| Products > Test Equipment |
| Fool for the 8656A Sig Gen |
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| Tony_G:
I can see how that would be a problem... It would be interesting to see if you were getting clock into the keyboard shift registers (I think they generate the pulse train but I'd need get the manual again to confirm). TonyG |
| Tony_G:
Long time, no hear (actually I was on the road in MO and UT and then out at the cabin here in WA so I was pretty much out of contact and thus my fault). Thought I'd just reply to see how you're going? My 8657B is probably my fav of the HP sig gens I have so I'm interested in seeing you get this one going again. Look forward to hearing from you. TonyG |
| jrharley:
Hey Tony G, no worries, thanks for checking in. Although I've had to take a few unrelated sidetracks recently, I have discovered something that I didn't notice before. Not sure how I could miss it. At any rate, I've discovered that when I jumper pin #2 into the circuit, (see the photo I posted a few comments ago for the connector), The 5.4 V rail indicator LED goes out! Or at least very dim. Something is pulling that rail down when pin 2 is connected. I simply didn't notice that before. So, I've been walking the dog along the schematic path looking for potential culprits. This means that every surface in my shop is covered in schematic diagrams! I can't use a lack of documentation as an excuse, that's for sure! Anyway, pins 1,2 and 3 on this connector are all originate from the 5.4 V rail, but only #2 causes this. The next stop on the path for pin #2's signal appears to be an IC labeled "DEMUX" on the schematic, which I guess is a de-modulator. There's also a diode straight to circuit ground in the path too, and I'm currently hunting that one down to test it since it just seems more unlikely that it would be an IC problem. Then again, I'm really green when it comes to the digital world. So, that's where I am. I'll locate and test the low hanging fruit on this signal path and report back with any news. Thanks for your interest! I'll be struttin' around like Richard Pryor and Gene Wilder if I do get this beast working, and I really appreciate everyone weighing in. Best regards, JRH |
| Tony_G:
I decided that I couldn't help anymore without getting the manual so I just bought the Artek copy - Where are you looking at the supplies from J2 (so I don't need to go find it all myself :))? |
| jrharley:
Thanks TG, I really appreciate your interest in this misadventure! I'm in the middle of getting my bearings on exactly what you're requesting, so, standby for that info. At the moment though, I'm replacing the battery on a laptop that was clearly designed to discourage anyone from doing just that, including service techs. Gotta' get this out of the way before diving back in to the HP. For what it's worth in the meantime, I started with the power supply schematic, sheet 22, page 8-127, 128 I think. J2 is shown in the lower right corner of the diagram and for pin 2 you follow to the "H" in other section schematics for where pin 2's path goes. Yeah, I'm still trying to learn how to follow the bread crumbs...... More info soon, JRH |
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