Fault Finding Noisy Intermittent Transistors in Amplifier & Receiver. Popping noise, crackle sound

Просмотров 3,9 тыс.

% 76

UPDATE VIDEO HERE, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-r4D9XPOsuEI.html
In this video I look at replacing a faulty noisy transistor in a vintage old HiFi Cassette Deck, though these noisy transistors could be in an Amplifier or Receiver.
The transistor was noisy when recoding to tape so was transferring the noise onto any cassette that I recorded.
This 2sc458 has been replaced with a 2sc2240 transistor

Опубликовано:

5 июн 2022

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 34

@hoobsgroove 2 года назад

I check the data sheet on both of them and they're not the same match, transition frequency is a lot low on the replacement 50MHz not 115MHz and capacitance is lower at 3pf. and doesn't show the new one as an equivalent replacement, the is about 10 you could used but not that one mentioned, where did you get the information to use that transistor?

@MichaelYates 2 года назад

Hi,, Thanks for the comment. I looked at a few forums audiokarma.org/ being one and there was 3 or 4 other transistors that were recommended as well as the 2sc2240 as a replacement for the 2sc458. Going by the reactions of people that used the 2240 as the replacement I chose that one, I did not look up the data chart on either TBH . But for this unit the 2240 seems to be working fine as far as I can tell. Though I would have gladly try any of the other substitutes on the unit as well

@hoobsgroove 2 года назад

@@MichaelYates can't put any indication of address blocked my comments.... right what does it sound like with a recording on playback? better or just as good as the other channel? I just look on (transistor.. c,o,m), and it gives you the alternative, I did notice somebody did change the capacitor on there as well I'm not sure if they're bipolar the orange once usually they are plastic coated on the bottom not rubber bipolar but say in the schematics. worth changing them out for polystyrene or film capacitors if low value, in the record and playback section, always use high voltage 100v+ if possible. And the silver adjustment pots need cleaning they can cause noise turn into a diode, clean the whole connective surface with acetone on a Q-Tip with the paper straw not plastic.

@MichaelYates 2 года назад

@@hoobsgroove Hi, well did quite a bit of listening today with the 2SC2240 and was pleased with how the unit sounded, seemed both channels compared well against each other. But then I had my amp at full volume with the record and pause in place as shown in this video and thought I could detect a very faint clicking noise coming from the right channel the one with the 2sc2240, even though this was with the amp on full volume, the left just had a faint hiss. So I used my Tascam recorder set the input sound level to full and recorded the sound coming out and the clicking or oscillating noise was a little more apparent. I will do an update video on this.. Also today the 2sc2sc1815 transistors turned up, I ordered these at the same time as the 2sc2240 as the 2sc1815 was also being used as a sub for the 2sc248 by some members on Audiokarma with good results. So I swapped the 2sc2240 for a 2sc1815 and the result was the oscillating had gone and both channels were identical. Thanks again for pointing out the 2sc2240 was not a good replacement.

@raceingdemon6464 2 года назад

When I Fixed My Dear Old Sansui AU101 Amplifer Faulty (Output Stage) Recapped it With Good Quality Caps And Set The Bias Much To My Surprise The Phono Pre Amp On The Tone Board One Channel Had Become Very Noisy So I Replaced The Two 2SC871R Transistors With 2SC1815 in The Phono Pre Amp This Cleared Up The Noisy Channel And Now The Amp Sounds As Sweet As a Nut Thanks For Uploading Michael Great Stuff Regards mike.

@MichaelYates 2 года назад

Thanks Mike, funny you should mention the 2SC1815 as I have just tried one in place of the 2SC2240 in this and seems to work better as an update video will explain. Nice you can do the work yourself as not easy finding a repair man these days, bit of a dying trade.

@messageobliquespe100 Год назад

Ta 4 doing the vid. Just going around various RU-vid’s picking up info for noise / transistors etc as I’m looking to improve a design done years ago in a receiver unit & want to improve noise figures. One thing I’ve re picked up along the way - whether it makes much of a difference in what you have - is those variable pots to set levels of left n right channel. Ok - they’re great if you want / require them - but if they weren’t in line - are the meter levels the same? Does the signal enter the main chain for signal into the amplifier circuit? I’d prob look at bypassing them - but might need a fixed resistor - low noise one - might require fixed wire soldered on board between too - as long as they don’t perform other functions in the circuit. Less component on the line in - the less noise. Any noise generated from those pots will enter the first transistor (you’ve changed) which will probably have the highest gain / lower noise figure than the others in the circuit. What I also learned t is the first transistor in the chain is generally the ‘better’ transistor for gain / low noise figures - the remaining transistors in the circuit are generally lower spec as circuit designers determine the cost not so important. Thanks again. Where did you get the standard chopsticks from 🤔😂👍 Obvious tip for the signal tone generator - dependent on whether your phone has a headphone Jack - just plug in suitable lead with Jack plug & RCA leads out (which you’re using already) & search the internet for site which can generate the signal tones out. No need for the portable CD player!

