Junkyard AG-1980P repair?

[mistateo]

So I picked up a Panasonic AG-1980P from Ebay (it was relatively cheap at $200 shipped). I already knew the risks, having read a ton of posts here, so I wasn't expecting a working unit. The seller description was "I think it's working, just needs a fuse" Though I will put it out there that I scored a beautifully working HR-S7800U for $150 shipped from ebay (the model number was malformed, and I found it on accident). Only thing I had to do was pop a loading pulley back into place after the shipping monkeys threw the box around.

First repair was the power supply. I put in a new fuse, and nothing. So upon further inspection, I discovered the board and traces were cracked under the power pins (as if someone tripped on the cord and it was violently yanked out). I completely disassembled the power supply box, jb welded the circuit board, and soldered some relatively heavy wires to make the connection points and carefully checked the rest. I then installed a second screw to hold the power port (one screw was missing). Then the unit powered up!

Next challenge was loading tapes... I would put a tape in, it would try to load, and slip off the take-up guide. I pulled out the deck and did my very first mechanical alignment, using the pictures in the service manual. The take-up post gear was out of phase with the rest. I also pulled out and cleaned the mode switch and cleaned/re-greased the metal tracks while I was in there. Did one test load and still had trouble. Then noticed the little plastic part next to the pinch roller assembly had become dislodged. I popped the foot back into the hole and tested again with success. It now loads, ejects, play, ff, rew just fine. I tried out the knob for slow forward and reverse. It worked fine, but felt flimsy because the plastic screw hole broke on the left side (also repaired with JB weld, now solid).

So now onto my current problem: video quality.... I KNOW someone had been in there, mucking around as the tape path alignment was off. The sound was missing the "higher frequencies" and the picture quality was crap. With TBC off, no picture showed, when on, it displayed, but looked pretty awful. So I fiddled with the supply and take-up posts (after watching a 12-volt vids video on youtube). I got it as close as I could by eye (going to borrow a scope next week to dial it in). One thing that wasn't covered in the video is that there are multiple positions where the picture and sound are pretty stable (as long as the two sides are correct relative to each other). So what I ended up doing was adjusting down JUST until I saw the tape start curling on the bottom, then backed off half a turn on each side. I then did very fine adjustments until the picture and sound were the best I could get them. Is my tape riding too low? Should it be a little higher? Again, I am going to check it with a scope once I get one. The only other adjustment I could see was next to the pinch roller, but I left that alone. Now the picture shows up with the TBC on or off, with significantly more stable picture while turned on. Though some of my nearly new SP commercial tapes show a little flagging on the top.

Now for the dreaded issue, worn out capacitors... To my surprise, the front display is bright and vibrant. I can tell someone has replaced some caps before, but definitely not all of them. I am fairly certain there are more bad caps in there. Today after sitting unplugged overnight, the picture looked horrific when I first plugged it in and played a tape. It was overly dark and picture was pretty bad. After it "warmed up" it got significantly better. But the main issue I see now are dark horizontal lines (see image). These are present whether playing, paused, or slowly advancing via the shuttle knob (they slightly move in position when advancing or reversing frames). There are also "wavy lines" that shift position, also seen on the right side of the image.

I have a good bit of experience with electronics repair, so I am CONSIDERING doing a full recap. Or possibly seeing if Deter is still doing full recaps for $500. But before doing that, I am hoping to verify the video heads are in good shape. I cleaned the entire tape path with 99% isopropyl alcohol, and used the folded printer paper with alcohol to clean the heads. They weren't all that dirty, so I didn't see much perceivable improvement. Since replacement heads are insanely expensive and not even brand new, I don't want to bother with a recap unless I can verify my heads are good first. How would I tell if my problems are related to the head, vs bad capacitors? Can I even verify the quality of the video head without recapping first? I was thinking I could do a pass through test for video (first I need to acquire more s-video cables, and some BNC to composite adapters to test those ports). What could I learn from testing video pass through?

Thank you in advance for the help!

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[latreche34]

Heads are usually checked with special alignement tape playing a special test pattern and an oscilloscope connected to the RF test points for most VCR's. What does the service manual say?

