Hallo perl

Ich bin Portugiesisch, ich spreche nur Portugiesisch und Englisch und ein bisschen Spanisch.

Das Oszilloskop HM305 ist eine einzige, keine anderen Zahlen, seinem einen alten Oszilloskop.

Ich weiß, Elektronik, und wie die Komponenten zu überprüfen und können mit SMD arbeiten.

Das Problem ist in beiden Kanälen, und der Unterschied zwischen CH1 und CH2 in minimalen Position ist ca. 3cm.

Ich werde einige Fotos von ihm und mit einem Transformator.


Ich benutze einen Übersetzer so leid für mein schlechtes Deutsch



Si hablas espagnol entao deve sener mas facil hablar contigo en espagnol.
Lo problema esta en los 2 canales, no passa para la parte negativa de lo eixo Y. Yo tiengo lo manual con los esquemas de hameg mas no consigo encontrar lo problema.

gracias

[ Diese Nachricht wurde geändert von: carlos2020 am 23 Aug 2010 20:36 ]

Zitat : carlos2020 hat am 23 Aug 2010 20:35 geschrieben :

Das Oszilloskop HM305 ist eine einzige, keine anderen Zahlen, seinem einen alten Oszilloskop.

Doch,haben ziemlich viele.Ich mußte bei meinem auch erst lange suchen.
Schraub es mal auf,auf der Platine steht meist irgendwo,was das nun genau ist.

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Manche Männer bemühen sich lebenslang, das Wesen einer Frau zu verstehen. Andere befassen sich mit weniger schwierigen Dingen z.B. der Relativitätstheorie.
(Albert Einstein)

You can use English for special technical problems.

Some people here can read texts in technical English.
Many translators produce shit if a technical problem is to be described.

DL2JAS

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mir haben lehrer den unterschied zwischen groß und kleinschreibung und die bedeutung der interpunktion zb punkt und komma beigebracht die das lesen eines textes gerade wenn er komplizierter ist und mehrere verschachtelungen enthält wesentlich erleichtert

Here you can find HAMEG manuals, schematics often included:
http://www.hameg.com/manuals.0.html.....its]=

DL2JAS

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mir haben lehrer den unterschied zwischen groß und kleinschreibung und die bedeutung der interpunktion zb punkt und komma beigebracht die das lesen eines textes gerade wenn er komplizierter ist und mehrere verschachtelungen enthält wesentlich erleichtert

If i can speak in English then is better to me and to descrive exactly the problem.

The model is HM305, nothing more, is not hm305-x..

I have schematics of it, i contact hameg and they provide me them


I could upload it if anyone wants

Hameg technician told me that the problem could be in XY- board in Y-final amplifier, i change all the electrolitic capacitor of xy board and check resistores on board and all them seems to have right values, diodes seems to be all okay and transistors too, i cant find where could be the problem

I turn it on and both channels appear in the upper part of crt, i cant move it less than Y=0 with the calibration pot in the minimum position, this happens in both channels but channel 2 its a bit less than channel1, like Y=-1


Could someone help me with that?

thanks

Zitat :

If i can speak in English then is better to me and to descrive exactly the problem.

Very good. My spanish ist even worse than my english.

Zitat :

Hameg technician told me that the problem could be in XY- board in Y-final amplifier

He presumably is right.
Do you have a Digital Voltmeter to check some voltages?
200V DC range is sufficient.

Be aware not to touch anything at the socket of the CRT or in its vicinity. Chances are, that the high voltage there will damage your instrument and the circuitry in the scope.


Is this http://www.hameg.com/manuals.0.html.....f3810 the correct manual?

As the 305 has a built in component tester we might use this as a test pattern generator.
Please connect a 510 Ohm resistor to the component tester and see if you can get a display like the one shown on p.20 of the manual.
If not then what are the differences?

Yes i have one digital multimeter

I know that there are high voltages on it, i take care

No the manual is not that one, that one only have specification, the one that i have from hameg tecnician is the full schematics manual, with all the circuits and components with values, like transistores references, resistors, capacitors, etc. if you send me your mail i could send it to you and you could check better than me where could be the problem.

