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6561-101

hegedusis
Hi,
 
I have a broken VIC20 which seems to have a bad VIC. Does anyone know where can I buy one for a fair price?
 
Thanks
Hege
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Re: 6561-101

Didier Derny

Hi


hard to find...

I find one there:  http://www.mutant-caterpillar.co.uk/shop/product_info.php?products_id=3689

no idea of the prices so hard to say if the price is fair....

but in any cases 17£ it's far less than the prices of LittleDiode....


On 25/10/2016 22:07, Hegedűs István wrote:
Hi,
 
I have a broken VIC20 which seems to have a bad VIC. Does anyone know where can I buy one for a fair price?
 
Thanks
Hege

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Re: 6561-101

Francesco Messineo
In reply to this post by hegedusis
Hi

On Tue, Oct 25, 2016 at 10:07 PM, Hegedűs István <[hidden email]> wrote:
> Hi,
>
> I have a broken VIC20 which seems to have a bad VIC. Does anyone know where
> can I buy one for a fair price?

what's the symptom? The 6561 was reliable enough. I can't remember
changing any in the '80s (but VIC-20s were already almost estinct when
I started repairing commodore stuff, so don't flame please).
As far as I remember, the 6561 was only used for the VIC-20.
Some IC traders might have them in stock, but I'd say it's a question
of luck to get good chips instead of bad/fakes nowadays.
I can help in troubleshooting your VIC-20 (as surely many others here)
if you're unsure.

Best regards
Frank

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Re: 6561-101

hegedusis
In reply to this post by Didier Derny
Hi,
 
Thanks. I got quote also from Alibaba but the postage and minimal amount is too high. Taking into account that it can contain Chinese fakes or broken chips it is a high risk.
This one looks better, I have sent a query for postage cost. Probably I will go for it.
 
Thanks
Hege
Sent: Tuesday, October 25, 2016 10:19 PM
Subject: Re: 6561-101
 

Hi

 

hard to find...

I find one there:  http://www.mutant-caterpillar.co.uk/shop/product_info.php?products_id=3689

no idea of the prices so hard to say if the price is fair....

but in any cases 17£ it's far less than the prices of LittleDiode....


On 25/10/2016 22:07, Hegedűs István wrote:
Hi,
 
I have a broken VIC20 which seems to have a bad VIC. Does anyone know where can I buy one for a fair price?
 
Thanks
Hege

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Re: 6561-101

hegedusis
In reply to this post by Francesco Messineo
Hi,

It has black screen of course. I know that the Kernal ROM or VIC used to be
the guilty ones. I have burnt a 27c128 with Kernal but still have to build
an adapter so I cannot 100% rule out Kernal issue. The guy who sold it said
that the 6502 is also sick (he has tried the CPU in an 1541), though with
oscilloscope I have seen e.g. proper phi2 signal coming out. I have bought
some Rockwell 6502s to replace it. Anyway even if it turns out that VIC is
good it is better to have a spare IC.
I should hook up my logic analyzer to it but so far I had no time (or I was
just too lazy).

Thanks
Hege


-----Original Message-----
From: Francesco Messineo
Sent: Tuesday, October 25, 2016 10:23 PM
To: [hidden email]
Subject: Re: 6561-101

Hi

On Tue, Oct 25, 2016 at 10:07 PM, Hegedűs István <[hidden email]>
wrote:
> Hi,
>
> I have a broken VIC20 which seems to have a bad VIC. Does anyone know
> where
> can I buy one for a fair price?

what's the symptom? The 6561 was reliable enough. I can't remember
changing any in the '80s (but VIC-20s were already almost estinct when
I started repairing commodore stuff, so don't flame please).
As far as I remember, the 6561 was only used for the VIC-20.
Some IC traders might have them in stock, but I'd say it's a question
of luck to get good chips instead of bad/fakes nowadays.
I can help in troubleshooting your VIC-20 (as surely many others here)
if you're unsure.

