In most cases you have an opamp that is pegged (output pins near supply voltage or ground)
 |
RIP to BT Garner of MindRec.com... BT passed away early 2023 from health problems. He was one of the top PCE homebrew developers and founder of the OG Turbo List, then PCECP.com. Condolences to family and friends.  |
This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.
#2
Console Repair/Mod Center / Re: PC Engine Duo - bad sound (recapped)
07/07/2026, 03:24 PM
Ok the system has 3 sound sources
Chiptunes from the 6280 covers all card based audio
It's stereo
PCM audio used for high compression audio, often during movie scenes (depends on the game)
And CD audio (basic CD player sound from a DAC chip)
The 3 run through resistor/amp mixers
Chiptunes from the 6280 covers all card based audio
It's stereo
PCM audio used for high compression audio, often during movie scenes (depends on the game)
And CD audio (basic CD player sound from a DAC chip)
The 3 run through resistor/amp mixers
#3
Console Repair/Mod Center / Re: PC Engine Duo - white screen
05/25/2026, 06:46 PM
D7 is always used
All chipset versions are interchangeable
Don't recall saying to remove the chip
The bus is bidirectional, controlled by/we and /ce signals from the 6280
Most issues are bad address traces
Card to 6280 is direct
All chipset versions are interchangeable
Don't recall saying to remove the chip
The bus is bidirectional, controlled by/we and /ce signals from the 6280
Most issues are bad address traces
Card to 6280 is direct
#4
Console Repair/Mod Center / Re: duo full of problems
02/28/2026, 02:08 AM
I break them loose by holding the body of the pot with small pliers and turning the knob
If you just turn it without support, you could damage the legs or board
If you just turn it without support, you could damage the legs or board
#5
Console Repair/Mod Center / Re: duo full of problems
02/24/2026, 02:50 AM
The pot on the laser was glued at factory
I generally break them loose
I generally break them loose
#6
Console Repair/Mod Center / Re: duo full of problems
02/22/2026, 10:44 PM
6280 doesn't handle image at all
The picture is rendered in the 6270 and scaled and colored in the 6260
6260 does have RGBSHV available at the chip
The picture is rendered in the 6270 and scaled and colored in the 6260
6260 does have RGBSHV available at the chip
#7
Console Repair/Mod Center / Re: duo full of problems
02/21/2026, 12:50 AM
Note this is a standard Sony cd chip set
Any cd player using this chip set should have the same adjustment procedure
Any cd player using this chip set should have the same adjustment procedure
#8
Console Repair/Mod Center / Re: duo full of problems
02/21/2026, 12:43 AM
Also note the pot under the 2 caps (vr103?)
It's all the way right and shouldn't be
It's all the way right and shouldn't be
#9
Console Repair/Mod Center / Re: duo full of problems
02/21/2026, 12:41 AM
Vr102 may still work
Set your scope sync to left and the pattern looks ok
Im thinking you vr102 is all the way right and should be about center
The getting stuck issue if I understand what you're talking about could be a bad tracking motor (seen it a few times)
Set your scope sync to left and the pattern looks ok
Im thinking you vr102 is all the way right and should be about center
The getting stuck issue if I understand what you're talking about could be a bad tracking motor (seen it a few times)
#10
Console Repair/Mod Center / Re: IFU Backup Memory corrupted?
05/11/2025, 03:37 AM
I had an issue with one I solved by lifting the CE and WE pins and adding 1K resistors in series with the 2 pins
The chip has a certain amount of capacitance and the signals were ringing
The resistors stopped the ringing
The chip has a certain amount of capacitance and the signals were ringing
The resistors stopped the ringing
#11
Console Repair/Mod Center / Re: IFU Backup Memory corrupted?
04/28/2025, 10:56 PM
Congratulations on the fix
What ram did you use?
The control signals are noisy so faster ram causes problems
What ram did you use?
The control signals are noisy so faster ram causes problems
#12
Console Repair/Mod Center / Re: IFU Backup Memory corrupted?
