TECH: Electrohome G08 (Sega color XY) repair info
Duncan Brown
In article <5k28gf$h...@drn.zippo.com>,
ep6...@shellus.com (Wade Tsai) writes:
> Interestingly, neither of the two fuses (F600 and F700) blew through
> this whole ordeal.
Amazing, isn't it? Nothing can make those fuses blow, not even
the ambient heat from nearby flames (somethiung they're exposed to
a lot...)
Duncan
Wade Tsai
A week ago I had asked for information about what might be causing
R636 (100 ohm) in my G08 to smoke instantly. It turns out that
the deflection transistors that the Zanen kit supplied (3716's)
were woefully underrated. All four 3716's shorted out the moment
power was applied and took out R636 and a few other components
with them.
Scounging around the shed, I mananged to dig up four 6259's
(which are the original transistors that's used in the G08-003)
to replace the fried transistors.
Here are the components that were KIA:
R636 - 100 ohm 1/4 watt.
R??? - 100 ohm 1/4 watt. This one is soldered directly across the
collector and emitter leads on one of the deflection
transistors.
R736 - 100 ohm 1/4 watt.
D201 - 1N914 (You can get these from Rat Shack)
Q202 - 2N3904 (I pulled this from an Asteroids PCB)
Q703 - 2N6558 (I pulled this from another G08 deflection board.
Anyone know where I can get these from?)
R??? - 1K, 1/4 watt. This one is soldered from the base of Q703 to
one of
connectors on the solder side of the PCB.
Interestingly, neither of the two fuses (F600 and F700) blew through
this whole ordeal.
On another note, with D201, Q202, and Q703 blown, the right half
of the picture was missing (that's what led me to find the dead
components :-). The problem looks similar to the WG color XY
deflection failures. I would imagine if the same components died
in the Y section, either the top or bottom half of the picture
would be missing.
The only problem left in the monitor is that there is a slow wave
that distorts the vectors as the wave moves over them. It almost
looks like a hum bar. Anyone have any ideas on this problem? Is
it being caused by a failure in one of the large caps on the
deflection board? I hope not, since I can't seem to find a
suitable replacement for them :-(
Wade
ep6...@shellus.com
Shell Oil Inc.
Mark Jenison
> that distorts the vectors as the wave moves over them. It almost
> looks like a hum bar. Anyone have any ideas on this problem? Is
> it being caused by a failure in one of the large caps on the
> deflection board? I hope not, since I can't seem to find a
> suitable replacement for them :-(
Hosfelt Electronics is the place to go for caps. A while back when I was doing
a cap kit from scratch on a G08 I purchased the large ones from Hosfelt, but
ended up not using them. If you're interested in these, let me know.
--
________________ ______ ___ _____ __
/ __/ / / / |/ / / |/ //|/|/|_______________
Mark Jenison / __/ /_/ / / / | // | / |__ __/ _ /__ \
jen...@cig.mot.com /___/___/_/_//_/_/_/|_//__|/__| / / / // / /
Sega XY FAQ author /_/|_| /_/ /____/_/|_|
________________ The One and Only 4-player vector game
Rick Schieve
In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
>
>A week ago I had asked for information about what might be causing
>R636 (100 ohm) in my G08 to smoke instantly. It turns out that
>the deflection transistors that the Zanen kit supplied (3716's)
>were woefully underrated. All four 3716's shorted out the moment
>power was applied and took out R636 and a few other components
>with them.
>
>Scounging around the shed, I mananged to dig up four 6259's
>(which are the original transistors that's used in the G08-003)
>to replace the fried transistors.
I was thinking the other day about the problem of gettting
replacement transistors that would handle the current. If one of
the serious double E types out there looked at the circuit I'm sure
multiple transistors could be used in parallel to share the load.
A few resistors would need to be added to balance the load between
the multiple transistors (which is where the EE comes in) but it
should be do-able and there is plenty of room on the cabinet for
some extra heat sinks.
