Panasonic AG-1980 worth it for VHS-C?

[lordsmurf]

Not that I'm aware of. The last time I did anything with an AG-1980P was before my MS, more than a decade ago. Back then, Youtube was mostly just a joke, the "I like turtles" site. I couldn't do such a guide these days.

For the most part, people that learned this decided to capitalize on it, which I'm fine with, I understand it. No desire to give away secrets that would harm their side gig (or even main gig). The only real problem with this is when a weak half job was done, such as TGrant repairs. So I think there does, at least, need to be a checklist of expected repairs, and optional repairs. Even if not monkey-see/monkey-do dummy guide.

I'll add that to my post-upgrade to-do list.

[jbd5010]

Quote:

Originally Posted by lordsmurf

For the most part, people that learned this decided to capitalize on it, which I'm fine with, I understand it. No desire to give away secrets that would harm their side gig (or even main gig). The only real problem with this is when a weak half job was done, such as TGrant repairs.

Agree, if you work to learn a skill or gain specialized knowledge, being compensated for it is legit. But it seems Deter is the primary reliable source, and the demand far exceeds his capacity or willingness to perform repairs. And even if a guide were published, I think that would continue to be the case. Plenty of folks who wouldn't try to take on the project even with a guide published, I suspect. Not sure how Aramkolt would feel about it.

Quote:

So I think there does, at least, need to be a checklist of expected repairs, and optional repairs.
I'll add that to my post-upgrade to-do list.

Would love that! And some sort of summary of potential pitfalls and pro tips. Like "don't remove this board without disconnecting X first or you'll rip the traces off the PCB, ask how I know"

[lordsmurf]

That scary part is that, in order to make such a guide, I'd have to rip apart a machine again. For photos, for my own memory. I may need to get with aramkolt on this.

There were actually some things that deter didn't want to try/learn, but I think aramkolt will be more amiable to it. By the time I saw it, I just couldn't do it anymore. My brain needs steady hands. Perhaps we can tag-team it online.

[aramkolt]

It's not really a mystery as to what Deter does since I've re-repaired a couple of his machines now and anyone that has bought one of his machines can verify. On the unit I had from him, He changed 5 through hole caps surrounding the small transformer on the front LCD board, and the SMT caps on the TBC card - and that was all in terms of recapping.

Not saying that won't take care of a lot of common issues, it just isn't future-proof or likely going to give the best result overall in my humble opinion. Could also be that what he does to VCRs varies from unit to unit, that's just a sample of one, but that was a VCR that was sold through his videohelp thread for something like $1200 or whatever the posted rate is.

He also used Wurth Electronik brand caps which can technically be made anywhere in Asia, though the actual company is based out of Germany, but none of their caps are made in Germany to my knowledge. If they were made in Japan or Germany, they would want to state that as that'd be good from a marketing perspective. On paper, the specs look nice, but I find it hard to believe that they came up with a better formulation for most of their caps than Nichicon, Nippon-Chemicon, Panasonic, and Rubycon which are exclusively made in Japan and those are the only brands I use, all sourced from Mouser.com so that there is no question of authenticity. In the short term, there's probably minimal difference in visual performance (even cheap Chinese capacitors work fine for a while), but long term, who knows?

For my refurbs, I replace all of the power supply caps, all caps on both front boards, all caps on the head amp, all caps on the TBC card including the through hole ones (in addition to the SMTs), as well as a few other select caps that are in high-heat areas. I do all of this basically for the same price or less ($750 including return USA shipping) and I don't charge anything until the refurb is successful. It's really not possible for the refurb not to be successful because I have parts machines I can pull from if I need to.

My turnaround time is also usually 2 weeks or less, not sure how long Deter's is, but guessing it is longer. I'm sure if I had more volume, it would take longer, but for now, I've been able to keep up with demand.

I've heard at least one case of Deter not resolving an issue that was discovered upon delivery from a buyer who used a VHS-C adapter on a just-purchased AG1980, which Deter told that buyer voided his warranty. See the post here if you're curious about that machine. It doesn't explicitly talk about the warranty being voided, but the user would have sent it back to Deter for a free repair if he'd have accepted it (instead of paying me to fix a just-refurbished machine):
https://www.digitalfaq.com/forum/vcr...-ag-1980p.html

As for what he does with his mechanisms, I didn't see anything particularly unique there, but the issue with the VHS-C adapter was due to the refurbished mechanism not being refurbished well enough (apparently) as I didn't have to swap any parts to get it going, just rebuilt and re-lubricated it.

Not saying my refurbs all my refurbs arrive perfect, I've have had a couple of machines that needed to be sent back for issues which I believe occurred in return shipping, but I'll always strive to make it right.

