Re: Tape port trouble on a PET 2001N

From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2002-11-10 10:21:09

On Sat, Nov 09, 2002 at 12:13:22PM -0600, David Wood wrote:
> Does this occur when the PC is -and- is not hooked to the cn232?

I didn't ask, but I think yes, it occurs in both cases.  The device works
properly in port #2.  I haven't measured the current consumption of the
C2N232 lately, but I think it would be in the order of some tens of
milliamperes.  Connecting something to the RS-232 port shouldn't matter,
since all RS-232 contacts (except ground) are routed via a DS14C232CM or
MAX232CSE.  It could still be a ground loop, but the device does work
in the other port.

On Sun, Nov 10, 2002 at 12:44:21AM -0500, William Levak wrote:

> It sounds like you have a short on the cassette port.  Probably one
> of the transistors that drive the port (Q4, Q5, Q6), the voltage
> regulator (VR2), or capacitor (C70).  Since the operating conditions are
> different, a marginal component may behave differently.  
> 
> There may also be a marginal short on the connector or circuit traces.
> 
> Another, simpler  possibility is that the connector does not line up
> correctly with the card edge.

Thanks for the suggestions, I'll pass them on.  One thing that occurred to
me from the schematic diagram
(http://www.funet.fi/pub/cbm/schematics/computers/pet/2001N/320349-3.gif)
are the cassette jumpers.  Could they have been set inappropriately?

	Marko

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