Re: [time-nuts] Lab upgrade
The fault was found by somebody with a heck of a lot more experience than yours truly. Turns out the 5v regulator had shorted out, a protection diode did it's thing and popped the fuse protecting the rest of the system. J. On 29 Jul 2015 2:49 am, Robert LaJeunesse lajeune...@mail.com wrote: One of the cheap and dirty ways to find a short is current tracing. Use a voltage and current limited source and a matching detector to find where the current flows. I've used a current limited DC supply as the source and, for the detector, an old DVM with 10uV resolution. For an AC approach a simple audio oscillator (or function generator) works nicely as the source, while a the detector starts with an audio playback tape head (from an old VCR), then some sort of amplifier-speaker, or maybe just an oscilloscope. If you are lucky you have an old HP logic pulser and current tracer set that do the same thing... Bob L. ... I'll buzz out the pins on the connnector there and see if I can find the probably short and let people know. Cheers Jason ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lab upgrade
One of the cheap and dirty ways to find a short is current tracing. Use a voltage and current limited source and a matching detector to find where the current flows. I've used a current limited DC supply as the source and, for the detector, an old DVM with 10uV resolution. For an AC approach a simple audio oscillator (or function generator) works nicely as the source, while a the detector starts with an audio playback tape head (from an old VCR), then some sort of amplifier-speaker, or maybe just an oscilloscope. If you are lucky you have an old HP logic pulser and current tracer set that do the same thing... Bob L. ... I'll buzz out the pins on the connnector there and see if I can find the probably short and let people know. Cheers Jason ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lab upgrade
Ok - not so bad. One of the 250v 5Amp inside the case blew on the 10v line. Now to work out why... J. On Sun, Jul 26, 2015 at 1:05 PM, Jason Ball ja...@ball.net wrote: Recently I've been on the hunt for test gear so facilitate moving up into the microwave bands (ham radio), accurate timing being one of the basics to be sorted. As part of this I've recently acquired a HP 5335A with OCXO and HP5350B microwave frequency counter, both picked up today. I've setup a test stack using a stanford research function generator and my existing HP 5384A counter to compare all the kit, it was nice to see everything lock in within +5Hz @ 10MHz using only the internal reference. I'll have a GPSDO running in a couple of days to provide an external reference as well. Unfortunately after running for 15 minutes the HP 5335A literally went 'clunk' and now has no display which is disappointing as I wanted some of the measurement functions this unit provides. There's no odd small (for an old system) so I'm hoping its a reasonably simple problem, I'll open the case tonight. Does anybody have any experience with issues on the HP 5335A's ? Cheers j. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lab upgrade
And I have seen them without scorch marks - the tatalums are especially prone to failing with a dead short. Use an ohmeter to confirm that the 10V is shorted to ground and then use a soldering iron and lift one leg of the cap until you find it (them all). 20-30 years is about the magic number. I am also into electronic music and lots of people just go ahead and re-cap an instrument if it is that old - cuts the hassle-factor by several orders of magnitude. Dave -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Sunday, July 26, 2015 14:07 To: ja...@ball.net; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lab upgrade Hi Look for electrolytic / tantalum capacitors on the 10V rail with scorch marks.. Bob On Jul 26, 2015, at 12:59 AM, Jason Ball ja...@ball.net wrote: Ok - not so bad. One of the 250v 5Amp inside the case blew on the 10v line. Now to work out why... J. On Sun, Jul 26, 2015 at 1:05 PM, Jason Ball ja...@ball.net wrote: Recently I've been on the hunt for test gear so facilitate moving up into the microwave bands (ham radio), accurate timing being one of the basics to be sorted. As part of this I've recently acquired a HP 5335A with OCXO and HP5350B microwave frequency counter, both picked up today. I've setup a test stack using a stanford research function generator and my existing HP 5384A counter to compare all the kit, it was nice to see everything lock in within +5Hz @ 10MHz using only the internal reference. I'll have a GPSDO running in a couple of days to provide an external reference as well. Unfortunately after running for 15 minutes the HP 5335A literally went 'clunk' and now has no display which is disappointing as I wanted some of the measurement functions this unit provides. There's no odd small (for an old system) so I'm hoping its a reasonably simple problem, I'll open the case tonight. Does anybody have any experience with issues on the HP 5335A's ? Cheers j. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lab upgrade
Hi Look for electrolytic / tantalum capacitors on the 10V rail with scorch marks…. Bob On Jul 26, 2015, at 12:59 AM, Jason Ball ja...@ball.net wrote: Ok - not so bad. One of the 250v 5Amp inside the case blew on the 10v line. Now to work out why... J. On Sun, Jul 26, 2015 at 1:05 PM, Jason Ball ja...@ball.net wrote: Recently I've been on the hunt for test gear so facilitate moving up into the microwave bands (ham radio), accurate timing being one of the basics to be sorted. As part of this I've recently acquired a HP 5335A with OCXO and HP5350B microwave frequency counter, both picked up today. I've setup a test stack using a stanford research function generator and my existing HP 5384A counter to compare all the kit, it was nice to see everything lock in within +5Hz @ 10MHz using only the internal reference. I'll have a GPSDO running in a couple of days to provide an external reference as well. Unfortunately after running for 15 minutes the HP 5335A literally went 'clunk' and now has no display which is disappointing as I wanted some of the measurement functions this unit provides. There's no odd small (for an old system) so I'm hoping its a reasonably simple problem, I'll open the case tonight. Does anybody have any experience with issues on the HP 5335A's ? Cheers j. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lab upgrade
Thanks for that Bob. From the circuit diagram the path to ground appears to be on either the 3v the 5v lines that are fed via this fuse. When I disconnect the power supply from the rest of the system the fuse doesn't blow which suggests the fault is in the logic board, of course it could simply mean that connector completes the circuit. I'll buzz out the pins on the connnector there and see if I can find the probably short and let people know. Cheers Jason. On Mon, Jul 27, 2015 at 7:06 AM, Bob Camp kb...@n1k.org wrote: Hi Look for electrolytic / tantalum capacitors on the 10V rail with scorch marks…. Bob -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Lab upgrade
Recently I've been on the hunt for test gear so facilitate moving up into the microwave bands (ham radio), accurate timing being one of the basics to be sorted. As part of this I've recently acquired a HP 5335A with OCXO and HP5350B microwave frequency counter, both picked up today. I've setup a test stack using a stanford research function generator and my existing HP 5384A counter to compare all the kit, it was nice to see everything lock in within +5Hz @ 10MHz using only the internal reference. I'll have a GPSDO running in a couple of days to provide an external reference as well. Unfortunately after running for 15 minutes the HP 5335A literally went 'clunk' and now has no display which is disappointing as I wanted some of the measurement functions this unit provides. There's no odd small (for an old system) so I'm hoping its a reasonably simple problem, I'll open the case tonight. Does anybody have any experience with issues on the HP 5335A's ? Cheers j. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
