Osciloscope hameg 512-4 channel 2 no horizontal line

Status
Not open for further replies.
A

Armand alla

Newbie level 6
Joined
Nov 7, 2021
Messages
11
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
57
Hi to all ,i have an old osciloscope hameg 512-4, i have a problem with channel 2 ,i have not the second horizontal line in the screen ,i push the button mono/dual but it do not come and when i rotate the vertical button of channel 2 it rotate the horizontal line of channel 1,also signals put in channel 2 and volt/div button let say all the function of channel 2 control horizontal line of channel 1 , i have changed all 1uf tantalium caps to new ones but i do not have the second horizontal line of ch2.
Please help me .
 

Attachments

  • pdfslide.net_hameg-512-4-schematic (2).pdf
    2.6 MB · Views: 161

Sort by date Sort by votes
Hi

Please show a photo of the scope where we can see all the setup and the screen.

Klaus
 

Upvote 0 Downvote
Thankyou for answering .Those are the buttons .if necesary i take a video what it do on my problem
 

Attachments

  • 16362953843449048419117776513133.jpg
    1.4 MB · Views: 122

Upvote 0 Downvote
Hi

No need for a video. A photo is sufficient.
* switch ON the scope
* press the "dual" button
* press the "chopper" button
* set timebase to 0.1ms/div
* set trigger to "auto" (fully left?)

If you see one horizontal line:
* move Ch 1 vertical offset. Check whether the line moves
* move Ch 2 vertical offset. Check whether the line moves

Klaus
 

Upvote 0 Downvote
I did and 1 horizontal line is present.and it moves also with ch1 ofset and ch2 ofset up and down.it also can move without pressing dual and chopper button. I have clean the switch in dual button but second line no come.i didnt fimd on circuit where ch1 and ch2 signal is going together to check.it looks that ch1 and 2 use the same x line on crt
 

Upvote 0 Downvote
Hi

If there is a single line (we don't see on your photo) and it moves eith Ch1 offset as well as with Ch2 offset, then most probably you have an "ADD Ch1 + Ch2" enabled.

Klaus
 

Upvote 0 Downvote
Yes klaustst is like you have sayed .Look like there is an Add ch1+ch2 .
I will verify later putting 2 dc voltage one 5v other 9 v and see if its an add ch1+ch2.as i see the front pannel of scope does not have such a button ADD button
 

Upvote 0 Downvote
I also do have nothing when i push Hor.ext button .it should be X-Y plot but no point on the screen.
 

Upvote 0 Downvote
Thankyou tony for responding i have checked a bit the voltages on the mutivibrator and i have seen that some voltages are 4v low.i have checked some resistors there and instead of 51 ohm i have 32 ohm ,.will take the X board out and to check for those resistors +/- 5% and change them as is in the manual after i gave info.it will take a while i think
 

Upvote 0 Downvote
Yes it looks like is an ADD fuction of both signals on my oscilloscope .i put a squere vave in ch1 and a sawtooth wawe in channel 2 .it show me a sawtoth signal 90 degre of squere signal.so those 2 signals are mixed somewhere and i want to divide them .as y ofsset ch1 and ch2 up and down is arranged by 1 ch Xline.infact if dual is not press on this osciloscope y offset of both channel can move the line verticaly ,when i push dual another second X line should come but is not coming so i am looking to bring it back .thats it
 

Upvote 0 Downvote
Sir Stewart ,
I just get out the Y board to check and i have some resistors that has more than 50% ohm down ,(anyway will verify after getting those resistors out the circuit),but there is a change to the transistor of ch1 and 2 ,i checked the manual on the photo and 2 of them are not as the manual look .2 of them are reversed i send a photo of manul and my board .i think that there should be the problem anyway i will check those 4 transistors from the manual book the connections .(i never have change those both they guy before me hav dome that i think) anyway thankyou
 

Attachments

  • 20211110_013353.jpg
    705.3 KB · Views: 111
  • Screenshot_20211110-013226_WhatsApp.jpg
    625 KB · Views: 117

Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…