Hi all,
My Yamaha A420 it's dead!!!
Here I think it's my fault, I've connect it on a PC without checking the soundcard volume output, that was at max volume.
I turn on the amp and it came out like a frying sound at low volume slowly disappearing completely, even trying regulating the volume on the Yamaha amplifier. Until no sound came out.
The max volume of the PC has burned something?
Please, what is the first thing that I can check to replace inside the amp?
Bobhoskin
Member
Last Activity: 11-27-2021, 06:35 AM
Joined: 03-25-2012
Location: italo
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Yamaha A-420 amplifier damaged from PC?
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Re: Sansui R-303, Distorted audio......
Like you see on the rear panel there is some oxidation due to water of the previous owner that give it to me.
I hope it's fixable.... -
Re: Sansui R-303, Distorted audio......
Here the photos of the front and rear panel:
[URL="http://i.imgur.com/B05EKer.jpg"]http://i.imgur.com/B05EKer.jpg[/URL]
[URL="http://i.imgur.com/CnoEGb6.jpg"]http://i.imgur.com/CnoEGb6.jpg[/URL]
Precisely the 2 big Caps are 42V 3300uf
If can help, I can make a video and post on youtub, to listen how bad it works.Re: Sansui R-303, Distorted audio......
Here the photos of the front and rear panel:
[URL="http://i.imgur.com/B05EKer.jpg"]http://i.imgur.com/B05EKer.jpg[/URL]Leave a comment:
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Re: Sansui R-303, Distorted audio......
Thank you budm
By now I've tried what you suggested on both pin 9 and 7 gives 33volt each, those match with the two big caps, but the value of the caps its 42 volt.
I have clean all buttons like tape monitor...Leave a comment:
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Re: Sansui R-303, Distorted audio......
Here the photos of the STK Board... on the top view you see the 2 resistors on the left, R8r and R8l, both measure about 10 ohm..... please, give me advise:
Top side:
[URL="http://i.imgur.com/cASXAil.jpg"][URL]http://i.imgur.com/cASXAil.jpg[/URL][/URL]
Bottom side:
[URL="http://i.imgur.com/RdjaatF.jpg"]http://i.imgur.com/RdjaatF.jpg[/URL]
Sansui R-303
[URL="http://i.imgur.com/z2kyQxH.jpg"]http://i.imgur.com/z2kyQxH.jpg[/URL]Re: Sansui R-303, DistortedLeave a comment:
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Re: Sansui R-303, Distorted audio......
Sorry guys for late reply, now I can make tests.
I've tryed moving the STK, and I remade solder on all 16 pins, same problem ....I will try to tap (you mean like give knocks with the screwdriver??)
I've tryed following the 2 resistors that are directly connected to pin 5 and 12, those are named like r8l & r8r, and they measure 10.1 ohm and 10.2 ohm, not really 4.7 ohm (with unit OFF but I didn't disconnect the resistors from the circuit board, bad idea?)....Leave a comment:
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Re: Sansui R-303, Distorted audio......
Help
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Re: Sansui R-303 Stereo Receiver
Hi LCDman, I've the same Sansui R303, with the same bulb problem, do you found a solution?
Other than this, I've a bigger problem, audio it's all distorted and can't regulate Volume.....
here: [URL="https://www.badcaps.net/forum/showthread.php?p=339542#post339542"]https://www.badcaps.net/forum/showthread.php?p=339542#post339542[/URL]Re: Sansui R-303 Stereo Receiver
Hi LCDman, I've the same Sansui R303, with the same bulb problem, do you found a solution?
Other than this, I've a biggerLeave a comment:
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Sansui R-303, Distorted audio......
Hi everyone,
Sansui R-303 with a big problem, the audio output it's distorted and if I turn the Volume knob, I can hear something from 10%, than it's all the same, even at 100%, very low volume.
I've tryed every input, tape, Fm etc.. same problem.
The tranformer seems ok, good voltages.
All Caps seems ok (by eye), I've just tryed change the 4 ones that goes to the "Stereo Amplifier STK 4803", nothing changed.
