Hardware Hacking

Clarifier Modification

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the red wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the orange wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.

This should give you about 6khz of slide.

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the YELLOW wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the RED wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.
4)Cut the brown wire off the clarifier knob.

1) Mount 2 SPST toggle switches in a good loacation on the radio.
2) Locate and unsolder the 11.1125mhz Crystal and replace it with a 11.3258 mhz crystal.
3) Locate pin 10 of the mb8719 chip.Cut the trace that is connected to it.
4) Solder the wires onto the switches and pins of the chip like in the diagram above.

Peaks and Tweaks

VR 10 is AM power
VR 6 is ALC
VR 5 is AM Modulation
VR 7 is RF Power meter
VR 1 is S-meter adjust

TX coils- L34, L35, L36 and L26
RX coils- L3 - L8, L10 and L11

Superstar 3900 Beep Removal

Version 1:
Remove TR 33 located by the 3 pin plug-in at the mic socket
thanks to Larry D Lawrence Jr. for sending me this mod !

Version 2:
Cut J9 Jumper and leave it open making sure the legs are not touching anything.
This will disable the Roger Beep, I have done it to my radio and works fine.
If one wanted to make it so it could be turned on/off it could be put on the CH9 Switch.
This mod was sent to me by Harold Bates / cb442 / KB5SXV
Power tweak

1. Replace R174 (10k) with a 1 K
2. Replace R187 (10k) with a 1 K

MODULATION: VR14 or cut R249
AM POWER: VR13
SSB POWER: VR12

Clarifier

1. Find the GREEN WIRE located at point 54 and UNSOLDER it.
2. Resolder this GREEN WIRE to POINT 14 (8.7 V) or to TR 41 collector.
3. Find the YELLOW WIRE on the clarifier control and UNSOLDER it. Insulate the cut end.
ææThis wire is no longer used.
4. Find D75 (located near POINT 53 and VR15) and lift one end.
5. Find R135 (33k) and lift one end.
6. Double check all work for shorts.

NO EXPLOSION? Then you should be able to track on TX and RX!

3900 mod, Sent to me by a visitor

There is a RED wire on the solder side of the PCB, it is up at the front of the pcb when you take the top cover off.
Unsoldered this wire and check the freq. it should be 26.965 to 27.405 MHz with the band switch in the Hi position, the other switch is on D/A.

Richard (dickie) G.
Channels

CONVERT THE SS3900, 28 Mhz VERSION TO NORMAL OPERATION

These radioÍs are normally supplied by the manufacturer operating on 28 MHz only.

When sold by dealers they have usually had this mod done, but occasionally there is a need for this infomation

There is also a jumper near the centre front of the main board which enables the pull switch band functions.
On a super star 3900 that there are 4 resisters near the front to the right side of the radio that kept the radio from going 25.615 to 28.305 remove the resisters and the frequencies are expanded.

10 Meter additional channels

1. Locate pins #12 and #13 on IC7 (MC14008BCP chip).
2. Using a SPST toggle switch, wire as follows:
Center of toggle switch goes to pin #13
The other goes to pin #12

Your channels should work with your band selector on band D. It should be able to go from 28.300 Mhz. to 28.500 Mhz.

Super Star 3900 Gold and Cobra148GTLX Gold

(These 2 radios are the same except for the name)

VR1 - AM/FM S METER ADJUST
VR2 - SSB/CW S METER ADJUST
VR3 - SSB SQUELCH RANGE
VR4 - AM SQUELCH RANGE
VR5 - FM DEVIATION ADJUST
VR7 - CARRIER BALANCE ADJUST
VR8 - RF METER ADJUST
VR10 - FINAL BIAS ADJUST
VR11 - DRIVER BIAS ADJUST
VR12 - ALC ADJUST
VR13 - AM POWER ADJUST
VR14 - AMC
VR16 - CW MON ADJUST
VR21 - Tx FREQUENCY ADJUST
TR32 - IS THE AMC LIMITER

“I don’t recommend removing TR32 as it disables VR12 ALC, SSB power will be at full blast.
Instead clip or remove R249. This only disables AMC not ALC.
Tune L40, L43, L44, and L33 for maximum forward swing on wattmeter.
Adjust AM power for no more than 5 watts dead-key - if running a linear amp set at 3 watts dead-key.
Adjust ALC for no more than 20 - 25 watts PEP on SSB.
For Talkback remove D80.”
Superstar 3900 Plus Gold

Superstar 3900 plus gold dual finals.

Same board as Galaxy 2517 & DX48T.

Move jumper to different pins to get 25.615-28.305 Mhz.

That’s it.

This mod was sent to me by Crazy Bob, thank you.
SuperStar 3900

+ 10 KHz Jump Switch

1)Get a SPST switch and mount it in the radio.
2)Find IC 6 & 7 by the PLL chip. You will see J68 and J 69
3)Solder a wire from one side of the switch to J68.
4)Solder a wire from the other side of the switch to J69.
5)That’s it .Flip the switch to jump up one channel.

Open Clarifier

1)Find D75 and R135 and cut one end of them.
2)On the back of the clarifier knob follow the green wire to the PC board. Cut this wire from the PC board.
3)Now Solder this wire to a constant 8VDC source, like the collector of TR41.
4)Take the yellow wire and cut it from the knob. Tape this wire it is not needed.
4)This should make the radio TX/RX on the same frequency.

10 Meter Mod

1) Find IC7 near the PLL chip.
2) Get a SPST switch and mount it in the radio.
3) Solder a wire from one side of the switch to Pin #13.
4) Solder a wire from the other side of the switch to Pin #12.
5) That’s it .Put the radio on ‘Band D’ then flip the switch to jump up to 28.300 to 28.500.

Tweak and peak

Audio Limiter - Cut R249
AM Power - VR13
SSB Power - VR12