I definitely wouldn't do any of this if I didn't enjoy fixing electronics. However, I also want to provide an alternative to more expensive services that (in my opinion) aren't likely to be as robust in the longer term as they could be (due to fewer components being replaced and using components of possibly inferior quality), all while doing it at a lower price and faster turnaround time. I'll also beat his price for already refurbished AG1980's and have several ready to ship immediately.

Feel free to PM me if interested in any services or already refurbished VCRs.

-- merged --

I apparently misremembered the situation since it has been a while, the AG1980 I inspected/that had the VHS-C issue was one that Minotz had refurbished as a service, not one that was purchased as a pre-refurbished unit per his post linked above.

[dinoman64]

I wouldn't be opposed to making a guide or a video since I have my machine completely disassembled at the moment, but I don't think a guide would really be that helpful to be honest, there's already enough good info on this forum and if you are unexperienced in electronics repair it probably is a bad idea to mess around with a expensive item like these VCRs. (not that you shouldn't try to learn, just get experience on cheaper stuff first)

Capacitor lists aren't that useful since part availability changes constantly, you are going to have to substitute some regardless. I used MrPete's list from this thread but I can't recommend it since I've already found a few that are missing from that list and I'm not even done yet. It saved me some time though, so I still appreciate it.

The other issue with a guide is, there's no clear consensus on what is necessary to replace or repair on these machines. LordSmurf claims you absolutely must replace all electrolytic capacitors on all boards in the VCR. Others say this is unnecessary and you only need to replace caps on certain boards. I'm personally still not sure what to think. I'll probably try aramkolt's method first and if there's issues go back and do the rest.

Maybe a compilation of all the most valuable info on repair in one post would be the best thing to do. I don't believe for a second that there's "secrets of the trade" for repairing these specific VCRs. It's a tedious job, you need electronics skills and knowledge, you need the right tools and experience, that's what's protecting their business.

I think if you don't already have the skills to figure it out on your own with help of the info on this forum, you should probably leave it to the "pros". But for the people who do, a compilation of tips and information should suffice.

[jbd5010]

Quote:

Originally Posted by dinoman64

I wouldn't be opposed to making a guide or a video since I have my machine completely disassembled at the moment, but I don't think a guide would really be that helpful to be honest, there's already enough good info on this forum and if you are unexperienced in electronics repair it probably is a bad idea to mess around with a expensive item like these VCRs. (not that you shouldn't try to learn, just get experience on cheaper stuff first)

I think the main thing RE: info on the forum is the scattered nature of the information, combing through hundreds of posts, etc. (Far from unique to this forum or this topic).

Quote:

Capacitor lists aren't that useful since part availability changes constantly, you are going to have to substitute some regardless. I used MrPete's list from this thread but I can't recommend it since I've already found a few that are missing from that list and I'm not even done yet. It saved me some time though, so I still appreciate it.

I think the list is incredibly helpful even if it still requires verification when compared to starting from scratch. Otherwise everyone would have to develop the list, check production status, find currently-available equivalents, etc. on their own for each capacitor in the machine. The list saves a bunch of time if you type the part # in and it's still available from DigiKey or Mouser. Cuts down on the volume of work significantly.

Quote:

The other issue with a guide is, there's no clear consensus on what is necessary to replace or repair on these machines. LordSmurf claims you absolutely must replace all electrolytic capacitors on all boards in the VCR. Others say this is unnecessary and you only need to replace caps on certain boards. I'm personally still not sure what to think. I'll probably try aramkolt's method first and if there's issues go back and do the rest.

Definitely a judgment call and requires at least basic understanding of electronics, how VCRs work, ability to read and understand the service manual, and how various circuits could affect one another. Replacing every single capacitor is kind of the fool-proof approach/maximum insurance policy, assuming you don't botch it. Personally, I like Aramkolt's method as well, especially for repairs on your own machine vs. doing it for others as a service. I can always pop my own back open and replace more caps if something fails.

Quote:

Maybe a compilation of all the most valuable info on repair in one post would be the best thing to do. I don't believe for a second that there's "secrets of the trade" for repairing these specific VCRs. It's a tedious job, you need electronics skills and knowledge, you need the right tools and experience, that's what's protecting their business.

This is exactly what I had in mind.

Quote:

I think if you don't already have the skills to figure it out on your own with help of the info on this forum, you should probably leave it to the "pros". But for the people who do, a compilation of tips and information should suffice.

Yup. If someone needs to be spoon-fed step-by-step instructions, they probably don't have the skills and background to tackle the project. My suggestion a few posts up isn't for that type of guide, but rather a tips/tricks and knowledgebase type thing. I think we're on the same page!

