Sunday, May 6, 2018
DON'T FORGET THAT 330 OHMS RESISTOR FROM THE 6 VOLT BATTERY.
PUT YOUR TESTER ON rx1 AND TEST THE INPUT FOR THE BATTERY AND GROUND. IF THE TESTER FULLY DEFLECTS, YOU HAVE SHORT!
IF YOU HAVE SOME RESISTANCE, THEN OK, FIRE IT UP. PUT THE BATTERY.
CHECK THE VOLTAGE OF THE COLLECTORS OF ALL THE FIRST 3 TRANNIES. DAPAT LAHAT MAY SAME VOLTAGE AS THE VOLTAGE AFTER THE 330 OHM RESISTOR.
SET THE TESTER TO RX1 AGAIN AND GROUND THE RED PROBE. THE BLACK PROBE PUTS OUT A + VOLTAGE. SCRATCH THE BASE OF THE THIRD TRANNY. MAY SCRATCH BA SA AMPLI? THE THE BASE OF THE SECOND TRANNY, THEN THE FIRST. DAPAT MAY
SCRATCHES SA AMPLI.
LATER NA ANG ALIGNMENT.
PUT YOUR TESTER ON rx1 AND TEST THE INPUT FOR THE BATTERY AND GROUND. IF THE TESTER FULLY DEFLECTS, YOU HAVE SHORT!
IF YOU HAVE SOME RESISTANCE, THEN OK, FIRE IT UP. PUT THE BATTERY.
CHECK THE VOLTAGE OF THE COLLECTORS OF ALL THE FIRST 3 TRANNIES. DAPAT LAHAT MAY SAME VOLTAGE AS THE VOLTAGE AFTER THE 330 OHM RESISTOR.
SET THE TESTER TO RX1 AGAIN AND GROUND THE RED PROBE. THE BLACK PROBE PUTS OUT A + VOLTAGE. SCRATCH THE BASE OF THE THIRD TRANNY. MAY SCRATCH BA SA AMPLI? THE THE BASE OF THE SECOND TRANNY, THEN THE FIRST. DAPAT MAY
SCRATCHES SA AMPLI.
LATER NA ANG ALIGNMENT.
5/7/18
Ok, lets go. The transistors used are ED1402. It is NPN, meaning negative ground(emitter). Four coils in cans. The red is the oscillator, the yellow, white, and black are tuned transformer coils (all in in cans). The diode is a 1N4148. Ok to use 1N34 if you have one. Volume Control. Will check value later, 5k or 10K ok.
After the diode to the volume control, it is the audio amp.
AFTER THE DIODE AUDIO IS PRESENT AND THE VOLUME CONTROL PUTS THE AF TO AN AUDIO AMPLIFIER.
YOU MUST VIEW THE RADIO AS HAVING TWO SECTIONS, THE RF SECTION UP TO THE DIODE AND THE AF SECTION.
The audio amp uses 4 transistors. The transistors in the final stage (last 2 trannies are the popular NPN and PNP pair, the S8050(NPN) and the S 8550 (PNP). These could be B324 and D352.
The drivers are the ED602 and ED 1702.
FOR BUILDERS, GOOGLE THESE TRANSISTORS AND GET THEIR PIN CONFIGURATION. PRINT IF POSSIBLE. KEEP IT ON HAND. MANY ERRORS COMMITTED ARE IN THE PIN CONFIGURATION. IF YOU HAVE A DIGITAL TESTER, TEST EACH TRANSISTOR. YOU CAN USE AN ANALOG FOLLOWING THE INSTRUCTION ON HOW TO CHECK A TRANNY.
BUILD THE AUDIO AMPLIFIER FIRST. IT IS EASY TO CHECK IT. JUST CONNECT ANOTHER SPEAKER INTO THE VOLUME CONTROL AND SPEAK INTO IT. OR A MICROPHONE.
HELLO, HELLO. TESTING MIC 1-2-3. OK BA. KUNG OK, ALAM MO WALANG PROBLEMO ANG AMPLIFIER. THAT IS NOT THE RADIO RECEIVER. THAT IS ONLY TO AMPLIFY THE SOUND.
Ok, let's go the radio receiver itself, the RF section.
CHECK ALL THE TRANNIES. USING A DIGITAL TESTER IS SIMPLER. BUT IF YOU HAVE ONLY AN ANALOG TYPE, HERE IS HOW TO CHECK THE TRANNIES.
Set the tester to RX1. Put the red probe to the Base and check the E and C. then put the black probe to the Base and check E and C. It will be PALO ,PALO, then NO PALO, NO PALO WITH EITEHR PROBE IN THE BASE. Then check the E-C, there should be NO PALO or LOW PALO in both directions of the probes.
PALO=DEFLECTION OF THE METER
THEN CHECK ALL THE TRANSFORMER COILS. CONTINUITY TEST LANG ON THE PRIMARY AND THE SECONDARY. MAKE SURE WALANG OPEN.
