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HP 5342A processor board
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Jim
Hi,
I am repairing a 5342A counter that has a bad A14 processor card. I have traced the problem to the CPU board by trading cards with a known good unit. Are there any common failure modes with this processor assembly? EG CPU failure, ROM failure? The processor is a socketed MC6800L and there are three soldered ROMs. Is there anything special about the "L" revision of the 6800 other than the ceramic/gold package? Thanks in advance, JIm N8ECI |
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Didier Juges
Jim,
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Have you tried the obvious of pulling and re-inserting the CPU and ROMs (and any other chip on socket)? My 5370A has needed that treatment at least 3 times, in spite of Deoxit ProGold. Each time it's been a different chip. I have had problems on on the ROM card (twice) and the last time on the CPU card (with a little PLD, probably used for address decoding). The fix is simple, simply pulling the chips and putting them back fixed the problem, but the last time I put some Deoxit on the chips of the ROM card and the ROM card seems to be working solid now. I have had a similar problem with a Marconi sweeper, but none of the other HP gear I have has given me these problems. Maybe it was a bad batch of sockets? Didier KO4BB Jim wrote: Hi, |
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Jim Miller
--- Didier Juges <didier@...> wrote:
Have you tried the obvious of pulling andHi Didier, Thank you for the suggestion! I had already tried removing/reinserting the CPU which is the only socketed chip. I had even painted its legs with deoxit gold before reinsertion. Several iterations of remove/reinsert produced no results. I am getting clock signals on the test points and the RESET line looks as it should which is why I am suspecting CPU or ROM failure. Jim N8ECI __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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DON CRAMER
Many years ago with microcomputers which came with low quality sockets, I had an assembler remove the sockets and solder the ICs in directly. That eliminated intermittent crashes in some 24/7 applications we were using them in. Something to consider in the general case.
Don Cramer Beaverton, OR From: Didier Juges <didier@...> Reply-To: hp_agilent_equipment@... To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] HP 5342A processor board Date: Mon, 18 Dec 2006 12:13:01 -0600 Jim, Have you tried the obvious of pulling and re-inserting the CPU and ROMs (and any other chip on socket)? My 5370A has needed that treatment at least 3 times, in spite of Deoxit ProGold. Each time it's been a different chip. I have had problems on on the ROM card (twice) and the last time on the CPU card (with a little PLD, probably used for address decoding). The fix is simple, simply pulling the chips and putting them back fixed the problem, but the last time I put some Deoxit on the chips of the ROM card and the ROM card seems to be working solid now. I have had a similar problem with a Marconi sweeper, but none of the other HP gear I have has given me these problems. Maybe it was a bad batch of sockets? Didier KO4BB Jim wrote: Hi,traced the problem to the CPU board by trading cards with a known good unit.failure, ROM failure? The processor is a socketed MC6800L and there are threesoldered ROMs. Is there anything special about the "L" revision of the 6800 other thanthe ceramic/gold package? |
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Didier Juges
Jim,
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There is a possibility that one of the ROMs might be bad. You may be able to get the code from Blue Feather Tech and burn new ROMs. If the CPU is getting it's clock and the reset is good, you should see the CPU clocking away at random code, pretty much continuously and if so, the address lines will have lots of digital garbage on them. If the address lines don't move, the CPU is toast. I have a defunct Tek 7L5 CPU card, the processor is a Tek 155 0198 00, which I believe is a 6800. Someone on the list may be able to confirm. It is in a socket, so if you need the chip, let me know. Didier Jim Miller wrote: --- Didier Juges <didier@...> wrote: |
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Didier Juges
Good point, I guess with 20 years old gear, you are not worried about having to upgrade the software :-)
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I am seriously thinking of doing that with my HP 5370A if the problem comes back. Alternately, I could put in good quality machined sockets, those in there right now look downright cheap. Didier DON CRAMER wrote: Many years ago with microcomputers which came with low quality sockets, I had an assembler remove the sockets and solder the ICs in directly. That eliminated intermittent crashes in some 24/7 applications we were using them in. Something to consider in the general case. |
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I would replace a supect socket with a good quality one rather than solder the IC in. If the IC is bad, it just means more work and possible damage to remove it again.
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-Dave -------------- Original message --------------
From: Didier Juges <didier@...> Good point, I guess with 20 years old gear, you are not worried about having to upgrade the software :-) I am seriously thinking of doing that with my HP 5370A if the problem comes back. Alternately, I could put in good quality machined sockets, those in there right now look downright cheap. Didier DON CRAMER wrote: Many years ago with microcomputers which came with low quality sockets, I |
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