[lordsmurf]

FYI, there are multiple versions of the AG-1980P. That's why you find so many differences.

[dinoman64]

So I replaced all the caps on the Y/C card, head amp, rf amp, power supply, and VFD display board. Put it back together tonight and powered it on, no more noise from power supply, screen is bright again. All seemed to be ok but before I could put a tape in it, smoke started emanating from underneath the main board.

I took it apart again, inspected the 2 cards I had worked on and found nothing wrong so far, neither of them smell bad but the main board definitely stinks. Hoping it's just something small... I'll inspect more tomorrow. Maybe replacing the power supply caps has overloaded a weak component somewhere...

Also, not sure if anyone cares about these updates on fixing this thing, I'm not intentionally trying to turn this thread into one about electronics repair, I'm just sharing my full experience with this project and hopefully the information is useful to someone.

[billct97]

I find it interesting. It might be me someday.

[Gary34]

Quote:

Also, not sure if anyone cares about these updates on fixing this thing, I'm not intentionally trying to turn this thread into one about electronics repair,

I like the updates.

[timtape]

Quote:

Originally Posted by dinoman64

So I replaced all the caps on the Y/C card, head amp, rf amp, power supply, and VFD display board. Put it back together tonight and powered it on, no more noise from power supply, screen is bright again. All seemed to be ok but before I could put a tape in it, smoke started emanating from underneath the main board.

I took it apart again, inspected the 2 cards I had worked on and found nothing wrong so far, neither of them smell bad but the main board definitely stinks. Hoping it's just something small... I'll inspect more tomorrow. Maybe replacing the power supply caps has overloaded a weak component somewhere...

One of the reasons some suggest only replacing failed, close to failing, or likely to fail caps, such as heavily used main power supply caps, is to greatly reduce the total number of caps replaced, reducing the chance of replacing caps incorrectly such as accidentally reversed cap polarity installation, or bridged PCB tracks, or incorrect capacitor values. The damage caused by such errors including the time taken to locate them among all the other replaced caps can mean a full recapping may be hard to justify.

The benefits of a full recap are generally long term such as 30 or more years of reliable caps, depending on the type and application. If the VCR's use is merely short term such as transferring tapes over a short time frame of say 6 months, a full recap may not make much sense.

[dinoman64]

I spent a few hours today inspecting the VCR. Didn't find any evidence of burnt components which is strange. Maybe it was flux burning off? weird. I reassembled the whole thing, plugged it in, no smoke, no smell.

Put a tape in, loads it fine, starts playing, all functions seem to work. Hooked it up to the tv and.... No video, no hifi audio. Linear audio works. Jog/shuttle mode doesn't respond to the dial or wheel, it just jogs forwards until you press stop.

I hooked up the oscilloscope to the RF test point and there's Nothing. No output from the head amplifier. Not sure how that's even possible to be honest. I even probed the flat flex connectors on the head amp for RF signals and all I saw on the scope was a steady +0.5 volts on the pins marked RF_Y and RF_C, the voltage would drop to 0 when playback was stopped.

I inspected the head amp (silver box behind the head), looks fine, tested all the components, re-flowed solder joints, nothing worked. This was one of the parts I replaced the caps in.

The service manual for the ag5710 is frustrating. Very confusing and limited information on signal paths and test points. Like the manual saying the RF test point is "TP3001" when on the board it's actually marked "TP ENV" referring to RF envelope.

I'm gonna assume for now the smoke thing was a fluke and my problem is more likely related to something that was disturbed while replacing the caps and or disassembling the machine. I'm not yet ruling it out as a cause yet though.

Need some help here if anyone has any ideas.

[lordsmurf]

Quote:

Originally Posted by dinoman64

smoke started emanating from underneath t

Upon reading this, I uttered "aaww, f--ck" to myself. Anybody that has ever fixed/modded knows that gut punch feeling.

Quote:

Originally Posted by Gary34

I like the updates.

Me too.

Quote:

Originally Posted by timtape

One of the reasons some suggest only replacing failed, close to failing, or likely to fail caps, such as heavily used main power supply caps, is to greatly reduce the total number of caps replaced, reducing the chance of replacing caps incorrectly.

Eh ... hmmm .... uh .... ehh.... .... no.

I see your attempted point, but I don't like it. I find the reasoning too specious. Just be more careful. (Hint: Write down notes!!! Take many photos before starting work!!!)

Quote:

Originally Posted by timtape

If the VCR's use is merely short term such as transferring tapes over a short time frame of say 6 months, a full recap may not make much sense.

