Re: [TenTec] Fw: Problem with Paragon I

[Robert & Linda McGraw K4TAX <RMcGraw@Blomand.Net>]

My thoughts:

I suspect that C5 on the logic board has reduced value due to age.  Not
uncommon.  Replace it.  It's a 4.7uF that is off of the RESET pin #25 of U7.
If an exact 4.7 uF value is not available then go to the next larger size.
It will only slow the MP initialization process for a few milli seconds and
that won't cause any harm.

I suspect that the MP is trying to initialize before Vdd is stable from VCC1
source.  This is caused scrambling of data from ROM/RAM addresses.


73
Bob, K4TAX



----- Original Message ----- 
From: "Phil Chambley Sr" <k4dpk@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, August 27, 2005 5:46 PM
Subject: Re: [TenTec] Fw: Problem with Paragon I


> Bob's references to the effect of unstable voltage on the uProcessor
> reminded me that, about 6 months after I got my first Paragon, the logic
> board began behaving really squirrelly.
>
> Dotted lines, lock-ups and every LED lit were the symptoms as I recall.
>
> Turned out, some of the early matching power supplies had the filter caps
> mounted with #10-32 screws through the PC board.  Evidently, transformer
> vibration (or something) had loosened the screws, making for arcing due to
> intermittent contact between the filter cap and the board foil.
>
> Cure was to re-build the foil with brass shim stock, since it had been
> pretty well burned away by the time I found it.  After repair, never
> happened again.
>
> Since then, I have repaired several others that had loose power 
> connections
> in various forms, even at the Molex connector.  All of these were first
> thought to have Logic Board problems.
>
> 73
>
> Phil
> K4DPK
> www.k4dpk.com
> VFO Stabilizers and PEP adapters for wattmeters...
>
> ----- Original Message ----- 
> From: "Robert & Linda McGraw K4TAX" <RMcGraw@Blomand.Net>
> To: "Tentec" <tentec@contesting.com>
> Sent: Saturday, August 27, 2005 8:15 AM
> Subject: [TenTec] Fw: Problem with Paragon I
>
>
> > Tried sending this direct to Vic at his address but it was rejected by 
> > the
> > server.  Hope he sees this.  Thanks for the bandwidth on the reflector.
> >
> > 73
> > Bob, K4TAX
> >
> > ----- Original Message ----- 
> > From: "Robert & Linda McGraw (K4TAX)" <RMcGraw@Blomand.Net>
> > To: <zrdc28@hiwaay.net>
> > Sent: Saturday, August 27, 2005 6:54 AM
> > Subject: Re: [TenTec] Problem with Paragon I
> >
> >
> > > Vic:
> > >
> > > I've seen your post and several of the responses.  Before you start
> > > digging into the radio let me ask a few questions to clarify some
> points.
> > >
> > > From my memory of your problem, it appears that the microprocessor
> > > initialization from ROM is not being done correctly.    MP's do require
> > > that the Vcc come up to correct value and stabilize before running the
> > > initialization code.  The process is controlled by the RESET pin and 
> > > the
> > > external to the MP the RC components.  Usually if the C value decreases
> > > with age, typical of electrolytic caps, then the initialization is too
> > > fast thus scrambled data is loaded from RAM .  I'll look at the
> schematic,
> > > but at present it is at my shop and I'm here at the house.
> > >
> > > Here's the questions:  No battery installed in all cases.
> > > 1. With the PS and radio off, turn the radio on then turn the power
> supply
> > > on in that order.  What happens?
> > >
> > > 2.  With the PS off and the radio on, turn the power supply on.  What
> > > happens?
> > >
> > > 3.  With the PS on and the radio off, turn the radio on.  What happens?
> > >
> > > I think you may have stated these in your post but I no longer have it.
> > > These answers will better allow me to assist you with your problem.
> > >
> > > 73
> > > Bob, K4TAX
> > >
> > >
> > >
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec