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| SDG1025 Damaged CH1 Repair |
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| hesam.moshiri:
I'm trying to repair my Siglent SDG1025 function generator which has damaged CH1. CH2 works properly. I replaced two components (U19 and Q3=BAV99) but channel one shows a weird waveform. U19 = THS3095 is a special OpAmp that can be turned ON-OFF via its PIN-8. so it's likely that it's OFF. I spent a lot of time, but I could not find a trace connecting to PIN-8 of U19. I can see a tiny track and a VIA on the PCB connected to PIN-8, but it goes from mid-layers to somewhere unknown. if somebody has this device please check the voltage on PIN-8 of U19, when channel-1 is active and Vpp is above 2 volts. |
| fzabkar:
https://www.ti.com/lit/ds/symlink/ths3091.pdf (datasheet) As I see it, you need to compare the PD* voltage on pin #8 against the REF voltage on pin #1. |
| hesam.moshiri:
--- Quote from: fzabkar on November 18, 2024, 08:07:28 pm ---https://www.ti.com/lit/ds/symlink/ths3091.pdf (datasheet) As I see it, you need to compare the PD* voltage on pin #8 against the REF voltage on pin #1. --- End quote --- REF (Pin-1) is grounded, so I'm looking for the PIN-8 connection on the board. The voltage on Pin-8 is low (max 0.4V) |
| fzabkar:
Are you able to trace pin-8 of the working channel back to its source? |
| hesam.moshiri:
--- Quote from: fzabkar on November 18, 2024, 11:54:44 pm ---Are you able to trace pin-8 of the working channel back to its source? --- End quote --- for sure if it was designed like that, I was spotting it. This opamp is only used for CH-1 |
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