From: William Levak (wlevak_at_cyberspace.org)
Date: 2003-03-20 05:57:47
I do have a schematic that I have labeled NP-090B. It is probably on
funet, but may not be labeled as NP-090B. It uses one quad op-amp
(AN-6562) instead of two dual op-amps (AN6564). They are functionally the
same. The changes would be applied to both versions.
The only differences I see are:
NP-090 NP-090B
IC2-1 pin 3 IC1-4 pin 12
2 13
1 14
IC2-2 pin 5 IC1-3 pin 10
6 9
7 8
These circuits are very noisy and someone may have changed the resistors
and capacitors to improve the quality of the signal. I know people who
have done this, but they know more about recorder circuits than I do.
On Wed, 19 Mar 2003, Daniele Gratteri wrote:
> ----- Original Message -----
> From: "William Levak" <wlevak@cyberspace.org>
> To: "CBM Hackers" <cbm-hackers@cling.gu.se>
> Sent: Wednesday, March 19, 2003 5:37 AM
> Subject: Re: About the Datassette update
>
> > There is a 1984 Techtopics that list changes to the board. It should be
> > on funet somewhere. C4 is changed to 470pF and C9 (.0033uF) is added
> > across R1 and R2.
>
> I know, it is the one in the link I posted. But, how can I identify the
> resistors? There's written nothing on the PCB... I downloaded a schematic
> and I think I have found the right resistors but they are connected
> differently to the AN6562: could it be because my PCB is the NP-090B while
> the schematic refers to the NP-090?
>
> My NP-090B PCB uses two AN6562 op. amp. and a 74LS14.
> __ ____
> /// Daniele Gratteri, Italian Commodore-Amiga user / ___|____
> __ /// E-MAIL: daniele_gratteri@inwind.it RITMO S75 | | |___/
> \\\/// Nickname: FIAT1100D - ICQ: 53943994 FOREVER! | |___|___\
> \/// URL: http://spazioinwind.libero.it/danielegratteri \____|
>
>
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>
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