Modifications and upgrades of various console - guide

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krzysiobal
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Modifications and upgrades of various console - guide

Post by krzysiobal » Fri Jan 01, 2021 2:29 pm

Modifications and upgrades of various console - guide

I decided to gather my experience in repairing / remaking consoles and put them in one place. The post will be gradually expanded (I'm affraid this bbs engine does not support anchors to make hyperlinks to places in my own post)

IQ502 rev 1
IQ502 rev 2
IQ502 rev 3
MT777DX
Terminator
Rinco Thompsonic (chipped)
Super Pegasus
Hitex
IQ2000
GT-105S (2 slots, single PCB, mt777dx like)
1818P, 2 slots, single PCB)
Daryar DY-656, blob

0. Warning
Do not start repairing if you do not have specialized equipment and knowledge. On many forums, various pseudo-experts suggest more or less nonsensical advice (e.g. replace all capacitors, replace the stabilizer prophylactically). Later, other peudoservicemen decide to try their hand (grabbing a soldering iron for the first time in their lives) and often do more harm than good. Examples of hits:

Replacing the stabilizer in the console, in which the pseudo-specialist:
a) removed the original 7805 stabilizer, breaking all traces and solder points
b) he soldered a new stabilizer 7809, as a result the console got 9V instead of 5V
c) screwed it to the heat sink so that the plate was bent and hardly touched the heat sink, limiting heat dissipation.

Trying to desolder integrated circuits, breaking most of the soldering points and internal vias - repairing something like that requires 3 times more work and checking each connection.

IQ502 rev 1[/b]
The console's PCB look like below
Image Image

a) Fixing metalic, saturated sound:
Replace both selected 1k resistors for 100R

b) Restoring proper (higher) sound volume
Follow the audio signal path on the A / V / DC sockets board, from the audio socket to the gray tape. If there are any resistors in series, replace them with jumpers

c) Removal of vertical stripes in an image
You should cut the path from pin 21 of the PPU processor and lead the signal directly from this pin to an external video amplifier based on the added PCB. The video signal output from the amplifier should be connected to the video socket with a shielded cable, cutting the original connection of this socket.
An example implementation with a comparison of image quality before and after modification below:
Image Image Image

IQ502 rev 2
The console's PCB look like below (the PCB with audio/video sockets appeared in few different versions):
Image
a) Increase the sound volume
As standard, in this model, in series in AUDIO path, there is a 4.7k resistor, which effectively suppresses the sound volume (R7 on the board with A / V sockets). It should be replaced with a jumper or if the sound volume turns out to be too high - reduce it to a value of e.g. 1k
Image
b) Sound noise removal
The 1u capacitor should be soldered to the bottom of the board in the marked places in accordance with the polarity. It is important that it is positioned as shown in the photo, because then it will not interfere with the cartridge eject mechanism.
Image

c) Image quality improvement
Some examples of this model have redundant / missing elements in the video path (e.g. soldered 2.2k resistors with one leg cut off). Retrace the video path and, if necessary, modify it to look like the diagram below:
Image

d) Incorrectly connected switch
Make sure that the switch and the LED diode are connected to the appropriate plugs, otherwise the console may start but will not work properly

e) Correct mounting of the cartridge ejection mechanism
The spring should lie under the plastic, and when you press the mechanism, the console's PCB should not bend or move:
Image
f) Securing the ejection mechanism with a tape against falling out
Read below

g) Protection against incorrect power supply
Read below

IQ502 rev 3
The console's PCB look like below
Image

a) Improving color saturation and restoring proper contrast:
Image
Do the following:
* remove the J jumper,
* remove the capacitor C (the hole in the right leg is very small, suck out the tin well. If the end of the leg is flattened, cut it off)
* in place of R1 solder a 2.2K resistor,
* in place of R2, solder the resistor 220R
* in place of Q, solder a PNP transistor (e.g. A733)
* solder the previously removed capacitor C to the cartridge socket on the reverse side:
Image

