CQ DX

TS140-S Chapter 4/8 Corrective and Preventive Maintenance
Now we unhook the connectors and flat cables that connect the equipment panel to its general circuit. You will notice that there are 4 small metallic pieces, in the shape of the letter L, promoting the fixation of the small electronic board, mounted behind the numerical display. You will not need to loosen the existing connections on this small board, just loosen the 4 screws that fix it to the metal frame of the panel assembly, preventing the small pieces in the shape of the letter L from returning misaligned in their subsequent assembly, or even being damaging your sensitive screw threads.
Before you have the main board of the panel free for maintenance, remove the power activation key and also remove the microphone connector, paying attention to the small capacitor that is soldered on the fixing screw of this part, promoting a filtering for the ground microphone's negative audio signal. Be careful with this soldering job as there is a plastic connector very close to the heat the soldering iron will generate. Think about placing a sheet of hard card paper to protect the heat diffusion from reaching the plastic part.
With the plate loose, you can damage the S Meter galvanometer, so it is important to protect it from torsion, support, high temperatures, or even an accidental fall.
When removing the rotary counter from the board, use solder flux in abundance, ensuring that the circuit tracks will not suffer from the high temperature to which they will be exposed, until the 8 soldered pins on this board, release with the suction process. There are two pins that only maximize the mechanical fixation of this potentiometer, and the other 6 remaining solder points, promote the connections of the VFO's sensitive pulse signals.
With the rotary counter released from the plate, we will open it very carefully, as its metallic tabs are fragile, and when bending them, do not let the metal create a crease. Before bending them to 90 degrees to release the potentiometer axis, wedge the surroundings of your metallic mug, avoiding the formation of creases and possible breakage, which will permanently render it unusable, and we aim to repair and return it. it to the proper functioning of the radio.
In this rotary counter, we will be very careful with the little arms (pantographs) that follow the movement of the axis, and also in removing dirt from the carbon track, we have to act delicately, surgically.
Already in the first test of contact pulses, in measurement with the multimeter (it was difficult to use the probes to measure the alternating impedances) they presented the expected result, and the enthusiasm to return this potentiometer soldered to the board, was demonstrated.
TS140-S Chapter 004 Corrective and Preventive Maintenance
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TS140-S Chapter 3/8 Corrective and Preventive Maintenance
In this movie 3/8 we are disassembling the panel, and we recommend using good tools so as not to damage the panel's delicate screws. The extraction of each part of the panel must be done with care, especially with the potentiometer shafts which are fragile. Have a smooth and solid surface from the beginning of the maintenance of any equipment, so that you can pack each screw or piece so as not to invert positions, lose small components. This will make things easier when reassembling the equipment. For the definitive extraction of the plastic mask from the panel, after there are no more screws or drive buttons, pay attention to the 4 tabs that hold this part by pressing the fit. There are 2 small screws on the front sector of the VFO position that must be extracted as well, don't forget them.
When removing the plastic mask, pay attention to the protective foams that are present on the inside of the selector buttons. They are very sensitive, and if they are dried out by the action of time, they will easily crumble into crumbs.
Be careful not to scratch the plastic lens that covers the frequency meter display. Use only pure, neutral silicone without any abrasiveness. Silicones sold for car cleaning can bleach plastic lenses and dry out keys and buttons in an attempt to clean them. The company XEROX still distributes a pure and neutral liquid silicone, of the highest quality for this purpose. Use cotton or a soft cloth with as little moisture as possible.
Also regarding the VFO's crystal lens, be careful when removing, cleaning and replacing it, as it is quite sensitive.
Never start these works without first consulting the service manuals and the circuit diagrams, as the maintenance intervention must rely on your prior planning, to avoid forcing fittings, or even not identifying the correct positions of each item to be extracted, or temporarily manipulated to access certain areas of the assembly blocks.
When the metallic box that contains the panel structure is already on display, analyze the best way to separate the connectors and the flat cables, as they are ultra sensitive and require delicate handling, avoiding the rupture of these tapes or the dismemberment of the wiring of the connectors that if you pull these wires separately, they will come loose from the eyelets of the connectors
TS140-S Chapter 003 Corrective and Preventive Maintenance
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TS140-S Chapter 2/8 Corrective and Preventive Maintenance
We started Film nº 002 with the equipment already open in all its maintenance access areas, and we insistently recommend that they operate the checks and findings with the workbench completely organized and clean, preventing tools or any metallic utensils from being close to the open circuit of the equipment while it is being supplied with energy on its plates.
Instinctively, I directed my checks at the LPF board first, with the suspicion about the correct performance of its relays.
