Advice on gaining troubleshooting skills - Page 1
Forum section: electronics / repair

author: diegoperez
author_rank: Contributor
timestamp: August 15, 2015, 10:41:16 pm
content: Hi, just a quick question,I'd like to gain some skills in electronics repairing. Therefore I thought of buying some old and for parts repair hp test gear on ebay so as train myself. Since those equipments usually are well documented (detailed service manuals (SM) are easily available) this should make the process more guided.I wonder if it would be a good idea to begin with something like this?http://www.ebay.com/itm/HP-5334A-Universal-Frequency-Counter-/261999050933?hash=item3d005c40b5which according to the SM page3-49http://literature.cdn.keysight.com/litweb/pdf/05334-90044.pdf?id=722710is an interprocessor handshake failureThanks for helping! Any advice, comments or suggestions will be appreciatedPS, My current lab equipment are some DMM, an analogue 2ch-scope, a function gen and some PSU.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 15, 2015, 10:54:58 pm
content: I don't know much about troubleshooting but I have the same equipment as you. I have found when troubleshooting things a digital oscilloscope would be very useful. Digital scopes can single shot capture things and that is what you need for troubleshooting. You can still troubleshoot with out one it is a lot more difficult and limited.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 15, 2015, 11:02:14 pm
content: Practice and study are the only good ways to develop skills. What works best depends on you. The TE you are proposing to start with is relatively complex. You may have to learn a lot before you make progress. Some people find these long intervals without reward daunting, others thrive on it. If you are one that needs more frequent demonstrations of progress you may want to start with simpler items. Vintage AM and FM radios are simple, and often have schematics pasted inside, or available on the internet.Whatever way you choose to go, dive in and do it.

author: tautech
author_rank: Super Contributor
timestamp: August 15, 2015, 11:49:36 pm
content: Quote from: Aodhan145 on August 15, 2015, 10:54:58 pmFor example most DSO's include a counter the OP thinks he needs.While handy, frequencies of interest can be calculated from a waveform on an analogue CRO.Basic understanding of themanybuilding blocks in electronic circuits has been the most valuable thing for me, then use of what gearyou havein whatever manner to confirm correct circuit operation.

author: wn1fju
author_rank: Frequent Contributor
timestamp: August 16, 2015, 01:23:42 am
content: While HP and Tektronix vintage gear are your best bet because of their service manuals, be wary of models with specialized hybrid ICs. Always scan through the parts list before buying something. Failure of those ICs can spoil your whole day. Might I suggest you start your repair career with some of the older HP single or dual power supplies. Three reasons: 1) you can never have enough power supplies, 2) they mostly use standard obtainable parts and 3) you will gain experience in understanding power supplies which you will find probably account for 50% (or greater) of the repairs of broken equipment you'll find on eBay.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 16, 2015, 02:28:35 am
content: Quote from: Aodhan145 on August 15, 2015, 10:54:58 pmI've done an awful lot of troubleshooting over many years,& the number of occasions when it would have been useful to "capture" things is vanishingly small.

author: singapol
author_rank: Frequent Contributor
timestamp: August 16, 2015, 06:26:01 am
content: Quote from: diegoperez on August 15, 2015, 10:41:16 pmThis is just me rambling...based on what I have read about tektronix scope being junked just beacause...of a component.HP5334 was a serious piece of counter hardware but it's a boat anchor because of it's size.A more compact vintage would be HP5315/6. What test gear you have is more than sufficient to handle thiscounter.Of course it helps if you understand the building blocks/function that make up this hp5534.The failure you described " interprocessor handshake failure" may sound complicated actually meansduring startup and selftest it failed to read a certain memory which it needs to initialise. I post linkrefering to the 4 types of memory in HP5334:http://www.keysight.com/en/pd-5334A%3Aepsg%3Apro-pn-5334A/100-mhz-universal-counter?cc=SG&lc=enghttp://www.keysight.com/main/techSupport.jspx?cc=SG&lc=eng&nid=-536900193.536897949&pid=5334A%3Aepsg%3Apro&pageMode=OVThere is one memory that is battery backed cmos memory and as usual the battery is dead because of age. Now what the tekkies do is to buy new unit and copy contents ( just last turn on/current instrument settings /calibration) but some do surgery to replace the lithium battery in the original memory saving the hassle of reprogramming the new one.Nonetheless the battery will wear out and the process is repeated.Let's just hope it's this cmos memory that is out of commision.The fact that it can do self test means it's processor memory is intact ( processor rom). Anyway if you can get it to work you can always resell it to fund another piece of test gear for your learning. I believe you can do a recal if you don't want to reprogram the memory but just insert a new cmos memory or is it a simple case of replacing said battery like the lithium battery like that of computer motherboards.Good luck.

