Re: Plastic welding machine repair and hints
marking code is the same. original ones are from ON semiconductors. I found it to buy too. i wish to understand first if sonotrode is absorming too much current (more than 30A (from specs of transistor)
conan981
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Last Activity: 01-14-2022, 04:20 AM
Joined: 08-19-2011
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Re: Plastic welding machine repair and hints
hi, please explain more.. output from MJ802 should be nearly 100v on the COLLECTOR, right? i did some other photos on the main transformer and his plug (10 pin)
on main capacitors, i have 81V DC. (when machine is ON in standby) so i suppose mj802 are inactive
Also this machine have not an heater element but a vibrating element called sonotrode
from wikipedia :
A sonotrode usually consists of a stack of piezoelectric transducers attached to a tapering metal rod. The end of the rod is applied to the...Last edited by conan981; 06-28-2019, 12:28 PM.Leave a comment:
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Re: Plastic welding machine repair and hints
thanks to all for the hints. about heating, that machine have a fan even if i dind't made a photo to it. and last time was working 1 hour BUT not correctly. i checked quite all the passive elements except the inductances that i cannot verify and seems all to be ok. only two big capacitors i found that are 800uF /900uF and have MANY hours of work, but i don't think they are the culprits for this defect
6v and 12v are perfect and stable, what should be 55v really is 61v but is stable too.
how can i check if elements connected...Leave a comment:
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Plastic welding machine repair and hints
hi, i have a welding machine with ultrasonics. it's REALLY old
btw since now i could use it without any trouble. now i have the HIGH POWER NPN TRANSISTORS MJ802 that keep shorting after 1-2 hours of using.
this board is powered with a transformer that from 220V give 55v, 6v, 12v
MY question is : why these transistors burn?
i wish someone expert can give me some hints and what to check on the board.
There are few components luckily. i am uploading photos of the board so you can have an idea. if something else is needed i can do measurements or else...Last edited by conan981; 06-26-2019, 07:57 AM. -
Re: help indentifying component please
mosfet does not switch on when 3v are applied to gate. so i have no ground to my motor.
btw thanks to all for the answers.
i wonder how you could identify this component, since i tried on smd lookup marking codes table and found nothing.
thanks again
sometimes our english is not the best i know, (i am not english native too..
) but i hope we can understand each other
Last edited by conan981; 03-15-2019, 03:05 AM.Leave a comment:
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Re: help indentifying component please
hi, thanks for your answer
YES 1,2,5,6 are connected together on the pcb.
YES i read 4T6V but coulnd'nt find nothing with this code.
NO, i can't see any dash above the V.. but on the side there is what seems "1B"...Leave a comment:
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help indentifying component please
hi to all
i hope someone can help me with this component found on my mouth hydrocleaner. it's china style gadget and coulnd't find what this IC is..
Device is working with a lithium battery 3.7v and can be charged with usb 5v.
any hint is really appreciated..... -
Acbel pca023 power supply repair help
hi, i have this power supply from a dell computer that does not work at all.
i found that there is a problem with primary part (220v) .
220v Fuse is ok, i found at first sight a 10 ohm resistor (in the photo) that is interrupted.
Replaced it and resistor burn again..
then i checked all the resistors in the primary, and found 4 resistors shorted at all..(0 ohm)
and main capacitor interrupted.
So i have:
MAIN CAPACITOR 180uF 420v => interrupted
R31 that should be 10 ohm => 0 ohm
R34 that should be 10.8 ohm => 0 ohm... -
Re: smd transistors recognizing problem
[edit] I just found that these trasistors are quit difficult to find.. there is any way to find a compatible one?
many many thanks againLeave a comment:
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Re: smd transistors recognizing problem
great i don't know how did you find it but many thanks
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smd transistors recognizing problem
hi, i hope someone can help me to recognize these transistors, that i found burnt on my wife's toyota yaris dash.
transistors are marked MK. photo is taken from internet just because it's of better quality than mine
thanks in advance...
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SONY KDL-40bx400 ONLY GREEN LED
hi, i hope someone can help me to repair this old one.
I have black screen, no response at all, when i plug the power cord the standby led stay GREEN (not red as should be) but tv is dead.
I found service manual for what seems to be my board, but i need help to go ahead.
On the power supply board the AC part is working ok, and i have 3,3v on CN6401
pin 1 and 2. nothing else..
in attachments some photos and link to service manual
[url]https://mega.nz/#!ZdUwxLzI!v55n2OVaUpIXQzOGzP3L9ors_6fgCHCXyQASXbC_5U0[/url] [url]https://mega.nz/#!YV8VgYhS!uZ7DOwMVXGZQSfgkuyBg_ykqT5ZPB2cCg5qyGqWNkkc[/url]... -
Re: component identification help
thanks mate
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component identification help
hi, can someone help me to find what this component is?
it is marked on the board RD1 and it's glass. here is a photo
thanks in advance... -
Re: Component detection help
an image from another perspective. red disc legs are connected to diode
Also i resoldered the joints that seems dry..
thanks...
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Re: Component detection help
G1 is in first photo post #1 component 07d151k.
@stj
yes, it's a TIG welder.
Capacitor is ok.. tested with capacimeter its just darker since was near to broken component and i didn t clear it . Also all the two pin are connected with the diode. I ll clear board and will do some other photosLast edited by conan981; 10-17-2017, 07:10 AM.Leave a comment:
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Re: Component detection help
Thanks to all
Here are photos of front and bottom of pcb. if some other detail is needed let me know....Last edited by conan981; 10-17-2017, 02:41 AM.Leave a comment:
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Re: Component detection help
So do you think it is not a varistor?Leave a comment:
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Re: Component detection help
Great
Thanks mate, i'm going to try
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Re: Component detection help
diameter is 7mm
i read 180Z
on second line 3811 (third char is 1 for sure)Leave a comment:
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