Best regards
Frank

       Message was sent through the cbm-hackers mailing list


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Re: 6561-101

Francesco Messineo
On Tue, Oct 25, 2016 at 10:38 PM, Hegedűs István <[hidden email]> wrote:

> Hi,
>
> It has black screen of course. I know that the Kernal ROM or VIC used to be
> the guilty ones. I have burnt a 27c128 with Kernal but still have to build
> an adapter so I cannot 100% rule out Kernal issue. The guy who sold it said
> that the 6502 is also sick (he has tried the CPU in an 1541), though with
> oscilloscope I have seen e.g. proper phi2 signal coming out. I have bought
> some Rockwell 6502s to replace it. Anyway even if it turns out that VIC is
> good it is better to have a spare IC.
> I should hook up my logic analyzer to it but so far I had no time (or I was
> just too lazy).

An oscilloscope is more than enough most of the times. I repaired a
VIC-20 with black screen (it's on youtube) and it turned out to be the
basic ROM. I'd check the data lines on CPU side and on RAM side
(there's a 74LS245 separating RAM from CPU/ROM data bus). The ROMs are
usually much more likely to go bad.
Given the symptom and that you have the CPU clock output from the VIC,
I'd bet in a ROM gone bad :)
Of course, first replace the 6502 if it's sick.


Frank

>
> -----Original Message----- From: Francesco Messineo
> Sent: Tuesday, October 25, 2016 10:23 PM
> To: [hidden email]
> Subject: Re: 6561-101
>
> Hi
>
> On Tue, Oct 25, 2016 at 10:07 PM, Hegedűs István <[hidden email]>
> wrote:
>>
>> Hi,
>>
>> I have a broken VIC20 which seems to have a bad VIC. Does anyone know
>> where
>> can I buy one for a fair price?
>
>
> what's the symptom? The 6561 was reliable enough. I can't remember
> changing any in the '80s (but VIC-20s were already almost estinct when
> I started repairing commodore stuff, so don't flame please).
> As far as I remember, the 6561 was only used for the VIC-20.
> Some IC traders might have them in stock, but I'd say it's a question
> of luck to get good chips instead of bad/fakes nowadays.
> I can help in troubleshooting your VIC-20 (as surely many others here)
> if you're unsure.
>
> Best regards
> Frank
>
>       Message was sent through the cbm-hackers mailing list
>
>       Message was sent through the cbm-hackers mailing list

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Re: 6561-101

Clockmeister
In reply to this post by hegedusis


On 26/10/2016 4:38 AM, Hegedűs István wrote:

> Hi,
>
> It has black screen of course. I know that the Kernal ROM or VIC used
> to be the guilty ones. I have burnt a 27c128 with Kernal but still
> have to build an adapter so I cannot 100% rule out Kernal issue. The
> guy who sold it said that the 6502 is also sick (he has tried the CPU
> in an 1541), though with oscilloscope I have seen e.g. proper phi2
> signal coming out. I have bought some Rockwell 6502s to replace it.
> Anyway even if it turns out that VIC is good it is better to have a
> spare IC.
> I should hook up my logic analyzer to it but so far I had no time (or
> I was just too lazy).
>


Whilst mask ROM (and RAM for that matter) failures are common on vintage
equipment, the last two VIC-20's with a black screen that I repaired had
a bad 6561-101.
In my case both were easy to diagnose by simply plugging in a cartridge
or blind loading a game. On both occasions the game you could hear the
game playing even though there was a black screen.





