I'm actually having a hard time trying to learn electronics. I've approached local universities, etc. for courses but nothing is there to suit any more. Becoming self taught is the only way open... but I'm aware that if I leave these things until I know more, then it will be too late. As a consequence, I'm shopping for capacitors, etc. having little clue as to what I'm ordering. So I'm very reliant on parts lists from those who have gone before. I do have a Lindy magnetic wipe thingy on the way, which seems a good idea. Also a large notebook, so I can draw the boards and note what capacitors, etc. go where, and what polarisations. Ho hum... it's all in the fun of it, I suppose. I just don't want to make a rookie mistake that wipes out a vintage unit.
I doubt if Universities are the right places for learning practical stuff. Have you tried Colleges, although I did have difficulty finding anything in a quick search. In 1978 I spent a year of afternoons doing an Engineering Industries Training Board course learning about electronics construction during which we built a Mulitmeter, Audio Oscillator, and Power Supply. The most memorable bit was that after spending one lesson working out how big a heatsink we would need for our PSUs in the next lesson we went to the foundry to cast them ! The adjacent classroom was used for the TV repair course, although I doubt if there is much call for that these days. In my searching for you I did find http://hitechtraining.co.uk/electronic-equipment-repair-1/ Five days seems awfully short given the content. I am beginning to think that the lack of courses might explain why the average age at the electronics company where I work is about 55. All the youngsters are learning programming (although electrical installation courses seem to be popular - I guess that can't be outsourced to China) while no one is learning how to solder together an interface lead. Another suggestion which would be more part time would be to do a Radio Amateurs course. That includes lots of electronics theory (in addition to things like licencing condions) and for the intermediate course you actually have to build a project. Many people choose a simple radio. Good luck in your search. I think I have just discovered how much things have changed since 1978 when most people rented their TVs as they broke so often and companies like Granada sent people to college to learn how to fix them. p.s. A bit more searching and I found they still teach electronics in Glasgow. http://www.glasgowclyde.ac.uk/courses/course-finder/hnc-electronic-engineering That is the equivalent to the course I was doing in the mornings. I would expect it to be full of 17 year olds sent by their employers.
Glasgow is a little far away from Sussex ... but good catch. It'll be useful to someone !!! I'm reading up on those course prices and they seem reasonable. It would take a serious chunk out of my wages, but worth it. As long as the timings are flexible enough for me to do them.... then superb. Many thanks for the links.
I am sure there are other courses around (as I suggested a Radio Amateurs Exam Course would be quite a good option). On interest what do you do as a job ? Does it have any connection to technology ?
Yes, I'm an IT "technician." I used to be software, then board level hardware replacement, and now I look after networks, virtual server farms, cloud telephony services, etc. But board level was as far as I went. I.D. which board failed and swap it out... dragging loads of spares from the boot of the estate car, all over various towns and cities. Now, I'm in an office. Radio amateurs course.... I'll look up what's around my area.
Sorry for the delay in replying. I went elsewhere to have a rant about Apple updating my ipad to IOS11 without my permission . The problem with some of the components like BGAs (Ball Grid Array) used in modern products like motherboards is that they are impossible to fit without £1000s worth of specialist equipment. I could write an entire thread on my attempt to fix an ipod touch. I am sure that the original problem was simply a dry joint on a connector. the problem was the connector had a lead pitch of about 0.25mm ! Changing the subject, you might not know that Hugo (Walkman Archive) has the database containing years of repair tips etc from the previous Stereo2Go site which ran on the Hoopla platform. At least one other person has an archive made using a site scraper. The problem is that no one has worked out a way of loading them into this site. I just thought I'd mention it in case you are, or know someone who is an expert in such things. I would understand if you want to stick to analogue stuff outside of work though.
