HP-53131a fails FRN end in self test - Page 1
Forum section: electronics / repair

author: gfiber
author_rank: Contributor
timestamp: February 27, 2015, 09:33:17 pm
content: I have an opportunity to purchase a non functioning HP-53131a frequency counter. The seller wants nearly $500.00 for it and the counter exhibits a message during the self test FAIL: FRN end. I am asking if any of you HP-53131a owners have seen this message and what the cause may be.A quick glance through the HP service manual suggests it is a front end failure. To me this could easily mean someone whacked the counter with several watts of RF or to high input voltage. HP says it could be the main board or AC power supply.I would like to have one of these counters but hate to spend this kind of money to find out I need more very costly repairs such as a main board. Exchanging a component to even a few would be acceptable.Thanks for any insight you may be able to provide.Gary K8IZ

author: HighVoltage
author_rank: Super Contributor
timestamp: February 28, 2015, 03:39:53 pm
content: I am not sure what the error is. But for that price you will find a working 53131A. Unless the one offered to you has the 3 GHz option and the ultra stable timebase, the price seems too high. I paid $ 800 about 2 years for one with all options installed and in like new condition.Sometimes they are easy to repair but sometimes it takes a lot of effort.I would start with testing all the voltage rails.

author: gfiber
author_rank: Contributor
timestamp: February 28, 2015, 05:54:50 pm
content: Hi Highvoltage,Thanks for the advice. This person has two on ebay one is a HP-53131a and the other is a HP-53132 both apparently exhibit the Self Test failure and FR END error. I asked if he would drop down the price, he did but to me it is not enough to take a chance. Reading the HP literature all it says is a possible motherboard or power supply Except of the unit passes the Self Test but fails a specifically asked for FR END test the counter is likely ok. I suspect this person powered it up and just allowed it to do the self test and experienced the FR END failure during that test which could mean lots of troubles. I asked here as after reading this eevblog forum, you folks are always fixing some fault in a broken piece of the test gear to make it work again. Thought if anyone had seen this issue in the past it would likely be on here or the yahoo HP/Agilent group.Neither unit have any accessories like a 3 GHz option or High Stability time base. I already have a Philips PM 6676 that does 1.5 GHz and seems to work nicely. I have it connected to a Trimble Thunderbolt running through a modified video distribution amp with 5 other pieces of test gear, soon to me 6 when I connect up the Siglent SDG1025 also. I always want something just a bit better it seems. I'll save up for a working HP-53131a if I still want one later, looks like a very nice piece of equipment..

author: free_electron
author_rank: Super Contributor
timestamp: March 01, 2015, 04:46:05 am
content: FRN errors means the front end is fried. typically the first stage amplifier is dead. the schematics are avaialble. should be fixable. they do use some Agilent made HEMT's ( high electron mobility transsitors) but you can find those on ebay.

author: KJDS
author_rank: Super Contributor
timestamp: March 01, 2015, 04:59:34 pm
content: I'd want a working one for that price

author: gfiber
author_rank: Contributor
timestamp: March 02, 2015, 02:04:32 am
content: Thanks for the insight Free_Electron,This seller wants $449.00 for the 31a and $419.00 for the 32A in a buy it now sale. He did drop some on the 31a but still to much in my mind for a possible pig in the poke. I figured $200.00 as my max for a broken counter. He probably has to much in those counters to be able to drop to much. So in a couple of months if I still want a HP 53131a counter I'll look again.Some of the prices on broken equipment seem a bit much to me though there are plenty of you tube videos showing some of it is a pretty simple fix and the sellers know that I suspect.

author: idpromnut
author_rank: Unknown
timestamp: March 02, 2015, 05:09:07 pm
content: Quote from: gfiber on March 02, 2015, 02:04:32 amI have my eyes on those two units as well; I threw an offer on the 31A and got a counteroffer of 425USD. Hardly a "deal" for a broken unit. I find that sellers (who don't even well describe the problems with the units) merely price a "broken" unit (even if it is a case of being unable to test it) at a significant percentage of a known working unit.

author: gfiber
author_rank: Contributor
timestamp: March 26, 2015, 08:45:45 pm
content: I found on Ebay an operational HP-53181A for $525.00 plus shipping. Have the 3GHZ prescaler ordered from Poland and one of Gerry Sweeney's timebase boards.Though I will likely use it connected to the Trimble Thunderbolt most of the time, having a good timebase allows it to be accurate when using it portable.

author: VK5RC
author_rank: Unknown
timestamp: March 26, 2015, 10:56:30 pm
content: I have a 53131 with the non-hp 3ghz option and mine works well and is slightly more sensitive than specified, a review of the 3ghz prescaler is on the signal-path youtube site, a good value non hp oxco is also available, dave reviewed it a month or so ago.

author: gfiber
author_rank: Contributor
timestamp: March 27, 2015, 10:11:30 pm
content: Hi VK5RC,The prescaler that was built buy the same person as reviewed on the Signal-Path site is the one I have ordered.Gerry Sweeney has built and shipped to me a timebase designed by him. I will have to take a look at Dave's oxco review.