Hello All
The problem probably lies in damaged tracks or pads on the PCB.
I have fixed 3 P6's and all had this problem .
Some were worse than others, but all worked good after fixing the tracks and
pads.
I use 30 awg wire wrap wire to replace the tracks and to go to a pin if the
pad is damaged.
I also believe the P6 schematics are all online.
Check the files section of this group or Old Crows site.
Thanks to old Crow as well.
Because of his site and info on the P6, I decided to purchase my first P6
off of
ebay a couple of years ago,
He documented the main problem of battery corrosion and how to fix it.
Also how to clean the keyboard switches. All my P6's suffered from keyboard
problems as well.
I washed all the keybord PCB as well as the membranes,
I then cleaned each switch contact and dabbed a small amount of caig cleaner
on the pcb traces.
My keyboards have worked fine since.
You need to fix all the tracks and pads first thing.
You need to be patient and deliberate.
Also neat and clean soldering.
Then get a schematic and using a meter measure from pin to pin around all
the
signals coming from the CPU and support chips.
Make sure you have continuity all around.
Use an enlarged copy of the schematic, and with a colored pen or pencil,
color eachline on the schematic from point to point.
When every line and connection is colored, you know for sure all connections
are a-ok.
It is meticulous and slow, but the only sure way to guarantee success.
If all this fails, then you probably have a bad chip or two as well.
When replacing, always use "machined" IC sockets or strips, for the new
chip.
Do not use inferior types as they will present their own problems in the
future.
Also at this point, the use of a scope is highly recommended.
Aside from a decent meter, the scope is the best piece of test equipment to
own.
You'll be able to see all the data , address , interupts, chip selects ,
etc. and see what isn't working.
Luckily, I did not need my scope to fix any of my P6's.
Good luck in your P6 repair.
Thanks
Kim S
----- Original Message -----
From: "stefan irinass" <st@rinass.de>
To: <PolySix@yahoogroups.com>
Sent: Saturday, January 25, 2003 7:02 PM
Subject: Re: [PolySix] Common symptons of battery leakage damage?
> Thanks but i believe you can forget my Boards, they are -really-
destroyed.
>
> But what i found out afterwards, are those A,B and C lines of CN11 on
> the KLM-369 which switch the Input sources of the HD14051 and NEC D4051
> 8 Line analogue multiplexers.
>
> What i believe is: The 8048 Main processor set those lines on KLM 369
> and KLM 370. The (1)4051 send back over the DATA line the actual Voltage
> of the choosen Variable resistor. The result voltage goes over the DATA
> line of CN11 back to KLM-367 and the LM393 comparator.
>
> So if the Main Processor DOES NOT set the Adress lines for the (1)4051
> located on KLM 369 and KLM 370, you ill not get back any voltage on DATA
> and so the Knobs won´t work! So in fact the 8048 would be responsible
> for the defect (or one of those A-B-C-traces).
>
> I thought the 4051 was a A/D-Converter but it is not true, he is
> completely analogue. In fact you select on three adress pins of the 4051
> a input pin, then he check the voltage which comes from the variable
> resistor (cutoff, attack, decay etcpp) and send over DATA the Voltage
> back to the LM393 located on the KLM-367.
>
> Too bad that i found it out too late :) Also bad that i have no
> schematics....
>
> Greetings
>
> Stef
>
>
> Chromatest Pantsmaker wrote:
>
> >----- Original Message -----
> >From: st@rinass.de
> >Date: Wed, 22 Jan 2003 12:15:56 +0100
> >To: PolySix@yahoogroups.com
> >Subject: Re: [PolySix] Common symptons of battery leakage damage?
> >
> >
> >
> >>I have exactly the same problem. Changing the two 74LS08, the 5514 RAM
> >>(Replacement:2114) and the D/A-Converter below the RAM doesn´t help. I
> >>
> >>
> >
> >
> >the problem could very well not be the chip itself! if the chip is
socketed, check for continuity from the socket to wherever the trace goes...
or you can trace from the chip pins. I was having a few residual problems
with my p6 and they were all attributed to weak traces. I scraped, and
soldered new wires/traces and it worked much better afterwards!
> >
> >good luck!
> >
> >
>
>
>
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