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Postby simbo » Sat Mar 11, 2006 12:17 am

i recently bought a falcon 030 from ebay

the first thing i noticed when i opened it to check it out
was the usual fried capacitors in the psu

SYMPTOMS :- poor tv output; slow refresh;
and warm psu after just a few mins on time

My camera is a bit funny {cant get it to work in XP yet}
sorry no pic till later ...

so here below is exactly what i have done and changed to fix it


MACHINE CA401332-003


TOS 4.04


atari type - C302867-001

looking at the +12v rail i noticed a 239mv ripple using the oscilloscope @ +11.39v output
looking at the +5v rail i noticed a 132mv ripple using the oscilloscope @ +5.28v output
looking at the modulator{type C-100185}
the +5v supply I noted lots of noise in excess of 200mv

adding a 100uf cap and also a 10nf cap between this input and the metal can
reduced this to 20mv and final psu fixes in place this was reduced to ~<< 1mv p-p

{ youll see this pin has a low value safety resistor and is the far right pin
of the group of three pins that supply the modulator can with signals and power}

firstly you can tell if a capacitor is really starting to suffer
becouse the plastic that encloses it starts to shrink back from the top
exposing more of the metal can inside this means its getting hot !!
so the electrolyte inside has dried up
as usual
be warned to connect electrolytic capacitors the correct way around
becouse they are polerised like a battery

C11 1000uf @ 16volts {5v rail prefilter smoothing }
C12 1000uf @ 16volts {5v rail prefilter smoothing }
C13 1000uf @ 16volts {5v rail post filter smoothing }

replaced C11 and C12 with 2200uf @16v 105deg type's {not in maplin}
left C13 at the original value watch for the size of the new 2200 caps
they maybe too big remove and take along one of the 1000uf caps to check the sizes are within usuable limits

I got all the capacitors from RS components in Glasgow via electromail
{easy to setup account} except the main smoothing cap C5
i got this one in maplin

C14 330uf @25volts changed for 470uf @25v {12v rail pre filter smoothing
{330 uf is hard to find so used a 470uf 105deg type here}

C17 47uf @25volts changed for 220uf @ 16v {12v rail post filter smoothing}

C10 22uf @25volts stays the same value { optical coupler transient decoupling cap}
C16 47uf @25volts { change for 100uf @ 16v { regulatory feedback {IC3} +5v supply smoothing }}

and most important I changed the main HT resoviour cap, in this psu it is

C5 33uf @ 400v replace with 47uf @ 400v a little bigger physical size

so i mounted it sideways and used a little hotmelt glue
to set it in place, adding some sleaving to its legs.

I changed this becouse of the slightly increased inrush current
due to the larger value output smoothing caps C11 & C12
and mainly becouse its usualy this one causes all the other problems
it sits there and most engineers will assume its ok
the main symptom is that a unit takes 5 mins to warm up {lol}

i also rewound L3 and L2 ! very important
{note: rewind them the same way in direction}
these two filter coils get warm/hot and the varnish degrades
on the wire with time and starts to flake
causing short circuits between turns
the worse the capacitors get
the more ripple they try to absorbe so the hotter they get
and so on and so on
as the eddies get bigger and bigger in there ferrite cores

although it wont cause a direct problem with this shorted turns
it will degrade the output filter stages ripple rejection qualities
i used 1mm wire ECW {enamaled copper wire} {maplin or RS}
{use rs there wire is better quality}

I also removed the power switching {chopper} transistor Q1
{unscrew the heatsink from below and desolder the other side
{one side has a screw the other is soldered }}

and cleaned off and reworked the heatsink grease compound
to get a better thermal contact as this dries up with time
i used a silicon graphite type you usualy get a tube of this higher quality stuff with a new processor you can ask the local pc shop
if they have some {usualy free may cost £1}

did the same with D2 the double diode rectifier package
also mounted on a heatsink TO220 type package

after replacing and rewinding etc
looking at the +12v rail i noticed a ~< 1mv ripple using the oscilloscope
looking at the +5v rail i noticed a ~< 1mv ripple using the oscilloscope

as you can see this fixed the psu completely and it now
properly filters the supply rails

as a final point
it is worth tuning in the tv to the atari
then plug the antenna back into the tv
if there is a carrier there like channel 4 or 5

you definatly need to move the ataris TV output signal
to a clear bit of the band where there is no tv signals
[ to do this you need to lift the metal shell and pcb out the case completely and carefully put it all together