Any EEs out there looking for something to play with? ;-)
Rick Schieve
sch...@lucent.com
John Robertson
Wade Tsai wrote:
>
> A week ago I had asked for information about what might be causing
> R636 (100 ohm) in my G08 to smoke instantly. It turns out that
> that distorts the vectors as the wave moves over them. It almost
> looks like a hum bar. Anyone have any ideas on this problem? Is
> it being caused by a failure in one of the large caps on the
> deflection board? I hope not, since I can't seem to find a
> suitable replacement for them :-(
>
Hi, Wade!
Which game is this for? I suspect you have ripple in the +5VDC supply
for the game board. Typically the power supply for the game had bad
power connections. This will BLOW your monitor again! Replace the power
supply with a switching supply, please... and, if you are clever, use a
+12VDC relay to only allow power to the monitor when the switching
suppply is running!
:-#)#
--
(Pinballs, Jukes, Video Games) | John's Jukes Ltd. 2343 Main St.
VOICE (604)872-5757 FAX 872-2010| Vancouver, BC, Canada V5T 3C9
mailto:j...@flippers.com | http://www.flippers.com
"Old pinballers never die, they just flip out."
Duncan Brown
In article <5k52gn$a...@ssbunews.ih.lucent.com>,
r...@ihgp3.ih.lucent.com (Rick Schieve) writes:
> In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
>>
>>A week ago I had asked for information about what might be causing
>>R636 (100 ohm) in my G08 to smoke instantly. It turns out that
>>were woefully underrated. All four 3716's shorted out the moment
>>power was applied and took out R636 and a few other components
>>with them.
>>
>>Scounging around the shed, I mananged to dig up four 6259's
>>(which are the original transistors that's used in the G08-003)
>>to replace the fried transistors.
>
> I was thinking the other day about the problem of gettting
> replacement transistors that would handle the current. If one of
> the serious double E types out there looked at the circuit I'm sure
> multiple transistors could be used in parallel to share the load.
> A few resistors would need to be added to balance the load between
> the multiple transistors (which is where the EE comes in) but it
> should be do-able and there is plenty of room on the cabinet for
> some extra heat sinks.
Remember the extra fans bolted to those extra heat sinks, is there
room for those?!
> Any EEs out there looking for something to play with? ;-)
You could team up with someone majoring in combustibility or fire
suppression and do your research in parallel, heh heh heh...
Duncan
Zonn Moore
On 29 Apr 1997 15:01:43 GMT, r...@ihgp3.ih.lucent.com (Rick Schieve) wrote:
~ In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
~ >
~ >A week ago I had asked for information about what might be causing
~ >R636 (100 ohm) in my G08 to smoke instantly. It turns out that
~ >the deflection transistors that the Zanen kit supplied (3716's)
~ >were woefully underrated. All four 3716's shorted out the moment
~ >power was applied and took out R636 and a few other components
~ >with them.
~ >
~ >Scounging around the shed, I mananged to dig up four 6259's
~ >(which are the original transistors that's used in the G08-003)
~ >to replace the fried transistors.
~
~ I was thinking the other day about the problem of gettting
~ replacement transistors that would handle the current. If one of
~ the serious double E types out there looked at the circuit I'm sure
~ multiple transistors could be used in parallel to share the load.
~ A few resistors would need to be added to balance the load between
~ the multiple transistors (which is where the EE comes in) but it
~ should be do-able and there is plenty of room on the cabinet for
~ some extra heat sinks.
~
~ Any EEs out there looking for something to play with? ;-)
About a year ago I answered a post about a universal X/Y monitor. I had
nominated the Sega X/Y. (Ok laugh! It won't be the first time!)
Really. It's the fastest so it can play all the games, including the Sega games
(of course) and Cosmic Chasm, which requires a fast monitor. It's also the most
sensitive, so playing the Atari game would require only a resistor divider in
front of the monitor as opposed to an amplifier. And last (and maybe least) it
is already compensated for the bowing effects of Yoke/Picture-tube
non-linearities. This means it'll run Star Wars and other ampliphone type games
as is (with the Resistor divider). And with Tempest and other pre-compensated
games, one simply removes a resistor from the game board, which is much easier
to do than to come up with a WG -> Ampliphone adapter type board.
