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Pinörkel · 14th May 2020, 1:09 am

Just measured all components again and de-soldered some components where necessary. Everything was near perfect or at least well within tolerance, except for C414. This was a 33 μF capacitor at 32 μF, that hat been put in place of the required 22 μF at that point. Since this seems to be a filter capacitor, I think this should be OK. So I pulled the PC149 out of the case and did some live measurements on the voltages going in and followed their path. Now, I finally got 25.3 V at the collector side of TR408 and 26.1V at the emitter side of TR405 but still no output at the connector. Since all I had done was reseating some components and resoldering several connections, I suspected some cold solder joints. So I checked the traces from the emitter of TR405 to the PCB connector and both of the beefy vias on the path were dead cold solder joints. After fixing this, I got my +24V. Then I did a rudimentary PSU calibration and the scope started running again. I should probably touch up all the solder joints on PC149 just to be on the safe side before continuing with the rest of the scope and then recalibrate the PSU.

14th May 2020, 1:09 am	#117
Pinörkel Pentode Join Date: Jun 2019 Location: Dortmund, Germany Posts: 161	Re: Telequipment D75 scope. Just measured all components again and de-soldered some components where necessary. Everything was near perfect or at least well within tolerance, except for C414. This was a 33 μF capacitor at 32 μF, that hat been put in place of the required 22 μF at that point. Since this seems to be a filter capacitor, I think this should be OK. So I pulled the PC149 out of the case and did some live measurements on the voltages going in and followed their path. Now, I finally got 25.3 V at the collector side of TR408 and 26.1V at the emitter side of TR405 but still no output at the connector. Since all I had done was reseating some components and resoldering several connections, I suspected some cold solder joints. So I checked the traces from the emitter of TR405 to the PCB connector and both of the beefy vias on the path were dead cold solder joints. After fixing this, I got my +24V. Then I did a rudimentary PSU calibration and the scope started running again. I should probably touch up all the solder joints on PC149 just to be on the safe side before continuing with the rest of the scope and then recalibrate the PSU.