All,
To add some explanations/advice to my A9 Power Board 'repair/upgrade'
thought process and reasoning, here is a sequence of postings I made
before and during and after I made the changes, using new low ESR
capacitors mentioned by Barry.
This upgrade cost less than $10 including shipping last year, and
made a significant positive difference to display quality and stability.
I don't work for Ten-Tec and they were not consulted about my
changes. But everything is still working fine after almost a year and
a dozen or so long RTTY contests.
You assume any risks making these changes........ soldering irons are HOT ;)
73,
Ben - WB2RHM
> > > --- In
<mailto:orion565@yahoogroups.com>orion565@yahoogroups.com, "WB2RHM"
wb2rhm@ wrote: > > > > > > > > Sam, Rick, Onno, Paul,
lurkers, > > > > > > > > I have removed all of the electrolytic caps
from the A9 board. > After > > reading and re-reading the spec sheet
of the LT1054, and looking at > the > > schematic of the A9 board, I
ordered 50V extra low ESR caps from > Mouser > > to replace all
electrolytics. > > > > > > > > Also after reading the LT1054 spec, I
am going to use 22uf 50V low > > ESR caps to replace all three of the
10uf 35V electrolytic caps on A9. > > AND I am going to change the
100uf 35V C2 electrolytic to a 220uf 50V > > low ESR electrolytic (to
maintain the 1/10 ratio for C2/C4 as > mentioned > > in the spec, and
also match up the values of C3 and C4 to 22uf.) > > > > > > > > The
parts should arrive from Mouser on Friday, and I hope to get > > them
installed in time for the VOLTA RTTY contest this
weekend. > > > > > > > > Thank you for all your advice, I will let
you know what occurs > > sometime early next week, after the
contest. > > > > > > > > 73, > > > > > > > > Ben - WB2RHM
> > --- In
<mailto:orion565@yahoogroups.com>orion565@yahoogroups.com, "pa1ap"
wrote: > > > > Interesting changes Ben. Please let us know how it
goes. I suggest > you > > meassure the voltages, especially the
negative lcd voltage, prior to > > connecting it to the lcd. Not sure
if the capacitor change influences > > the output voltage somehow.
Best regards, Onno
> --- In <mailto:orion565@yahoogroups.com>orion565@yahoogroups.com,
"WB2RHM" wrote: > > > > > > Onno, et al, > > > > I will measure the
no-load voltages at the JP1 connector, and also the > > +5V
output > > pins, I might also find a way to record them. > > > > FWIW
From the LT1054 spec, the Cin and Cout capacitor (C4/C2 on A9 > >
schematic) values do not > > affect the output voltage level
produced. > > > > However, since you are using C4 and C3 as part of a
voltage doubler, > C4 > > and C3 should be about equal. The value of
C2 has a direct effect on > the > > output voltage ripple, changing
it to 220uf should decrease any p-p > > output ripple. > > > > ???? I
always wondered why the C8 - 100uf cap on the +5V line only had >
a > > 6.3WVDC rating..... cost? size??? > > > > FWIW(2) - TIP - Since
I did not really care about the condition of the > > 'original' caps
on the A9 board, I did a 'distructive removal' .... to > > enable the
cleaning of the PC board holes easier, and to also prevent > >
overheating the PC board, from trying to remove the old caps
(which > > really are just large heat sinks, when trying to > >
unsolder them from below). This is an old 'US Navy electronics
repair > > depot' trick. To remove the 'dead/old' electrolytic caps ,
Without > > heating, I grip the body of the cap with pliers, or my
fingers, and > bend > > the body of the cap over to the PC board.
Electrolytic caps, like the > > ones on the A9 board, the internal
connection of the leads inside the > > body of the cap break
clean.... allowing you to pull the entire > > capacitor body off of
the remaining two moounting leads. This action > > leaves only two
'wires' connected to&through the pc board. They are > > completely
easy to heat, and remove, from the pc board without > damaging > >
the PC board from excess heating. Then, I heat one side of each PC >
board > > hole with a pointed soldering iron tip centered on the
hole, and using > a > > round (not flat) wooden toothpick, I push
through the melted solder > from > > the opposite side of the PC
board. The solder does not stick to the > > wooden toothpick, and the
toothpick body displaces all the excess > solder > > from inside the
PC hole. So, the PC hole is left open and solder free, > > and ready
for the new component to be inserted. > > > > 73, > > > > Ben -
WB2RHM > > > > > >
--- In <mailto:orion565@yahoogroups.com>orion565@yahoogroups.com,
"WB2RHM" <wb2rhm@...> wrote: > > > All, > > Here are my
results....... > > All the new electrolytic, A9 board, caps arrived
from Mouser, total cost > less than $10US including USPS Priority
shipping. I had no problems > installing all of the 'new' 50WVDC
Panasonic LowESR caps into the A9 > board. However, two of the 470uf
caps did not sit perfectly flat to > the A9 board because they are an
RCH ( :) ) larger in diameter than > space allows.... No problem, if
you tilt them slightly away from each > other, this allows for easy
placement and soldering. > > To test before installing A9 into the
565, I used an external regulsted > power supply to supply +13.8VDC
to the A9 board input pins. When > measured, the +5V Output pins
provided +5.1VDC and there was NO > detectable ripple on the +5V A9
pins. The -20.5VDC A9 JP1 pins, > measured on my DVM, showed
-20.4VDC, with a 'flat line' ripple displayed > on my 35MHZ Elenco
O'Scope. > > Based on the isolated A9 test, I installed the A9 into
my 565. > > WOW! From power-on, after the system initialization, the
Blue on White > or the White on Blue displays were CRISP, and the
characters appear to > be SHARPER, with no contrast change from
Power-on to +15 Hours of 100% > duty cycle......... (the duration of
the Volta RTTY contest last > weekend). Some of this could be due to
how OLD my 565 had aged over > the past 10 years......... BUT it is
like having a new display in a > new 565. > > However, nothing has
changed about the angle-of-view flicker for the > replacement Blue
display........ the clearest viewing is restricted to a > narrow
angle +/- off of straight-on line of sight. But, when you are >
viewing it almost 'straight-on', it is perfect White-on-blue or >
Blue-on-white................... The inherent 'flicker' of the >
replacement Blue display is still there...... and that is the next >
thing to 'fix'. But any warm-up fading/horizontal lines are gone. > >
$10 bucks.......... you cannot miss on this update if your display
has > aged. > > 73, > > Ben - WB2RHM >
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