battery sub for testing - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: April 29, 2025, 10:32:57 pm
content: Hi ,I have brought a Schlumberger SI 4031 radio test set non working ,I see it has a varta 2.4v onboard soldered battery , can i hookup a 3.6v lithium thionyl chloride battery up in its place with a couple of 1n4001 diodes in series for testing if the original is flat?,cheers.

author: ME
author_rank: Frequent Contributor
timestamp: April 29, 2025, 10:39:23 pm
content: The battery can be seen here at about 40.36 in

author: jwet
author_rank: Frequent Contributor
timestamp: April 30, 2025, 05:05:25 pm
content: You could use your Li Thionyl plus 2 diodes for a test, but its not a suitable replacement- it won't be charged- it depends on how big the off load is but it will flatten the battery. HP used a circuit like this in their Network Analayzer usually with a battery soldered to the board. If you don't turn them on for a few months, they lose their memory. In active use, they stay charged. If the instrument has been stored for a while, leave it on for a day, it might just come back. The trickle charge is very slow- probably a C/30 kind of rate.2.4V is likely a two cell stack of NiCds. These are usually trickle charged in circuit when the instrument is on as above. These batteries are notorious for leaking and leak caustic stuff. My standard fix is to get the right stack of NiCd in AA or AAA size, put them in a little battery holder and run wires with to the board. I then would double stick foam tape the battery pack in place in some spot like on the back panel, where a leak wouldn't matter much.

author: jwet
author_rank: Frequent Contributor
timestamp: May 01, 2025, 01:35:29 pm
content: That's a beauty. I have an HP4396 Network/Spectrum analyzer of similar vintage that has similar functions. I like this Era of equipment. It looks to be running in your video, are those small problems left? Take care.

author: ME
author_rank: Frequent Contributor
timestamp: May 01, 2025, 04:42:16 pm
content: Its not my vid or unit,i won one on ebay , heres the sellers discription :Schlumberger SI 4015 Stabilock communications monitor.Not working. Powers up ok, as can be seen from photos. Also meter readings a bit haywire when not even measuring.Fails a number of self-tests. A replacement demodulator unit would probably clear most of the tests.https://www.ebay.co.uk/itm/205440758912

author: jwet
author_rank: Frequent Contributor
timestamp: May 02, 2025, 05:00:33 pm
content: Ok, I see- it looked pretty right. The whole trick to this is getting service data. Older HP gear (I also have an HP4195 Network/Spectrum Analyzer) has component level service data freely available. The HP4396B only goes down to board level. Good luck.

author: ME
author_rank: Frequent Contributor
timestamp: May 03, 2025, 02:35:45 pm
content: Well so far i have not meashured the pcb battery as i dont think that is the main issue ,every smd electrolytic cap tests bad for esr,most at 5ohms but a lot at 10+ohms esr, No signs of any leaks tho!, just waiting on new caps to get delivered , Fit those then look to see how its does with the self test.

author: jwet
author_rank: Frequent Contributor
timestamp: May 03, 2025, 08:39:22 pm
content: That's a good start. I assume you've checked all the power voltage rails.