Can be the STK 4803 with that big designed dissipator?
[URL="http://i.imgur.com/DRcAvop.jpg"]http://i.imgur.com/DRcAvop.jpg[/URL]... -
Re: Yamaha Bass Amplifier
Thank you again Selldoor,
you have good eyes and intuition, I forgot to put the plastic washer,
now it's working all perfect.
Leave a comment:
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Re: Yamaha Bass Amplifier
Ok, I'll just attach picture next.
Dissy, sorry I mean the heatsink. Yes, the TDA2030A is on the end of the extension and it's the new one.
I think you found the possible problem, because I try it mounted on the box without the plastic washer on it.
Tomorrow morning I try and let you know, thank you (you have good eyes
)
Hi Midibob,
If can help, I just test yesterday the transformer unplugged from the board, and gives about 14,5V ~
Tomorrow I'll check the speaker too.
...
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Re: Yamaha Bass Amplifier
Thank you Selldoor,
I confirm:
b) 574 ohm
c) no reading
d) no reading
e) 574 ohm...Leave a comment:
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Re: Yamaha Bass Amplifier
I'm in doubt with the last letter of the TDA2030, because it's in melted condition.... here to pics:
Seems like a "M", if it's an "A" strange it's without the middle - (like a V upside down)
...Last edited by Bobhoskin; 07-28-2012, 10:16 AM.Leave a comment:
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Re: Yamaha Bass Amplifier
Ok, I understand how it works,
out of board, terminals:
2-1, 3-1, 4-1, 4-2, 4-3 reads ok (574ohm) except 4-1 gives about double ohms.
of course 2-2 gets no reading in both direction.
all other directions, no readings.
It's a good bridge rect., right?
What can I try doing now?...Leave a comment:
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Re: Yamaha Bass Amplifier
The rectifier is a D2SBA - 20
I set the multimeter at 2000 ohm, I get readings in all combinations with positive to the right and negative to the left of all terminals (all 574ohm) except the two in the center gives no reading.
Testing in the opposite side, I don't get any reading.... but if I set the Ohms to 20k, I get readings in all directions (about 15.40 kohm) except the first and last terminals gives about 6 kohm. Same the 2 in center gives no reading.
It's better to remove the Bridge rectifier...Leave a comment:
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Yamaha Bass Amplifier
Here I am with a Yamaha F 20B Bass Amplifier
a day I plug it in and found it dead, with smell of burn.
Open up, I found the IC (the one on the dissy) was burn... on it I can read TDA2030 with a final letter that seems an "A".
Then the fuse was dead.
I order the TDA2030A and change it, the fuse too, plug in, button to ON, and after 2 sec. the fuse will blow up.
What can I try to check?
Maybe the TDA2030 final letter is not an "A"? ....and so what are the differences of the final letters?
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Re: HP w2007 PTB-1773 - Where to start?
Thank you,
I can't find the way to modify it, sorry
this case the photos are not to heavy, just around 175kb each....Leave a comment:
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Re: HP w2007 PTB-1773 - Where to start?
Update,
I've changed C826, C829 (1uF) and C807 (82uF to 100uF like an repairer suggest me).... at last I've change every capacitor except the 3 big in the middle (70uF 35v).
No results, dead.
I desolder one leg of every resistence on the board and test them, all have good values, some not really perfect but near.
I will like to test even the Tea1530, if I need an Oscilloscope I'm happy because I have one from long time and never know how to use it (philips pm3234).
I don't understand a thing, I have...Leave a comment:
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Re: HP w2007 PTB-1773 - Where to start?
Hi to all, I'm Cindy from Italy,
I will say sorry for my not perfect english,
time passed for this thread, I will keep it open a while if you can help me .....i've the same identical Powersupply PTB-1773,
Here I post the same photos maverich made... to help remember
Reading all pages of this thread, I report same test made by Maverick530, and same results... then I desolder even a leg of 2 diodes and test (D803, D804), on one side I see a value, the other nothing ....they...Leave a comment:
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