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  #41  
03-30-2019, 05:00 AM
RS456 RS456 is offline
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Quote:
Originally Posted by dpalomaki View Post
With my AG-1980 there were two primary symptoms of bad cap; i.e., dim display and barber pole-like interference on colors. There may have been additional symptoms but they were less obvious. Keep in mind that yours could be different.

The electrolytic caps are typically used in bypass and filter applications including power supplies. The precise visual playback image symptoms will depend on which capacitors are bad. In some cases you can spot a bad cap because the case is leaking, bulging, or split, but that covers only some cases. An in-circuit ESR tester can help identify bad and marginal caps with no obvious physical symptoms.
Seems like a very handy tool and a very handy tip. I think my multimeter has at least two of the functions the ESR tester has. I think my good AG-1980 has subtle barber pole-like interference on colors red, green, and blue which comes and goes. Possibly an indication of a dying capacitor from what you told me. What about the dim lcd display? For that where will the problem be? Is it the same board (Y/C picture board) or will that problem be in the main board? Any brand of capacitors I should look at or all basically the same. In your experience on fixing AG-1980 have you ever faced a problem changing capacitors in the Video output ports board?
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  #42  
03-30-2019, 07:24 AM
dpalomaki dpalomaki is offline
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The dim display resulted from capacitor(s) on the so called "timer" board. The board that holds the displays. As a mater of routine I replace all electrolytics on that board.

I replace all electrolytics on the Y/C board.

I replaced most electrolytics on the power supply.

I replaced the surface mounted caps on several other daughter boards and any radial lead electrolytics that had an out of spec ESR, but did not replace any caps on the main board, TV tuner board, the I/O jack board on the back, or the Audio board with the daughter card soldered on it.

Take plenty of photos along the way to help with routing of cables and other parts for reassembly.

I ordered caps from Mouser Electronics, mainly Panasonic brand. Because some boards are crowded and the space between boards is limited be sure any substitute rating or brand you order will fit in the available space.
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  #43  
03-30-2019, 09:32 AM
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I found the confirmed bad capacitor in the Y/C board. It is C17 10uF 16V Aluminum Organic Polymer Capacitor. That is bad because it has continuity. None of the others have continuity. Is the top number on Aluminum Organic Polymer Capacitor in uF or F? If uF I found several going bad.
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  #44  
03-30-2019, 10:05 AM
dpalomaki dpalomaki is offline
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Generally microfarads for electrolytics in the VCR. I believe that C17 on the digital Y/C board is C33017 an ECEV1CA100 in the parts list.

A farad would be is a rather large capacitor. About the only place I've run into capacitors approaching a farad in consumer electronics is the storage capacitor powering the standby memory in some receivers; e.g., a Panasonic super capacitors with a values of 0.47F at 5.5 vdc.
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  #45  
03-30-2019, 10:51 AM
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So all of them are most likely uF. Maybe they are too small for my multimeter to measure or almost all of them are really close to going completely bad. Maybe I will just get ESR tester to know for sure.
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  #46  
03-30-2019, 09:51 PM
dpalomaki dpalomaki is offline
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In general you cannot get an meaningful in-circuit measurement of capacitance.
https://www.youtube.com/watch?v=tXxOHcUhVfE

However, ESR check is easier.
https://www.youtube.com/watch?v=qDABYKoVO4Q
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  #47  
03-31-2019, 08:17 PM
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Well I already ordered an ESR tester. Just waiting for it to come.
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  #48  
04-01-2019, 07:39 AM
NJRoadfan NJRoadfan is offline
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Don't bother testing the capacitors, just replace them. There is no doubt they are bad at this point if the VCR is misbehaving. If you are new to recapping surface mount capacitors, you do run the risk of damaging the board (lifting pads in particular). Leaking electrolyte on the board makes things worst.

One thing to keep in mind, if you start a repair and decide its too much (or damage something) and decide to mail it in..... a repair service will increase the estimate for repair. They now have to fix what you damaged and charge accordingly. The estimates given are for normal failures, not DIYer mistakes.
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  #49  
04-01-2019, 09:32 PM
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From what I see it seems they have been replaced at one point. They all look new and intact. Only one is confirmed bad as of now. There is no point changing everything if some are still giving reading almost exactly as specified. I am not new to soldering. Also this is a spare AG-1980 and a good learning experience. I kept the good one on the side till I can confidently recap it learning from fixing the spare.
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  #50  
04-08-2019, 04:55 AM
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Mission accomplished. Spare is unexpectedly fixed. It now plays better than my good one.
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  #51  
04-08-2019, 06:13 PM
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Recapping AG-1980 is not as hard as it seems if you have the right tools. Frustrating and hard part is getting the main board out. Once it is out it is not that hard if you have a fine tip soldering iron. From what I seen even the cheap smd capacitors work just as good as the the expensive ones like Panasonic but I don't know how long they will last yet. Correct me if I am wrong. Now I ended up with a fully working spare AG-1980 and confidence to fix my good like new looking AG-1980 one.
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  #52  
04-08-2019, 06:44 PM
dpalomaki dpalomaki is offline
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Considering the time and effort to do a recap, and the overall low cost of decent caps relative to the effort and value of the machine, there is little reason to cheap out on the capacitors if you intend to keep the machine for more than a few years.

Good caps should last a long time (consider the age of the favored JVC's and AG-1970s that did not have the cap problem). Cheap caps will last maybe (???) half as long.

I used Panasonic caps from Mouser Electronics for mine.
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  #53  
04-08-2019, 07:10 PM
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Small issue when playing tapes the picture sometimes gets distortion lines and some distortion. It is very frequent in SLP tapes and not so frequent in SP tapes. Is that an indication another capacitor going bad?

SLP sample https://streamable.com/ioft6

SP sample https://streamable.com/63vp2


Attached Files
File Type: mp4 SLP Sample.mp4 (40 Bytes, 8 downloads)
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  #54  
04-08-2019, 07:32 PM
dpalomaki dpalomaki is offline
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A 40 byte attached file???
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  #55  
04-08-2019, 07:54 PM
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Go to the streamable.com links. Attachment didn't properly convert.


SLP sample https://streamable.com/ioft6

SP sample https://streamable.com/63vp2

SLP distorion very clear in this sample https://streamable.com/k47n3

Last edited by RS456; 04-08-2019 at 08:48 PM.
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  #56  
04-09-2019, 08:10 AM
hodgey hodgey is offline
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That does look a bit like either tape guide alignment or the head switching point is a bit off.

You could try to carefully adjust the tape guides (most likely the left one since the error is at the top), or if you have access to a scope, follow the procedure in the service manual (Use a commercial tape in that case).
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  #57  
04-09-2019, 06:15 PM
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So I have nothing to worry about regarding the capacitors and just try to adjust the guides?
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  #58  
04-09-2019, 07:49 PM
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UPDATE: It seems like it was caused by gunk on one of alignment heads. Left side had noticeable gunk when wiped. As of now I don't see that issue again yet.
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  #59  
04-10-2019, 06:39 AM
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Is this problem caused by a capacitor issue on AG-1980 or Tape Alignment issue ?

Sample video : Sample Video
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  #60  
04-10-2019, 07:43 AM
dpalomaki dpalomaki is offline
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Likely some of both.
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