[mistateo]

You are correct. Having RTFM(s) I have determined I am supposed to use Alignment Tape VFJ8125H3F, or VFM8080HQFP depending on which manual I trust. The manual from digitalfaq titled "Panasonic AG-1980P K-Mechanism Section1-4" (aka VSD9402M632) calls for alignment tape VFM8080HQFP. The manual from digitalfaq titled "Panasonic AG-1980P Mechanical Adjustments" calls for alignment tape VFJ8125H3F. I wonder if these are indeed the same thing, one with an updated part number? In any case, both of these tapes are absurdly rare and cost a kidney each...

These tapes appear to display color bars with 6khz audio, but most importantly recorded on a k mechanism deck in perfect alignment. The "mechanical adjustments" manual suggests all kinds of specialized alignment plates, gauges, tools etc to do the "approximate alignment" first. The "K-Mechanism Section1-4" manual says for "approximate alignment" to screw p2 and p3 all the way down, then unscrew two full turns, then play a tape and fine adjust until there is no curling visible, so I think I will do that. Without having the special alignment tape, the best I can do is a like new condition major release tape and get the waveform as flat as I can, which SHOULD be better than just eyeballing.

In case anyone was wondering, CH1 of the scope goes on the Head Amp output (TP3001) and CH2 goes to the Head switch pulse (TP2001). The The "mechanical adjustments" manual mentions turning the tracking VR clockwise/counter clockwise and setting it to the "fixed position" as well. The outside of the ag-1980p doesn't have a knob, only + and - buttons. So I am assuming there is a hidden potentiometer somewhere in there for the tracking as well (at least that's what I assume, VR = Variable Resistor = Potentiometer). The "K-Mechanism Section1-4" manual doesn't mention a tracking VR and calls to adjust the tracking + and - buttons for maximum envelope and the inverse, so I will go with that.

Also, tangentially related: section 3 of the manual from digitalfaq titled "Panasonic AG1980P Service Manual VSD9509M264" has the instructions for calibrating many other video/audio adjustments with potentiometers (using a scope, color bar generator, video sweep generator, VHS/SVHS blank tapes (for rec functions), alignment tape, multimeter, etc). Adjustments include: (Servo Adj) PG Shifter, REV slow tracking, (Video Adj) EE Y E Level, VHS/S-VHS Rec current, VHS/S-VHS Y PB Level, Cos EQ Peak, S-VHS Frequency Response, (Audio Adj) EE Level, Level Meter, Normal Bias Current, Normal PB Level. I only brought this up because I recall seeing a conversation between Deter and Lordsmurf about mysterious potentiometers and what they were for. Or maybe I am mistaken, and there are yet EVEN MORE pots not mentioned in the service manual.

-- merged --

Also, as a quick update, I got more of the VCR's history from the seller. He apparently sells mostly refurbished lower end VCRs and Dvd/VCR combo units. The ag-1980p was his personal deck for digitizing VHS tapes. He said he had it for 7 years and it was a great performer, etc. He then sold it to ebay member tpventure, who immediately claimed it didn't power on and sent it back to him for a refund. It sat in a closet for a while and he re-listed it as "for parts, not powering on" when I bought it. Apparently the tpventure ebay member is somewhat infamous for buying functional electronics, and then immediately returning them in non working condition (found his name on reddit, mentioned by multiple ebay sellers). He also does electronics "repair" and sells on ebay. The unit had the same serial number upon return, so we think he basically bought it, swapped power supplies with a bad one and returned it. Hopefully that was the only thing swapped... I asked the seller if he smoked indoors, which he says absolutely not, not even a smoker etc. But the power supply box REEKED BAD of stale cigarette smoke, while the rest of the unit had a faint smell of cigarette smoke with the power supply removed.

Given that the unit performs SO poorly when first turned on, but actually gets fairly decent when fully warmed up, I am going to start by replacing all the caps in the power supply and see where that takes me. When using a new SP professionally recorded tape, and the unit is fully warmed up, I see no dropouts and the strong horizontal lines and wavy lines from my image above are gone, the picture is pretty stable with TBC on or off (picture gets SLIGHTLY darker when turned on, which indicates more bad caps). This suggests to me that the heads may still be okay. I can actually hear when the upper cylinder is spinning (it's fairly quiet), where as my JVC head is practically totally silent, so I am a little nervous about that. Can other ag-1980 owners hear their upper drums spinning at all?