I was always correct in suspecting the relays, and at the slightest touch of inspection, we already obtained proof of the malfunction of the relays in the 21.5 Mhz area, up to 30 Mhz.
I also recommend that any transmission test in phone mode be operated with the original dynamic microphone of 600 Ohms, avoiding saturations in the circuit modulation, and offering a more in tune reading for the measuring instruments of the transmission audio elements and their adjustments. of frequency deviations of microphone signals.
Everything is correct with the adjustments and operation of the equipment for its transmission mode, and we went to intervene in the receiver circuit.
We went over the adjustments of the FI coils and all the balance of this set. We also replaced the already salinized ceramic filters, and reached the correct references of the reception adjustments, and the quality of these received signals. there were capacitors showing some fatigue and we replaced them with identical components from the manufacturer ELNA. I can say that we now have a reception equivalent to that of the TS940-S equipment. We don't have the complexity of the numerous adjustments that the TS940-S can offer, but we have the same power for our receiver.
We have tested the Receiver at 160 Meters, 80 Meters and also Beacons at Very Low Frequencies VLF, and have been very satisfied. We also did Qso's on Low Bands with only 15 Watts, and our signals and our broadcast audio quality were appreciated very positively.
Now we will dismantle the panel's plastic mask, as well as the components integrated into the panel. We ask you to be very careful when extracting the plastic k***s, due to the sensitivity of the potentiometer axes.
Also in this film, I explain that my English language is very poor, and I have no intention or investments for these films to become maintenance landmarks, but I just want to make friends around the world, who are interested in electronics, classic radios and the best way to fix them. I'm not ashamed of not speaking English properly, I'm just determined to improve it for the next maintenance films. Well, let's get on with our work.
TS140-S Chapter 002 Corrective and Preventive Maintenance
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TS140-S Chapter 1/8 Corrective and Preventive Maintenance
Hello lovers of Classic equipment. Today we have a wonderful and well-preserved specimen of a Kenwood TS140-S.
As soon as it was turned on on the maintenance bench, we could see that its reception was completely attenuated, and there was no possibility of listening to any stations on the tuned frequencies. With some tests on the transmission part, we could see that after passing the Radio Frequency voltage through the LPF Board relays, signal reception returned to good levels of sensitivity, but in a matter of minutes the problem was detected again. We could suspect right from the start about mechanically immobile, locked relay contact blades, or even problems with coils or receiver drive components. We also detected the Audio Frequency Level Adjustment Variable Resistor failing to trigger.
The rotary encoder that triggers the command of steps in Khz on the VFO, was also not showing regular operation, and failed when we tried to operate it to change frequencies.
For a few minutes we did some reception tests and noticed a lot of noise in the receiver. There were noises similar to the effect of the arrival of rain and electrical discharges, which soon led us to have doubts about the possibility of salinization of the ceramic filters in the circuit.
We started dismantling the top cover of the equipment, and we emphasized the attention needed for this essential screw that joins the 2 blocks of the equipment that will receive maintenance.
Now, with the equipment open as if it were a book, we could see both the side of the general circuit of the transceiver, as well as the P.A board. and the LPF circuit.
the PA board draws attention to its 2sc 2879 transistors, very robust and with a great power capacity, but we are aware of keeping the transmitter limited to 120 or 130 watts maximum, respecting the fragility of the other components associated with the equipment
Now we will analyze the equipment in its lower part, and soon we will find the IF-10 board that, through a serial port, will be able to connect it to a computer. We will test the memory battery life as well.
We took the opportunity to install a DB-9 connector on the rear panel of the equipment, without enlarging the existing holes or mischaracterizing its original conditions. We used the optional ACC-3 connector installation point that was already available for this installation. End of Movie 001
TS140-S Chapter 001 Corrective and Preventive Maintenance
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FT1000 D 4 Months after several Bench Total Restoration
This movie was recorded at the final moment of the restoration of this FT1000D. Even before placing the covers and closing it completely, I had the need to explain a problem that I had detected for 29 years, but only now after the restoration did I succeed in solving this native problem in the audio line during the mix between the receiver #1 and receiver #2. There are 12 films on my channel youtube.com/ that show moments about this whole endeavor in my study and development workbench (I don't serve customers to carry out maintenance, I just love electronics and radiofrequency). This work consumed 158 days of my time during the Covid Pandemic on Planet Earth.On all recordings, my late friend Rod, PY2KC accompanied me, asking pertinent questions, and learning some specifics of classic analogue transceiver circuitry. 73 for All Friends of Radio. Check out my other films, very rudimentary in editing, but with important information to prevent any damage to the equipment during the investigation of defects, malfunctions and the real sensitivity of the parts of this equipment that we want to dismantle and correct.