It's disadvantage, compared with the Ampliphones, is that it has lower
resolution.
The biggest problem with the Sega is the underated Transistors (The second
biggest is all the proprietary ICs).
To fix the transistor problem you can do just what Rick suggests. Parellel two
power transistors for each one currently being fan cooled.
Since I have a dead Sega X/Y in the garage, I'll be trying this trick real
soon...
The thing to do is to get two of each transistor, connect the bases and
collectors together. Then connect a resistor from each emitter to the place the
old emitter used to go...
+-------------------+-----------------> to old collector connection
| to old base |
| ^ |
\ c | c /
\| | |/
| b | b |
|-------------|
>| |<
/ e| |e \
| |
| |
\ \
/ .39 ohm 1W / .39 ohm 1W
\ \
/ /
| |
+--------------------+----------------> to old emitter connection
(Pretty bad drawing huh?)
This is only shown for the PNP transistor, do the same for the NPN's.
The .39 ohm resistor allows the transistors to be hooked in parallel without one
transistor going into thermal runaway and trying to drive the whole load itself.
(A good place to find out more about hooking transistors in parallel is a
Voltage Regulator handbook of somekind)
The value of .39 ohms was stolen from the Atari schematic for the 19k6400 series
of monitors, were they did exactly the same thing. The 19k6400 might be a
better choice for a universal X/Y monitor, but good luck finding one. It was
used in Aztarac(sp?) and was spec'd in the Cosmic Chasm manual, but I've only
heard of the G0-8 being used in Cosmic Chasm. I'll probably calculate my own
value for the resistor (when I look up the formula), But I'll bet it ends up
being damn close to .39 ohms, 1W.
-Zonn
Rodger Boots
On 29 Apr 1997 15:01:43 GMT, r...@ihgp3.ih.lucent.com (Rick Schieve)
wrote:
>In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
>>
>>A week ago I had asked for information about what might be causing
>>R636 (100 ohm) in my G08 to smoke instantly. It turns out that
>>the deflection transistors that the Zanen kit supplied (3716's)
>>were woefully underrated. All four 3716's shorted out the moment
>>power was applied and took out R636 and a few other components
>>with them.
>>
>>Scounging around the shed, I mananged to dig up four 6259's
>>(which are the original transistors that's used in the G08-003)
>>to replace the fried transistors.
>
>I was thinking the other day about the problem of gettting
>replacement transistors that would handle the current. If one of
>the serious double E types out there looked at the circuit I'm sure
>multiple transistors could be used in parallel to share the load.
>A few resistors would need to be added to balance the load between
>the multiple transistors (which is where the EE comes in) but it
>should be do-able and there is plenty of room on the cabinet for
>some extra heat sinks.
>
>Any EEs out there looking for something to play with? ;-)
>
>
> Rick Schieve
> sch...@lucent.com
One of the most important things to watch on these monitors is the
input power. Input voltage is 91 VAC nominal. You're better off
running lower than higher. Lower will reduce writing speed. Higher
blows output transistors.
If someone wanted to build an indestructable G08 the thing to do would
be to use eiither a stacked output stage (high voltage for moving the
beam, lower voltage for holding it) OR a MOSFET output stage. The
killer is secondary breakdown and one of the benefits of MOSFETs are
freedom from secondary breakdown.
Rodger Boots
On Thu, 01 May 1997 02:00:51 GMT, zo...@concentric.net (Zonn Moore)
wrote:
>
>On 29 Apr 1997 15:01:43 GMT, r...@ihgp3.ih.lucent.com (Rick Schieve) wrote:
>
Most all of these monitor used ONLY NPN outputs. There was a version
that used a complimentary/symetry output stage (PNP and NPN), but I've
never heard of anyone ever seeing one of those.