{dont forget to add the floppy drive back in} youll find a screw on the back of the rf modulator metal can {beside the output socket} for this purpose]

as this presance of a tv signal basicaly under the atari signal
is what really throws the picture off completely

esp as TV channel 4 and 5 came around
after the atari was made and released
most ataris use RF ch35 as standard and this is mostly occupied by CH5
here in the uk
in glasgow the best channel to retune the atari to is TV RF CH31

i also use TV selection channel 0 or 8 as these two channels
most tv's process differently from normal signal channels {like 1 2 3 4 5 6 7 etc}

so ch0 and ch8 tv selection is best
whatever one you dont use for the video etc...

if you use scart for video to tv or dvd etc etc to tv
then use one of these channels 0 or 8 {better to stick to ch0}

the picture is now fully clean crisp and clear

with no 'static' or guff in the picture

and just as it should be

measuing the voltages on load
the psu now produces +11.98v for the +12v rail and +5.03v for the +5v rail {perfect!!}

and the heat output from the psu is now reduced by magnitudes

I also stripped the mains switch
and cleaned it with a burnish brush

and cleaned the psu mains input connector
and replaced the mains cable for a new one

the total cost for replacement parts
was £5.62 and took me 1hr 20 mins to complete it

a good tip is make a parts list
and get all the bits and tools you will need FIRST !!!

and never ignore a capacitor thinking its ok esp the smaller value ones

1000uf @ 16v or 25v 105 degree c X1 {RS} or maplin
2200uf @ 16v or 25v 105 degree c X2 {RS}
470uf @ 16V or 25v 105 degree c X1 {RS} or maplin
220uf @ 16v or 25v 105 degree c X1 {RS} or maplin
22uf @ 16v or 25v 105 degree c X1 {RS} or maplin
100uf @ 16V or 25v 105 degree c X2 {RS} or maplin
47uf @ 400V or higher X1 {maplin}
10nf polyester or better is ceramic

250 gram reel 1mm ECW wire...

tube good quality graphite silicon heatsink paste
comes with a new processor/heatsink or costs about £1 from pc shop
or you can buy it in maplin or RS

2 meters or more good quality coax {has to have foil screen and braid
1X phono plug {gold plated} to make a better tv cable
1X new mains cable for the atari
little bottle of varnish {clear laquor nail varnish is fine use sparingly }
this is to make winding the coils again easier

oscilloscope {if you have one not really needed for this}

star screwdriver number 2 philips

soldering iron 17 WATTS MAX... for computer work {dont use a 25watt or more}

desolder pump {cheep from RS or MAPLIN}

thin rosin core solder

digital volt meter {essential you can get a cheep £5 one in maplin }
{dont use an analogue meter its not accurate enough }

burnish brush for metal cleaning {maplin cost is £3 or so...}

Last edited by simbo on Sun Mar 12, 2006 2:32 pm, edited 30 times in total.

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Postby simonsunnyboy » Sat Mar 11, 2006 9:30 am

Why tangle with the RF modulator anyway?
On the ST its quality is ugly, on the Falcon it looks more like white noise.
So it is even worse...

The rest of the information sounds useful though for resurrecting Falcon PSU's
Simon Sunnyboy/Paradize - http://paradize.atari.org/

Stay cool, stay Atari!

1x2600jr, 1x1040STFm, 1x1040STE 4MB+TOS2.06+SatanDisk, 1xF030 14MB+FPU+NetUS-Bee


Postby simbo » Sat Mar 11, 2006 10:28 am


mostly its the presance of other tv signals that causes big problems
from cross / intermodulation
this will cause

move your atari output channel to a clean channel

dont know about german tv maybe more channels have arrived there also to clutter the band ....

even the best interconnection cables will leek signals in and out
and you can even get mixing products from distant channels that occur in the demodulator from the tv's RF mixer products
most tv's have very poorly designed Rf mixers and adjacent channel rejection levels are bad {some cb'ers and hams will know this as bleedover}

so ... to cure this

i use double screened cable
{satalite tv cable..good quality has a foil screen and a braid most interconnection cables just have braid so ...will leek }
i use a good quality gold plated connectors
a normal connector {any connector}
has a minimum instertion loss of 1DB

a gold plated plug is far less instertion loss
atleast use a gold plated phono for the atari end
if you cant find the tv ends belling lea type in gold plate
dont worry too much as long as the cable is good

also the addition of digital tv signals on top of the analogue ones
does'nt work wonders ...
it makes the bandwidth the tv signal uses bigger
{or more cluttered and digital noise is a bigger problem}

this is really important
if you live less than 20miles from any tv transmiter masts
esp in flat countrys.... like holland or england

i always drill a small hole in the back of the plastic case
so i can adjust it if needed {use a 2mm drill bit}
{not quite level with the center of the modultator output socket{more to the bottom edge to the phono output socket to the center of the new hole}

see above post .. for more details

above all
ripple and crap in the supply rail {the computers bload}
will eventualy cause chips to fail
or will make them fail faster ... so everone be warned

and WILL slow down the machine by as much as 40%


read this then get an old stfm ... or ste
or i did surgery on an old comodore 64 to get mine !!!
this one gave 10mw carrier level ... read on ....