No need to apologise... it's taking time to get all the ducks lined up anyway, and the credit card is crying surrender, until the 4th of Jan when it gets another power pill. Re Apple... don't get me started! I hate Apple, Google, Microsoft... and a few others... for reasons which could easily cause the DBA of this site to receive warnings about data store usage. I have handled databases of various types through the years, and I do know some HTML and PHP, as well as running a few web sites myself, so it is possible that I might be able to have a look and see if there is anything I can do. Hugo from Walkman Archive, if it is the same Walkman Archive I'm thinking of... has probably got my email addy set to direct straight to trash, after I possibly badgered him a little too hard as to whether he wanted to sell one of his PX303 units. I know I recently sent an e-mail enquiring about a HS-P202 that he did have listed for sale, but he didn't reply and I've got the P505 units in the mean time anyway... so I'm unlikely to be able to reach him. But yes, I'd have to do it outside of work. I just happen to set servers off on tasks, and then have a few moments while they complete them, to be able to hit refresh on web sites, before I have to give them their next commands. And some post notification e-mails come straight to my hip, so it can look like I'm 0n-line all the time, but actually I'm not. Well, I'll sling him an e-mail again, and see if he responds. That's the best I can do. It'll probably be diverted straight to the electronic bin... and I can't blame him :-D
The two Hugo's are probably different people as there's been no response to the e-mail. - I've PM'd the Hugo on the forum, to ask if he wants help.
I have some of those threads saved, and some of the rest can be found on the link to Old Stereo2go. Is there anything in particular you are looking for?
Not particularly. Longman picked up that I.T. is my career, and thought I might be able to help Hugo get the threads out of the old Stereo2go site and translated for this new one. So I'm actually just trying to offer some help.
OK - Hugo has been in touch and that part is progressing. However... back to capacitors.... I have had a live chat with a Farnell person and the recommendation is polypropylene for audio work. I went to their site and looked for what was available at 100uF and the lowest voltages are, like, 50v. Just at the point where I'm thinking I'm getting a handle on this, my understanding turns to mush. Also... why were tantilums suggested in one list, and then decided against in a later list? Can anyone shed any light on this please?
A 100uF polypropylene capacitor would be about the size of a small Walkman. 100nF is a more typical value. Don't worry about the high voltage. As the name suggests layers of polypropylene plastic are used as the insulator so it will naturally be high. I presume you realise there is no problem in using a higher voltage capacitor in any position. I found a good guide here http://analogrules.com/capacitors.html
??? Just buy the recommended electrolytics if you want the Walkman to sound the way it was designed! No need to chat with the store, just add the right parts to cart! They are not Walkman specialists! Tantalums were suggested in the past due to space restrictions, but now electrolytics in the right size are easy to find. Any other type of cap will affect the sound!
http://uk.farnell.com/panasonic-ele...j221wp/cap-alu-elec-220uf-6-3v-smd/dp/1973281 http://uk.farnell.com/panasonic-ele...101war/cap-alu-elec-100uf-6-3v-smd/dp/2326086 https://www.digikey.co.uk/product-detail/en/nichicon/UMW0G101MDD/493-15585-ND/2598834 https://www.digikey.co.uk/product-d...tronic-components/ECE-A0GKS221/P954-ND/160534 https://www.digikey.co.uk/product-detail/en/nichicon/UMW0G221MDD/493-15586-ND/2598835 https://www.digikey.co.uk/product-detail/en/united-chemi-con/EMVY6R3ADA221MF55G/565-2411-1-ND/757572
My main problem was that I went by the old list, not knowing that there were new caps around. I had a text chat with someone from Farnell, and he knew that tantilums were not ideal for audio work, and slung some references at me. So it seems reasonable that if something new comes on the market that is better suited for audio applications... then they're going to be the first to know about it. I'm going to use the tantilums to repair the P505 units... partially because I've got them now... (and the credit card has gone off to claim sanctuary until February) and the P505's are learning boards... I'm making mistakes and finding things out... like this morning I found out about using UV blacklight to see trace damage below the coating that the naked eye can't see. What I need now, I need to get from RS and Farnell... I only need to replace the tantilums now and the DigiKey postage and import duties on a small order would be more expensive than the parts!!!
