wouldn't sell me a wrong chip. But, the MOS chip doesn't work as well. The same behaviour, with the only difference, that with this SID my C64 is able to boot, but with the first one it wasn't even booting.

Seems like there is some pattern, or I'm really unlucky... I've asked poly.play but they haven't answered yet.


I think it's just bad luck. Ask for a replacement by poly.play and contact the ebay seller also. If he didn't make clear upfront that it might be faulty, you should be able to return it. If it's a EU company, you should be able to send it back under EU cosumer law (https://europa.eu/youreurope/citizens/consumers/shopping/guaran..)

I once bought an 8580 SID chip from ebay, a respectable seller even, and the SID was faulty. The seller said it was normal behaviour. Well, since EU consumer law allows us to send back goods within 14 days after receiving it, I just sent it back and got my money back. Since then I only buy full c64s if I need a new SID (that's only some 20 euros more expensive) ;-)

Since you smell things burning, please also try following up on lft's suggestion.
2018-01-26 18:14
Groepaz

Registered: Dec 2001
Posts: 8472
when you are buying individual chips, there is also always a chance that you get a fake. or at least some half broken untested something :)
2018-01-28 16:24
Bago Zonde

Registered: Dec 2010
Posts: 28
@lft
The voltage on PIN 28 is 9.21V.

-----------------
www.commocore.com
2018-01-28 21:35
lft

Registered: Jul 2007
Posts: 352
That's close enough; with a steady 9.21V you should be safe. We can't rule out the PSU as a culprit (there might be a lot of ripple), but at least it's not frying the chips with 12V.
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