Metrix 803B Oscilloscope power supply issue

[rbarreiros]

Re: Metrix 803B Oscilloscope power supply issue

Seems I jumped the gun, the issue I had was this one, which, like it's said in the thread, it's a bad contact in the green cable. Fixed !!

http://www.electro-tech-online.com/t...oscope.146957/

[rbarreiros]

Re: Metrix 803B Oscilloscope power supply issue

Any news on the RS232 front ? I'm also curious at controlling the scope through RS232.

Best regards,
Rui

I had 5 minutes to spare today, to check the signals on J18 this is what I have so far.

The colours in the list below are just those of the bit of ribbon cable I used, so they have no particular significance.

 
J18 Pinout - Pin1 at PSU end (same as J19)

Pin- Colour - Signal
1 - Blue1  -  0V slight periodic ripple (Polled output perhaps???) 
2 - Purple1 -  0V slight periodic ripple (Polled output perhaps???) 
3 - Grey1  -  0V slight periodic ripple (Polled output perhaps???) 
4 - White1  -  0V slight periodic ripple (Polled output perhaps???) 
5 - Black   -  0V slight periodic ripple (Polled output perhaps???) 
6 - Brown  -  +12V
7 - Red    -  -12V
8 - Orange  -  10ms +5V pulses (20ms pk to pk square wave)
9 - Yellow  -  0V slight periodic ripple (Polled output perhaps???) 
10 - Green  -  Ground (Confirmed zero ohms to BNC Earth)
11 - Blue2  -  0V but not tied to ground (serial port I/O perhaps???) 
12 - Purple2 -  0V but not tied to ground (serial port I/O perhaps???) 
13 - Grey2  -  +5V slight ripple (serial port I/O perhaps???))
14 - White2 -  +5V slight ripple (serial port I/O perhaps???))

I'll take a closer look at the signals, take a few pictures of the scope traces and probe with the multimeter to see if I can determine which are inputs and outputs when I get more time.

Now that i know the serial port protocol and that it can use 3 wires i.e. no hardware handshake and xon/xoff I can then experiment with a TTL level 9600 baud serial signal fed to which ever I think might be the inputs, so see if I can control the front panel.

The serial port consists of 5 wires and is described thus...

Serial link characteristics

Oscilloscope connector : 25-pin cannon plug
Cable : five wires (two transmission wires, one ground wire, two
control wires)
Protocol : RTS
Data rate :
Data format :9600 bauds
8 bits - no parity - 1 bit stop
Protection : per EIA RS232C standard


.. which may match up with the bottom 5 wires on J19


I haven't found any 3V3 signals so far, so I think everything should be 5V TTL

Pin 8 is interesting, I presume this is an accurate 50Hz pulse, which is the same frequency as the UK mains, and this might be for blanking sync perhaps for the A/D daughter cards. Pure speculation on my part of course.

[itsthatidiotagain]

Re: Metrix 803B Oscilloscope power supply issue

Very late reply, but @rbarreiros the short answer is yes. Your PSU issue sounds very similar. Follow through the thread and check/replace the parts I replaced first.
Once you have done this, if it is still not working, check the HT side of things.

[smdportugal]

Re: Metrix 803B Oscilloscope power supply issue

Dear sir , i still have one Metrix OM803 that bought at about 25 years ago. It has been all types of faults . The first one when swithc on some relays goes crazy and the osciloscope coulnt start ok , i ´ve found some capacitors in the power supply unit with low capacitance and after replace it works good . After some years starts to not enter in some menus like components tester , It was a fault in a conector inside . After some more years lost the left deflection but as the transistor are smd types and cant see the reference and as i dont have the schematics i give up . I still have it here but with horizontal left deflection fault. Anybody has the Schematics diagram ?