Assembled it back and voila! Dc power back on at CP102 and my radio cassette player power on and i am enjoying the good old day radio now.
Many thanks to all the forum members who had been helping. Another old school item saved from the dump.
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mikey5791
Badcaps Veteran
Last Activity: 05-14-2026, 02:45 AM
Joined: 12-19-2014
Location: Sabah
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Yesterday i resoldered the switch connector as described by R_J, then taking it apart and sand paper off those oxidised contacts. (As picture attached)
Assembled it back and voila! Dc power back on at CP102 and my radio cassette player power on and i am enjoying the good old day radio now.
Many thanks to all the forum members who had been helping. Another old school item saved from the dump....
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Appreciate all the above replies.
Referring to dankva, on the two test points i detected dc 14v. But still no voltage on CP102.
Fyi, the black thing between the ac socket and transformer is an ac voltage setting switch.
I don't see any transistor on board and attaching two more pictures of the board....Leave a comment:
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Thank you for your reply.
Fyi, i plugged a standard 2 pin (only has live and neutral) type connector into the wall ac 220v outlet on my power testing this board.
Are you suggesting to solder the wires to the ac connector so i can get dc 9v on CP102? Kindly correct me if i misunderstood your meaning....Leave a comment:
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Generic psu for National radio RX-CT800
Hi to all forum members,
Recently i am reviving a very old model of radio cassette player but the power board has no dc 9V power output on CP102.(As per the white plastic connector shown on power board RUP2540XAC)
The transistor seem to be working as i can detect dc 9v from the electrolytic cap on C357. Is it safe if i just solder two separate wires from C357 to CP102 to get the dc power i needed to run the radio board (not in picture here).
Kindly advice and comment. Thank you.... -
mon2,
Thank you for the good tip on making an audio probe.Leave a comment:
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If looking at front side of output transistor, is the base the left side pin, middle pin is collector, the right side pin is emitter?
How do i check what drives the base? By tracing the solder point continuity from base and trace backward...?
Kindly advise....Leave a comment:
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Help on car amplifier only one channel works
Hi all forum members,
Fyi, i have been working on this old model PCT-4082 (4 channel car amplifier). The owner said only one channel is working.
My initial finding is this amp originally use Toshiba 2SA1943 and 2SC5200 transistor for its output but after opening the top casing i found it used Toshiba A1941 (pnp)and C5198(npn). I desoldered all the 4 pairs transistors and found 1 piece A1941 open(tested "OL" on all legs) and replaced the 1st pair with 2SA1943 and 2SC5200, thats why you can see in the picture it is the bigger size transistor. The other A1941 and C5198 all... -
Hi to all forum members,
Yesterday i received the new relay from our local online store and installed on the fridge pcb at RY2.
The fridge has been working normal again since last night. The freezer compartment has ice cube solid frozen this morning and the fruit compartment is cooling too.
Hope this fridge will work for many years to come.
Cheers to everyone who had contributed their kind assistance and patience to help me revive this old fridge to working condition.
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Hi lotas,
Thank you for your kind assistance and guidance. I will order the needed relay. Fyi, i did installed a jumper for testing and the compressor starts and running. Running it for an hour, the half glass water become semi solid ice. After that i shut it off.
Will update this forum soon after installing the new relay.
Once again, thank you to those forum members who had contributed with helpful comments....Leave a comment:
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I applied dc12v(300ma),negative to terminal with diode image and positive to terminal near D5 marking. Immediately i can hear the relay one click sound.
But you mentioned about checking the continuity of the closing contacts, is it the opposite two separate terminals(near RY2 marking)? I didn't get any continuity from the two contacts as per your picture....Leave a comment:
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The starting capacitor is 4uF 400vac, it is reading about 3.79uF from a capacitor meter.