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Re: 6561-101

hegedusis
The problem is that this is my first ever VIC20 so I have no cartridges...
The idea is however good.
Thanks
Hege


-----Original Message-----
From: Clockmeister
Sent: Wednesday, October 26, 2016 3:00 AM
To: [hidden email]
Subject: Re: 6561-101



On 26/10/2016 4:38 AM, Hegedűs István wrote:

> Hi,
>
> It has black screen of course. I know that the Kernal ROM or VIC used to
> be the guilty ones. I have burnt a 27c128 with Kernal but still have to
> build an adapter so I cannot 100% rule out Kernal issue. The guy who sold
> it said that the 6502 is also sick (he has tried the CPU in an 1541),
> though with oscilloscope I have seen e.g. proper phi2 signal coming out. I
> have bought some Rockwell 6502s to replace it. Anyway even if it turns out
> that VIC is good it is better to have a spare IC.
> I should hook up my logic analyzer to it but so far I had no time (or I
> was just too lazy).
>


Whilst mask ROM (and RAM for that matter) failures are common on vintage
equipment, the last two VIC-20's with a black screen that I repaired had
a bad 6561-101.
In my case both were easy to diagnose by simply plugging in a cartridge
or blind loading a game. On both occasions the game you could hear the
game playing even though there was a black screen.





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Re: 6561-101

Gerrit Heitsch
In reply to this post by Clockmeister
On 10/26/2016 03:00 AM, Clockmeister wrote:
>
> Whilst mask ROM (and RAM for that matter) failures are common on vintage
> equipment, the last two VIC-20's with a black screen that I repaired had
> a bad 6561-101.
> In my case both were easy to diagnose by simply plugging in a cartridge
> or blind loading a game. On both occasions the game you could hear the
> game playing even though there was a black screen.

While we're at it... Does someone know the difference between the 6561E
and the 6561-101?

Another common failure in a VIC-20 are the MOS 65245 if they are present
on the board in question. They can be replaced with 74LS245.

  Gerrit



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Re: 6561-101

Didier Derny
In reply to this post by hegedusis
Hi

to repair your vic20 you can use this product:

http://vic-20.de/x1541/hardware/petram.html

it replaces ram and/or rom...

it helped me to fix a old cbm 8032...


it is clear that if the VIC is not correctly initialized you probably
get a black screen.




On 26/10/2016 10:33, Hegedűs István wrote:

> The problem is that this is my first ever VIC20 so I have no
> cartridges... The idea is however good.
> Thanks
> Hege
>
>
> -----Original Message----- From: Clockmeister
> Sent: Wednesday, October 26, 2016 3:00 AM
> To: [hidden email]
> Subject: Re: 6561-101
>
>
>
> On 26/10/2016 4:38 AM, Hegedűs István wrote:
>> Hi,
>>
>> It has black screen of course. I know that the Kernal ROM or VIC used
>> to be the guilty ones. I have burnt a 27c128 with Kernal but still
>> have to build an adapter so I cannot 100% rule out Kernal issue. The
>> guy who sold it said that the 6502 is also sick (he has tried the CPU
>> in an 1541), though with oscilloscope I have seen e.g. proper phi2
>> signal coming out. I have bought some Rockwell 6502s to replace it.
>> Anyway even if it turns out that VIC is good it is better to have a
>> spare IC.
>> I should hook up my logic analyzer to it but so far I had no time (or
>> I was just too lazy).
>>
>
>
> Whilst mask ROM (and RAM for that matter) failures are common on vintage
> equipment, the last two VIC-20's with a black screen that I repaired had
> a bad 6561-101.
> In my case both were easy to diagnose by simply plugging in a cartridge
> or blind loading a game. On both occasions the game you could hear the
> game playing even though there was a black screen.
>
>
>
>
>
>       Message was sent through the cbm-hackers mailing list
>
>       Message was sent through the cbm-hackers mailing list


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Re: 6561-101

hegedusis
Hi,

I have managed to repair my VIC20. It was the SN7406 next to the 6522 ICs.
When I have removed the 6522s the computer came alive but with garbage
characters on the screen. When the 6522s were in place there was just black
screen.
After replacing the SN7406N everything was ok, the 6522s work fine. How
could this 7406 cause this problem when it is not connected to the databus
only to the 6522s?

Istvan

-----Original Message-----
From: Didier Derny
Sent: Wednesday, October 26, 2016 1:57 PM
To: [hidden email]
Subject: Re: 6561-101

Hi

to repair your vic20 you can use this product:

http://vic-20.de/x1541/hardware/petram.html

it replaces ram and/or rom...

it helped me to fix a old cbm 8032...


it is clear that if the VIC is not correctly initialized you probably
get a black screen.