03/29/2025, 01:50 AM
This differs from a DUO in one very significant way (and several smaller ones)
The DUO maps the CD system ram and ROM, where that is handled by the CD system card in this case
The duo uses 1 SMD ram chip for data buffer where the IFU uses 2 DIP package chips to do the same
The sample ram is the same on both
The DUO maps the CD system ram and ROM, where that is handled by the CD system card in this case
The duo uses 1 SMD ram chip for data buffer where the IFU uses 2 DIP package chips to do the same
The sample ram is the same on both
#13
Console Repair/Mod Center / Re: IFU Backup Memory corrupted?
03/28/2025, 04:28 AM
The lines are evenly spaced, likely a stuck data bit
Test CD player (music)
Should be informative
Test CD player (music)
Should be informative
#14
Console Repair/Mod Center / Re: IFU Backup Memory corrupted?
03/28/2025, 04:23 AM
Could actually be bad ram
I have run into that before
Obviously check traces
Logic probe is your friend, floating lines don't work
I have run into that before
Obviously check traces
Logic probe is your friend, floating lines don't work
#15
Console Repair/Mod Center / Re: Dead CD Spindle Motor? How to Replace?
11/12/2022, 10:59 PM
Yes they are connected together
1081 is the source of the signal and 1082 listens for it
1081 is the source of the signal and 1082 listens for it
#16
Console Repair/Mod Center / Re: Dead CD Spindle Motor? How to Replace?
10/22/2022, 12:56 AM
Your system is failing between position check and focus lock
#17
Console Repair/Mod Center / Re: Dead CD Spindle Motor? How to Replace?
10/22/2022, 12:54 AM
Ok for starters the issue was unlikely motor related
Order of operations
Start sent from software
Check door switch
Check head position by bumping the limit switch
Mirror check (laser bobs)
At this point the laser head will trigger the F ok pin on the CXA1081 to the CXA1082
If the 1082 sees the pulse it moves to focus check (spools spindle and moves lens up into focus lock)
If focus lock is achieved it adjusts spindle speed to match data clock and begins read
Order of operations
Start sent from software
Check door switch
Check head position by bumping the limit switch
Mirror check (laser bobs)
At this point the laser head will trigger the F ok pin on the CXA1081 to the CXA1082
If the 1082 sees the pulse it moves to focus check (spools spindle and moves lens up into focus lock)
If focus lock is achieved it adjusts spindle speed to match data clock and begins read
#18
Console Repair/Mod Center / Re: Buggy Duo Pics
10/05/2018, 12:02 AM
odds are its actually open connections between the HuC6270 and its ram chips
the traces open up where they pass through the board
the traces open up where they pass through the board
#19
Console Repair/Mod Center / Re: AC Power works but Battery Power does not: Turbo Express
09/23/2018, 02:20 AM
1 pole of battery is routed through the Jack as NightWolve just said
The indicators are fragile and often get decapitated when someone digs in the sealant
The indicators are fragile and often get decapitated when someone digs in the sealant
#20
Console Repair/Mod Center / Re: AC Power works but Battery Power does not: Turbo Express
09/21/2018, 02:36 AM
the battery power not working is normally from tarnish in the external power jack
#21
Console Repair/Mod Center / Re: AC Power works but Battery Power does not: Turbo Express
09/16/2018, 02:27 AM
odds are its just a dirty power jack, but could be something more obvious
#22
Console Repair/Mod Center / Re: Blog of my Turbo Duo repair
09/16/2018, 02:23 AM
air stations are great for some applications, but risky for others
some of the plastic parts melt way too quick and these old caps will burst before the solder melts
some of the plastic parts melt way too quick and these old caps will burst before the solder melts
#23
Console Repair/Mod Center / Re: Blog of my Turbo Duo repair
09/10/2018, 11:55 AM
honestly your blog seemed about right (didnt really promote the mistakes)
as for the old solder, it doesnt all have to come off as long as its clean (a touch of flux restores it as long as its not soaked in cap fluid), but the old cap leads must
the fluid corrodes under the solder sometimes so the pads dont bond anymore, removing the old legs exposes that
solder should always cover the pad thin, because a thick blob can mask poor adhesion
The way i do it is I prep the pads with a puddle of solder on them, then add a drop of flux to the top
next i hold the cap in place and reflow the solder melting the cap leg into it
the flux on the pad preps the surface of the wire and helps the solder bond to it
as for the old solder, it doesnt all have to come off as long as its clean (a touch of flux restores it as long as its not soaked in cap fluid), but the old cap leads must
