Electronics > Repair

E4407B Tracking Generator Repair

<< < (21/27) > >>

analogRF:

--- Quote from: smgvbest on October 16, 2020, 11:37:11 pm ---these 2 Sot-23's marked 8F I think are 5.1v zeners but 8F can be a NPN transistor as well
both read strange but reading is in-circuit.  one reads 24.7K forward and reverse and other is like 30meg forward and reverse.   I'll get them out of circuit to test but they are connected to V1/V2

--- End quote ---

clearly they are not transistors (they are marked by CRxx) and they are definitely diodes. seems to be used for clipping/clamping a signal or a dc voltage (from top and bottom)

use diode test mode not resistance mode in your multimeter ::)

analogRF:

--- Quote from: smgvbest on October 17, 2020, 06:43:46 am ---Here's another area.   all but the one with a ? is identified but  I marked one component that looks damaged?   any thoughts on that?

--- End quote ---

the ? element looks like RF amp but it has an extra supply pin (other than the usual one that is connected through a ferrite bead) that is a bit puzzling
maybe it has a on/off  switch in it too? there must be a marking on that package. what is the marking??

the discolored element does look like damaged but at that point i dont think there is anything stressful to elements, maybe it can be cleaned? can you try to clean it? looks like a capacitor of course but it could be a resistor so check with multimeter

after those you have a bandpass filter at 784MHz I think..

smgvbest:

--- Quote from: analogRF on October 17, 2020, 12:28:35 pm ---
--- Quote from: smgvbest on October 16, 2020, 11:29:44 pm ---Looking for help in identifying some components
in PICT0007.jpg   looking to identify all marked ones.  the one I put a D on,  the D is the only marking on the component.   I think this is a dual diode package for the peak detector.

I loose allot of power at the point of this component.   like -25dB.   this is suppling the 786.5hz RF to the Mixer (5x that but I can't measure on my 1.5Ghz SA)
in  IMG_2867-1.jpg

--- End quote ---

the white elements are most likely resistors. you can check with multimeter
the "D" element is most likely HMPP-3890 single schottky diode by Agilent/Avago but are you 100% sure about the marking? sometimes it is tricky to read the labels
seems that all 4 pins of it have been used  ??? also for a good temperature compensated peak detector it makes sense to have two diodes in one package but if the marking is only a "D" then I couldn't find anything other than HMPP-3890 which is still applicable...

the element with red dot is what is used to generate 5th harmonic if i remember correctly from previous discussions, so it is probably a diode of some kind.

--- End quote ---

The White elements do read as resistors of 50 and 125 ohm

for the part with the D marking.   see image for best I could get 
Using the Diode test here are reading for all 4 pins (see image for pin numbering used)  all reading Vdc

1-2  1.3908v/1.447v
3-4  1.6304v/0.1447v
1-3  0.0691c/0.0691v
2-4  1.4398v/1.3723v

for the damaged element

Did multiple checks
Resistance Open
Capacitance 0
Diode open

see image for better view

smgvbest:
heres image of damaged part

smgvbest:

--- Quote from: analogRF on October 17, 2020, 12:32:46 pm ---
--- Quote from: smgvbest on October 16, 2020, 11:37:11 pm ---these 2 Sot-23's marked 8F I think are 5.1v zeners but 8F can be a NPN transistor as well
both read strange but reading is in-circuit.  one reads 24.7K forward and reverse and other is like 30meg forward and reverse.   I'll get them out of circuit to test but they are connected to V1/V2

--- End quote ---

clearly they are not transistors (they are marked by CRxx) and they are definitely diodes. seems to be used for clipping/clamping a signal or a dc voltage (from top and bottom)

use diode test mode not resistance mode in your multimeter ::)

--- End quote ---

Here are reading for CR1/CR2 Forward and reverse voltages  meter set for 15V test

CR1  0.789v/2.773v
CR2  0.789v/2.763v

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod