Author Topic: Aron BS-601 Oscilloscope vertical amp issue (FIXED)  (Read 2281 times)

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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #25 on: January 28, 2019, 06:07:47 am »
Yes, I assume you probe is at Divide by 10;

Those are under low voltage 5 or 12 V supply, don't expect 120V reading.   ;D
 

Offline ZayneTech

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #26 on: January 28, 2019, 06:32:04 am »
How did this happen in the first place?
If it ain't broke, don't fix it.
 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #27 on: January 28, 2019, 06:33:18 am »
Let's persist on until we conclude to the deflection plates;

Volt meter measure all the Base Collector Emitter Voltages of the followings Transistors with respect to GND;

Q15 Base =     V
       Collector =    V
       Emiter =       V

Until Transistor Q24.

Wow,  well all right then, just to clarify these are off a standard multimeter ...(The Dave multimeter  no less ) This is part 1, Q19 and Q20 seem odd...... Also ive just noticed thAt most of these transistors have either been replaced or reflowed, so im guessi g he last person couldnt fix it either.

q15
B= 11.62V
C= 11.7V
E= 12.2V

Q16
B= 11.62V
C= 11.7V
E= 12.2V

Q17
B= 11.67V
C= 11.62V
E= 11.96V

Q18
B= 11.7V
C= 11.62V
E= 11.93V

Q19
B= 116.8V
C= 117.1V
E= 11.97V

Q20
B= 116.7V
C= 117.1V
E= 11.93V


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Online tautech

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #28 on: January 28, 2019, 06:38:45 am »
...... Also ive just noticed that most of these transistors have either been replaced or reflowed, so im guessing he last person couldnt fix it either.
Warning, engage full detective mode !

Consider anything and everything could be in error.
Take nothing for granted and check every part/area previously worked on could be hiding some poor workmanship and/or use of incorrect parts.

Keep eyes wide open for errors.
Avid Rabid Hobbyist
 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #29 on: January 28, 2019, 06:43:16 am »
Ok and part 2

Q21
B= 11.44V
C= 5.9V
E= 12.15V

Q22
B= 11.29V
C= 6.0V
E= 12.02V

Q23
B= 116.5V
C= 120.3V
E= 116.3V

Q24
B= 116.5V
C= 120.3V
E= 116.3V

*Takes a small drink*



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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #30 on: January 28, 2019, 06:43:26 am »
Yep, because the downstream measured correctly, I assume he probe wrong point, so I ignore it for the moment.

@Todd; still missing some Transistors not measured. I can see at VR6 the 120V disappeared....but until you finished measurement then we conclude.
 

Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #31 on: January 28, 2019, 06:45:14 am »
Check VR6 voltages;
 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #32 on: January 28, 2019, 06:48:21 am »
How did this happen in the first place?

Because university.

I actually got a few of these all simular problems, these were used at the university, some idiot probably tried connecting it to 240v or somthing, somone else tried to fix it and ecetually got throen out. its not even about havinf a fixed product in the end (although it is nice as i hate waste)  but about fixing the issue and learning how.

some people like tradional 1000 pieces puzzles, I like my puzzles 240V ;)


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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #33 on: January 28, 2019, 06:51:15 am »
Check this 3 components;

Also check VR6

 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #34 on: January 28, 2019, 06:51:34 am »
...... Also ive just noticed that most of these transistors have either been replaced or reflowed, so im guessing he last person couldnt fix it either.
Warning, engage full detective mode !

Consider anything and everything could be in error.
Take nothing for granted and check every part/area previously worked on could be hiding some poor workmanship and/or use of incorrect parts.

Keep eyes wide open for errors.

Oh yes I went full picachu on this, testing every knob and switch, resolder any dry joints, push and pull Dave style random partsof the PCB looking for any change. and visual clues where little plebs have tried to fix things before,  but no, thisis a hunt the faulty componet game.


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Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #35 on: January 28, 2019, 07:08:17 am »
Check this 3 components;

Also check VR6

Yes i thought this may be the issue, i thought the diode was pullj g down the voltage..... But here is the details

the voltage in the centerpoint is 11.56v
voltage other side of d10 12.23v
Voltage other side of r80 116.8v (yes thats corect)

Diode reading of D10 in circuit
0.672  and reversed  2.22

Resistor reading of r80 in circuit (This is interesting)
0L one way and 22M ohms with probes swapped over

Doth we have an open resistor?



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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #36 on: January 28, 2019, 07:10:19 am »
Take those out of circuit and measure;

Remnant current may play wonders with your meter.

Also the capacitor.

 

Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #37 on: January 28, 2019, 07:12:14 am »
Most likely you found the fault;
 

Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #38 on: January 28, 2019, 07:16:01 am »
Don't miss out VR6, just check it for added assurance.
 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #39 on: January 28, 2019, 07:36:34 am »
Take those out of circuit and measure;

Remnant current may play wonders with your meter.

Also the capacitor.

EUREKA!!!! Found the problem!!! R80 was an open line! replaced with 43k and well, now we have full range on vertical, ...however there are no Rising or falling lines, is this a calibration issue or sothing else faulty?




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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #40 on: January 28, 2019, 07:42:04 am »
Turns out, a cheap Resistor... ahahahahaha  :-DD :-+ :-+ :-+ :-+

As I have long suspected, a common bias issue.

Regarding the vertical lines,,,,, assume you have super fast rise and fall time, so fast you cannot see it..... joking...

try adjusting the focus and brightness control.  Cheers!


I suspect one of the common biases is OUT.
 

Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #41 on: January 28, 2019, 07:51:30 am »
Turns out, a cheap Resistor... ahahahahaha  :-DD :-+ :-+ :-+ :-+

As I have long suspected, a common bias issue.

Regarding the vertical lines,,,,, assume you have super fast rise and fall time, so fast you cannot see it..... joking...

try adjusting the focus and brightness control.  Cheers!


I suspect one of the common biases is OUT.

Just went through all the knobs, and both sides same isue. hmmmm so is this a fault, a calibration issue, and if so cabration on witch board, power supply, vertical or time?


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Offline Armadillo

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #42 on: January 28, 2019, 07:54:53 am »
You mean the Rise and Fall vertical lines..... I don't think is a fault... is normal to me... this is not a DSO scope...

You imagine the lines are there....  ;D

Or use a Sine Wave to enjoy.
 
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Offline The_Todd

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Re: Aron BS-601 Oscilloscope vertical amp issue (FIXED)
« Reply #43 on: January 28, 2019, 08:17:30 am »
You mean the Rise and Fall vertical lines..... I don't think is a fault... is normal to me... this is not a DSO scope...

You imagine the lines are there....  ;D

Or use a Sine Wave to enjoy.
oh really?

well then ill just calibrate everthjng else and call it a day, thanks for all your help :)


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