#1  
02-25-2021, 11:07 PM
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Somebody send me a "working" AG-1980P deck that didn't work.

He wants me to remove certain parts, send those to him. Fine. I guess. Not what I wanted to do, not really something I have time for. I tinker with it as I have time, it's at the bottom of my priority list.

When it comes to these decks, I have almost no patience. Great quality video/audio output, when the decks work. But the problem is these SOBs break too much, and are money pits.

There are so many wires and board in here, nothing to grasp. I've not taken an AG1980 deck in at least 8+ years, but I just do not remember it being a box filled with dead squid and sharp LEGOs. I'm not sure if this exact deck is a POS, or certain production lines/dates were made badly, or what.

Anyway, I finally got the mainboard loose, yanked some plugs and boards to get access to the TBC board. Removed it. But it has wires connecting the TBC board to some other board under the deck. So removed metal deck bottom, fed the underboard into unit to get access. No help. Those plastic clips have a death grip.

Right now, I have VCR that looks as if an animal ripped out it's entrails. Just crap all wired together, nothing loose.

Any ideas?

If not, I'm ready do give up now, I have more important things to do.

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  #2  
02-25-2021, 11:39 PM
latreche34 latreche34 is offline
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Never worked on Panasonics, I'm more familiar with JVC stuff, Especially the newer models, I can literally take it all a part and put it back together in less than 20 minutes. Anyway have you checked the service manual, Those connectors that you called death grip maybe soldered to the PCB and cannot be removed without disordering, If you post pictures of the upper side and underside of the connectors I should be able to tell you if they are a plug type or permanent attachment.
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  #3  
02-26-2021, 10:58 AM
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The service manual is worthless for actual step-by-step how-to info on disassemble the unit.

The clips are plastic, not soldered. (But some sort of glue may exist. And that likely wouldn't be a stock manufacturer, but something that some idiot did.)

The entrails of an AG-1980 unit are not easy to take photos of. Everything has overly short and tight connecting wires that pull everything into a mess. Nothing wants to stand still long enough for a photo, before collapsing again into a pile of e-sh!t. If the cables would remove more easily, photos could be taken, but of course this thread wouldn't exist.

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  #4  
02-26-2021, 12:46 PM
latreche34 latreche34 is offline
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Don't know why Panasonic kept the old bulky design of circuit boards for that many years when the technology of SoC (System on a Chip) was widely used by most manufacturers, JVC with their digital technology of synchronizing motors, managing the control system, using video and audio processing chips, they managed to put the entire VCR components on a single chassis including the power supply, And they protected every sub system with PCB mounted fuse to avoid any catastrophe, That's the design that every repair technician hoped for.
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  #5  
02-26-2021, 01:51 PM
hodgey hodgey is offline
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Panasonic moved to that as well, the AG1980P, and the PAL NV-HS1000/AG4700 were among the last to use this design I think. I don't know much about the later US SVHS models (and the non-SVHS US ones seem to be totally different from the ones released in europe), but the 1995 NV HS950 and HS900 have a bottom mounted circuit board with the mech on top in the middle, and similar with the lower end models. They seem to have stuck with using separate head amp and power supply boards for a bit longer though.

I don't get why they designed the circuit board to sit upside down in this weird way, I've worked on the NV-HS1000 and it's designed in a similar manner, same with several generations before it. You are like meant to flip the whole bundle of circuit boards out and put them on top of the mech with an insulating sheet in-between when testing, and ideally use some sort of extender cable when calibrating the video boards (which these days you would never find). The internal cables are short, the mainboard is not hinged like in some other brands, and the connectors between the boards are really hard to disconnect. I was afraid of breaking the circuit board every time I disconnected any board (I literally had to carefully "pry" the video board off. I don't have any good suggestions on how best to do this though.

If the main board was mounted at the bottom, with the other boards sticking up instead it would have been so much nicer to work on (they did this on the (standard vhs hi-fi) NV-HD600 and NV-HD650 which seem to be a sort of in-between model with bottom mounted boards, but side mounted mech, before moving to mid mounted for the next models.)
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  #6  
02-26-2021, 03:37 PM
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My latest attempt to remove that clip is a real WTF: I used pliers (jeweler pliers!), and the inner plastic of the clip is now outer plastic. And some of the teeth broke off. And yet, the little SOB will not budge from the socket. It happened within the span of a blink. How did that happen?

This unit is nuts.

I'm about to open my oldest AG-1980, just to confirm I'm not insane. Because I do not recall it being this hard. Something is up with this deck.

-- merged --

Alright, I shoved some things around, to get images.

Front:

1980-mess-cable1.jpg

Now-mangled back:

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For comparison only, this is a much larger plug used on the power box. It's still a PITA to remove, but all it requires is jamming a small flat screwdriver, and wiggling out the connector:

1980-mess-cable2.jpg

What moron designed these.



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  #7  
02-26-2021, 04:49 PM
hodgey hodgey is offline
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Yeah those are a PITA. I've managed to damage some as well.
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  #8  
02-26-2021, 05:58 PM
latreche34 latreche34 is offline
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You are not suppose to just pull on those connectors, you will have to release the catches first with a small flat screw driver or a pocket knife as illustrated, you can do one side at a time and lift one side slightly and do the other side for a full release, I've done a lot of those on cassette decks.