On the other hand, if I am going to replace power supply caps, it's almost a certainty that there are other bad caps all over the place. If Deter is still doing full cap replacements for $500 plus shipping, I may just go that route.

[lordsmurf]

Quote:

Originally Posted by mistateo

I got more of the VCR's history from the seller. He apparently sells mostly refurbished lower end VCRs and Dvd/VCR combo units.

eBay is like the shady dudes in the parking lot of a flea market, trunk/boot open, in the 80s-90s. Just online, and you can't see how skeezy the seller looks.

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The ag-1980p was his personal deck for digitizing VHS tapes. He said he had it for 7 years and it was a great performer, etc. He then sold it to ebay member tpventure, who immediately claimed it didn't power on and sent it back to him for a refund. It sat in a closet for a while and he re-listed it as "for parts, not powering on" when I bought it.

None of that means anything. I have decks that were "perfectly working" when put into "storage" (office closet) years ago, and were failed when last tested. The unit age, used or not.

The fact that the seller went from "I think it's working, just needs a fuse" to "sells mostly refurbished" shows cognitive dissonance. My BS-o-meter is in the red. The more likely scenario is that he doesn't know his ass from his elbow, when it comes to VCRs. However, he does have a gift of acquiring low-end crap from yard sales and putting it on eBay. And that happens quite a bit. The term "refurbished" can mean "wipes the outside clean" to some people. (Worse yet, it's still not clean!)

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Apparently the tpventure ebay member is somewhat infamous for buying functional electronics, and then immediately returning them in non working condition (found his name on reddit, mentioned by multiple ebay sellers). He also does electronics "repair" and sells on ebay. The unit had the same serial number upon return, so we think he basically bought it, swapped power supplies with a bad one and returned it.

No idea who that is. I see a single mention on Reddit, and it's a throwaway comment without any details.

But I doubt it. More likely is that seller is an eBay flipper/opportunist, buying undervalued items, and reselling for more on eBay. that happens often. The Houston VCR scammer does this. The difference may be that the Arizona seller actually verifies that his buys work as described, whereas the Houston butthole just relists. He saw the deck didn't work, and returned it. I really do believe this was the actual scenario.

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I asked the seller if he smoked indoors, which he says absolutely not, not even a smoker etc. But the power supply box REEKED BAD of stale cigarette smoke, while the rest of the unit had a faint smell of cigarette smoke with the power supply removed.

The PSU in the 1980 can smell awful, almost like cigarettes. Mostly the oldest 1980 units, however. My "Big Bertha" antique VCR smells awful similarly, but it's the aging of the unit itself. Not anything external.

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On the other hand, if I am going to replace power supply caps, it's almost a certainty that there are other bad caps all over the place.

Yes.

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If Deter is still doing full cap replacements for $500 plus shipping, I may just go that route.

He probably won't touch it. He only wants to handle virgin units now -- aka naturally aged, never "fixed". So no DIY botch jobs from eBay. He's now asking where decks were sourced, and he will reject units that are fubar inside.

TGrant is doing the same now, but even more draconian. He now charges $1k, twice as much, for decks he didn't originally sell. But here the kicker: he now charges $525 for decks that are "out of warranty" (his own TGrant warranty), for 90-365 days.
Ask yourself this: Why would his refurbs fail in 90-365 days?
His work never lasts, many of us have costly "refurbs" (HA!) that failed in a short time.
He also rejecting certain serial # lines, and I don't understand why.

Owning AG-1980 decks sucks, and is usually simply not worth it these days.

[mistateo]

Yeah, mentioning the whole ebay thing was a mistake. All it does is detract from my actual questions.

[lordsmurf]

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Originally Posted by mistateo

Yeah, mentioning the whole ebay thing was a mistake. All it does is detract from my actual questions.

I don't know why you think that. These days, knowing the origin/source of a deck is extremely important. The entire reason eBay decks are seen as crap is because 90%+ of them are. And the sellers all swear it's "working" and "tested", and it's all total BS.

Deter, myself, others -- we ask this question. And we'll know (and heavily dislike) if anybody being evasive. We need to know what we're getting ourselves into.

