Six Common Mistakes Made When Recapping Vintage Electronics
2024 ж. 12 Мам.
454 411 Рет қаралды
Short little video on common mistakes seen when recapping (replacing capacitors) vintage electronics. This would include vintage stereos, radios, equipment, CBs, ham radio receivers & transmitters, calculators, computers, you name it.
Hopefully this will provide you some tips and hints to use when you go to recap your piece of vintage gear.
Topics include:
- Mistaking Factory Glue for Leaking Capacitors
- Factory Boards and Manuals Marked Wrong
- Capacitors Installed Incorrectly
- Using Larger Capacitors Than Specified
- Buying Electrolytic Capacitors off Ebay
- Replacing Everything at Once
And the number 1 mistake... failing to pull out your cell phone and take a few pictures before you start pulling out capacitors.
Didnt make that mistake with caps on an old valve amp, but i did with the resistors, both photos and thinking 70 year old resistors have same tolerances as new stock. Caps worked well an improved operation. I destroyed the project by replacing resistors...😢 (only a hobbist, not classically trained)
As a retired electronics tech I can say that this is good advice. I've subscribed because your video is clear & succinct and not padded out to 30 mins like many others do.
Nice video. Seeing gear with surface mount PCBs considered “vintage” makes me feel old.
If you're recaping really old stuff (20's and 30's era), capacitors had a lot of internal conductance that was accounted for in the original circuit that new capacitors don't have. You may need to add a resistor in parallel to keep the circuit 'in tune', and guessing the size of that resistor is really just a guess.
That's what I did when I reccaped my Victor RE-45. It works amazing. That's a very good advice for people who don't know.
Interesting 😮
Two important issues when recapping with a higher value; 1. never do this with starting capacitors in motors, they need the exact right value. 2. Recapping with a much larger value in a power supply can cause damage to the bridge rectifier, because the current peak when staring up, is much higher then. An other important issue is the temperature which is mentioned on the capacitor. The switching power supplies before the 1990's often used capacitors, marked with 85°C. This was also one of the reasons of the caused problems. Always use 105°C capacitors for switching power supplies!
"Trust what's on the board not what's in the manual..." Ha yes! I write code for a living. One of the first things they taught us was it maters what the computer does - not what the manual says. Great video thanks for posting it!!
Not "Good Stuff". This is "GREAT STUFF". Informative, concise and pragmatic. Bravo Sir!
Great video and full of info. Had VCR many years ago with Alzheimer's. Sometimes responded to controls sometimes not. After hours of troubleshooting and consultation with others in the biz, turned out it was an adhesive foam pad (several) on bottom of circuit board between it and metal bottom of machine. After removing pads found affected traces in different states of degradation . The adhesive had eaten into traces and was semi-conducting between them, thus the Alzheimer's symptoms. No clue until pads actually removed to see damage. Rock solid after repair. Do not underestimate any "material" on a board to cause trouble.
Great advice!! I'm guilty of the shotgun approach because I wanted to listen to my vintage receiver right away. More than once, I spent more time trying to figure out where I went wrong with my DMM, hooking up my DBT, reading voltage/current values through everything and trying to read the blurry values from a scanned service manual, playing the AM/FM tuner, hooking up a turntable and using the phono/EQ board, etc. etc. You get the idea. Take your time. Do one section at a time, and then test your receiver. Another piece of advice is pay attention to the orientation of new transistors vs. old ones. Some older transistors tend to have EBC instead of a more modern ECB.
What's nice about troubleshooting stereo equipment is that the channel that is in good working order can be a good reference for measurement comparisons. Hard to find problematic components can be detected this way. Just make sure that your reference input signals are exactly the same for the left and right channels. An oscilloscope can also be an excellent visual aid to compare for abnormalities in the defective channel.
One thing I would add, having worked on computer monitors in the past ( 25 years ago) some brands had that hold down glue that would over time become unstable from heat and age and become conductive on the board. We had to scrape it all off and clean the board really well.
AKA, Sony Bond. It affects all kinds of electronics. If it starts to turn dark brown or darker, get it off the board.
That's a great point.!!, I too have seen glue become conductive and cause many problems in TV's.
lol yeah the white glue is okay most of the time, but that transparent stuff is nasty. Another fun one are those fancy looking motherboards with chipset coolers that have stickers/decals on them... those come loose over time because of heat and get trapped in the fans.
