Hello and asking for help with HP 67 power unit

[Tapti]

Yes, I you're right. On my good board they are also black as on the photo, on the damaged board, they are red ...
But ! You wan't believe it, my board seems to be self repairing ! Since this afternoon the maschine is running fine, although Vgg is still only -10.1 V. Only thing I did was removing it once again from its place inside the calculator and doing some measurements with a DVM, nothing else. I really hate these situations, because it's now even harder to find the fault, which must be somewhere and which certainly will come up sometimes later on. I'm still concerned about the low Vgg. Perhaps I will exchange those two tantalums anyway. But in the meanwhile I think the problem is somewhere else on the board since the calculator seems to work well with a voltage that low. Perhaps it was a contact problem (some oxydization) somewhere at the long chain of contacts along the lower side oft the board. Due to the frequent removement and reinstallation perhaps the contact has cleaned up ?
Keep you informed when I have news
Stefan