On 26/10/2016 10:33, Hegedűs István wrote:

> The problem is that this is my first ever VIC20 so I have no cartridges...
> The idea is however good.
> Thanks
> Hege
>
>
> -----Original Message----- From: Clockmeister
> Sent: Wednesday, October 26, 2016 3:00 AM
> To: [hidden email]
> Subject: Re: 6561-101
>
>
>
> On 26/10/2016 4:38 AM, Hegedűs István wrote:
>> Hi,
>>
>> It has black screen of course. I know that the Kernal ROM or VIC used to
>> be the guilty ones. I have burnt a 27c128 with Kernal but still have to
>> build an adapter so I cannot 100% rule out Kernal issue. The guy who sold
>> it said that the 6502 is also sick (he has tried the CPU in an 1541),
>> though with oscilloscope I have seen e.g. proper phi2 signal coming out.
>> I have bought some Rockwell 6502s to replace it. Anyway even if it turns
>> out that VIC is good it is better to have a spare IC.
>> I should hook up my logic analyzer to it but so far I had no time (or I
>> was just too lazy).
>>
>
>
> Whilst mask ROM (and RAM for that matter) failures are common on vintage
> equipment, the last two VIC-20's with a black screen that I repaired had
> a bad 6561-101.
> In my case both were easy to diagnose by simply plugging in a cartridge
> or blind loading a game. On both occasions the game you could hear the
> game playing even though there was a black screen.
>
>
>
>
>
>       Message was sent through the cbm-hackers mailing list
>
>       Message was sent through the cbm-hackers mailing list


       Message was sent through the cbm-hackers mailing list


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Re: 6561-101

Julian Perry
Re: 6561-101 The same 7406 also drives RESET from the 555 timer, and inverts θ0 (clock) from the VIC. It's likely it was holding reset down, or otherwise messing with the clock.

As to why removing the 6522's triggered a change, I'd guess that this was due to some weird interaction between inputs arising from failed silicon on the die of the 7406.
Always nice to hear of another VIC brought alive!  The numbers of working VICs continue to shrink alarmingly.

Julian


> Hi,

> I have managed to repair my VIC20. It was the SN7406 next to the 6522 ICs.
> When I have removed the 6522s the computer came alive but with garbage
> characters on the screen. When the 6522s were in place there was just black
> screen.
> After replacing the SN7406N everything was ok, the 6522s work fine. How
> could this 7406 cause this problem when it is not connected to the databus
> only to the 6522s?

> Istvan

> -----Original Message-----
> From: Didier Derny
> Sent: Wednesday, October 26, 2016 1:57 PM
> To:
[hidden email]
> Subject: Re: 6561-101

> Hi

> to repair your vic20 you can use this product:

> http://vic-20.de/x1541/hardware/petram.html

> it replaces ram and/or rom...

> it helped me to fix a old cbm 8032...


> it is clear that if the VIC is not correctly initialized you probably
> get a black screen.




> On 26/10/2016 10:33, Hegedűs István wrote:
>> The problem is that this is my first ever VIC20 so I have no cartridges...
>> The idea is however good.
>> Thanks
>> Hege


>> -----Original Message----- From: Clockmeister
>> Sent: Wednesday, October 26, 2016 3:00 AM
>> To:
[hidden email]
>> Subject: Re: 6561-101



>> On 26/10/2016 4:38 AM, Hegedűs István wrote:
>>> Hi,

>>> It has black screen of course. I know that the Kernal ROM or VIC used to
>>> be the guilty ones. I have burnt a 27c128 with Kernal but still have to
>>> build an adapter so I cannot 100% rule out Kernal issue. The guy who sold
>>> it said that the 6502 is also sick (he has tried the CPU in an 1541),
>>> though with oscilloscope I have seen e.g. proper phi2 signal coming out.
>>> I have bought some Rockwell 6502s to replace it. Anyway even if it turns
>>> out that VIC is good it is better to have a spare IC.
>>> I should hook up my logic analyzer to it but so far I had no time (or I
>>> was just too lazy).



