RE: 6540 ROMs replacement ?

From: Jürgen Sievers (
Date: 2003-02-05 03:13:42

> -----Original Message-----
> From:
> []On Behalf Of Nicolas Welte;
> address is valid for replies (Re:) only!
> Sent: Wednesday, February 05, 2003 12:39 AM
> To:
> Subject: Re: 6540 ROMs replacement ?
> Jürgen Sievers wrote:
> > The sockets installed are very sheap and so the new sockets
> could not fit
> > into the old sockets.
> > The renewed only touches the side of the top parts from the old
> sockets. But
> > without much pressure and so some pins don't getting into
> contact. I can't
> > press the new sockets into the old sockets deep enough.
> Then you should replace the old sockets. Precision sockets give the best
> contact and will last for decades, but some people (including me) have the
> opinion that they look ugly in an old PET. Low cost sockets with a double
> contact spring are what looks most like the old sockets, and they
> also give
> very good contact.

Yes, that's was the solution. After I have removed the fixture from the old
sockets I saw the dilemma. Some of the springes was broken.
By the way. A good way to remove the old sockets is to cut up the fixture by
using a small drill tool with a cutter wheel on it. Then you can remove each
pin with a soldering iron and a pliers.

But one of the 6540 may be really damage.  But what's the cause, why your
adaptor doesn't work on the systems ROM but on the character generator?
When I look on the circuit diagram diagram I can see 2316B instead of 6540A.
Maybe I have a wrong plan.

> BTW, I have no problems if I put my adaptors with gold contacts
> into the old
> sockets. It seems the contact problem is also caused by corrosion
> on the old
> chips and on the socket contacts.

Do you have a prefabricated constructed one for me ?

> Nicolas
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