the fluid corrodes under the solder sometimes so the pads dont bond anymore, removing the old legs exposes that
solder should always cover the pad thin, because a thick blob can mask poor adhesion
The way i do it is I prep the pads with a puddle of solder on them, then add a drop of flux to the top
next i hold the cap in place and reflow the solder melting the cap leg into it
the flux on the pad preps the surface of the wire and helps the solder bond to it
#24
Console Repair/Mod Center / Re: Turbo Duo CD-Rom issue
09/09/2018, 02:41 AM
what KC said was correct
there are 2 huge traces that run across the front of the unit sending 5V to the CD system
the VIA near the 47uf caps by the LED gets eaten away and you lose 5V to the chips causing this issue
there are 2 huge traces that run across the front of the unit sending 5V to the CD system
the VIA near the 47uf caps by the LED gets eaten away and you lose 5V to the chips causing this issue
#25
Console Repair/Mod Center / Re: Blog of my Turbo Duo repair
09/09/2018, 02:36 AM
im sure your iron was a big part of the issue
i used a 40W temp controlled one @700F
liquid flux helps allot as well
simple rule (less is more) you want the solder to be smooth and follow the surface of what your soldering
any lumpyness to the solder indicates low temp or contamination and should be cleaned and redone
i used a 40W temp controlled one @700F
liquid flux helps allot as well
simple rule (less is more) you want the solder to be smooth and follow the surface of what your soldering
any lumpyness to the solder indicates low temp or contamination and should be cleaned and redone
#26
Console Repair/Mod Center / Re: Blog of my Turbo Duo repair
09/09/2018, 02:24 AM
Final diagnosis
this was entirely solder and prep issues
several caps were not soldered down on both sides
some of the old cap legs hadnt been removed from the pads, and the solder hadnt been heated enough to flow
the 3.3uf cap was overlooked
the new cap legs were excessively long and some were touching other traces
removed all caps and reinstalled completing the cap change, unit started right up loading fine with some audio drops
slight adjustment with scope and its running well
this was entirely solder and prep issues
several caps were not soldered down on both sides
some of the old cap legs hadnt been removed from the pads, and the solder hadnt been heated enough to flow
the 3.3uf cap was overlooked
the new cap legs were excessively long and some were touching other traces
removed all caps and reinstalled completing the cap change, unit started right up loading fine with some audio drops
slight adjustment with scope and its running well
#27
PCE/TG-16|CD/SGX Discussion / Re: Good shooters
08/26/2018, 04:10 PM
most shooters on the system are actually good, but not many have complex scoring or a way to grind
#28
Console Repair/Mod Center / Re: Turbo Express - Button 1 does not work
08/26/2018, 02:50 PM
worst case i designed and turbokon sells complete replacement controller PCBs
#29
Console Repair/Mod Center / Re: Duo R & RX perform well after Audio CD plays (Only)
08/23/2018, 12:34 PM
these things are still quite reliable, we just deal with so many we are bound to see the bad ones
also the age means a few more have failed
to the OP issue, getting nothing on CDR is generally a bad laser
some lasers just dont work at all on CDR and poorly on pressed (or visa-versa)
also the age means a few more have failed
to the OP issue, getting nothing on CDR is generally a bad laser
some lasers just dont work at all on CDR and poorly on pressed (or visa-versa)
#30
Console Repair/Mod Center / Re: Duo R & RX perform well after Audio CD plays (Only)
08/23/2018, 01:20 AM
a warm up could be a few things, but caps are the most common
all the adjustments effect the CXA1081 and CXA1082 function as those 2 chips work in tandem to lock the laser onto the track and generate a pulse train from the CD
the CXD1167 reads the pulse train and adjusts its speed based on buffering
the NEC chips deal with translation between the core system and the sony chips
any of the 3 sony chips can cause issues and become intermittent (seen many bad)
also some switching supplies can cause read issues (try an old style one)
all the adjustments effect the CXA1081 and CXA1082 function as those 2 chips work in tandem to lock the laser onto the track and generate a pulse train from the CD
the CXD1167 reads the pulse train and adjusts its speed based on buffering
the NEC chips deal with translation between the core system and the sony chips
any of the 3 sony chips can cause issues and become intermittent (seen many bad)
also some switching supplies can cause read issues (try an old style one)
#31
Console Repair/Mod Center / Re: Please close cover! Audio issues!
