The Analogue Turbo Duo clone shipped in time for Christmas 2023. Are you happy with yours ?? Find firmware updates here.
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Messages - thesteve

#151
the cd system runs across the cart pins, so likely not it
also cd uses all the chips, where cart uses half
look for dirty or damaged cart slot and check card region vs system region
also check for region mods as they could have been done badly or simply in the wrong mode
#152
if it plays cd audio perfect, its most likely bad cd work ram (the ram chip near the controller port)
any dead traces/vias around that ram would also do it
#153
thats me, yes im in cali
#154
you wont get a new one, used from DUO, DUO-R, SCDR2
they rarely fail
what you should be looking at is the signals to it
i use a logic probe, and if anything looks funny check it at the 6280
if they dont match trace that signal (most go through a chip by the card slot)
#155
without the electoral college the rest of the country would have kicked California out years ago
#156
nailed it beemer

as for the EC, it prevents a ballot stuffing operation in one state from overriding the rest of the country
that only works however if the census isnt rigged/tampered
#157
if you do have a pin bent in the slot that would do it
you could likely swap just the pin from a different slot
#158
Cracks are most likely
They also crack by the heatsink screws in
#159
Was just working on one with the same issue
Had an open via from corrosion hidden behind the card slot
Was missing a signal at ic501
#160
please dont whiten anything with the boards in it
its extremely corrosive and can destroy them
#161
well my IC501 pinout should help, but in your case the system is waiting to hear from IC104
IC105 is the interface between IC501 and IC104, IC105 gets its clock from IC103
#163
i measured pin for pin
note the main bus is all buffered
some of the pins were identified partly by how the signal worked
#164
almost every time its a missing address signal to the mapping chip under the board
most of the 22uf caps by the card slot are power filtering for buffer chips on the address bus, so a missing voltage there will do it
also checking signal at the mapper with a scope or logic probe should quickly find it
https://www.pcengine-fx.com/forums/index.php?topic=16503.0
that has all the signal info to solve your issue
#165
bump
can we get this stickied in the repair info section
it applies to DUO and SCDR2
#166
thats not it
that pin has 5V without card and ground with
#167
I mapped and posted the mapping chip
Search it on here, full pinout in text file

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#168
Well if nothing's moving check your wiring

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#169
lets consider for a sec that 3.3v inputs are never an issue and dont require more then a resistor for compatibility on most chips (worst case resistor and diode)
so for arcade pro we would need to read/decode the whole bus, and produce from it chip select lines for ram
we would also need a few registers to respond back to the system
if we use 5V ram, the registers will need level conversion
if 3.3v ram the data lines will need level conversion
a 3.3V regulator can be used, or 2 diodes will suffice to convert 5V to 3.6V
as for a pro card to test, im sure we can come up with a loaner if you are willing
#170
Quote from: XLR-VIII on 07/30/2016, 04:29 AM
Quote from: Keith Courage on 07/29/2016, 02:56 AMLooks like something isn't getting the correct voltage. Make sure there are not any broken traces to any of the caps you installed.
I'm getting 7.8v from an AC adapter.
When unit powers on it drops to 3.8v
Checked some the caps, most read about 3.5-3.7v
Measured on pin 3 of the display ribbon cable only get -2.5v

Anything else I should check and where does the 24v start ?

Thanks
if your supply is dropping below 6V it wont work
#171
Lol

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#172
well the 2.5" doesn't really improve the dot pitch, slightly improves contrast and loses tuner compatibility
the 3.5 doesn't look stock, but the screen improvement is significant (also loses tuner)
#173
mine is a NEC plasmasync from around 2004 (PX50XM3A)
had it several years, with little issue
#174
Yes it was plasma, with mainly NEC and pioneer units
Pioneer even had some 4:3 units

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#175
for me personally its not the scan lines but the lack of image processing on the CRT that i prefer
my plasma PVM doesnt show gaps, but does faithfully reproduce the image line by line so its not bad, but CRT still wins for fast display updates
#176
Early 90s I was repairing sets found  curb side
Even my 77 Quasar had clean lines (I would adjust the focus by them)

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#177
OK a few points
1 the consumer TV did not line double back in the day, that wasn't until the 480p days
It would place the lines by simple timing
2 the advantage of visible lines it to not display what's not in the original image

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#178
OK the noise is oscillation in the focus or tracking circuit
In most cases it is the laser set too strong (pot on lens assy)
Could be any of the gain pots, but that effects read more
Spindle speed is based on buffer filling, so its neither constant or critical
#180
looks like the -24V is dropping out
dont know why yet
#181
my point wasnt that you need 3 chips, just you need to properly map 3 chips (4 for SGX)
#182
that is awesome
cycle accurate PCE requires 2 more chips, but 6260 is simple enough
add 1 more chip for SGX
add 1 more for cd system
#183
these are as stated a PCB sandwich
they are glossy smooth and cold to the touch (feel like glass)
they are also very rigid
#184
lets send TheOldMan some boards, let him see what we are doing
#185
I make a clip from a cap lead

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#186
Currently working on new timing generator for the system to generate interlaced output

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#187
Ok lets answer a few questions
The video bus is available on the back
The scan timing is generated by a clock divider in the 6260
the pixel clock is also a divider in the 6260 sent to the 6270
Pixels are sent real time in 9bit from the 6270 and the 6260 assigns the colors to the data

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#188
white screen could still be almost anything
#189
black screen no sound?
if you have rock-on try it as it doesnt need pixel clock for sound
im guessing the ram chip on the card slot board is bad
#190
Well said zeta
These never ran hot enough to be an issue and used 2 regulators for noise isolation, not load reasons

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#191
Check your -24V supply
Its the larger 22uf cap and nearby pot

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#192
note the pots are laser specific so when swapping lasers they will need adjustment
#193
ok on the ribbon swap moving the pot to match the original was correct
you will need to adjust the pots on the board
#194
Off-Topic / Re: Tire Question
05/28/2016, 03:18 PM
no thats just bizarre
you should have a front and back spec, but left right should be balanced
#195
ok, propagation delay shouldnt be the issue as these are not gates in the conventional sense
the issue is as you approach VCC the pass-through resistance increases
also because its not a true gate its output voltage is dependent on the signal input not power input
LS is low-power Schottky and has a 9ms delay on switch
HC is high speed cmos having the same pinout and delay as LS
on these chips the propagation delay is only in play during control functions (/CE and A/B) so it is out of play well before reset goes high
#196
on the bright side the 3383 based mods work on 5V on all but a few systems
#197
a few notes on the chips
because these dont buffer the signals, the outputs will still be a bit below the inputs regardless of the power source
only danger/issue is the ESD protection afforded by the clamp diodes in the switch chips is disabled by the higher rail, making card/system damage more likely
#198
Ic520 is the only common failure
Cards work with it removed

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#199
if it has a 225 laser in it the wide ribbon needs to be centered in the connector
#200
that sounds right
so you have some chips running hot, which ones?