Panasonic AG-1980 capacitor repair?
 

I'm involved in replacing the 100+ electrolytic capacitors in my AG1980. It's quite a daunting task :smack:

I'm almost done, but I'm wondering if it's also necessary to replace any of the SMD capacitors?

There's also a nasty double-sided circuit board (the one with the metal case attached) that has the capacitors soldered on both sides of the board, has anyone dealt with that?

Thanks!

the detachable board with the metal covers is very important - it is the Y/C card.
if the caps go bad on that you get nasty diagonal red and blue lines in the picture
many AG-1980's get this issue

IIRC the tuner also has metal covers - that shouldn't be a real concern
the tuner is the card that has the RF/VHF connectors -the ones that use coaxial cables

bad smd caps
 

volksjager is right about the y/c video section. Replaced several 1uf and 10uf smd caps. Too many to count. Just replace them all. Bad, bad smd electrolytic caps. Also, try to maintain the uf specs. Don't go up in your farads. Also, there is at least one bad cap on the display pcb. I believe is the 220 uf or 100uf (right side of display, about midway of the pcb. Good luck. In addition check motherboard for high esr 47uf electrolytics. Finally, it should have been first, there are leaky disc type filter caps in power supply. They are housed in a clear rubbery boot. Hard to see the leaky oily cap in the circuit because of the overcrowdedness. Let us know how it goes.

Thanks so much guys! I appreciate the help. I haven't found any "exploded" or buckled capacitors yet, but I have found two that were reading only about half of their marked ufd (can't remember where they came from now, it's been a long haul)

Yes, volksjager it's the Y/C board... that's the one I fear working on. Since it's double-sided it looks like I may have to cut off the electrolytics to get at the solder joints under them, then also desolder the other side too. This will be fun :mad4:

Thanks rumburaski for your tips on the Y/C SMDs. There's probably no way to tell which one's are bad, so as you suggest, replace them all. I may leave the SMD's until the end, and see if replacing the tubular electrolytics helped (picture was black & white and muddy looking, before I started on this project)

This may take a few weeks, a board at a time, but if I haven't shot myself by then, I'll report back :)

Removing SMD caps is likely the tricky part. I just did a board with them and found that cutting them off with side cutters then wiggling/pulling off the cap works best. The leads that remain on the board can be easily desoldered without lifting pads. For long life, polymer or ceramic caps should be used to replace them. They cost more, but are worth it. I don't recommend tantalum caps for beginners mostly because they explode if installed in the reverse polarity.

Just take your time and use a temperature controlled iron. Too much heat is a bad thing as it can damage the PCB. Make sure you throughly clean the leaked electrolyte off the board too. If you aren't confident in doing the job yourself, I can send you a link to someone I have used for SMD recaps in the past with excellent results.

Also..... this thread needs pictures! A parts list would be nice too, the service manual's part list leaves a lot to be desired.

i dont do soldering work - only mech repairs.
i have 2 bad Ag-1980 Y/C cards i would like to get re-capped if anyone can do the job for reasonable

smd electrolytic cap clarification
 

When I said smd caps I meant smd aluminum can electrolytic caps. These are polarized caps. I don't think they can be replace with nonpolarized polymer or ceramic, do they NJRoadfan? I would be afraid to use side cutters on these due to their delicate pcb. It doesn't take much to lift up those traces. For example, too much pulling. I use a hot air station. Very fast. When is time to install them I use soldering iron. Perhaps two soldering irons set to 350C would work. I rarely seen a leaky/bulged smd aluminum cap. Don't rely on the bulge, as they are completely flat because they are dry. Usually they are dry/high esr when they fail. Definitely, pictures are the weakest link.

Dried electrolyte isn't all that visible. An indication of leaking is dulled/dirty looking solder on the components in question. Hot air stations can be very dangerous in the hands of the unskilled. I was actually surprised how well the cut'n'pull method worked. Usually the can pops right off the leads leaving the plastic base to chip away. I must have had beginner's luck because the method resulted in no lifted pads or any other board damage.

They do make SMD "tweezer" style soldering irons for the job, but I don't have one laying around here.

http://upload.wikimedia.org/wikipedi...ing_a_0805.jpg

I'd love to get a hold of a broken down AG-1980/5710 to repair and document a re-cap, but they are crazy expensive in busted form!

Yes, I think a hot air station is the way to go. I have one of those smd "tweezer" type soldering irons....mine is more clunkier looking than the one in your photo. It doesn't work as well as I'd hoped.

And yes, those broken AG1980's go for too much..everyone says "plugged it in and it powered up"......but you know it's gotta have bad caps, or worse :(

i'll give you a whole broken 1980 if you'll recap a Y/C card for me :)

NJRoadfan - Thanks for your tips on removing the SMD caps.....I appreciate it!

desoldering
 

Nice tweezers NJRoadfan. Who makes them? I could use some for some smd inductors.

Photos would be handy, I'm curious as to how many need to be replaced. I'm also curious if recapping the display board fixes the dim display issues.

Remember, I am not liable if anything breaks. Proceed at your own risk, work slowly and watch a few tutorial videos. Practice on scrap boards you don't care about to get a feeling for it beforehand.