NEXT, GET A SANDPAPER AND SAND OFF THE COPPER SIDE OF THE BOARD TO REMOVE THE OXIDATION.
THEN, SCRAPE THE PINS OF THE COILS AND THE TRANNIES FOR EASY SOLDERING. (ALSO THE RESISTORS AND CONDENSERS AND DIODE).
INSERT THE CANS, SOLDER THEM IN PLACE. INSERT THE TRANNIES AND SOLDER THEM IN PLACE. THEN THE OTHER PARTS.
THE ANTENNA COIL
BE CAREFUL OF THE FERRITE BAR. IT BREAKS. THE COIL HAS 4 TERMINALS. THE SINGLE END ON THE FAR SIDE IS TO THE TUNING CAP THE PAIRED ONES IS TO GROUND. THE OPPOSITE SINGLE END IS TO THE .02 CAP TO THE BASE OF THE TRANNY.
.
Ok, lets go. The transistors used are ED1402. It is NPN, meaning negative ground(emitter). Four coils in cans. The red is the oscillator, the yellow, white, and black are tuned transformer coils (all in in cans). The diode is a 1N4148. Ok to use 1N34 if you have one. Volume Control. Will check value later, 5k or 10K ok.
After the diode to the volume control, it is the audio amp.
AFTER THE DIODE AUDIO IS PRESENT AND THE VOLUME CONTROL PUTS THE AF TO AN AUDIO AMPLIFIER.
YOU MUST VIEW THE RADIO AS HAVING TWO SECTIONS, THE RF SECTION UP TO THE DIODE AND THE AF SECTION.
The audio amp uses 4 transistors. The transistors in the final stage (last 2 trannies are the popular NPN and PNP pair, the S8050(NPN) and the S 8550 (PNP). These could be B324 and D352.
The drivers are the ED602 and ED 1702.
FOR BUILDERS, GOOGLE THESE TRANSISTORS AND GET THEIR PIN CONFIGURATION. PRINT IF POSSIBLE. KEEP IT ON HAND. MANY ERRORS COMMITTED ARE IN THE PIN CONFIGURATION. IF YOU HAVE A DIGITAL TESTER, TEST EACH TRANSISTOR. YOU CAN USE AN ANALOG FOLLOWING THE INSTRUCTION ON HOW TO CHECK A TRANNY.
BUILD THE AUDIO AMPLIFIER FIRST. IT IS EASY TO CHECK IT. JUST CONNECT ANOTHER SPEAKER INTO THE VOLUME CONTROL AND SPEAK INTO IT. OR A MICROPHONE.
HELLO, HELLO. TESTING MIC 1-2-3. OK BA. KUNG OK, ALAM MO WALANG PROBLEMO ANG AMPLIFIER. THAT IS NOT THE RADIO RECEIVER. THAT IS ONLY TO AMPLIFY THE SOUND.
Ok, let's go the radio receiver itself, the RF section.
CHECK ALL THE TRANNIES. USING A DIGITAL TESTER IS SIMPLER. BUT IF YOU HAVE ONLY AN ANALOG TYPE, HERE IS HOW TO CHECK THE TRANNIES.
Set the tester to RX1. Put the red probe to the Base and check the E and C. then put the black probe to the Base and check E and C. It will be PALO ,PALO, then NO PALO, NO PALO WITH EITEHR PROBE IN THE BASE. Then check the E-C, there should be NO PALO or LOW PALO in both directions of the probes.
PALO=DEFLECTION OF THE METER
THEN CHECK ALL THE TRANSFORMER COILS. CONTINUITY TEST LANG ON THE PRIMARY AND THE SECONDARY. MAKE SURE WALANG OPEN.
NEXT, GET A SANDPAPER AND SAND OFF THE COPPER SIDE OF THE BOARD TO REMOVE THE OXIDATION.
THEN, SCRAPE THE PINS OF THE COILS AND THE TRANNIES FOR EASY SOLDERING. (ALSO THE RESISTORS AND CONDENSERS AND DIODE).
INSERT THE CANS, SOLDER THEM IN PLACE. INSERT THE TRANNIES AND SOLDER THEM IN PLACE. THEN THE OTHER PARTS.
THE ANTENNA COIL
BE CAREFUL OF THE FERRITE BAR. IT BREAKS. THE COIL HAS 4 TERMINALS. THE SINGLE END ON THE FAR SIDE IS TO THE TUNING CAP THE PAIRED ONES IS TO GROUND. THE OPPOSITE SINGLE END IS TO THE .02 CAP TO THE BASE OF THE TRANNY.
.
May 7, 2018
It's 2018 and the query of Ergic in elab.ph about the CMC 707 promts me to continue with this blog. The CMC 707 has been a mainstay kit of the CELCO group as far as I can remember. I assembled many and have seen this kit change a bit by bit like using other transistors and even using an IC audio amp. There is romance in the all transistor type. First, I will post eh schematic diagram of the CMC 707.
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