for non modified or tapped falcons etc.. rf signals boosting methods

adding a video recorder to the rf chain is a good idea
a certain amount of processing filtering and band pass is applied to tv signals this way

and tuning the falcon to say rf ch 31 and the video to rf ch39
then activate the video and tune it to receive rf ch31 atari
on your tv tuned to rf ch39 to receive the video

will filter all the remaining rubbish out the signal
and transforms the crap tv signal as the atari falcon
{small can modulator }
seems only to produce on my 1GHz RF milliwatt meter less
than .5mw actual carrier power

the older can from the atari stfm produces 5mw

so to test it i connected a rf modulator from an stfm up to the falcon

man oh man what a differance !

if you dont have this you need it

simply carry the three wires out from the 3 pins
to an stfm /commodore/sinclair {aztec} extracted modulator 3 pin

they are all the same pheewe !!!
some have lots more output power than others
{most far more than the falcon/ste and other ataris
{small square can type}}
and are better at ' fighting ' background crap from the atmospheric terestrial tx
seems saving space was the aim and f... the rf picture }

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Last edited by simbo on Sun Mar 26, 2006 12:21 am, edited 11 times in total.


completely dead psu ??? read this

Postby simbo » Sat Mar 11, 2006 5:32 pm

in the above psu i notice that R4 is missing

this will be a high value 10 or so.,.. Mega ohm resistor
called a bleeder resistor

and is used to discharge the capacitor C5 safely
and you would think it should be fitted as standard
{add one}

if the psu you have is dead
this is the approch to use

first dont plug it in and out then check it by hand

if the chopper {Q1 } isnt running and the fuse looks ok
then most often your charging the big 400V cap

this can give you a very nasty shock

best if your psu is completely dead to use a rubber glove anyway..!

and on and using the right hand only

to pick it up and to then test the cap with a meter to see if it is charged up

this will tell you a couple of things

1} the mains rectifier stages is working fine if its charging
2} there is a problem with the pwm drive output to this chopper stage
3} the chopper fet {field effect transistor Q1 has died}
or one of the diodes around the chopper has gone open or short circuit

you can bleed this cap using a 10M ohm resistor or fit R4 first
do this each time you power it up

if R4 isnt fitted fit one this can be important to your health

its most often the startup resistors that have gone open circuit
they supply voltage to the Q1 FET's pwm driver stage {IC1}

first you need to measure the Q1 K1507 {this is a 2SK1507 in reality}

for a short circuit from its center pin to the two outside ones
there should be a very high resistance here

if this is ok there may have just been a surge thats killed the two startup resistors R2 and R2A {150K each }

or the fet can have gone open circuit !!! instead !! so watch for this
fets are strange depletion devices that work by a magnetic field
and are very linear devices most often power mos fets like this
go short circuit from gate to drain but can go completely open circuit

very occasionaly they go completely short from drain to source or totaly short all over

and go bang removing there front cover in the process

or ... the SK8085 driver chip IC1 is dead or the optical coupler IC2
has died or D1 has gone short or C10 is shorted internaly

however if the opto coupler has died it will try to start and shut down
so it will light the atari then die

check high tension parts and chip's like this by replacement
with exactly the same part only !!!!!

as the bridge rectifer is so crap DB1 you may find its gone ,,,,
and will supply no or little voltage to the resoviour cap

a test of this part first will tell you {esp if the fuse has gone black}
i replace this anyway with a 3 amp version and make the holes a little bigger to squeeze a new better one in

appart from this the rest is simple
if there is 12v and no 5v output then the double diode D2 is probably gone
or the zener DZ1 is short circuit {usualy the 12v rail will be low and the psu will shut down after 3 or 4 seconds can be confused and looks like a blown optical coupler chip IC2

watch out also for DZ2 it is another zener on the mains side
and if it goes short there will be the same symptoms as if the pwm drive had failed so its worth checking this

if you find it blows mains fuses even with no bridge rectifer fitted {db1}

then C4 is shorted or C1 is shorted

above all if you get stuck or need any advice

your welcome to find me on msn messanger using this email address


good luck and post results and questions below
and ill try to help further

DATASHEETS and suppliers urls

http://www.datasheets.org.uk/pdf/2sk150 ... sheet.html

sk8085 {IC1} cant find the datasheet via google
but plenty of suppliers carry this ic if needed