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  #9  
02-26-2021, 06:29 PM
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I opened another deck, and it's not a PITA like this one is. (Still a PITA, but not using kryptonite clips.)

This 2nd deck is not working due to hiss, and injecting askew random horizontal noise in the image (not interlace-like, not even, no power related that I can tell). And this was one that TGrant had fixed in 2018. The fix clearly did not last.

What I really want to know is why the power box often emits a cyclical high pitched hissing sound. It's really loud, very obnoxious to even be in the same room as the VCR.

It can happen:
- when turned on
- then tape inserted (but stops when playing)
- then when playing a tape
- then when turning stations (all static)
- just plugged in

It starts small, just when turned on, disappears with A1/A2 input (not channel) and tape playing. Then eventually even being plugged in causes is to hiss-scream loudly. The noise gets louder and more obnoxious as time goes on.

Swapping the power box really has no effect -- and yet, the hissing comes from the power box. Any power box in a no-hiss deck will not hiss, and any box will hiss in hissy decks. WTF? That means the boards/something is causing feedback into the power box. So, unlike JVCs, you can't swap anything. A recap is apparently required -- and replace ALL caps. All of them, 100%.

In the very beginning, it will hiss when plugged in, then stop once the unit has been plugged in for a while. It only starts again when the unit has had no power for an extended period. This is why "unplug when not in use" is a double-edged sword with AG-1980P decks.

This is an area where I wish deter would share more info, and why TGrant needs to participate on the forum.

Quote:
Originally Posted by latreche34 View Post
You are not suppose to just pull on those connectors, you will have to release the catches first with a small flat screw driver or a pocket knife as illustrated, you can do one side at a time and lift one side slightly and do the other side for a full release, I've done a lot of those on cassette decks.
Well, not exactly. You have to pull while cramming something into the opening, to wedge the little SOB open. These will not budge, period. I've almost ripped the plastic off by prying these apart, and the entire thing has start to lift off the board. The pliers was to grab the plastic, and not just yank off wires. Ironically, pulling the plastic somehow resulted in wires coming loose. This whole thing is a great big POS. If it were anything else, I'd already be putting soap or oil into the slot.

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  #10  
06-04-2023, 05:40 AM
grandmair grandmair is offline
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I have a simplier beginner question on this subject. I have a similar old panasonic vcr. How to disconnect one board ( does not matter - audio, video etc) from the main psb? Are they soldered or is it ok just to pull it out? Just affraid to pull it if its glued or soldered to the main pcb. Thanks in advance!
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  #11  
06-04-2023, 06:01 AM
dpalomaki dpalomaki is offline
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They should pull out of the main board, but may have small "ears" as the arrows show in latreche34's post #8 above holding the daughter card captive. Probably best to remove outside boards (where you can see the connectors) first working you way in. The beast is a pain to work on. Not designed as a "toss-it-when-broken" like most more recent consumer electronics but something skilled technicians can work on. As I recall a daughter board or two may be soldered together; e.g., one in the audio section.

Many things are not is repairable today because bench time is more expensive than the device thanks to SoC technology.
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  #12  
06-04-2023, 06:13 AM
grandmair grandmair is offline
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thanks for your answer but the answer #8 is about wires connected via sockets? I dont have a problem disconnecting these. My question was how to pull out one board (like audio board for example) from the main pcb.

-- merged --

ah sorry, you probably mean that a daughter board connected to the main pcb the same way as shown on the picture with the connection sockets. I will double check it but last time I checked I did not see those ears.. It would probably be easier to take a pic

-- merged --

by advice from the forum I have created a separate thread on this issue.
https://www.digitalfaq.com/forum/vcr...ull-board.html
but its strange that I was unable to find this info neither on the internet nor on youtube..

-- merged --

attached pics in the new thread. may be better to post new comments in there
https://www.digitalfaq.com/forum/vcr-repair/13561-how-pull-board.html#post91122
I dont see any ears or any other things apart from the plastic connection itself
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  #13  
06-10-2024, 09:55 AM
MrPete MrPete is offline
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FWIW, I have had success jamming a very thin screwdriver into the gap between socket and plug. Start on one side, not the middle. You can force one side loose, then the other. Works also for a whole series of connectors on a larger board.

I suspect good quality conducting grease could help make it easier to redo in the future.
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  #14  
06-11-2024, 11:56 PM
aramkolt aramkolt is offline
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Ah, you've got the "extra annoying" variant there that has the extra wires in several places. Most AG1980's do not have that separate control board on the bottom and those are the ones that some refurbishers won't take based on their serial number. I've refurbished two of those - one worked fine, other didn't, but I didn't really troubleshoot or try to swap parts out of it, so that could have been some other error on my part - though the extra wires do make it more difficult to access the capacitors that you need to replace without disturbing them....

As far as the high pitched noise, counterintuitively, it's usually the front LCD board needing some capacitors replaced, even though the noise isn't emitted from there. It causes some sort of odd feedback/resonance back in the power supply when those are bad. If that doesn't take care of the noise completely, then recapping the power supply will (I always do both as a standard on my refurbs). But yeah, if the noise was the only issue, there's no need to take out any of the main compartment stuff other than the power supply which can be removed without disturbing anything else.
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