Yes it's true that there are better alternatives to electrolytics in reliability, space, and specs today- in fact, the latest DAP Walkmans proudly claim they use polymer caps like OS-CONs. Even some later slim Walkmans use tantalum caps in the audio path, although these usually do not sounds as good as earlier models with more driving power. The problem is that vintage walkmans were designed with electrolytics in mind (and in fact, limited by them)- replacing with tants and props will work but they can affect the sound in a bad way and should only be used as last resort! The reason why I recommend certain models of capacitors is because: 1. They are identical, or as close to identical as the original caps as possible. You get as close to a new stock unit as possible. 2. They are easy to find, and are not expensive. They are the smallest in the market, which is very important for Walkmans as space is limited! 3. I (and some others) have tested/installed them successfully in many Walkmans (mostly Aiwas). I plan to write a new Walkman re-capping tutorial in the future. Here are some quotes from some old Plop Aiwa threads I archived, when we were both discussing and learning about finding replacement capacitors. I've highlighted some of his important points. As for his notes on new Polymer capacitors, since then I have discovered the Chemicon MVY series, which is my preferred capacitor range due to ideal size, higher ripple current. However, the MVY is only available in limited selection and stores, so I have compiled a list of alternatives from the MVA/MVE range, that to my ears, work just as well. I have tried some larger value Polymers and they work OK, but in most cases I prefer the sound of electrolytics in the audio path. For this reason, I hesitate to recommend them, but you can try them. Since then, The Panasonic KS series and Nichicon UMW series has surfaced, which are even smaller, and come close to the size of some of the 2V originals, making replacement even easier. PLOP: First of all make absolutely sure that all traces of cap juice and crud is off the board on all the components. Use as much sodium bicarbonate and PCB cleaner (I use IPA) to clean this off as is required. If leakage is as bad as you say the acid will have leaked to even some of the least expected parts of the unit. Once you are satisfied it is completely clean, then you will need to check the areas where most of the acid was found for signs of corrosion on the traces. Any traces corroded will need replaced or strengthened. I was very fortunate that none of the traces on my board were affected. YMMV. Also check to see that no other component was damaged eg resistors or ceramic capacitors. I had a couple which were slightly corroded, but they still worked. Any that are badly corroded will need replacing. If any IC chips are corroded, then the PCB is pretty much a write off. At best you may as well keep it for spares. I did also re-tin some connections on the board that looked decidedly dry/oxidised. If you are having volume control issues, check that the pot is not shorted out eg contaminated with acid or cleaning product. You can replace with tants, but they are expensive and on the audio path they may not have the desired acoustic reproductive qualities of their electrolytic equivalent. Be sure to check the polarity. Tants have a tendency to ignite or violently explode if incorrectly installed. I could scan you my user manuals for the JX505/707, let me know which pages you are particularly interested in (I don't fancy scanning the whole manual) There are no free scanned copies of the service manuals available for the JX505 or JX707 on the internet - at least that I've found. PLOP: The Panasonic WX series have the same endurance ratings of 2000 hours @ 85°C too (alas Digi-Key does not stock a WX 47uF value). Incidentally the Panasonic HB series is rated at 2000 hours @ 105°C, but you'd pay more for that. There are some rumours amongst audio purists that higher endurance capacitors don't sound as good. As with a lot of claims by audiophiles regarding capacitors, I am somewhat skeptical about this. The ripple current values will be higher as the voltage rating is greater. I am not entirely convinced, but impedance may just another word used by Chemicon to refer to ESR. There is no mention of ESR in the MVY series, but they do mention it in the MVS series. Testing a few new MVY and comparing against those values may rule it in or out. BUB: Have you found any other small size 220uf 4v caps like the Chemicon MVS series? Those seem to be really ideal in size. PLOP: I've credited you for the Chemi-con 6.3V caps in the guide. These are a better sized cap, and to be honest I'll be ordering these instead from now on too. PLOP: The tantalums are to replace the 100uF 2V caps. Regular 4V SMDs are just too big, and in some situations 4V through holes won't fit in the spaces vacated by the 2V ones. PLOP: Thankfully there are only a few models where you would struggle to fit a 6.3mm diameter 220uF 4V and have to resort to this 5.0mm diameter 220uF 2.5V