PC111 {IC2} optical coupler is easy to find

1431T {IC3} is an AN1431T or TA1431T and is easy to find

the double diode package {D2} is a standard part...

for continued safety always replace all components
like diodes and ic / transistors with exact parts ONLY

a good sence of smell is handy
and a good sniff round the board {after you brush it clean of dust}
youll get a feel for gubbed components
they smell gubbed ....

and if the caps are dry you can smell the electrolytic fluids scent
smells a bit like a leeky alcaline battery


known psu revisions please

Postby simbo » Sat Mar 11, 2006 11:52 pm

if others can look and check there falcon 030 or TT psu

and basicaly what revision maker etc it is

and please could you take a good quality picture of its pcb

top and bottom

and pm these to me

{you can use a flatbed scanner to do this also !! place it in leave the hood open and use a black piece of cloth or a jacket to cover it over for scanning }

pm and post allows for a max file size of 300K
thru the board

so if you like you can also email them too me using


max size is 5mb maximum allowed in my mailbox at once

if you need to send bigger files to me pm me with details or use msn {details above}

this info will be really handy !!!!

and will allow me to do a virtual census of these other revisions
im sure i remember 4 revisions
{its been over 10 years since i last set eyes on a falcon guts }

and used to drool over them when i was younger and there price was heavy at over £600 for a stock model

if its a skynet also then i have this info

{you can with a quick scan confirm this from the info above as other skynet versions may exist not so sure myself}

and this will help others if we can all band together
i dont mind doing the donkey work aswell
to sort a few problems

most falcon users moan and grown about there faulty falcon and it's this and that crashes etc

i can help and dont mind using time to do it

so please help if you can be bothered

thanks from everyone...!




Postby simbo » Sun Mar 12, 2006 5:01 am


i now know a little more info about the falcon psu's

you get a maximum of 200ma from the 12V rail
and a maximum of 7 amps from the 5v rail

i am going to checkout exactly what current levels the falcon draws under full load

and ill report back my findings tomorrow night

i feel 200ma @12v is not enough

then not to cause a problem ....

personaly im gona fit an atx supply to my falcon as an inside mod

and publish details

first feelings is to change all the opamps it uses for low current types

the fan also runs from 12V if this is at all gubbed clogged or slowed in any way not normal
then the machine can draw far more than 200ma total
and the 12v rails voltage will colapse

partialy due to psu resistor R14 {here it is 39ohms}
and is a current limiter / load resistor

and youll get audio problems
anything from clipping to distortion or reduced volume
or prob all three symptoms
and the psu switching transformer is in danger

1st problem solved

method to check is simple
use a digital meter set to 1 amp or 2 amp range

the power supply header that connected from the psu to the motherboard
carefully use a pin or needle to remove the 12v connection wire from it{blue wire}

then place the meter probes in series with this blue wire and where it connects to the main board

SO your connecting the BLACK meter probe to the motherboard where the blue wire goes

and the RED probe to the blue wire and tape it up

this way you can measure the total current on the 12v rail

if its near to or above 200ma

your in need of probably at least a new fan or you need to take it to bits and clean it up grease it using heat proof silicon grease

try unplugging the fan and recheck the current again

it will fall but by how much ???

make very sure the probes are well connected all the time

as a drop out of 12v can cause problems in other parts of the machine

so this supply must connect well
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Postby simbo » Sun Mar 12, 2006 4:36 pm

After a few tests
i noticed the fan draw 142ma when it was running

this is outwith the normal dc requirements this fan is quoted to use

and it sounded loud

so... i removed it {didnt bother to desolder it}

i didnt remove the lower metal can instead i pulled it foward at the front to reveal the fan unit

removed the two screws and was carefull to check the nuts that are mounted on the underside and safely retained them

so.. i pealed off the label on the surface

and with a jewelers screwdriver
carefully pried off the little bearing cover underneath
to releave a neopreen fan blade retainer

this 'slit washer' is easily carefully removed to release the blade

i was then able to remove and clean the blade from the fan shell fully

i gave the spindle special attention and used a cloth made for polishing gold and silver
to give this a nice sheen

using some high tempreture silicon grease {not heatsink compount}
but good quality mechanical grease

i also filled the resoviour in the coil side of the fan shell
and refitted the blade

adding back the neopreen washer and also then filling the resoviour
under the label and bearing cover with grease
refitted the cover

this was a little tricky but i got there and finaly gave the shell where the label came from a clean with some alchohole

this ensures that the label will stick back on

to add to it i used a little prit stick glue
and placed the label back on
and refitted the fan and screwed it back on

