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  1. HellasTechn

    Who needs SolderMask !

    Ok so this is a PCB that i made without solder mask just for fun. This PCB is a little larger than a US 25 Cents coin. It is a TDA2005 10W+10W power amplifier. Beleave it or not it works perfect! Not a single short circuit ! Besides conformal coating will protect copper just fine.
  2. HellasTechn

    HOME CINEMA HITACHI HTD-K150

    Hello friends ! I have a weird problem with this Hitachi htd-k150 home cinema system. It works all right but some times when i power it on i get noise from the speakers and then i can no longer control volume. It either play sound at steady low volume or not at all. when i press the volume +...
  3. HellasTechn

    Testing Transistors With Digital and Analogue Multimeters.

    Hello ! I have a silly question of which the answer i am sure is simple. Why when testing transistors with DMM we put positive probe to P side and negative to N side while with AMM we go reverse (negative to P side and positive to N side) ? Thank you !
  4. HellasTechn

    GPS NMEA, Failover Circuit upgrade attempt.

    Dear friends, About 3 years ago i came up with the idea of creating a circuit that would be used as a safety feature in a computer that requires GPS at all times (the reason for that is not important now). At that time Chris provided me with a very simple but yet very reliable LM555 circuit...
  5. HellasTechn

    Replacing a faulty SMPS

    Dear friends, I have in my hands a Whirlpool L1373 (invensys 475560 board from a washing machine. The PSU on the board is damaged, blown capacitors, LNK304PN switch chip, and a broken (broken leads) smps transformer marked 13ES-X33. My problem is that it is impossible to find a replacement...
  6. HellasTechn

    ZD 985 Desoldering station

    Good day to all ! Has anyone ever used the station on the below link ? http://www.ebay.com/itm/261894908005?euid=1f704b119010450ab81a68023a20da6e&cp=1 Where do we get spare parts for this like filters ?
  7. HellasTechn

    Voltage rating of Capacitors.

    Good day to all ! Like most of us, i have come across various types of capacitors with many different voltage ratings. strange thing is that on computer motherboards most capacitors are rated 6.3 Volts and that value i have only seen on computer motherboards. Isn't that strange ? anyone knows...
  8. HellasTechn

    Bench PSU

    Hello every one and Happy New Year ! I have in my hands a big transformer ripped from an old HiFi system (SONY STR-W550). I am thinkin to use this to make a bench power supply. What circuit would you Recommend that i use ? I have searched the net for info about this transformer and the only...
  9. HellasTechn

    Better understanding of Electricity.

    I accidently came across this video and after watching it i think that what says is correcrt. What do you think ?
  10. HellasTechn

    PSU board problem (LCP106830-0001)

    Hello ! Today i got my hands on a Philips HST335W/12 home cinema unit. The problem is that no sound comes out from the wired speakers. there is a supply line running from the PSU to the speaker board that is marked as 39VDC while the voltometer only reads 3.something VDC. I have...
  11. HellasTechn

    Samsung TV wrong settings in service manu

    Good day dear friends. A colleague of mine brought to me a Samsung TV model: LE40A536T1FXXH (from now on called "my tv") this tv when turned on would display weird colours for example black background was displayed purple. At first and after reading posts on the internet i thought that it would...
  12. HellasTechn

    Through-hole & SMD components.

    Dear friends. For some time now i have been using SMD components on my PCB's. The only thing i find hard to do is to find equivalent SMD to through-hole components. Isnt there a database or something telling us the code of the SMD's ? For example i want to use a BD679 transistor on a PCB that...
  13. HellasTechn

    question about ALPS potentiometer.

    Hello everybody. I have an old audio amplifier what has a bad volume control potentiometer. Bad thing is that it is an old ALPS potentiometer 4 pin (3+ center tap for loudness control). It is impossible to find a replacement. If i use normal 3 pin potentiometers i can not use the loudless...
  14. HellasTechn

    PC question (VCORE voltage)

    Good day friends, Today my question is not of traditional electronics nature. I have a pc with an ASUS P5KPL-VM motherboard with amibios version 1003 and a Q6600 cpu. The cpu is running hot (about 55-60) deg idle with 30 deg ambient temprature. I tried a couple of heatsinks and compounds but...
  15. HellasTechn

    Weird problem.

    Hello friends. A couple of weeks ago a friend brought me an opel car key to change its buttons. the buttons where shorted and the remote operation was not working. After replacing the buttons and attached battery it was dead. When i looked closer i noticed that the transmitter led lits...
  16. HellasTechn

    Wanted: D-SUB 90 Degree Backshell

    Deos any one know where i can order online this backshell from ? E-bay doesnt have it. http://www.made-in-china.com/showroom/xieqing1314/product-detailQKunyZgPJtkf/China-D-SUB-90-Degree-Hood-9pin-D-SUB-Connector-Hood.html Thank you.
  17. HellasTechn

    Yamaha RX-V496RDS problem

    Good day, Theese days i am working on a Yamaha RX-V496RDS. Here is a description of the problem. The device blew a fuse (2.5A) on the PSU board. I replaced it and it blew again. When i pushed the power button i could hear the standby relay click on and on second power button press click off...
  18. HellasTechn

    PCB building

    Dear friends, From now on i would like to dedicate this topic to demonstrate The PCB's i have made. Enjoy !
  19. HellasTechn

    Add current limiter on Bench PSU

    Dear friends. I have a 2-30 Volts DC 10A bench power supply that has no current limiting capability. I would like to add that feature. What i have in mind is by use of a potentiometer to set the maximum current that a circuit can draw (not to kill current when limit is reached) A circuit for...
  20. HellasTechn

    Help with potentiometer.

    Dear friends. I need to replace the volume potentiometer on a DENON PMA-280 audio amplifier. The old one is an ALPS 4 pin 30kbx2. I cant find the same one. Any ideas ? Could i use a normal 30k double potentiometer ? but then again what is pin 4 used for ? Here is how it looks like from...
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