>> Whilst mask ROM (and RAM for that matter) failures are common on vintage
>> equipment, the last two VIC-20's with a black screen that I repaired had
>> a bad 6561-101.
>> In my case both were easy to diagnose by simply plugging in a cartridge
>> or blind loading a game. On both occasions the game you could hear the
>> game playing even though there was a black screen.





>>       Message was sent through the cbm-hackers mailing list

>>       Message was sent through the cbm-hackers mailing list


>        Message was sent through the cbm-hackers mailing list


>        Message was sent through the cbm-hackers mailing list




--
Best regards,
Julian                            
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Re: 6561-101

hegedusis
Re: 6561-101
Hi,
 
You are right. I have not noticed it in the schematic...
This must have been the reason!
Thanks
Istvan
 
Sent: Thursday, November 17, 2016 11:11 PM
Subject: Re: 6561-101
 
The same 7406 also drives RESET from the 555 timer, and inverts θ0 (clock) from the VIC. It's likely it was holding reset down, or otherwise messing with the clock.

As to why removing the 6522's triggered a change, I'd guess that this was due to some weird interaction between inputs arising from failed silicon on the die of the 7406.
Always nice to hear of another VIC brought alive!  The numbers of working VICs continue to shrink alarmingly.

Julian


> Hi,

> I have managed to repair my VIC20. It was the SN7406 next to the 6522 ICs.
> When I have removed the 6522s the computer came alive but with garbage
> characters on the screen. When the 6522s were in place there was just black
> screen.
> After replacing the SN7406N everything was ok, the 6522s work fine. How
> could this 7406 cause this problem when it is not connected to the databus
> only to the 6522s?

> Istvan

> -----Original Message-----
> From: Didier Derny
> Sent: Wednesday, October 26, 2016 1:57 PM
> To:
[hidden email]
> Subject: Re: 6561-101

> Hi

> to repair your vic20 you can use this product:

> http://vic-20.de/x1541/hardware/petram.html

> it replaces ram and/or rom...

> it helped me to fix a old cbm 8032...


> it is clear that if the VIC is not correctly initialized you probably
> get a black screen.




> On 26/10/2016 10:33, Hegedűs István wrote:
>> The problem is that this is my first ever VIC20 so I have no cartridges...
>> The idea is however good.
>> Thanks
>> Hege


>> -----Original Message----- From: Clockmeister
>> Sent: Wednesday, October 26, 2016 3:00 AM
>> To:
[hidden email]
>> Subject: Re: 6561-101



>> On 26/10/2016 4:38 AM, Hegedűs István wrote:
>>> Hi,

>>> It has black screen of course. I know that the Kernal ROM or VIC used to
>>> be the guilty ones. I have burnt a 27c128 with Kernal but still have to
>>> build an adapter so I cannot 100% rule out Kernal issue. The guy who sold
>>> it said that the 6502 is also sick (he has tried the CPU in an 1541),
>>> though with oscilloscope I have seen e.g. proper phi2 signal coming out.
>>> I have bought some Rockwell 6502s to replace it. Anyway even if it turns
>>> out that VIC is good it is better to have a spare IC.
>>> I should hook up my logic analyzer to it but so far I had no time (or I
>>> was just too lazy).



>> Whilst mask ROM (and RAM for that matter) failures are common on vintage
>> equipment, the last two VIC-20's with a black screen that I repaired had
>> a bad 6561-101.
>> In my case both were easy to diagnose by simply plugging in a cartridge
>> or blind loading a game. On both occasions the game you could hear the
>> game playing even though there was a black screen.





>>       Message was sent through the cbm-hackers mailing list

>>       Message was sent through the cbm-hackers mailing list


>        Message was sent through the cbm-hackers mailing list


>        Message was sent through the cbm-hackers mailing list




--
Best regards,
Julian                           
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