now it reduced the noise it makes fully

and it now draws 120-122 ma 20 ma less current

and you cant hear it anymore with the machine running


Postby simbo » Thu Mar 23, 2006 5:44 pm

i bought another flacon 030 from ebay the other day and it arrived this morning

as usual i have a good look around inside and check out the psu and whats going on under the lids

well in the machine was a 3.5" quantum maveric 540mb ide drive
basicaly an upgrade larger drive than the 65-80mb normal 2.5" you get with it

so reading the label on the drive i was horrified to find that the drive
draws 330ma +5v and 300ma +12v rails

if you read above youll see the maximum current
that the psu can safely supply before there is
a serious risk of failure or it going on fire is
7amps +5v rail and ONLY 200ma from the +12v rail

as you can see this put's a big strain on the internal psu

and once i turned the machine on it ran up ok

but measuring the 12V rail it was only at +9.68v
and was drawing 480 ma

this just isnt good enought

i fired up a game an noticed terrible sound

so i routed all the psu rails out to a properly wired up pc supply
this gives 450W 17amps +12v and 30amps +5v plenty....

and the machine runs flawlessly with perfect sound
and about 3 times faster

so BE WARNED if you use big 3.5" drives
your over the designed capability of the machines psu

and this is dangerious and stupid

i note some members use this type of drive setup ...
i hope they have a good house insurance policy
Last edited by simbo on Fri Mar 24, 2006 3:14 pm, edited 4 times in total.

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Postby unseenmenace » Fri Mar 24, 2006 12:47 am

I think he's talking to me LOL. Just a thought but since I don't want to have an AT/ATX PSU hanging out the back of my Falcon and I can't afford to be buying a mini ATX PSU right now, would adding a second Atari (ST) PSU just to power the hard drive be a feasible idea?
Last edited by unseenmenace on Fri Mar 24, 2006 8:52 am, edited 1 time in total.
Several STFM's, 4MB STE, 2MB TT with 1.2GB Hard Drive and 14MB Falcon with 540MB Hard Drive,
Lynx 2 and Jaguar with JagCD
Member of GamebaseST and AtariLegend team
Check out my website at http://unseenmenace.110mb.com


Postby simbo » Fri Mar 24, 2006 1:54 am

i found a better way ... was to look for an old smaller aztec psu from ex equipment

however i use four ataris

and what i did was to daisy chain all four of them on one atx supply

and some thick cables adding an atx socket {RS COMPONENTS}
to the back of each atari
{still to do two of them the ste and an stf i have
{i have two stf one is for sale}

so this way i can power each on its own or add a harness
using a small board with three sockets on it

this psu im using is a 400W gives 24amps 5v and 14 amps 12v
came from a dell pc
{atx supply wont fit in the case very well esp if you use an internal 3.5"}
so i moved on from that idea

with soft power on all machines at once i think its lots more efficient for me than four small supplies

i think adding a second crap supply wont fit and will compound the issue

i think your best solution is an atx and adding a socket
the internal psu can be replaced then by a second ide drive

maybe you know i need to know what the maximum size drive i can use in the falcon internal bus??
ill look with a board search see if i can find info

im happy to share the circuit i used and any details

i want to build a good article on psu replacement by atx and heep of people ask
it would be cool to add this socket system i used write up

not just you USM most falcon users do this type of mod as 2.5" are harder to get now {best sell them for $200 ++}
found it to be 138Giga Bytes


Postby simbo » Fri Mar 24, 2006 8:21 pm

for each atari you need 1

if you use a chain you need two
leave a few " out the back of the old psu socket hole

you can always reverse this mod

simply reuse the internal plug and make a good job of it
using insulation and sleaving if needed soldering where needed

to power it up simply ground the green wire in the atx cable
or build the little flip flop board design i made up see atari st hardware section for the link
this allows soft power on for a press on press off
instead of a switch on or off

http://www.maplin.co.uk/Module.aspx?Mod ... U=Template

http://www.maplin.co.uk/Module.aspx?Mod ... U=Template

bare connectors cant find pcb types but these are ok
comes with pins

http://www.maplin.co.uk/Module.aspx?Mod ... U=Template

add some power for the hdd and floppy from a
different place than the main board

take the connector off this and reuse it or replace with a pc one

dont draw the power from the pcb for drives

leave all the voltages and thrus intacted
you never know when youll need a voltage
so better to leave them all there
for daisy chaining ataris
Last edited by simbo on Fri Mar 24, 2006 11:23 pm, edited 1 time in total.



Postby simbo » Fri Mar 24, 2006 11:08 pm

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