I know that it have a buil in component tester, thats why i bought it, mostly because component tester. When i put in component tester mode it shows me one horizontal line but it appears in the top of crt, if i connect one capacitor in component tester it shows me only half of the circle that a good capacitor should give. with resistors the same thing, it shows one line like Y=X (in mathematic) like the picture of hameg manual that you give me

Zitat :

if you send me your mail i could send it to you and

Please logon and you will see my email address.

hi perl

i sent you an email with schematics

Turn the Y-Position knobs to about midscale and apply GND to the inputs of both channels.
Normally this should result in a centered trace but not with the defect scope.
Can you still see the trace, or ist it off screen?

See p.10 "Y-Final-Amplifier" in the Schematic.
Layout and position of those components is on p.29
(page numbers of the pdf).


Connect COM-lead of the DVM to chassis.

a) Measure the voltage (ca. 85V) at the junction of the collector of T2001 and R2092
b) Measure the voltage (ca. 85V) at the junction of the collector of T2000 and R2030

c) Measure the voltage (ca. 3V) at the Pin8 of IC2002
d) Measure the voltage (ca. 3V) at the Pin9 of IC2002

e) Measure the voltage (ca. 4V) at the junction of the emitter of T2025 and R2402
f) Measure the voltage (ca. 4V) at the junction of the emitter of T2002 and R2401

If the results of e) and f) are very close, then try to make the difference exactly 0 using the Y-Pos controls.
If sucessfull, repeat a)..f)


Results?

hello

with gnd connected or not is the same, nothing happens

you said (ca 85v) ca means alternating current? ac? in ac mode it doesnt read nothing, only in DC

in dc mode with both Y-pos in center:

collector of T2000: 113v
collector of T2001: 59v

pin 9 of IC2002: 2.97v
pin 8 of IC2002: 3.23v

emitter of T2025: 3.9v
emitter of T2002: 3.86v


with near of zero the diference in t2025 and t2002:


collector of T2000: 112,3v
collector of T2001: 63.4v

pin 9 of IC2002: 3v
pin 8 of IC2002: 3.123v

emitter of T2025: 3.877v
emitter of T2002: 3.899v

its very difficult to put the same value in t2025 and t2002


regards

Zitat :

ca means alternating current? ac? in ac mode it doesnt read nothing, only in DC

Sorry about that, ca. means approximately and of course dc voltages are measured unless otherwise specified.
Ca. ist a quite common abbreviation in german and has about the same but somewhat restricted meaning in english: http://en.wikipedia.org/wiki/Circa


Your measurements are perfectly fine!
One can see that there is change of sign in the voltage difference (upper-lower transistor: +40mV, -20mV) at T2025, T2002 which means that the trace should change from the upper to the lower half (or vice versa).
The absolute voltage levels here are also akzeptable.

About the same difference and the change of sign should be visible between Pins 9 and Pin9 of IC2002, but it ist not.
The corresponding differences are (+260mV, +123mV).
This makes me think that something is wrong with this stage.

So, let's have a look at the Vbe of the IC2002 transistors.
For the upper transistor we have 670mV and 754mV,
for the lower transistor we have 890mV and 899mV.
A Vbe of about 700mV ist quite akzeptable, but nearly 900mV ist too much.
So obviously we have a problem with the lower transistors or components around IC2002.

Such a high value of Vbe may result if no collector current flows through these transistors.
No collector current through the paralleled IC2002C and IC2002E also means that there is no current through T2000.
This should result in a very high collector voltage of T2000 -- which indeed was found.

Since it is somewhat unlikely that both transistors IC2002C and IC2002E or both Resistors R2009 and 2010 are gone simultaneously there are only a few components to be checked.

First center the Y-Pos Controls to midscale again or align for 0V between Emitters of T2025 and T2002
Connect COMM lead to chassis Ground, DCV-range

a) Measure the Voltage at the base of T2000.
This should be +8.2V as stabilized by Zenerdiode D2000.
If the voltage is substantially lower, then probably R2001 is gone.

b) Measure the Voltage at the emitter of T2000.
This should read about 700mV lower than the base voltage you just have measured.
If the voltage ist substantially lower, then the transistor chip has lost its metallization and T2000 must be replaced.


If you must replace this transistor then it is best to use a matched pair with T2001.
Either obtain them through Hameg or, buy a few of these transistors and use those two with the closest current gains at about 30mA.
For this purpose you may want to construct a small test fixture consisting of a 9V Battery and a variable resistor to align the base current.

Problem solved. it was the t2000 damage, i change both and now it works.

But i have one question now, how to calibrate it... could you help me with that?
i have to shunt both Y and measure 85v on it?



Many many thanks for help me to solve my problem with it, you´re a genius


Regards