1 of the decks i have has a dim display, both need the Y/C cards repaired.
not sure how many caps would need to be replaced

http://www.digitalfaq.com/forum/imag...daa277b7-1.jpg

http://www.digitalfaq.com/forum/imag...137f5578-1.jpg

I don't see the tell tale signs of leaking electrolyte, but its not always visible. I'm guessing there are more caps under the metal shield? The parts list shows 33 electrolytics and 16 are visible there. Jeez, no wonder why repair centers hated these things!

follow up
 

In my particular case, half of the smd aluminum can electrolytics were bad, low uf. On the other hand, through hole caps were fine. Does it make any sense? There are more under those shields.

I'm not surprised. Early 90s SMD caps seem to use a crappy electrolyte recipe that lasts about 15 years tops. Meanwhile, all my stuff from the 80s with old school through hole radial caps work fine.

Here's some close-ups of the Y/C board with the metal cover removed. This is the "business side", the reverse side is mostly tiny SMD caps.

http://www.rentalmouse.com/samples/AG1980board.jpg

http://www.digitalfaq.com/forum/imag...980board-1.jpg

Argalby , Did you get the AG-1980 working? Did you have to replace all the SMD caps as well? I'm starting on the same project myself any advice would be helpful. Thanks

Hi: I haven't had a chance to work on it yet, and it might be a while. I'm working double shifts now, and I really need a big block of time to work on this. Everything I've read indicates it's the SMD's on the color board, that bears out what I suspected. I have second unit that works perfectly in BW mode, but color is screwed up, so it also looks like the color board. Lots & lots of SMD's on there :( Hope it works out well for you. Good Luck!

When you figure out what's wrong, let us know. :)

I just finished to replace all electrolytic caps on this unit and it works amazing. What Rumburarski said is very true. On this Y/C card replace them all. Some were still ok but since about half of them had readings off the chart I changed them all. Can be done with a thin tip iron but be very carefully to not damage the board. Probably hot air and tweezers are better choices. Takes time and concentration. I did NOT have any problems with the picture before . Once the caps replaced, the colors were vivid and I think it makes a big difference. I also want to mention that I found on the main board one capacitor at 47uf and probably 16V (not sure) that was electrolytic but on the board I did not see indicated any polarity ..... . It does not make sense. Anybody any thoughts.
Thanks.

Congratulations Videonut! For changing all the caps. Well, if the electrolytic does not indicate any polarity than it is non-polar. If this is out of specs I would replace it with same.

I'm reading this with great interest. :)

Yet, sadly, I don't know if I could ever do something like this myself, especially given my unsteadiness due to medical issue of the past years. (I do hope, however, that I fully regain my dexterity in the future.)

If you're interested in doing this for others, you could make a few bucks for sure. Interested? We've always on the lookout for responsible (non-scam, non-slow) people that can do this for others. Most people are not skilled with re-soldering capacitors. Even non-amateurs video folks like myself!

LSI DVD recorders have caps issues, too, and must be replaced (JVC, Panasonic).

$75 complete recap (aluminum cans). Bad IC's? (black and white or blue screen) additionally $55. If bad IC's are suspected, must ship whole unit. Client to pay shipping both ways.

I have a contact that I contracted work out to in the past. The work was top notch and prices reasonable. He primarily does computer equipment, but something like the Y/C board posted above is no problem. He does charge more though since there are more caps to replace.

I have attempted SMD cap replacement in the past. I landed up using wire cutters to remove the old caps. Usually the body of the cap pulls out leaving the legs on the PCB. From there you can add remove the legs without too much risk of lifting a pad.

Has anyone tried replacing electrolytics with ceramic or solid polymer caps? They should last a lot longer, but in some cases cause problems in circuits. Tantalum caps will work too, but I don't trust them since their mode of failure usually involves blowing up!

I also read somewhere (not here), people are substituting non polar for polar electrolytics and vice versa. I cannot comment on this because I never tried and perhaps never will. Wire cutters are never a good idea to remove smd caps or smd ic's, unless you have time (and funds) on your hand fixing broken pads.

I do not use wire cutters, so I do not understand your comment. I used just a simple iron station with the temp at 350C and a lot of concentration and detailed work. Everybody please be advised not to even try to solder if you do not know how to do it because it is very dangerous. Actually nobody should ever attempt to do a job that can be done by a professional.
The caps were the original ones, plus the values shown in the service manual are sometimes different. Why is it that way I do not know. Actually there were a couple of BP caps that I could not find. What would be a proper replacement for a BP electrolytic cap in your opinion?
Those caps you mention in your post I also found to be problematic from the beginning.
Thanks for for your help.