Zonn Moore
On Fri, 02 May 1997 09:31:15 GMT, rlb...@cedar-rapids.net (Rodger Boots) wrote:
~ On Thu, 01 May 1997 02:00:51 GMT, zo...@concentric.net (Zonn Moore)
~ wrote:
~
~ >
~ >On 29 Apr 1997 15:01:43 GMT, r...@ihgp3.ih.lucent.com (Rick Schieve) wrote:
~ >
~ >~ In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
~ >~ >
~ >~ >A week ago I had asked for information about what might be causing
~ >~ >R636 (100 ohm) in my G08 to smoke instantly. It turns out that
~ >~ >the deflection transistors that the Zanen kit supplied (3716's)
~ >~ >were woefully underrated. All four 3716's shorted out the moment
~ >~ >power was applied and took out R636 and a few other components
~ >~ >with them.
~ >~ >
~ >~ >Scounging around the shed, I mananged to dig up four 6259's
~ >~ >(which are the original transistors that's used in the G08-003)
~ >~ >to replace the fried transistors.
~ >~
~ >~ I was thinking the other day about the problem of gettting
~ >~ replacement transistors that would handle the current. If one of
~ >~ the serious double E types out there looked at the circuit I'm sure
~ >~ multiple transistors could be used in parallel to share the load.
~ >~ A few resistors would need to be added to balance the load between
~ >~ the multiple transistors (which is where the EE comes in) but it
~ >~ should be do-able and there is plenty of room on the cabinet for
~ >~ some extra heat sinks.
~ >~
~ >~ Any EEs out there looking for something to play with? ;-)
~ >
~ >About a year ago I answered a post about a universal X/Y monitor. I had
~ >nominated the Sega X/Y. (Ok laugh! It won't be the first time!)
~ >
~ >Really. It's the fastest so it can play all the games, including the Sega games
~ >(of course) and Cosmic Chasm, which requires a fast monitor. It's also the most
~ >sensitive, so playing the Atari game would require only a resistor divider in
~ >front of the monitor as opposed to an amplifier. And last (and maybe least) it
~ >is already compensated for the bowing effects of Yoke/Picture-tube
~ >non-linearities. This means it'll run Star Wars and other ampliphone type games
~ >as is (with the Resistor divider). And with Tempest and other pre-compensated
~ >games, one simply removes a resistor from the game board, which is much easier
~ >to do than to come up with a WG -> Ampliphone adapter type board.
~ >
~ >It's disadvantage, compared with the Ampliphones, is that it has lower
~ >resolution.
~ >
~ >The biggest problem with the Sega is the underated Transistors (The second
~ >biggest is all the proprietary ICs).
~ >
~ >To fix the transistor problem you can do just what Rick suggests. Parellel two
~ >power transistors for each one currently being fan cooled.
~ >
~ >Since I have a dead Sega X/Y in the garage, I'll be trying this trick real
~ >soon...
~ >
~ >The thing to do is to get two of each transistor, connect the bases and
~ >collectors together. Then connect a resistor from each emitter to the place the
~ >old emitter used to go...
~ >
~ > +-------------------+-----------------> to old collector connection
~ > | to old base |
~ > | ^ |
~ > \ c | c /
~ > \| | |/
~ > | b | b |
~ > |-------------|
~ > >| |<
~ > / e| |e \
~ > | |
~ > | |
~ > \ \
~ > / .39 ohm 1W / .39 ohm 1W
~ > \ \
~ > / /
~ > | |
~ > +--------------------+----------------> to old emitter connection
~ >
~ > (Pretty bad drawing huh?)
~ >
~ >
~ >This is only shown for the PNP transistor, do the same for the NPN's.
~
~ Most all of these monitor used ONLY NPN outputs. There was a version
~ that used a complimentary/symetry output stage (PNP and NPN), but I've
~ never heard of anyone ever seeing one of those.
~
And as usual, your right. I was just thinking of the Atari monitors and the PNP
ASCII drawing looked better than the NPN ASCII drawing...
-Zonn
