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| E4407B Tracking Generator Repair |
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| 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 |
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