Sorry i do not know how to check whether the contacts on the compressor relay close when 12v is supplied to the relay. Is it possible to test it using external 12vdc? Kindly guide on how to check.Leave a comment:
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Help repair Panasonic fridge not cooling
Hi all forum members,
Few days ago, i might have forgotten to close my home fridge freezer door completely. The next day, the ice cubes and frozen meat almost melted halfway and the freezer doesn't feel cool. I shut it off, wipe dry and let it air dry for one whole day. The next day i switched on the fridge, the compressor run for a second and it shuts off(no vibration and no sound at all) only the internal freezer compartment fan is running but is not cooling even i switched on a full day.
After shut off, i dismantle the rear water pan holder and reached to the compressor wiring.... -
Hi momaka,
As per your comment on post #16,
"To do that, remove the dummy load resistors and test each rail's resistance to ground as well as to each other... and make sure to leave your meter connected for a few second so that the readings stabilise - that should make it clearer to see what is going on.)"
Fyi, i removed all the 3 dummy load resistors 15ohm, 51 ohm and 270 ohm for all the 3 rails. The resistance test on 2k scale are as follows:
3.3v to ground="1"(this means infinite on my dmm)
5v to ground="1"
12v to ground=1.932k...Leave a comment:
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Sorry for late reply. Got some matters to attend lately.
Yes, my previous readings are in kilo ohm range.
Fyi, i did the voltage injection where i injected all 3.3v, 5v, and 12v simultaneously from a good psu.
The bad psu shows purple line standby votage of 4.54v and grey PG line of 5.26v. Then i removed the orange 3.3v line, the bad psu grey PG line goes up to 5.53v.
Next i removed the red 5v line, the bad psu grey PG line drops to 0.26v. May i know what all these tests are for? Is it saying there is still an issue at 5v line ? Kindly advice and guide if i need...Leave a comment:
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Btw, am i doing the voltage injection test correctly as per my post no.14? Or i need to inject all the three rails namely 3.3v, 5v, and 12v simultaneously...Leave a comment:
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As per your recommendation, i replaced R6 with a 2.2k ohm resistor. Those diodes 1n4148 connected to base of 13007bjt are tested good with one leg desoldered off board . Also both the 1 ohm resistors are good within spec as well.
In addition , the TO-92 transistor near the middle transformer are the c945 type. Off board, they tested good.
Upon power on ac with series light bulb still connected in place of the fuse. The light bulb lights a second then off, but there is still no dc voltage output on any rail. I wonder what other component could be the cause of no power, with 5v standby...Leave a comment:
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Fyi, i did checking for short circuit between the various rails by setting my dmm to 2k resistance mode. Here are the results:
3.3V to 5V is 0.039 ohm
3.3V to 12V is 0.163 ohm
3.3V to -12V is 0.508 ohm
5V to 12V is 0.186 ohm
5V to -12V is 0.531 ohm
12V to -12V is 0.655 ohm
(For info, this psu does not have -5V rail)
In addition, i tried the voltage injection method as suggested. I connect Ground wire of a good psu to ground of the bad psu. My red dmm(on 10A socket) to 3.3v rail of good psu while my black dmm to 3.3v rail of the bad psu, while...Last edited by mikey5791; 02-26-2025, 04:09 AM.Leave a comment:
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Fyi, i attached two old ide hard drives as load for testing but the psu fan remains still and there is no dc output ....Leave a comment:
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On secondary side, the dummy resistor at 5v rail is green,brown,black,gold(51 ohm) while at 12v rail is red,violet,brown,gold(270 ohm) and at 3.3v rail is brown,green,black,gold(15 ohm).
Did resistance test to ground, at red wire 5v rail resistance is 48 ohm while at yellow wire 12v rail resistance is 157 ohm and at orange wire 3.3v rail resistance is 10 ohm.Leave a comment:
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Before power on ac, i connect the psu power cable to a series bulb limiter and the bulb lights a second then complete lights off.
Is this confirming there is no shorts inside the psu or do i need further test to confirm the output diodes for shorts? Kindly advise. Thanks for the tip.Leave a comment:
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