Your "junkyard" deck was heavily abused, not just used. There is zero reason, no normal use, that would cause some of those issues.

Odds are, even after a full re-cap, you're still going to find issues.

I fully support you fixing this...

But Deter/etc are likely not options open to you, with a deck in that condition, a DIY botch job, from that origin/source. It needs to be stated. You can ask him, and he may agree (he can be a bit eccentric at times), but don't get your hopes up.

... so start on the re-cap. Hopefully that's all it is.

[mistateo]

I wasn't meaning it was a mistake to revel where I bought it. I did that intentionally in my very first sentence of my post. I just meant that the ebay discussion seemed to become the focus of the conversation, which I didn't intend. The seller sent me a bunch of screenshots I never asked for about the message thread between him the person he sold it to before me. Ultimately, as you pointed out, none of that really means anything. Even if the unit was purchased brand new by a single owner, used exclusively in a classroom to show videos to the class once a month, it certainly won't guarantee a good working unit since caps tend to die of old age, inactivity, etc. That would just lead to a better chance of a "virgin" with lower hours (but still failing) unit.

Video quality is a highly subjective thing. My wife can't really tell a difference between playback on my old crappy cheap sony deck and my HR-S7800U, but I was floored at how "good" a VHS tape could actually look with a decent VCR with built in Line TBC and DNR. Even VHS enthusiasts and people with a ton of experience in digitizing these legacy video formats have different opinions on what is considered "good quality", though the scope is narrowed considerably.

There were 2 reasons I bought this deck: I enjoy puzzles/challenges and have fairly extensive experience fixing both mechanical and electronic failure problems. The other being that I wanted a solid deck that will perform better for EP mode than my HR-S7800U. I may or may not achieve the second goal. But it was BECAUSE of reading those threads about capacitors in the ag-1980 that I fixed some stuff I had laying around (saved $200 on my furnace board by replacing 3 failed electrolytic caps rather than buy a new board for example).

I was just fishing around on here because I was hoping there was a "quick and easy" way to identify shot video heads vs bad caps because I just don't have the experience yet to know the difference. Basically if the heads are bad, there isn't much point in recapping this thing because replacement heads worth a crap are going to be ungodly expensive and hard to come by. Now that I have tested a larger amount of tapes, I am feeling like there MAY be hope for this unit. The fact that ANY tape looks SIGNIFICANTLY better once the VCR "warms up" for like 30+ minutes seems to suggest that there are AT LEAST probably several bad caps in the power supply. I imagine after fixing those, I will see some level of improvement, or at least a change in the "warm up" behavior.

So regarding the actual questions I asked (yes, I talk WAY too much):

Is the tape riding too low as I have adjusted it? (I have answered my own question after finding the info in the service manuals)

Are there any tests I can perform to determine if my video heads are okay before recapping everything?

Can others who have the AG-1980P hear the upper drum spinning, or are they supposed to be practically silent?

What could I learn from a "pass through test" (as opposed to playing a tape)? (I would assume this could definitely help determine if there are bad caps in the power supply and video board(s), but wouldn't tell me anything about the heads or TBC circuits)

Is there ANY point in trying to further dial in the p2/p3 post alignment without having the proper alignment tape, or with having bad capacitors in the unit? (I suppose the answer to this is found most quickly by just trying it, but just in case someone already knew the answer)

Regarding building a "library of test tapes" like other more experienced members have acquired, what are the basics I should look for? (A k mechanism alignment tape, a major movie release for SP, LP and EP speeds, SP camcorder recorded tapes, home VHS recordings in all 3 speeds, etc). I imagine there are some I missed, or some in my list that are unnecessary.

Lastly, does this unit log hours of use and is there any way to retrieve that info? (I assume no, because I couldn't find this answer ANYWHERE)

Again, I am very grateful for help of any kind. Looking forward to being able to help others in the future as I become competent in these matters.

[lordsmurf]

Quote:

Originally Posted by mistateo

Video quality is a highly subjective thing. My wife can't really tell a difference

This is misnomer, and too often stated.

When it comes to quality, there are very obvious technical flaws, which are not intended (at the rec/ISO/etc level), nor acceptable to virtually all watchers (and often regardless of claims made). Analog errors like snow and tracking errors are obvious, while modern digital errors like deinterlace artifacts are equally unacceptable.