b) Strenghening tracks around audio/video/power socket and voltage regulator
Due to the poor quality of solder joints and the poor quality of the laminate, in places exposed to higher forces (sockets), cold solder / soldering points may appear. In parallel to the existing paths (signal path of the audio, video, RF jacks, connections to the power socket, connections to the stabilizer) solder a rigid wire (silver plate) to strengthen and make the connection more flexible:
Image

c) Adding plugs to the power / reset / LED buttons
In this model (unlike rev1 / rev2), the power / reset / diode buttons are permanently soldered and secured with glue.
* It is more aesthetic and practical to add plugs to them and solder the sockets in the console.
* To strengthen the wire-button connection, first the goldpin pin should be soldered to the button, and the wire to it, and then the whole should be secured with a heat shrink tube.
* The cables should be twisted together to reduce the clutter of wires.
Image Image

d) Improving buttons operation
If the buttons on the console do not spring back well, there are a few things to watch out for:
* The buttons should be screwed with the side from which the wires extend towards the cartridge socket
* Buttons should not be tightened rigidly, but there should be a minimal play to allow them to "fit"
* If this does not help, take the button apart, unbend the spring and reassemble. The construction is shown in the picture below (when undressing, bend the black tab slightly)
Image

e) Joystick socket reinforcement
Check the quality of the solders (they are often of poor quality, caused by tarnish on the contacts before they are soldered).
* Vacuum the solders, remove the sockets, clean the tarnished tips, re-solder.
* The sockets are quite protruding, which makes them quite vulnerable to tearing off. Original thermo-glue (which is of poor quality) should be removed and glued with strong glue
Image

f) Securing the extension mechanism against falling out:
Stick the insulating tape as shown in the picture
Image

g) Strengthening the connection between the plates
It is worth desoldering the original tape, solder the angular pin strips on both sides and solder the tape to it, you can additionally strengthen it with a heat shrink tube
Image

h) Protection against incorrect power supply polarisation
Cut the marked place and solder a rectifier diode (preferably Schottky-ego 1N5819).
Image

MT777DX
The console's PCB look like below
Image

a) Removing noise from the sound
The console uses the 74368 digital buffer to amplify the sound, introducing additional noise. The board provides the possibility of soldering the transistor as an amplifier, which should be done:
* Solder the resistor R6 = 1k
* Solder the transistor Q8 = C945 (ECB looking from the top)
* Cut the jumper (you can see it well against the light)
Image Image

b) Improving color saturation and cooperation with some TV sets (especially newer ones)
* Desolder the jumper marked as R3 and solder the 220R resistor in its place
* You can remove the L1 choke and solder a jumper in its place
Image
* Cut the track in the marked place and solder R = 75R
Image

c) Correct placement of the modulator cover
The modulator cover has a cutout in the place where the strips connecting it with the plate come out. Insertion in any of the three other directions may cause it to close all pins.
Image

d) Proper mounting of the heat sink
The heat sink heats up to high temperatures during operation, There should be a distance of approx. 1 mm between it and the motherboard, otherwise the soldermask may fall off over time and a short circuit may occur (unfortunately there is a power path under the heat sink) - in the photo below the heat sink is too close to the board . Additionally, you should also pay attention that the heat sink does not come into direct contact with the console housing
Image

e) The correct position of the image amplifier transistor
The transistor should be mounted vertically. If it is too close to the heat sink, it may overheat and change parameters during operation, altering image quality. If it bends and touches the PCB, the top of the housing will press against it, causing the PCB to bend)
Image

f) Worn audio / video sockets
If the slightest movement of the plug causes a loss of picture / sound, the sockets may be dirty or worn. It would be best to replace them, but it involves the necessity of finding an identical model and desoldering the originals, which requires a good dust extractor and a strong soldering iron or hot air station.
A temporary solution is to bend the internal plates in the sockets so that they make better contact with the pin in the plug.
Image