KRK monitors had some black stuff where the liquid would seep out and cause corrosion, the rest of the glue became brittle. Have to remove that and hopefully before components are so wrecked you can;t even see what they were
@@Joetechlincolns is that still common? Thanks
That glue when it turns brown, instead of yellow, is actually CONDUCTIVE. Especially if it is near something that is starting to corrode. I've fixed many malfunctioning electronics just by chipping that glue off. When it turns brown it becomes brittle facilitating this.
In the past I had resolved CPU problems as well due to the heat sink compound getting on the CPU pins or on the visible CPU circuit. Wiped off the compound on those pins or other contact points and the computer worked fine then..
It next turns corrosive and eats the legs off components it’s in contact with.
@@porkchop3656 Yes acid (or caustic soda or other)
This is great advice. I definitely see these same issues when recapping. Thanks for putting this out there!
Thank you for putting the time into this video and helping keep us all safe.
This video is great, common sense and we'll worth watching! That shotgun tip is solid gold, I kind of had that one worked out already but to have it confirmed by an expert is really satisfying, the same for the rest of this excellent video...thanks!
This is a really great video! Thank you. It comes from someone that has a lot of experience, and I appreciate you sharing your knowledge. Thank you!
I particularly liked the point that there are factory mistakes as I have found several over the years but did not know about mistakes in service manuals nor was I aware of silk screen mistakes on circuit boards. Thanks for the info.
Good info...as always. Been needing to recap the power supply of my cassette deck. So very helpful.
Glad I caught this, recapping some old stuff, soon a 70's Pioneer, this is going to save me some head aches.
I just learnt so much from this short clip. I just dismantled a 1970s JVC amp to repair. I’m so glad I haven’t started on removing parts.
Very good info from years of experience! The best kind. Thank you. You have brought to mind things I wouldn't have thought of until after.
Nice tips; the last one indeed is the best. Regarding polarity mistakes, I've seen once one board with some pen corrections.
Wonderful! Back 2 Basics will never go out of style. Thank you
Thanks you so much, You gave answers to a lot of questions I "had" before I watched this. I feel much more comfortable recapping my old Luxkit A3000 and A3032 after I watched this.
excellent video! I am learning as I go and your videos are very helpful! Thanks for your efforts and contribution to the hobby!
Great common sense info. I got caught on the last item in your list when I recapped a Hallicrafters s-86. Won’t happen again! Thanks for producing videos like this one. I enjoy your channel very much.
Very informative video not only for newbies but for experienced ones too. Great guide. Love you man and thanks.
These are the types of videos that help me the most. That cover all types of electronics not just radios and such. I repair vintage and modern electronics, mostly test equipment and industrial electronics. A lot of motor drives, PLCs, and a lot of automation control equipment. I do see a lot of 1980s equipment that is still in service so I recap and repair a lot of stuff like that… And these are the videos that help me the most. Although I do enjoy radio repair, I don’t do it very often so these general subject videos that cover a broader range of electronics are extremely helpful!
I really appreciate this video with the explanations and advices. I think every electronic technician should keep this in mind always to proceed any repair. I wrote all in my notebook! Thank you! Best Regards!
Excellent video. Lots of stuff there I hadn't considered before. Good point about the board errors.
That was my post you featured in relation to the Sansui 9090 power supply polarity markings in the video, pretty cool, Thanks! 😎👍
Same as Storm 1 below - your video just popped up, but I'm glad it did as I found your video to be very informative and interesting - thankyou for posting it
Great tips, excellent video. Even guys that work on equipment regularly can get benefit from watching this. I learned something here thank you.
Some great points to take into consideration. Thanks for the video.
I am preparing to do some repairs on my Tascam M-30 and Teac Model 5 mixers. This is a great list of things to know and I'm grateful to learn these tips before I dive in.
Outstanding advice, my friend.
Thank you sir. Excellent video and tips especially taking the one section at a time approach.
Nice video! I use to snap a bunch of pictures of the PCBA before I start working. Nice way to keep track of orientations, values, and such. It has saved me a few times with bad PCB polarity markings as you showed here.
Thumps up Often I take pictures with my wirless phone. And every time I mark the capacitor (and the orientation from connectors). I use often diffenrent colours. I mark capacitors on top and at the PCB with a small dot.
Great advice. Very enlightening. Thanks for sharing the information!
