HP 8924C front panel buttons help

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xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

HP 8924C front panel buttons help

Post by xxx2fan »

I have a HP8924C setup to come on like a HP8920. The unit comes on with TX screen. It says passed all test. But the front panel buttons will not do anything, also the Cursor Control knob, will change fields but when you push it nothing happens. If anyone can give me a little insight on where to start looking it would be awesome.
Any info where to look would be great. Thanks
xxx2fan
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fineshot1
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Joined: Wed Oct 12, 2005 5:13 am

Re: HP 8924C front panel buttons help

Post by fineshot1 »

have you confirmed that the frequency standard output is reaching the panel buttons logic circuit?
I ask cause it sounds like the panel buttons logic is not working.
fineshot1
NJ USA
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

no I haven't this is a little over my head if you could give me a little help can I check it with my frequency counter. I also don't have a schematic of the unit at this time. Thanks for your help
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

Can anyone tell me if the 4 leds on the HP 08920-60395 A16 Host Controller Board For 8924C should be on or flash. Trying to narrow down the problem with the keyboard. I checked the 10Mhz out the back it is spot on. I check power supply at the connectors. All voltages match the data I have downloaded from the net for power supply repair. I'm thinking its the controller board. haven't reseated the controller board yet. Thanks for any info. Anyone point me more to check.
Thanks
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

the HP08920-60395 A16 Host Controller Board For 8924C the leds D1-D4 when you boot it the 4 leds light up until beep then the go out. I've reseated the cables and the I/O board. but still the same no keys work at all.
jry
Posts: 440
Joined: Fri Feb 06, 2004 3:14 pm

Re: HP 8924C front panel buttons help

Post by jry »

IIRC correctly the front panel goes directly to the processor board.

On the 8924C it may get routed through a filter assembly. 25 pin D connector with some chokes for RFI ...once again going by memory.

Nothing active on the front panel ...may be your processor board and the interface IC's
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

i checked at test point one I/O board there's 5v DC there. There is a buffer board (KEYBOARD FILTERS) A2 that the cable from keyboard to IO board (HOST CONTROLLER) A16 goes through. The I/O board has +5V DC which the block diagram says it should. I don't know how to check to see if anything is at the filter board, scope ??? not sure. There is no schematics for this thing. Think I would be safe if i got a parts unit and swapped the I/O board or maybe it will kill the I/). This was the best service monitor I have ever worked with. Sure would like to get it back up. I saw on reading I'm pretty sure you have to switch the calibration IC with a replacement to keep the calibration for the unit.
jry thanks so much for the information you've provided.
k2hz
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Joined: Tue Mar 01, 2005 7:27 am

Re: HP 8924C front panel buttons help

Post by k2hz »

It may be worthwhile for you to contact Rick Bowman at Amtronix:
http://www.amtronix.com/usequip1.htm

I have a HP 8285A modified to a "poor man's 8920B" purchased from him several years ago and the deal and subsequent support has been outstanding. He has a good stock of used HP units and parts and is very knowledgeable on HP service monitors.
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

I'm pretty sure thats where this unit came from I got it some years ago of of bay and had a paper that came with it from Amtronix. I will get a call to him in the next couple days I'm afraid to poke around too much and a parts unit is very expensive. This one has upgrade to 100W so i really want it back working. Looked it up I'm within 100 miles of his place. Be better to drive than to ship it.
Thanks.
k2hz
Posts: 527
Joined: Tue Mar 01, 2005 7:27 am

Re: HP 8924C front panel buttons help

Post by k2hz »

I recently had a problem with mine after 8 years. Would not power up due to both a power supply and memory backup battery failure. Rick offered me suggestions on components to replace but I elected to send it back to him for both repair and recalibration. Quick turnaround and very reasonable charge.

He may be able to diagnose your problem over the phone to determine if it needs to go back or if he can provide a card or parts for you to replace. It turned out the repair was exactly the parts he suggested but I was reluctant, with a totally dead unit, to tear into the major disassembly required to repair the power supply plus it was time to re-verify calibration although there were no apparent accuracy problems.
jry
Posts: 440
Joined: Fri Feb 06, 2004 3:14 pm

Re: HP 8924C front panel buttons help

Post by jry »

there should only be some chokes on the filter assembly ...iyou may have lost the +5 volt to the keyboard from the processor.

Sounds like the optical sensor /spinner is working but the select button is not

chances are if the keyboard is almost dead than it mostly likely a bad interface chip on the processor. You should be able to scope the connector on the processor and see it the keyboard signal is making it that far.

uses the same processor as the 8920B so you can use the CLIP for that.

Firmware is the only difference on the 8924C and 8920B processor cards .

If you do get another one from an 8924C ( 8924 E uses same board as well ...also different firmware ) make sure you move over the EEPROM with the calibration data.

There was a set of files /images to load the 8924C fimrware from the groups.io board ...takes a 4MB SRAM PCMCIA card ( actually takes two of them but you can probably load the images one at a time ) IIRC

I do have a keyboard for the 8924C as well as most of the other front panel parts in stock. Think all of my processor cards are flashed for the 8920B though.

biggest issue on the 8924C's is that they are built like a battleship and there are ton of screws to remove to get to anything.
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

thanks everyone jry how do i find the groups with the set of files / images firmware thanks for ton for all the info i'll do some testing and get back ,
thanks again for helping
think this thing is awesome svc monitor got to get back up
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

I made up my mind found that Amtronix Instruments, Inc. is 62 miles from me. I talked with Rick he repairs these HP8924C and 8920 s too. I took it to him today. He is doing the repair, also a CAL so it will be in specs when I get it back. I want to thank everyone for the input on my problem with this unit. I really want to thank
JRY for the help he has given me. The repair of this unit was way over my head. LOL beautiful unit but I really was hoping to have it CAL ed to know it was right on the money .
Thanks again jry for your help when I need it. Great guy.
Thanks all
xxx2fan
Posts: 82
Joined: Mon Oct 31, 2005 4:42 pm
What radios do you own?: HT750 Ht1250 CDM1250 CDM1550

Re: HP 8924C front panel buttons help

Post by xxx2fan »

My HP8924C keyboard DCU was bad. Replaced keyboard and keypad assy. Run diagnostics. Unit failed Spec A and receiver. Repace defective receiver synthesizer module. Repair fuzzy monitor. upgrade firmware from V6.33 to V8.04 Calibrate traceable to NIST with full performance evaluation.
Rick was very nice and very reasonable. Amtronix Instruments, Inc. Calibration due 2022 again. Turnaround was within a week. I was close so i could take it and pick up the unit.
Thanks every one here for their help here
I am very happy with the HP8924C POWERON as HP8920
jry
Posts: 440
Joined: Fri Feb 06, 2004 3:14 pm

Re: HP 8924C front panel buttons help

Post by jry »

surprised it had a bad keyboard ...fairly passive device but you may have lost the 5 volt through the cable. May have shorted and blown the trace.

Like Rick I would have just swapped it though. Parts for the 8924X are plentiful right now so even though these a very repairable parts often not worth the effort.

The good thing is that the 892X series has pretty extensive diagnostics so running the RF , Audio and Misc tests gives a really high confidence level in the units operational status.
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