08/18/2018, 03:34 PM
ok just fixed it
found Q304 failed open (very common sound issue)
switch had low on one side and floating on the other (not right)
found no pulse from IC104 (replacement solved switch issue)
laser was also bad (no light)
confirmed working with new laser
found Q304 failed open (very common sound issue)
switch had low on one side and floating on the other (not right)
found no pulse from IC104 (replacement solved switch issue)
laser was also bad (no light)
confirmed working with new laser
#32
Console Repair/Mod Center / Re: PC engine Duo-RX plays hu-cards but get either pink, green or cyan screen for CD
08/10/2018, 06:58 AM
you have an intermittent connection somewhere
i have see ones that wont boot till they have been on a while
i have see ones that wont boot till they have been on a while
#33
PCE/TG-16|CD/SGX Discussion / Re: PCE Duo-R hum
08/09/2018, 01:23 AM
im not saying that doesnt happen, but my impression was it was image related and the OP did specify it was an RGB modded system
this can easily be checked by using composite instead
this can easily be checked by using composite instead
#34
PCE/TG-16|CD/SGX Discussion / Re: PCE Duo-R hum
08/07/2018, 05:41 AM
on the express its power hum, but thats not the OP issue
he is having SCART hum which has to do with the current running through the grounds on the SCART cable
there are a few ways to reduce it (mostly shorter cables or larger wires) but you wont completely eliminate it especially on bright screens.
a dark screen will have little hum due to the low image current
he is having SCART hum which has to do with the current running through the grounds on the SCART cable
there are a few ways to reduce it (mostly shorter cables or larger wires) but you wont completely eliminate it especially on bright screens.
a dark screen will have little hum due to the low image current
#35
Console Repair/Mod Center / Re: Please close cover! Audio issues!
08/07/2018, 05:24 AM
im not opening your links
for IC520 you can use the HC or LS series chips, doesnt matter to it
only thing to watch is you need the narrow version otherwise install gets a bit tricky
also i dont think IC520 has failed
dont recall which pin gets the pulse from the lid switch, but start by probing the switch itself (should be pulse 1 side open, both sides closed)
either way trace it back to the chip, just if pulse confirmed you only need to trace the switched side
for IC520 you can use the HC or LS series chips, doesnt matter to it
only thing to watch is you need the narrow version otherwise install gets a bit tricky
also i dont think IC520 has failed
dont recall which pin gets the pulse from the lid switch, but start by probing the switch itself (should be pulse 1 side open, both sides closed)
either way trace it back to the chip, just if pulse confirmed you only need to trace the switched side
#36
Console Repair/Mod Center / Re: PC engine Duo-RX plays hu-cards but get either pink, green or cyan screen for CD
08/05/2018, 03:43 PM
ok lost of the same issue here sounds like
look for missing address pulses to the D91317GD (almost every time)
IC520 could be bad, but will often also keep cards from working (check pulses at slot with cart out)
look for missing address pulses to the D91317GD (almost every time)
IC520 could be bad, but will often also keep cards from working (check pulses at slot with cart out)
#37
Console Repair/Mod Center / Re: White PCE only giving a screen.