author: eas
author_rank: Frequent Contributor
timestamp: August 16, 2015, 06:28:28 am
content: Quote from: vk6zgo on August 16, 2015, 02:28:35 amI've only done a little electronics troubleshooting over the last year, and I've found being able to capture single-shot activity with a DSO useful when starting to debug digital communication and checking bench power supplies I'm refurbishing for proper power-on behavior, etc. In some cases, I might be able to get things to repeat at regular intervals so I could watch on an analog scope, but that would take added effort I'd rather put into figuring out what was wrong and fixing it.I've found troubleshooting bench older power designs and HP power supplies to be a good starting point for me.I've been fixing (and breaking) things my whole life, and I've found the general cycle is to observe the improper behavior, then start putting it in context of the overall system, then use that perspective to look more closely at the behavior, perhaps trying to perturb it, and drill in more deeply to the relevant areas of the system. The Power Designs and HP service manuals I've looked at have a good Theory/Principle of Operation section to help you understand the overall system. Its probably worth printing out the relevant sections (block diagrams, schematics, layouts, etc) so you can spread them all out in front of you to refer to as you read through. Make note of test points and expected values if they aren't already marked.

author: diegoperez
author_rank: Contributor
timestamp: August 16, 2015, 12:48:03 pm
content: Quote from: CatalinaWOW on August 15, 2015, 11:02:14 pmOk, I also think it would be too much to begin withQuote from: wn1fju on August 16, 2015, 01:23:42 amThat's a good ideaQuote from: singapol on August 16, 2015, 06:26:01 amAnd finally, just an aside question regarding the document referenced byvk6zgosingapol previously (http://www.keysight.com/upload/cmc_upload/All/5334A.pdf?&cc=ES&lc=eng) : How is it possible to have a ROM memory volatile, and a RAM non-volatile? Is this an errata in the document?Thanks for the feedback!

author: singapol
author_rank: Frequent Contributor
timestamp: August 16, 2015, 06:07:56 pm
content: QuoteThe article decribe it as battery backed ram so it's volatile.

author: mazurov
author_rank: Frequent Contributor
timestamp: August 16, 2015, 06:16:52 pm
content: A counter is not very useful for the beginner, you won't learn much from either fixing it or while using it later. Get an old spectrum analyzer instead, like 8565A. They are easy to fix and there is plenty of spares. Sellers are giving up on getting rid of complete units. They are now taking working instruments apart and attempt to sell pieces - you no longer need to pay $70 shipping when all you need is a first mixer :-).

author: vk6zgo
author_rank: Super Contributor
timestamp: August 17, 2015, 07:22:27 am
content: Quote from: diegoperez on August 16, 2015, 12:48:03 pmSorry,that wasn't me---don't know who it was!

author: Stonent
author_rank: Super Contributor
timestamp: August 17, 2015, 02:22:13 pm
content: Troubleshooting is a skill that can transcend technologies. It's a matter of always being able to see what happens next. Whether it is a computer that won't boot because of a software issue, debugging programs, a chemical reaction that fails or electronics.I like to start from the outlet (mains) and work inward.

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 17, 2015, 05:53:19 pm
content: Counters are kind of eh. Unless you have a specific need they don't get used much.HP and Tek are good choices, but you probably want to pick something that's useful and not too complicated. HP power supplies are great. They're cheap, easy to fix and very useful when you're done. Tek 465s are good too. They're fairly complex but still fixable without processors to get in the way. Sellable or usable after you're done too.A Tek 454 makes a nice project, all discrete except for a couple of nuvistors (or not, depending on the vintage).If you have a specific area of interest, look for equipment in that category. That will help keep you motivated when you get stuck.