@MichaelYates Год назад

Thanks for the comment, the variable resistors at the input would be required as one channel would more than likely have a liitle more gain than the other. But as you said you could adjust both to required level and then measure resistance and replace with a fix resistor. Also yes the less switches and variable resistors the better, again all switches could be shorted out ( speaker select switch as well ) and variables replaced with fix resistors. This would leave the amp/receiver set to your desired input, output and tone with just the volume still operating. Surprising how many switches and pots the signal goes through, even the tape monitor switch plays apart even when not engaged the signal still passes through the contacts. Phone signal generator is a good idea, thanks. Bad news the copsticks have all sold out since the video lol

@messageobliquespe100 Год назад

@@MichaelYates ta 4 reply - & ok the signal paths too - I’m modding something - it might well end up worse but nothing to lose! But learnt a few things along the way with the RU-vid’s out there - so it was good to see yours - a practical demonstration & using one’s ears to pick up noise as opposed to oscilloscopes / analysers etc. It’s a can of worms using em but they’re pretty cheap nowadays & a few basics unearths a whole world of electronics - as the comment you got regarding the gains on the transistors. Ones never too old to pick up these things! Ok no chopsticks! 😂

@-______-______- 9 месяцев назад

Thanks for the video, it's useful. Can you recommend an equivalent for a 2SC1740LN(S) transistor? I got some 2N2222A, but I stupidly overlooked that the pinout is different. This is for a marantz 5030 cassette deck. I swapped them out and then got no sound. I thought I'd well and truly buggered it up, but I'm pretty confident in my soldering! Now I have a bit of hope, after realising it's the pinout. I have just recapped all the electrolytics on the machine, too. Cheers.

@MichaelYates 9 месяцев назад

Trouble with a lot of replacements is the pinouts are different. Also one site may have the pinouts one way and other another way, so many mistakes about, thats when a transistor tester comes in handy to get the correct pinouts. Looking around it seems the 2CS1852 will be ok as well as a BC337 but the pinouts are different, so you will have to swap the legs around on the replacements thats pretty straight forward, I have not tried any of these myself so cannot vouch for any of them Here is a link to a datasheet and subs recommended www.npntransistors.com/2sc1740-transistor-pinout-specification-equivalent-datasheet/

@-______-______- 9 месяцев назад

@@MichaelYates Thanks mate

@voxpathfinder15r 9 месяцев назад

I am in the middle of trying to find a noisy transistor. But I don’t have a schematic. Just a heat laser infrared gun and cold spray. I found a bunch of transistors getting hot along with a bunch of capacitors in this guitar amplifier. I found the hottest transistor and three times - I hit it with cold spray and all the other components that we’re running hot are now running cool until that transistor heats up again. I won’t have the replacement transistor for a week. But I hope my technique works, what do you think? Can cold spray isolate a faulty transistor?

@MichaelYates 9 месяцев назад

Yes freeze spray can find a faulty transistor, not always but a good deal of the time. Sometimes the popping or static noise will almost disapear, then other times it may just be very suttle but still indicate a noisy transistor

@The411 2 года назад

How did you know your VU meters we balanced and showing the same reading for the same input?

@MichaelYates 2 года назад

As the left channel was working correctly, I just adjusted the right channel to be the same as the left channel. Using a test tone cd on a cd player plugged in to the input of the cassette deck, played the cd, pressed play and record and adjusted the front input levels to the same number ie number 5 on both and then just adjusted the varible resistor on the circuit board for the right channel to match the left. as 11.45 of video

@The411 2 года назад

@@MichaelYates Thanks. I was asking as I have some older equipment with VU meters that do not deflect the same with the same signal. One meter is "lazy" by a few dB so I cannot use the VU meter method to match the channels. Cheers.

@douglas2lee929 10 месяцев назад

The old cliche' ---Two countries separated by a common language.....

@ludovicferrando8394 2 года назад

For my part I'm trying to change the transistors C458 for some BC549 and don't know the pinout. I keep looking at some datasheets but sometimes they are different in terms of pinout so confusing. Logically the C458 and VC549 do not have the same pinout ? right Thank

@MichaelYates 2 года назад

I have some BC548 's and laying it flat side down and reading for left to right the pins are EBC, the 549's are just the same ( low noise version )

@ludovicferrando8394 2 года назад

@@MichaelYates OK thank you so the original are 2sc458 are read 321 flat down so the opposite. It means I need to switch the side I'm gonna put it in ? Thank you thank you

@MichaelYates 2 года назад

@@ludovicferrando8394 Th 2sc458 laying flat side down and reading left to right the pins are BCE so you will need to move the pins around a little, the 2sc1815 replacement would be much simple way of doing it as the pinouts are the same as the 2sc458. But still possible with the BC549 just a little of swapping around as the base is not in the middle

@ludovicferrando8394 2 года назад

@@MichaelYates oh I got, well I've just ordered some 2sc1815, so I won't have to worried anymore about the pinout and putting it the same way as the original thank. By the way I can use it to replace all of the transistors? C1312? Thank again for your help really

@MichaelYates 2 года назад

@@ludovicferrando8394 yes the 2sc1815 should be fine for the 2sc1312 as well looking at the subs for that transistor , please let me know how you go

@treadmillrepair754 Год назад

Today I fix an amplifier with cracking noise, after change many transistors I found a bad 22pf capacitor.

@MichaelYates Год назад

That can be a bit anoying, but narrowing it down to a small 22pf cap was a good job done well as these faults are not easy to find.

@treadmillrepair754 Год назад

@@MichaelYates That's right, the noise sound equal to a bad semiconductor. It was driving me crazy. The amplifier is an Audiosource AMP-101. Best Regards.