08/05/2018, 03:38 PM
before you get too far try Rock On
the game music doesnt wait for the video chips to start so often if the RAM and 6280 work, you will get sound
without a probe or scope it gets a bit tougher from there
full stop system check the CE pins on the 6280 to see what chip is currently active
there are 3 CER for the ram chip CE7 for the 6270 and CEK for the 6260
the 6270 also has a RDY pin which tells the 6280 to wait if low (often with a bad 6260 6270 or connection to 6270 this pin stays low)
also seen several 6280 with dead CE pins that simply dont ever go low (mostly CER)
the game music doesnt wait for the video chips to start so often if the RAM and 6280 work, you will get sound
without a probe or scope it gets a bit tougher from there
full stop system check the CE pins on the 6280 to see what chip is currently active
there are 3 CER for the ram chip CE7 for the 6270 and CEK for the 6260
the 6270 also has a RDY pin which tells the 6280 to wait if low (often with a bad 6260 6270 or connection to 6270 this pin stays low)
also seen several 6280 with dead CE pins that simply dont ever go low (mostly CER)
#38
Console Repair/Mod Center / Re: PCE duo blank screen only on cd system 3
08/05/2018, 03:26 PM
the quickest way to find this (for me) is to probe the data pins at the slot and the address pins at IC501
with cart out
the IC501 pinout is posted D91317GD
with cart out
the IC501 pinout is posted D91317GD
#39
Console Repair/Mod Center / Re: TurboDuo - 1 second of audio then cut to silence (Hu and CD)
08/05/2018, 03:21 PM
could also be an open connection to one of the center references
check C322 and C323 voltages
should be around 4V
check C322 and C323 voltages
should be around 4V
#40
Console Repair/Mod Center / Re: Why doesn't the LT work on a CDRom2?
08/05/2018, 03:04 PM
may need a separate power supply connected, but it does work
all the pinouts are the same RGB ect
all the pinouts are the same RGB ect
#41
Console Repair/Mod Center / Re: Please close cover! Audio issues!
08/05/2018, 03:01 PM
ZD302 is an 8V zener diode used to feed Q304
D306 is part of the anti thump mute circuit
D306 is part of the anti thump mute circuit
#42
Console Repair/Mod Center / Re: Please close cover! Audio issues!
08/05/2018, 02:55 PM
IC520 is a high failure part that is used to switch between card and cd system
IC104 handles the cd system I/O for switches and track counter ect
the lid switch gets a pulse from IC104 and sends it back to IC104
D102 is a simple diode used as ESD protection for IC104 (lid switch passes through it)
cd bios calls cd system and says please wait, cd system responds with lid open or active..........lid open is shown if thats the response
please wait is shown until the cd drive responds
IC104 handles the cd system I/O for switches and track counter ect
the lid switch gets a pulse from IC104 and sends it back to IC104
D102 is a simple diode used as ESD protection for IC104 (lid switch passes through it)
cd bios calls cd system and says please wait, cd system responds with lid open or active..........lid open is shown if thats the response
please wait is shown until the cd drive responds
#43
Console Repair/Mod Center / Re: Can any modders help with my PAL Turbografx?
09/20/2017, 02:19 AM
just reposted all the images from the original post
they had gone missing
they had gone missing
#44
Console Repair/Mod Center / Re: PAL turbografx NTSC mod
09/20/2017, 02:16 AM
/10202674018850378.jpg
/10202674018130360.jpg
/10202674017170336.jpg
/10202674016250313.jpg
/10202674015650298.jpg
/10202674015010282.jpg
/10202674014210262.jpg
/10202674013690249.jpg
/10202674013010232.jpg
the missing images from my original post
EDIT 2022: All images restored at top.
#45
Console Repair/Mod Center / Re: Switchless Mod: Why not for PCE/TG16
09/01/2017, 03:28 AM
well this thread sure ran off topic
#46
Console Repair/Mod Center / Re: MultiTap/TurboTap protocol and/or schematic
08/22/2017, 07:30 PM
Quote from: guestSchrödinger's switches can't be stacked and can.I drew this up when I started my cordless project
By the way, I like this project.
#47
Console Repair/Mod Center / Re: US Turbo Duo No Power
08/22/2017, 03:28 AM
just a note, the stock supply will get worm with a blown fuse as the fuse is on the output
#48
Console Repair/Mod Center / Re: US Turbo Duo No Power
08/21/2017, 11:50 PM
well i generally avoid ebay, as i want to keep in touch with the customers in case anything does go wrong or they have something else they want done
#49
Console Repair/Mod Center / Re: PC Engine Duo White Screen problem :(
08/21/2017, 11:46 PM
a short in IC520 will also do it as thats the interface chip between the systems
#50
Console Repair/Mod Center / Re: PC Engine Duo White Screen problem :(
08/20/2017, 12:46 AM
actually that is normal
white screen normally is in the core system, not the cd circuit so start there
white screen normally is in the core system, not the cd circuit so start there