Recent content by jpaudio

Hello again. Caps replaced, oscillator gone away! I replaced them with 56 pf. Original were 18 pf. I want o thank ecluser for valuable help. Regards, John

Correct! I will try to replace suggested caps today and see. Thanks a lot for your attention and help.

I meant tone control IC. It is not a driver obviously, sorry for my mistake...

Where? You mean if I replace it mysel? Yes, I did it. Also I checked all other components around. I replaced electrolytic capacitors connected to STK too. I didn't check if the self oscillation were there before I replace the STK. I assumed faulty STK was the only fault... John

Hi to all fellow members. Recently came to my hands a Technics SU-V4A amplifier with one of its power module dead. It is a STK8050. I replaced it with a new, knowing that is not original but I could do anything else. Now the amplifier is running but driving transistors are very hot and the front...

Hi. I am a little lucky since I have them as spares from a closed Electronics store back in 2010. But you can find substitutes easily. Look at yellow "owl" books and take care of pins identification. Regards, John

Long time since last reply. Better late than ever...Finally, I managed to repair my unit. It had the same behavior like initial post described, stand-by led on but no startup. Since I didn't find schematics, I measured around with DMM and Oscilloscope and I found out that initial Reset signal to...

Drilling is not a problem...The only thing that maybe bothers is that both channels will have different shape transistors, in case someone opens and see... About idle current trim, no, I didn't replace it but I will certainly do.

Hi. Thanks for reply. Transistors you proposed have different case. I assume I can use MJL-xxxx as they are plastic and can be installed easily. I do have a variac and in combination with Dim Bulb Tester will help a lot. Thanks again!

It happened at the same channel. Yes, the whole output stage shorted. No, I didn't replace kC10-11. Anyway, I will try once more looking carefully the whole circuit. I will try to use reliable substitutes now. Maybe new, modern types from Toshiba or ISCsemi.

Yes. About pin outs or PNP/NPN swap, no mistakes. Power transistors bought as original, SANKEN but not verified. I think is better to use same type but from a generic manufacturer (i.e. ISC semi) No, I have no bulb tester (I must build one urgently, are there instructions-schematic for this?)

Hi. Thanks for reply. I replaced all components with same type ones. Also power transistors but I don't know if they are genuine... The resistors which burnt are the R14, R15 (150 Ohm) that connect power transistors bases together. Initially, I found some other resistors open but with no burn...

Nobody has a clue about this amp and its problems? Are these failures common or happened to me only? I think it constructed too congested and pushed to its limits in order to produce such a power, without safe design and protection. Regards, John

Hello to all fellow members and friends. This amp came to my hands from my cousin with one channel blown. I thought it was simple to replace burnt components but it was not so easy... I replaced all burnt ones, output transistors too, the amp started OK with idle current at recommended levels...

Hello dear friends, I am looking for Teac CR-H500NT (or simple unit without Network player) schematics. Unit has burnt audio amp power transistors and two small resistors, R522, R545 that their values cannot be read. I would appreciate if someone can help, at least, with resistors values...