Please do not feel offended if i did not understand "landed up". Does "landed up" means "giving up"? Also, I see BP caps available for purchase and in a variety of values. I don't understand why would I be looking for a "replacement", when I can put back what came out. To answer you question, Yes. There are several youtube videos showing how to make BP out of two identical polarized caps. It also depends upon where in the circuit will those "make ups" be used. From my end I can see that is not recommended in smps or dry vs. wet electrolytics. "In general, this sort of trick should be considered a last resort. Since bipolar capacitors are usually needed for signals, it can often be arranged to require a lower bipolar capacitance. Multi-layer ceramic caps have advanced significantly in the last decade. If you can make do with 10 uF instead of 100s of uF, a ceramic can can probably do the job".
http://electronics.stackexchange.com...r-electrolytic

Soldering, like most things requires practice and common sense. I'm run across many "professionals" that I will never let near any of my equipment due to their shoddy work.

All ceramic caps are bipolar by design. I had no problem finding bipolar SMD electrolytic caps either.

Non-polarized can replace polarized without a problem. As for the wire cutters, I was a skeptic, but it worked. I wouldn't try it with ICs, just SMD caps. Its a lot easier to remove the legs when the cap and plastic body aren't on top of it!

The problem I am having with non-polarized caps are that they are not cost effective. Also, I recently worked on a jvc board. The JVC pcb can't take any kind a wiggling. In this rare instance I use hot air.

where are you located?

is it possible to replace the electrolytics with solid caps? if not at least better electrolytics?

I am located in New Jersey.

$75 cheap Chinese, tested, low esr, sometimes lower esr than Nichicon
$95 Nichicon caps

All caps are tested for low esr. 30 days warranty on all work performed. Regular electrolytics are more rugged than smd caps. In real life situation I compared the two brands and I haven't seen benefits of using Nichicon vs. Chinese. But if you insist of me using Nichicon (or other brand), I could do it. Bear in mind you are paying for 26 new caps plus complete labor. I think $95 is a small price to pay.

Well let me rephrase the question I had. Apparently I get replies to things I never said and questions I did not ask. I mentioned that on the MAIN board I noticed one electrolytic capacitor at 47uf 6.3V that on the MAIN board is marked as bipolar. It is locate somewhere in the front left area. I also mentioned that there are few more bipolar caps and I could not find something to replace them. This are not SMD caps. The question was how to handle those bipolar/non polar caps. Any ideas?

Now about the Y/C card: I changed only the aluminium electrolytic caps. Apparently there also SMD tantalum caps, correct me if I am wrong, and there are a lot of them. Good luck replacing them ( much more than 26 total).
I did replace the caps in this unit for myself only and took me about a week. I am sure there are people doing this for living. I would go with good brand name caps with long life. Low esr today and high esr few months later is not what I would look for. Low ESR and very high quality series caps equals very expensive.

On ebay those fixed units are probably only partly fixed, or fixed to work for a while ( for how long my guess is your guess). I could have change some of the caps in the power source and front panel, including the ones located next to the display and the funny noises disappear and the display is much better (NOT like new). But when I checked more components I realized that it needed a complete overhaul and this turned out to be very expensive. Of course this assuming the heads and the gears are still in good shape.....

About the mechanical part I can say it is very solid with the exception of some plastic gears and one small bolt that can give up. And yes do not attempt to take it appart because if you are out of alignment it will start acting funny. Is there any manual about alignment, just curious.

To me this was an expensive overhaul and I count only for the parts, but the result is sweet.
Good luck to everybody.
Nice forum.

Here is a start videonut http://www.mouser.com/ProductDetail/...t3hgt2nysJs%3d

Leave the tantalum caps alone, they are usually fine. The price difference between no-name and quality electrolytic is minimal. The price goes up substantially if you want ceramic or polymer replacements.

Themouser is so and so in regards to prices and do not have everything. Not my cup of tee, but thanks. The tantalum caps are really small and expect to last longer too. The no-name brands caps I do not prefer, to me is like playing roulette, some are good, many are garbage, but if you used some and you had good results, you know better. If you noticed the most sensitive components are always using brand name caps,unless is a cheap made product.
On a different note, what is a good lubricant that you guys use on this units?
Thanks again.

Molytone grease 265 (mor265) Sumico Lubricant

I've added this: http://www.digitalfaq.com/forum/vcr-...html#post29001

Nice to have another solid option. :congrats:

And replacing crappier caps with better caps is EXACTLY what I want to see more of. So many shops seemingly refuse to do this, and I often wonder if it's because of a limited understand of electronics.

I just wanted to post back about how the repair to my AG-1980's went. All I can say is it's much akin to brain surgery~ I got both of my units going but it's extremely tricky. You need to replace all the SMD aluminum caps in the video board. You need to be proficient in the use of a hot air rework station. Every now and again you're going to accidentally melt part of a connector, or blow a 2mm wide mini smd capacitor off the board. This isn't a repair for those feint of heart. It's about a 3hr job. You'll probably have about $30 in parts plus a rework station and other odds and ends, plus a bottle of scotch :)
By the way, in my experience, it just doesn't work trying to repair these SMD caps with a regular soldering iron, you just can't get in at the small connections. You can't get a good solder joint. Even getting the video board free from the main circuit board is tricky. The Ag-1980 is a very nasty, tricky, persnickety machine!

So all in all I got my unit back to good health and have another one ready to sell. The Big Reward is the happiness when you pop in a tape and see the glorious picture that these units give! It's worth the trouble and/or cost of repairs!