Chroma errors are equally nasty, but can be overlooked when the content is small, or the person doesn't care about it at all. Those who want to see the content do get bothered by technical issues.

The "subjective" part comes in when disagreeing over the exact shade of red. It's not subjective when the red is green, or the red was obliterated by analog/digital artifacts. There is a difference.

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but I was floored at how "good" a VHS tape could actually look with a decent VCR with built in Line TBC and DNR. Even VHS enthusiasts and people with a ton of experience in digitizing these legacy video formats have different opinions on what is considered "good quality", though the scope is narrowed considerably.

Sure. But don't accidentally make false comparisons, nor make false equivalencies. Disagreements about quality models doesn't somehow mean that bad/crap models are acceptable due to opinion. Which I believe is what you infer from "the scope is narrowed". My concern here is other readers could mistakenly thinking junk is on an even footing with quality. (I don't always respond directly to a poster, but to other potential readers. as well.)

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There were 2 reasons I bought this deck: I enjoy puzzles/challenges

Fair enough.

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The other being that I wanted a solid deck that will perform better for EP mode than my HR-S7800U.

And this is why I hope you can get it working.

But my point in the previously replies was that you won't be able to rely on anybody else for it. Nobody providing repair service wants to touch molested eBay VCRs anymore, because it's often overly time consuming, and results are not guaranteed. Those are always botched DIY repairs (units beyond fubar), and vastly out of spec from little to no upkeep.

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I was just fishing around on here because I was hoping there was a "quick and easy" way to identify shot video heads vs bad caps

Nope.
Well, almost nope.
You can remove the heads, inspect them closely with a magnifying glass. Bad heads is somewhat easy to see, though not always easy for a novice to see.

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because I just don't have the experience yet to know the difference. Basically if the heads are bad, there isn't much point in recapping this thing because replacement heads worth a crap are going to be ungodly expensive and hard to come by.

I have a pair of for-parts decks that I need to sell sometime. They're currently on loan, so not in my possession. I gave him 3 bad decks, he was able to frankenstein 1 good unit for me. The other pair is more like VCR-shaped parts that VCRs. But the heads are one of the good parts! These are decks I gave up on, and Deter refused (after getting them in-hand, seeing the mess, trying, then stopping before wasting too much time).

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r once the VCR "warms up" for like 30+ minutes seems to suggest that there are AT LEAST probably several bad caps in the power supply. I imagine after fixing those, I will see some level of improvement, or at least a change in the "warm up" behavior.

Agreed.

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So regarding the actual questions I asked (yes, I talk WAY too much):

What's a novel here and there between friends?

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Are there any tests I can perform to determine if my video heads are okay before recapping everything?

Look, see.

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Can others who have the AG-1980P hear the upper drum spinning, or are they supposed to be practically silent?

It's not silent. But it's not a jet engine.

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What could I learn from a "pass through test"

Nothing. No such tests.

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Is there ANY point in trying to further dial in the p2/p3 post alignment without having the proper alignment tape,

I never use alignment tapes. But I have a large library, and selected a couple dozen for fodder.

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Regarding building a "library of test tapes" like other more experienced members have acquired, what are the basics I should look for? (A k mechanism alignment tape, a major movie release for SP, LP and EP speeds, SP camcorder recorded tapes, home VHS recordings in all 3 speeds, etc). I imagine there are some I missed, or some in my list that are unnecessary.

A main miss is multi gens, as well as many varied VCR and camcorder sources. This isn't something easy to acquire at this late date. You need constants with variables, not all variables.

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Again, I am very grateful for help of any kind. Looking forward to being able to help others in the future as I become competent in these matters.

And we welcome you to our world.

[mistateo]

Quote:

Originally Posted by lordsmurf

I fully support you fixing this...

But Deter/etc are likely not options open to you, with a deck in that condition, a DIY botch job, from that origin/source. It needs to be stated. You can ask him, and he may agree (he can be a bit eccentric at times), but don't get your hopes up.

... so start on the re-cap. Hopefully that's all it is.

Well you were certainly right about that one. I told him it had no power, how I fixed that. Then I told him I fixed the deck alignment. He said NOPE!