Great tips and the reason I watched this is I have a sansui 7 receiver like what you showed. Some day I may need to repair it but so far it still works great since the day I bought it in the mid 70’s. Thanks
Very vital information when replacing caps.in vintage equipment. Thank you
"Smooth, rounded, flow. Smooth, rounded, flow. Smooth, flowing, stuff." I meditated and achieved internal peace there, what a voice! :D
Awesome tips, especially the one on the shotgun approach. Thank you!
Thanks for the flag up on the potential issues with board markings and service manuals. I've come across it myself, so what I always do is photograph what I'm about to remove and always refer back to the photo when I'm replacing.
Never seen your videos before, this popped up, I do a lot of vintage re-capping & I learned some good lessons here, especially the shotgun approach info :)
Right? That tip alone was firmly worth the time for the vid. It's deceptively obvious now, but I can imagine falling into the trap otherwise!
man these are awesome tips!! i'm subscribing to this channel so freaking hard. thanks man
Excellent presentation. I learned a lot. Thank you!
thanks for the insight of your experience, no wonder i followed through my amplifier’s service manual , even looking at the board themselves, and just to fry out poping my capacitors eventhough i believed i had done everything correctly. As much as i love my amplifier, taken extra care and steps , sometimes things happens.
Good tips -- especially the last one!
I have been working on vintage electronics for most my 60 years. and your video did make me think of a few things I had not considered. I often take a photo of boards to use as reference when recapping etc. Often a wire might break from moving things around and you are scratching your head where it came from.. And recently it came up that going too high in capacitance and voltage even in a power supply can be a mistake.. filter design depend also on resitance and inductance loads.. and even a supply is partly a filter.
Learning this for vintage studio equipment. THANKS
Just the tip on marking the orientations on the tops was worth the whole video!... lots of great tips..... Thanks!
I've also experienced improper markings on Marantz gear. Very good advice for all techs. Thank you.
It is really valuable author' advice with markings. Simple and clear. Also not bad idea today is to make sharp photo of board (with flash) with parts and connections in original placement. And to study original schematic for tracing damages - this saves unnecessary replacements which do not help and degrade overall condition .
Nice to see this! Many defend that a recap should always be done, regardless.
thank you -very good video and excellent tips. makes a lot of sense regarding doing 1 at a time and testing.
Amazing tips!
I thought I was pretty foolproof in identifying component glue, but in your example picture I would've been convinced that the upper right and lower left pics were leaked electrolite. I work in electronics and am working on getting into restoring (and in some cases modernizing) antique radios as a hobby, so videos like these have been good for picking up on stuff I wouldn't have realized right away with vintage stuff. Great video.
Good video. Never thought about marking the tops of caps ... good idea!
neither do I .. very good one ...
Number tops of caps 1, 2,3.. etc, in order, now you know polarity and position after removing from circuit.
I take lots of photos too. Your cell phone camera can be a real friend here. ;-)
Wonderful message it will save time and patience. Thank you
Great video, with many good points raised. Re: not trusting board markings. There's at least one infamous example in the computer world: one revision of the Sinclair ZX Spectrum shows incorrect polarity markings for one of its capacitors, which has caught many people out over the years (resulting in many dead ZX Spectrums in the process). As for marking capacitors i.e. the "measure twice cut once" tip, taking clear high res photos of the board you're about to work on _prior_ to starting on it is also a very good idea IMHO.
From someone who has rebuilt vintage electronics this video is EXCELLENT. Every new electronics tech should see this video.
#BIGFACTS & #2Thumbs&BigToes^UP^
Fabulous advice, very informative & interesting, thanks.
Thank you for sharing your experience!!!
Excellent information on Caps👍 This is the way.
Great point about the boards and schematics being marked wrong!!!!
I see this a lot. Even units where the manufacturer has marked the board incorrectly, and fitted capacitors backwards because they followed the board markings!
Thanks to made this video , I usually recap 70’s amp & Receivers This can be great information for who want to recap in first time 👍👍
I think your video is great and useful because a lot of electronic related video on the internet does and suggest very bad advice that create more confusion than clarification.
The mis marked circuit boards can get very interesting when power is applied! We blew up two brand new sets of capacitors before we caught on!
Fantastic helpful stuff, i'm just thinking of doing this on some old tube gear and would probably have made all these mistakes :D thank you.
