| Electronics > Repair |
| Advantest R3273 / R3267 Repair |
| << < (4/13) > >> |
| chick0n:
After some Reflowing, the CPU-Board is Booting again. :P But now, the Amplitude problem is showing again. When the Analyzer is cold, it shows the -10dbm cal signal as +2dbm, thats too much for the cal routine. After warm up, the whole Trace on the LCD drops (Not just the Peak getting smaller), and shows the signal as -22dbm. Whats really weird is, that the drop only shows after preset, or reboot. Which makes debugging extra hard... I measured the converter stage outputs again, after cold and warm (preset) state. 1st converter cold: -21dbm, warm: -20dbm 2nd converter cold: -18dbm, warm: -15.4dbm 3rd converter cold: +6,2dbm, warm: -21.8dbm (wow) |
| chick0n:
Further investigation: I dont think, the 3rd converter is broken. (Would be too easy) Theres some gain control voltage for the 3rd output transistor, that looks fishy. Voltage Cold: -5V (Shows +2dbm on analyzer) Voltage Warm (after Preset) -1,6~V (Shows -22dbm on analyzer) When I disconnect cable to the transistor, Voltage is -12V When I put in about -3.3V, from external power supply, analyzer shows -10dbm. The Cal Routine almost passes, but fails at the end. (She wants to adjust the control voltage herself?) The control voltage comes from the underside of the RF-Block, which makes debugging extra hard.... |
| chick0n:
I have the sneaking suspicion, my attenuator is crimped wrong. The Owner before me replaced it, and it works. But hmm... Does anyone have a picture from the underside of the R3273 RF-Deck? |
| serg-el:
No photos. Calibration guide is available. https://cloud.mail.ru/public/gG8r/DzJXmPxig |
| chick0n:
Ok..false alarm. The attenuator is connected correctly. And I have working CPU-Board now. The fix for "-10dbm CAL Signal showing as -40dbm on the analyzer", is bridging the Voltage Regulator, for now. (The RF Block gets 12.7V instead of 11.7V). Something seems to have degraded in the RF-Block over the years. And its not the Electrolytics, I changed every one of them. Made no difference. For me the Signal was still a little bit too low, to start calibration. Theres a 2db Attenuator in the RF input path (before the 3,6GHz Low Pass Filter), that I replaced with a 1db one. Now everything seems works fine. I have to let the analyzer heat up for at least 30min before doing calibration or measurements. |
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