This 8562EC had err 334, 356, 317, 319. I tracked down to U429B on the A14 board and found the inputs of the op amp are at -3mV and -8mV and the output is at 0.5V. According to the attached diagram the ref voltage at the input should be at -0.1 to -0.25V on pin 5 of U429B. I was wondering if anyone knows how to debug this issue. Which DAC to look for and etc..?
Also, where could I get the schematic for this spec?
Thank you!
Also, where could I get the schematic for this spec?
Thank you!
It seems that it is either a fail DAC or something along that path is problematic.
Your input will be appreciated.
Thanks!
I also measured the 600MHz ref and it looks right.
Attachments
Hereby a .jpg from A14 is this the same as yours ??
Ary
pa0alv
Attachments
Yes, it looks exactly the same!
Thanks!
I do have once the same problems.
Check the both diodes VR1 and VR5. VR5 have a brown shade of colour (overheathed).
Unsolder the diode, forward normal value but the oposite way an odd one.
May be it's the solution.
gl
Ary
Edited by: PA0ALV on Mar 30, 2015 2:36 AM
hedgehog, thanks for the tips as well. I did some measurement on YTO output today (jumper on test position), and found no output signal there.
I was wondering if main coil drive fail will also lead to no output at YTO. I am not sure and I am studying the circuits now.
The voltage between main coil + and main coil - is +3.5 for most of the frequency with zero span. Is that a reasonable reading?
I un-soldered the two zener diode, 5V and 10V and verified they are good.
Any suggestions would be appreciated.
Thanks!
Mike
Attachments
sri fo the delayed response.
An other possibilty is by using a sweep- or rf generator in CW mode. !
It is a lot of work! Disconnect the spa's YTO output rigid cable. (You have to take out the YTO)
Connect the sweep- or rf generator to the rigid cable.
Connect the 300 MHz "Cal signal" to the spa input connector.
Set analyser band "0" Freq 300 MHZ, center freq 300Mhz. "zero span"
Set generator appr. to 3,62 GHz +10 dBm (or calculate the frequency) and tune carefully back and forward
and look at the crt when the line goes up.
There's no sweep action so it can be difficult to see something.
When there is some movement during tuning it is sure the original YTO is malfunction.
The main- and fm coil are never defect, its "only" the oscillator transistor.
Measuring main coil current, it must change by turning the RPG. If so and no output from YTO, 2e conclusion YTO defect.
If main coil current did not change, driver or circuit not ok
Ary
pa0alv
sri fo the delayed response.
An other possibilty is by using a sweep- or rf generator in CW mode. !
It is a lot of work! Disconnect the spa's YTO output rigid cable. (You have to take out the YTO)
Connect the sweep- or rf generator to the rigid cable.
Connect the 300 MHz "Cal signal" to the spa input connector.
Set analyser band "0" Freq 300 MHZ, center freq 300Mhz. "zero span"
Set generator appr. to 3,62 GHz +10 dBm (or calculate the frequency) and tune carefully back and forward
and look at the crt when the line goes up.
There's no sweep action so it can be difficult to see something.
When there is some movement during tuning it is sure the original YTO is malfunction.
The main- and fm coil are never defect, its "only" the oscillator transistor.
Measuring main coil current, it must change by turning the RPG. If so and no output from YTO, 2e conclusion YTO defect.
If main coil current did not change, driver or circuit not ok
Ary
pa0alv
Dear PA0ALV ,
write me please to email minolta1 at cninet point cz I need your help about 8591A . Thanks!