On an old R-R tape recorder that I recapped recently, the electrolytic caps had a stripe on the side to indicate polarity. Unfortunately, as I discovered after replacing many capacitors, the stripe on the old caps marks the (+) positive lead rather than the negative end as on newer capacitors. I had to remove, test and reinstall every cap I replaced, since powering up a cap with wrong polarity can damage it. So, watch out for that too!
Good point! I've seen this too on older Toa amps!
I once encountered an LED which had the flat marking on the positive lead. It should be on the negative lead. I was so confused.
Diode: mismarked; ☺1 in thousands; thank God I cheched 'em all!
@@PunakiviAddikti yep, i have some like that, you must never assume the polarity, double check
wrongly polarized caps make nice fireworks , ask me how i know..
Thank you for this informative video. Currently have one older tape deck and one large cap in the back k of it has black gunk. I never saw black gunk like it before. Thinking it was a bad cap(cap itself looks fine), then I found your video and learning it was factory glue and not a leaky cap. Thanks again
Fantastic video! The shotgun approach advice was great!👍👍
Great video man. Love your channel. Regards from Ireland
Thank you for the video. Lately, I've been seeing a lot of parts like resistors and wire links eaten away by the glue used to hold down large parts. Somehow the 'brown' looking glue goes conductive and acidic.
What you are seeing is very old SonyBond glue used to hold capacitors and ferrite’s and other components especially in items that are moved a lot for example CB radios are notorious for having this glue in a lot of the old brands, and it is still being used today. It’s best practice to remove the glue around capacitors and crystals and wires with ferrite beads on them etc. As you have noticed once it turns brown its really very corrosive and conductive. It appears to be Latex based from experience and there are chemicals available to soften it so it’s removable.
Good job and great advice. I'm about to recap my Peavey Bandit 112 made in the States between 2000-2004. Kind regards from Mexico amigo!
Incredible vid. Thanks for sharing your wisdom
A note about that brown glue on some of the late '70s Japanese amplifiers.. the glue becomes corrosive later in its life and if it is touching metal leads of nearby resistors it may eventually eat through the lead and cause an open circuit. I always try to remove that glue from any metal leads nearby to prevent that from happening. As for the boards being incorrectly marked I have encountered that on a few occasions which is why I replace one capacitor at a time so when I pull out a capacitor and I know that the negative terminal is facing down I will say negative down as I go and grab a replacement capacitor and I will put the new one in negative down. Doing one capacitor at a time you can make sure that you put it in in the correct polarity and not be forced to rely on a silk screen which could be wrong.
This video is excellent, your methodology is all common sense for anyone experienced in servicing electronics. However, when it comes to factory glue, even if you can still identify it correctly, you must remain cautious and always observe precautionary. Some of these glues have proven corrosive or decompose in corrosive material, so if you notice oxidized copper tracks, rotten component legs, you'll probably have to remove that goo, restore PCB and probably change all components touched, resistors and semiconductors. Leaky caps can also smell badly: most of leaky SMD electrolytic capacitors include a fish oil impregnating everything. And here is also an important point, most quality electrolytics can still work fine after years if used and stored in proper condition. You also need specific equipment to check and test if they really need some replacement: you should measure values and ESR, and for specific uses like high voltage ones, a specific leakage test has to be performed. Of course, with experience or proper documentation, you have a number of specific condensers you will systematically change in 100% of equipment, mostly because their replacement is critical and always cheaper than the component they protect, like high voltage decoupling caps in tube electronics. And when it comes to components locations or sense, wiring and so, it's also interesting to take a number or pictures and notes along markings. Rule number one is to take the necessary time to observe and analyse any further action.
Very good advice! Thanks a lot!
A possible exception to your suggestion against "shotgun" recapping is when restoring very old equipment. 50 or 60 year old electrolytics are often shorted, or nearly so. Turning on the equipment with such caps in the power supply can cause serious damage. The same applies to interstage coupling caps in tube amplifiers. If those are electrically leaky, B+ will flow to the grid of the next stage and that is also damaging.