g) Protection against incorrect power supply
Cut the marked places on both sides of the board and solder a rectifier diode (preferably Schottky's 1N5819). Since the path to be intersected is thick, it is worth checking with a meter that there is really no connection.
Image Image

h) Correct twist of the console
The housing plate should be screwed with exactly 4 screws
* Omitting any of the screws will cause the plate to fall when inserting the cartridge and the ejection mechanism will not work properly or the power / reset buttons will not work stably
* Do not put the screws in the holes on the sides of the cartridge slot - the eject mechanism will not work properly

i) Repair of the cartridge ejection mechanism
* Replacing the missing spring - it can be replaced with a properly stretched rubber band
* Broken "nose" with a plastic element, in which the EJECt button is inserted - can be cut from sheet metal and screwed on.

Terminator
Since there are many models of these consoles (they differ in terms of both the interior and the housing itself), it is difficult to cover all the examples - you should adapt the described advice to your model
Image Image Image

Image Image Image

Image Image


a) Strengthening of mounting pins
I have often seen cases of broken mounting pins due to the poor quality of the plastic. All dowels at the base in both parts of the housing should be secured with a solid layer of good thermo glue (of course, you should wash the console first to get rid of dust / dirt). Be careful that the adhesive does not block the area for the POWER / RESET button
Image Image

b) Adding plugs for POWER / LESET / LED switches:
Image Image

c) Strengthening the connection between PCBs
You need to desolder the gray tape, solder the angular goldpin sockets and solder the tape to them:
Image

d) Replacement of the power supply block from a zener diode to a stabilizer with a heat sink
In this way, the console will be supplied with a more stable voltage, but most of all it will be able to draw more electricity (necessary especially when using cartridges on chips). Due to the different models of plates, you should check on your own where the stabilizer should be soldered. It is important to make sure that all its outputs are in contact with the rest of the board - leaving the hanging mass may, for example, cause 11V to the output despite the stabilizer in working order and damage the entire console
Image

e) Connecting audio / video sockets
In many models, the audio / video sockets, despite their presence, are not connected to anything. The signal path should be traced and the missing elements should be soldered (either on the board if there is a place for them, or underneath)
* in the case of audio - it is enough to connect the socket directly to the pin connector (optionally, you can add a 1k resistor in series to reduce the volume, add a capacitor in series to eliminate the DC component if present, a capacitor parallel to ground if there is noise)
* in the case of video - you need to add an NPN transistor with 220R and 75R resistors
* sometimes on the board with the cartridge socket there is also a place to connect a PNP transistor and 220R and 2.2k resistors

f) Protection against incorrect power supply
Cut the marked place and solder a rectifier diode (preferably Schottky-ego 1N5819).
Image

g) Adding missing connections to the 15-pin socket of the pad no. 2
Pad No. 2 also serves as an expansion port (it can be connected to a gun or other accessories, such as an external keyboard, splitter for 4 players, etc.). For this to be possible, the tape connecting both boards should have 18 wires (if there are fewer - usually 11, then only lines for connecting two pads and a gun are available).
However, it often happens that despite the fact that all signals are on the tape, they are not connected to the sockets on the board with joypad sockets - the missing connections should be completed according to the list:

Code: Select all

 Szara tasma           Gniazdo joypada 2
 1 | +5V 7805            1 | GND
 2 | VCC                 2 | AUDIO
 3 | $4017 CLK           3 | !IRQ
 4 | OUT2                4 | $4017 D4
 5 | OUT1                5 | $4017 D3
 6 | $4017 D4            6 | $4017 D2
 7 | OUT0                7 | $4017 D1
 8 | $4017 D3            8 | $4017 D0
 9 | $4016 D1            9 | $4017 CLK
10 | $4017 D2           10 | OUT2
11 | $4016 CLK          11 | OUT1
12 | $4017 D1           12 | OUT0
13 | $4017 D0           13 | $4016 D1
14 | $4016 D0           14 | $4016 CLK
15 | !RESET             15 | +5V
16 | GND      
17 | !IRQ     
18 | AUDIO    
Image Image

h) Replacing the cartridge holder
If the contacts in the cartridge socket are crooked or tarnished (which is not uncommon in this model), it is worth replacing the entire socket with a new one

i) Adding a 50Hz / 60Hz switch - if there are jumpers on the console board, it is possible to connect a 50 / 60Hz switch to them (for the best image quality it will also be necessary to connect a second quartz resonator)

