HP 54616B Schematics? - Page 1
Forum section: electronics / repair

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2017, 12:58:00 am
content: Does anyone know of any schematics for the HP54616B?There is a CLIP (Component level info package) for the 54000A series, but it's not the same.Having keyboard & rotary encoder issues.Front panel matrix diodes all look good, so I suspect the 74AC11244 drivers.

author: amspire
author_rank: Super Contributor
timestamp: March 18, 2017, 03:20:18 am
content: Looks like the service manual has no schematics. I assume you have the service manual?

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2017, 03:21:36 am
content: Yes, the service manual is useless.

author: amspire
author_rank: Super Contributor
timestamp: March 18, 2017, 03:50:36 am
content: Only thing I can suggest that may give some clues is the HP Journal (April '97) that discusses the design of this scope family. Talks a little about the architecture. Still no schematics unfortunately.https://ia600409.us.archive.org/33/items/Hewlett-Packard_Journal_Vol._48_No._2_1997-04_Hewlett-Packard/Hewlett-Packard_Journal_Vol._48_No._2_1997-04_Hewlett-Packard.pdf

author: amspire
author_rank: Super Contributor
timestamp: March 18, 2017, 04:31:25 am
content: Just one more thought, if the keyboard and rotary controller are slow to respond, check the 68000 processor is not getting spurious interrupts from somewhere. I have a different 68000-based instrument which is fully working, but has a very slow keyboard and this was on my todo list to check. I think there are 3 interrupt pins.

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2017, 05:18:05 am
content: Quote from: amspire on March 18, 2017, 04:31:25 amIt's only a part of the front panel that doesn't respond or responds weirdly. Some buttons + some encoders in a group. The other controls work 100%.Suspect a matrix line issue of some sort but I can't find it yet.

author: tautech
author_rank: Super Contributor
timestamp: March 18, 2017, 07:21:44 am
content: Quote from: EEVblog on March 18, 2017, 05:18:05 amInteresting. I've been corresponding with a local guy with a DS1052E with very similar symptoms, quite a switched on cookie and when desoldering the nonresponsive encoder the thing came to life.Sort of makes sense that one of the components on the front panel that could be subjected to physical stress might have had a cracked solder joint.Sometimes it's something unbelievably simple.

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2017, 08:48:20 am
content: Turns out the CLIP schematics for the 54000A series are pretty much identical for the keyboard buffer section on the 54616B. Designators are wrong, but otherwise seems correct.

author: amspire
author_rank: Super Contributor
timestamp: March 18, 2017, 08:52:47 am
content: Hope there is a video or two on this scope. Love seeing how HP did their magic particularly in the older designs.

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2017, 10:21:40 pm
content: Quote from: amspire on March 18, 2017, 08:52:47 amWell I have shot 40min worth of repair footage. Whether or not I release that depends on whether I get ti fixed or not :->Already fixed an ADC channel fault on it, but the keyboard one remains. Needs a bit more effort.Resoldering the encoders and connectors didn't help, but I didn't expect them too, as an open or shorted encoder should just affect that one encoder, not others, they are only soldered on a single side of the board, not being used as vias even.In any case I've measured the encoder contacts and they all seem to be doing their business.