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Print Search. I am trying to repair an HP Generator. When turned on most of the front panel indicators flash and a "1" flashed on and off in the first digit position. It then goes blank, no lights on and the fan runs.
The old battery has been removed and I do not see any corrosion in the area. Scope traces show that the processor is running, but there is no scan information going to the front panel via the wide flat cable. All power supplie voltages check OK. If I turn on holding down E.
I have looked closely at all the board components and there is nothing that looks out of place. I note that my Processor Board is made in Germany and is version I can only find a partial board layout in the update section that shows the row of eproms at the top of the board. Update 41 I think. Does anyone have an idea of where I should start the trubleshooting?
Battery removed or replaced? Battery needs to be there. There is a monitoring circuit that halts the cpu if the battery is too low or not there. Professional Electron Wrangler. Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer s.
Thanks I did not realie that! I read that the battery was only needed to keep a backup of the last configuration that you had when you turned it off. Without the battery I read that it would simply load the defauly configuration.
Maybe that is the difference with the German Veresion, I will install a 3 volt battery and see if it helps. Thanks, George. MarkL Supporter Posts: Country:. Try the battery, but from what I see in the service manual it doesn't matter if it's present or not in any revision.
There's no monitoring circuit I can see. What serial number is your unit? It sounds like the processor is not getting a chance to run for very long. Are the bootup symptoms exactly the same each time? What scope traces "show the processor is running"? Any stuck? You might try this with the processor in "free running mode", see Which service procedure section has you holding down E.
Just not familiar with that one As you've probably noticed, much of the service manual is oriented towards debugging with a signature analyzer.
You might need one for this problem. This processor board is made in Germany. Board is version Has 6 EProms across the top of the board and is considerable different from the schematic diagrams that I can find.
It is listed by HP as their Update 41 with a partial layout and schematic. But would be nice to have the full board layout and schematic. Thanks for your comments, I had hoped that the battery would fix it, but unfortunately it still is the same. There is very little signal activity on the board, there does not seem to be any scanning of the address lines going on.
Am going to explore the reset components next, just in case something has failed in that circuit and it is holding the whole board in limbo. Hi Mark, looks like you and I were posting at the same time! This instrument was German built. The free run procedure on I think I have it figured out but would like a confirmation before giving it a go. Here is a picture of what I think is the free run jumper point on this board. I think it needs to be moved to the PI tab to go into free run.
So now how do you think I should proceed, following the procedure on A step by step detail would be appreciated. Also any idea where to get the layout and schematic of this board?
The free-run doesn't help you. Hi George, I think your best bet on a schematic would be to look for an old version of the service manual that goes up to change 28 according to the backdating table for your serial number. Otherwise, I you're likely stuck with HP's backdating scheme.
It seems that the processor is not running, so "free run" would be a good way to observe the address and data and other control signals coming out of the processor. The procedure says to move the jumper to P1 and also disconnect A2W2. You should see the address incrementing at least. Unfortunately without the signature analyzer, this isn't going to prove it's working or that the ROMs are good, but at least you should be able to see anything that's stuck.
By setting up triggering on the various chip selects for the ROMs, you should be able to determine if they're outputting data. You can also try working through the signature table to verify signals are changing there too. If you have a EPROM reader, it might also be worthwhile to verify their contents if you can find a copy of the firmware lurking on the internet somewhere.
Was this unit working at any point? Or did you get it this way? I checked the voltage to the 4 pin connector near the battery. All of the power supply voltages are very close to spec. No blown fuses, fans run very nicely when turned on. When turned on several of the leds on the left side flash, the left display digit shows the number 1, and the RPT and OFS panel indicators stay on. Everything else on the panel is dark. Looking the the ribbon cable from the display unit, there are various pulse width signals on 5 of the many leads.
Some of the other remaining leads are either high or low. I moved the jumper to free run and absolutely nothing changed on the address or data lines.
Looking at all the pins on the processor, the majority have square wave date of various widths and frequency. Moving the jumper to free did not seen to affect any of those signals. My next step may to be note what each of the processor pins is doing, compare it to the schematic and see if there is any kind of a pattern addressing the sets of address and data line feed points.
Not sure this will really prove anything, but gived me something to do I guess! I am going to try and figure out the reset system as well. Would be nice if I know if it was normal high or low! Maybe I can find that in the service data as well. Guess I need to read through the service info carefully. This unit is absolutel pristene inside and out. I bought it for a very reasonable price on ebay, hoping I could find and repair the problem it is having.
Any further information or things to try will be helpful. Thanks a bunch, George. Sure do appreciate the conversation we are having so far. Did a lot of logic looking the past couple of hours. I have found that the Display Driver, U22, is showing some unusual conditions.
Several of the leads are showing a perminant high condition with just a slight bit of address pulse showing at the top. Looks like the high condition is 4. Many of the pins are showing good full 5 volt pulses. Unpluging it from the front panel display board does not change any of the above levels, so the problems is on the Processor Board.
I made a chart that indicates which pins are OK and which have the high condition and small pulse. That should help me to find out what the affected signal pins have in common.
HP 8116A Quick Manual
Repair and calibration agreements and per-incident services are available from Keysight Service Centers. Service Guide. Agilent Technologies. Serial Number Prefixes: This manual applies to any Maximum FM Deviation P. Power Meter. Power Range: 1 W to mW.
8116A 50 MHZ PULSE/FUNCTION GENERATOR