Rinco Thompsonic (chipped)
Płytka konsoli wygląda jak poniżej:
Image Image

a) Removal of the metallic sound
Due to the incorrect value of the current-to-voltage conversion resistors, the sound in the console is distorted. Replace resistors R25 and R26 with 100R

b) Improvement of image quality
Due to the sloppyly designed video path (the signal runs through the entire PCB to the amplifier, collecting noise), the image shows quite clear vertical stripes. You should cut the path in the marked place, and then build a dedicated amplifier on a small PCB, which should be soldered as close as possible to pin 21 from the PPU processor. Connect its output with a shielded cable to the video output, cutting the original connection at the video output
Image

c) Improving the connection between the plates
Both boards are connected using goldpin sockets, unfortunately it is a rigid connection that can develop over time. Better to replace this connection with two male pins + a wire connecting them together.

d) Addition of a 50Hz / 60Hz switch
The console is equipped with a rare set of TA-03NP1 / TA-02NP processors that allow switching between the 50Hz / 60Hz operating mode. There is even a place on the board for soldering a second generator: a quartz oscillator and its accompanying elements

e) Protection against incorrect power supply
as above

Super Pegasus
Płytka wygląda jak poniżej:
Image Image Image

a) Improving all soldered joints
In this copy, most of the solders are sloppy - most of them are of shameful quality (especially around the A / V sockets, stabilizer and joypad sockets) - suck out the old tin and put on a new one.

b) Improvement of image quality
There is an unnecessary capacitor in series at the output of the video track (next to the Video socket) - it should be desoldered and replaced with a jumper (J1) (otherwise some cartridges, e.g. 168in1, will display an unstable image)

c) Improving sound quality
The resistors and capacitors in the sound amplifier (R7 / R7 / C8 / C90 have incorrect values - locate them, desolder and solder the correct ones, according to the diagram below).
Image

Hitex
The console looks like below
Image Image Image Image Image

a) Adding missing connections to audio / vidoe jacks
In some models, the A / V sockets may not be connected to anything, you should make appropriate corrections of the connections (the audio socket directly to the sound output, and the video socket - by adding an appropriate current amplifier on the NPN transistor)
Image Image

b) Increase the sound volume
Replace the resistor below with a 1k resistor
Image

c) Humming Elimination
If there is a hum at times when in-game audio is muted, either
a) replace the upper buffer 74LS368 with 74HCT368 or 74HC368 (remember to bend or cut the same legs
or
b) Cut the path below (in this case, at port $ 4016.2, the console will no longer be able to read the microphone signal)
Image


IQ2000
The console looks like below:
Image Image Image Image Image Image

Improvement of video brightness
Due to incorrect connection of the R11 resistor, the image is too dark. Remove the original resistor and solder it as indicated below:
Image

GT-105S (2 slots, single PCB, mt777dx like)
PCB and diagram below, housing appearance probably red and white (like the original famicom):
Image Image Image

Possible improvements:
a) Replacing the C4 capacitor in the audio path with a jumper (solves the problem of the lack of low tones)
b) Addition of an external audio amplifier on the transistor instead of the 74368 chip (solves the noise problem)
c) Soldering jumper A - returns two grounds to each of the cartridge slots
d) Addition of missing filter capacitors (100n each): C7, C8, C9, C11 and two 47uf (the capacitor at C7 was inversely soldered). The addition of capacitors eliminated the problem of some cartridges freezing
e) Replacing C2 = 47uf / 10V cap on the power input to 470uf / 16V (the original one was too low voltage!)
f) replacement of the heat sink in the 7805 with a larger one
g) protection of the console against an incorrect power supply with a serial diode at the input of the power path,
h) installing sockets for all systems
i) adding an external video amplifier
j) turning off the existing video amplifier by shorting the Q2 base to VCC (the RF socket will no longer work, but who uses it),
k) adding a small PCB with two quartz and a switch - 26MHZ (for PAL PPU / CPU) or 21MHZ (for NTSC PPU / CPU)
i) removing the connection between CPU- / A13 and CIRAM-CS. Now compatible with games as in the original Famicom and other consoles with a single cartridge slot - this will allow you to play games that use a different nametable configuration than H / V / 0/1 (e.g. MMC5 or JY-Company games)
j) connecting pin 1 in player number 2 to the microphone (this is also the case in the mt777dx console)