one as a direct replacement. The PX10/101 is a prime example of this. It uses two 220uF 2V through hole capacitors on the final stage post amplification to block DC, space is limited so there is no chance of using a 4V replacement and using tantalum capacitors could run you into sound quality issues. So for the same price of a tantalum these would be an ideal replacement. PLOP: I am resurrecting this old thread because I am compiling a new order to Digi-Key for more capacitors. Since our previous discussions there have been developments in the technology with a larger number of manufacturers selling a greater range of them. I have also been looking at the previously ordered capacitors and now believe that ripple current should also be taken into consideration when specifying replacement capacitors, particularly where ESR is critical, since the two are interlinked. Not all specification sheets list ESR, but most do list ripple current which kind of helps. Nichicon in particular have enhanced their range of super small solid polymer based capacitors with ultra low ESR rating. Lower than a factor of 20 against some tantalum capacitors and comparable to the lowest. What this means is that in some cases it would make more sense to use these over the tantalum capacitors, especially when costs are considered. http://www.nichicon.co.jp/engl...fpcap_catalog_05.pdf On the basis of above I have review the previously bought capacitors and noticed that the United Chemi-Con (UCC) 6.3V low height capacitors in fact perform poorly in this regard when compared to the newer solid polymer electrolyte based capacitors mentioned above from Nichicon. UCC 100uF EMVA6R3ADA101ME55G : ripple current 55mA, no ESR rating given UCC 220uF EMVA6R3ADA221MF55G : ripple current 88mA, no ESR rating given Nichicon 100uF RFS0J101MCN1GS : ripple current 2.5A, ESR 24mOhms Nichicon 220uF RSL0J221MCN1GB : ripple current 3.2A, ESR 18mOhms I wouldn't write the UCC capacitors off completely, as the 100uf Nichicon is 5.7mm in height compared to the 5.2mm of the UCC, although the 220uF Nichicon is only a mere 4.2mm! Unfortunately Nichicon do not produce a 47uF using the new technology yet. But I did manage to find a slightly better 47uF Nichicon to replace it too, albeit with a height penalty of 5.8mm. UCC 47uF EMVA6R3ADA470MD55G : ripple current 33mA, no ESR rating given Nichicon 47uF UCL0J470MCL6GS : ripple current 160mA, no ESR rating given Panasonic have also brought out a super small diameter range of standard wet electrolyte capacitors too, suitable to replace the smaller 2V capacitors in a 6.3V tolerance. ESR is better than most general purpose aluminium electrolyte capacitors and close to average tantalum capacitors. Component selection would need to be considered as the height on these is 5.8mm, but at least these open up the possibility of not requiring tantalum capacitors especially when DC coupling on the audio path. 100uF EEEFT0J101AR ; ripple current 160mA, ESR 850mOhms 220uF EEEFT0J221AR ; ripple current 240mA, ESR 360mOhms Thankfully there are only a few models where you would struggle to fit a 6.3mm diameter 220uF 4V and have to resort to this 5.0mm diameter 220uF 2.5V one as a direct replacement. The PX10/101 is a prime example of this. It uses two 220uF 2V through hole capacitors on the final stage post amplification to block DC, space is limited so there is no chance of using a 4V replacement and using tantalum capacitors could run you into sound quality issues. So for the same price of a tantalum these would be an ideal replacement.
Thanks Bub. I've speed read it, and it sounds great. I'll re-read slowly tonight when I get back home from work. One of the questions on my mind, is potential to leak. I am going through so much grief with the P505 board, that I don't want to do this job repeatedly. In other words, I don't do soldering regularly... I do a project, and might not touch an iron for months, so I don't keep my skills up, and thus I'm more likely to damage something. I think that one thing I'd like to know, is the trade off between sound quality and cap reliability. For new caps, that might not yet be a known factor. What are your thoughts on this please?
Modern capacitors have improved reliability ratings compared to the old 80s types, when SMD caps was new. If you're worried, buy through hole caps such as the Panasonic KS. But even then the chances of leakage is very low, it will likely stay good for the next 30 years, and then we'll have different things to worry about, like unobtanium pinch rollers. Tantalums and Props fail too, but they fail for different reasons. See Nak Orange Cap disease. For sound quality reasons I would highly recommend NOT to use tants in your P505. It's potentially a very good sounding unit. I've repaired a few of this series, look out for weak traces. The PX303 is another matter as I do not own one but know that it uses 470uf, a very rare value. The UMW should be a drop in replacement IF the diameter is same, and I believe it is the same size as the polymer Plop used to recommend. You must measure!