I shot gun the caps in my vintage repairs. These caps are 40+ years old and way past their lifetime expectancy. And for s**ts and grins, I 'll use my ESR which says "yep.. it's fine" and use my old Heathkit leakage checker. 80% of the "good" caps fail leakage tests. The exception to this rant seems to be the smaller electrolyics normally used in the radio RX boards for example. Most of those I replace with WIMA anyways.. I hate having to redo my work. And fixing a unit just to have a ancient cap fail a few laters is stupid. I also replace driver transistors for the same reason. You have no idea how abused they are so I just replace them since I already have the unit apart on the bench. Zeners go to for the same reason. Carbon resistors in amplifier boards get replaced because most of drifted a fair bit and will continue to drift as they age even more. And I should say, I don't "repair" my projects.. I "restore" or "rebuild" them.. just like a car. And lets be clear.. this is my opinion.. nothing more. Everyone is entitled to their own opinion. My clients are happy with mine and how I do the work :)
@@MikeSweeneyMedia , Yeah, if you have to undo the dial string mechanism in order to pull up the RF, IF, and/ or MPX board (often those circuits are combined on one single long PC board), you want to be really certain that recapping is done with known good caps, and that you fix any problems or potential problems before you put the whole shebang back together.
I see your point. His advice is good if you are recapping something that works already.
Yes, better to replace the electrolytic and paper caps than destroying transformers and such that are made of "unobtainium" now. I do the same on old tube stuff.
Oh definitely, old caps can short out. So can small smd ceramic caps if they develop a micro fracture from mechanical stress.
Excellent, excellent advice. Thanks. I'm in the process of repairing 2 Ferrograph 2As and a Vortexion WVB. Your vid is good. :)
Most manufacturers of the electrolytic caps I have used recommend running them at 80% of the rated voltage to get the optimal life span. Read the data sheet on the electrolytic capacitor you are using as a replacement. Try to use exact replacements, otherwise you need to look at all the specs. ESR and surge and ripple current capability etc.
Excellent video i am just learning about this stuff and this video has a lot of useful info. Thanks for sharing your knowledge.
Great tips, 100% agree. I'd add 'use some respect when soldering'. Easy to damage tracks on *certain* boards.
@Rosetta Stoned Yah only being doing this for 40 yrs. Share your wisdom please :)
Good information and much appreciated.
Thanks for the tips. They are appreciated.
Great advice, thanks for sharing!
I did enjoy this one. I never considered the glue being mistaken for leaky caps. I can see myself making that mistake even though I was aware some are glued. The last piece of advice is by far the most important though. This has bit me more than once in many different fields.
Lots of people think the glue is electrolyte leakage... And yes, marking things helps, but I use photos, lots of photos from lots of angles. That has saved my ass many times. lol!
I believe that 'glue' used to hold electrolytics and larger parts is normally known as 'staking adhesive' . It turns brown over time and is frequently mistaken for leaking electrolyte.
Great pointers for doing things right.
At 00:55, The top-left CAPs have that rubbery glue to stop the component from vibration, (i.e.) subwoofer cabinet.
Remember the era when people used to mount their amplifier directly on the subwoofer box itself? LOL I made a lot of easy money repairing amps because the vibration had shaken loose anything heavy or tall. XD (the amps were usually mounted sideways)
Awesome tips Sir!!! Thank you very much
This video content is excellent. What you covered in 10 minutes took me 10 or more years to stumble across as a circuit designer. This video is a keeper and a "must see" video for anyone with a soldering iron. Thanks Mark.
The tip on wrongly printed polarity was new to me, thanks for that 👍
Same! I just finished recapping a TS-530S, and I checked each ones polarity as I pulled it out, just in case the marking on the board was buried somehow. But I never thought it could be wrong! I'll be marking my caps orientation before pulling them from now on!
While I don't work in the industry, I do electronic repair for myself. Marking the orientation is a great idea. I have removed caps only to then question the orientation on the board. I now mark orientation on everything I remove (for the most part).
All great tips. Thank you!
Great info and timely. I need to replace a 1uF tantalum Cap on a vintage Eventide H3000 Ultra Harmonizer, circa around late 1980s, early 1990s. Thanks for some well advised info. Phil NYC Area
I have many DIY'rs replace capacitors they thought were bad because of the glue/bond. Also have had many installed backwards. Good point to make all marks on the caps face one direction.
Very informative! Thank You!
I might add that, when bodging in two 1000u in series because you want 500, dont assume that each capacitor will have half the voltage across it. Overrate the voltage or, possibly, add a couple of resistors to swamp leakage and so equalize the drops, (or you can order the correct component:)
Excellent tips. Thank you.
Great advise !! Outstanding video !! Thank You