Post-fix appearance:
Image Image

1818P, 2 slots, single PCB
PCB and diagram below, housing appearance probably red and white (like the original famicom):
Image Image [/url]Image Image

Possible improvements:
a) Several pins from the SP80 chip are connected to GND or to nothing, although they are not ground. I analyzed their operation in the hope that they could be used for 50 / 60Hz switching, but unfortunately none of that. Maybe this is some interfest for debugging, I led out the pins to goldpins in the hope that maybe one day we will be able to analyze their functions
b) Adding missing filter capacitors (100n) between VCC / GND: CX1, CX2, CX3, CX4, C27
d) Shortening the legs of Q1 and Q2 transistors so that they do not look so bizarre,
e) replacing C1 with a smaller one so that it does not interfere with the cartridge ejection mechanism,
f) moving the electrolytic capacitor from C10 to C9 (i.e. there, gdize should be), then a few millimeters from 7805 so that it does not heat up.
g) adding the missing C10 = 100n
h) replacement of small quartz X1 with a normal size (bigger = more stable),
i) connecting pin 1 in player 2's socket to the audio input (microphone),
j) changing the connection between PPU-A13 in the slave socket to direct (previously it went through the lack of 4066) - maybe foregoo some games were glitching, because when there was a cartridge in the maser slot, PPU-A13 in the slave socket was then hanging
j) use of free gram from 4066 to switch CIRAM-CS in a slave slot (compatibility with MMC5, Jy-Company games),
k) protection against an incorrect power supply,
l) external video amplifier (but here the image quality has not improved significantly, probably the distortions are already added to the video signal inside the chip due to the tangled paths under the system),
m) disconnecting the internal audio amplifier and connecting the external one on the transistor

Post-fix appearance:
Image Image

Daryar DY-656, blob
Circuit board and diagram below, red and white case look (like the original famicom). Quite an interesting model, it comes with a built-in 400-in-1 cartridge connected in a strange way with a cable and additional fixes:

Image Image Image Image Image Image Image Image Image Image Image

Possible improvements:
a) Restoring normal sound:
-change R6 from 47k to 100k
- replacement of R5 from 20k to 12k
- C4 replacement from 100n to 1u
-addition of missing C5 = 1n

b) Improving color saturation - adding a PNP transistor with a 2.2k and 220R resistor in the video path

c) Adding the PAL / NTSC switch - when we connect the places marked as R9 and R8 and change the quartz to 21.xxx MHz, the console will work in NTSC mode (by installing the appropriate switch, it could manually switch the region)

d) The method of detecting the presence of the cartridge in the MASTER slot and deactivating the SLAVE slot is heavily overrated - I recommend:
- remove the D6 diode
- replace R10 with a jumper

e) The built-in cart drives the data (jumpers value) in the $ 6000- $ 7fff area. Unfortunately, nothing controls the R /! W or M2 line in the slave slot, therefore the game cartridge in the master slot is present, there would be a conflict on the bus - hence the additional cable connection. You can restore all connections in the cartridge to default and add a diode and a resistor which will cause the cartridge in the slave slot to see each cycle as a write when a cartridge in the master slot is present:

Code: Select all

master R/W -----1k--+- SLAVE R/W
                    |
master pin 16----<|-+
After corrections:
Image Image

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