Early 7904, no readout


Bruce Atwood
 

My new (to me) s/n B041515 7904 arrived DOA. (ebay, "not working, for parts".) With the help of my mostly trusty DSO138 I found the shorted 47/25V dipped tantalum on the -15 supply. Replaced it with a 470/25V aluminum electrolytic, 'cause that's what I had. It now has a beautiful and bright trace. I have ordered what I hope is an original paper manual for the early 7904s. The read outs do not work and all the manuals I have found online are for the later version, s/n B26000 and up. While waiting for USPS is there a downloadable version of the early manual somewhere? Point me to it please. thanks
PD I'm in the market for a 7A19 and a 7A26, any advice welcome.


Dave Daniel
 

Look at the TekWiki site. There are several manuals there. I don’t know what S/N ranges they cover.

DaveD

On Jan 5, 2021, at 17:30, Bruce Atwood <CCDman1@outlook.com> wrote:

My new (to me) s/n B041515 7904 arrived DOA. (ebay, "not working, for parts".) With the help of my mostly trusty DSO138 I found the shorted 47/25V dipped tantalum on the -15 supply. Replaced it with a 470/25V aluminum electrolytic, 'cause that's what I had. It now has a beautiful and bright trace. I have ordered what I hope is an original paper manual for the early 7904s. The read outs do not work and all the manuals I have found online are for the later version, s/n B26000 and up. While waiting for USPS is there a downloadable version of the early manual somewhere? Point me to it please. thanks
PD I'm in the market for a 7A19 and a 7A26, any advice welcome.





Bruce Atwood
 

Thanks Dave, as far as I can tell all the 7904 manuals on the TekWiki are for s/n b260000 and up.