kubaka
Newbie level 1
Hello
After a long time of struggle to get the digital part and main normalizations working I encountered a big and probably simple to solve problem. The PSU rails have too much ripple. The PSU is a Tektronix two stage supply:
1. PWM which generates +60V
2. Inverter which takes 60V and drives the main transformer .
It is probably a typical Tektronix PSU for 22xx series oscilloscopes. I have already changed caps, checked internal boards for loads and dry shorted caps. Ripple shows up when the YIG is sweeping and the load current changes. When load changes rapidly (teh sweep rate is high) ripple is almost gone. When I take some load off the PSU the ripple is even worse. When the YIG is not sweeping ripple is gone and the crt display is steady. Probably the ripple on +115V (for CRT) makes the display "blink" synchronously with the sweep. I am sure that YIG is OK - the same problem goes on when I turn on/off manually additional load (like graticule lights).
For example on the 115V rail (it is the worst):
**broken link removed**
On the secondaries of teh main transformer the switching looks like this I think it's not good
(clamping diodes and circuits checked on primary side) :
**broken link removed**
Maybe someone had a similar problem with a Tek PSU ?
PS: If anyone has a problem with 2710 feel free to ask maybe I can help
After a long time of struggle to get the digital part and main normalizations working I encountered a big and probably simple to solve problem. The PSU rails have too much ripple. The PSU is a Tektronix two stage supply:
1. PWM which generates +60V
2. Inverter which takes 60V and drives the main transformer .
It is probably a typical Tektronix PSU for 22xx series oscilloscopes. I have already changed caps, checked internal boards for loads and dry shorted caps. Ripple shows up when the YIG is sweeping and the load current changes. When load changes rapidly (teh sweep rate is high) ripple is almost gone. When I take some load off the PSU the ripple is even worse. When the YIG is not sweeping ripple is gone and the crt display is steady. Probably the ripple on +115V (for CRT) makes the display "blink" synchronously with the sweep. I am sure that YIG is OK - the same problem goes on when I turn on/off manually additional load (like graticule lights).
For example on the 115V rail (it is the worst):
**broken link removed**
On the secondaries of teh main transformer the switching looks like this I think it's not good
(clamping diodes and circuits checked on primary side) :**broken link removed**
Maybe someone had a similar problem with a Tek PSU ?
PS: If anyone has a problem with 2710 feel free to ask maybe I can help