I think this is where PAL vs. NTSC comes into play. Being PAL, I don't think you've ever used this deck, have you? When AG-1980P starts being used, it tends to break down quickly, often far less than 6 months. Most of these were used, stored -- maybe repeat a few times -- but time hasn't been kind. The internals are infamously known to break down. Not fully* re-capping an AG-1980P in the 2020s is really inexcusable. (*All caps on certain boards, at least.)

Quote:

Originally Posted by dinoman64

The service manual for the ag5710 is frustrating.
I'm not yet ruling it out as a cause yet though.
Need some help here if anyone has any ideas.

Well, even if your attempt fully fails, I really respect you for trying.

What you're trying is not easy, and failure is somewhat expected. Keep us updated.

I'd rather see more AG-1980P (5710) repaired, and less in landfills.

[dinoman64]

I think we really need to all agree to define a "full recap"

Replacing all caps on a section/board should be standard, with a few exceptions IMO like- Really large caps that test good, and very small value caps where replacements are unavailable - assuming these are name brand high quality caps to begin with. If a device has leaky/bad caps of a particular brand or series in one area but not another, I'd replace all caps in all areas of that same brand/series out of caution.

My ag5710 seems to be a later model, I'll have to check the serial no. again but I think it's from 2001-2002. I've only found a handful of through hole caps with out of spec ESR values. Surface mount Y/C card caps, not so easy to tell because they by nature have high ESR. None are leaking anywhere on my machine. Kind of regretting starting this project honestly, if I had just left it alone it might have done well enough without a recap. I didn't even get a chance to really assess the playback performance in detail before I just jumped into replacing the caps. My thinking was "well I don't want it to eat my tapes so I better just go for it".

Anyway...

I think I have a lead on what might be causing my no RF signal issue. On the 14-pin flat flex from the head amp, pin 5 is shown in the schematic as "EX_REC_5v", this pin is connected to the video head amp chip (IC501) on pin 1 marked "PB VCC" -I'm assuming this is the power source for the head amp, and it should be 5v as most chips of this era use 5v logic. When I probe the pin, it reads 1.5V DC. The same discrepancy is found on Pin 3 of the 9-pin flat flex powering the audio head amp chip. The 12v supply to the head amp when recording is unaffected, however, this source does not appear to power the chips directly, and so the recording function still does not work. I traced the 1.5V source back to the main board section marked "Ref no. 1000 series". Probing around the main board, I didn't find any other areas with unusual voltage levels. The power supply output voltages are all normal as well. That's as far as I got today.

Anyone wanna help confirm that 1.5 Volts is abnormal for the head amp?

I'm glad you all are interested. Makes me feel less insane for taking on a punishing project like this lol.

[timtape]

Quote:

Originally Posted by dinoman64

I think I have a lead on what might be causing my no RF signal issue. On the 14-pin flat flex from the head amp, pin 5 is shown in the schematic as "EX_REC_5v", this pin is connected to the video head amp chip (IC501) on pin 1 marked "PB VCC" -I'm assuming this is the power source for the head amp, and it should be 5v as most chips of this era use 5v logic. When I probe the pin, it reads 1.5V DC. The same discrepancy is found on Pin 3 of the 9-pin flat flex powering the audio head amp chip. The 12v supply to the head amp when recording is unaffected, however, this source does not appear to power the chips directly, and so the recording function still does not work. I traced the 1.5V source back to the main board section marked "Ref no. 1000 series". Probing around the main board, I didn't find any other areas with unusual voltage levels. The power supply output voltages are all normal as well. That's as far as I got today.

Anyone wanna help confirm that 1.5 Volts is abnormal for the head amp?

I'm glad you all are interested. Makes me feel less insane for taking on a punishing project like this lol.

When I read you saying there was no RF output I thought to myself "has he checked for correct DC supply to the head amp?"
Also, what might have caused a fault which appeared after changing the caps? What are the probabilities?

[dinoman64]

IT'S FIXED!!!

I found the ref no. 1000 schematic in the manual, it's lumped in with the "Video (main)" schematic. This area provides various 5v power sources for the whole machine, it contains a shunt regulator and 2 NPN transistors that output "REG_5V" and "DIGITAL 5V". Transistor Q1002 responsible for REG_5v was outputting only ~1.5 volts on the emitter, and transistor Q1001 responsible for DIGITAL 5V was outputting ~6.7V.

I replaced all the caps in the ref no. 1000 area, and removed the faulty transistor to find... A tiny bulge on the transistor! I found the source of the smoke! I replaced it temporarily (maybe permanently) with a TIP31 transistor I bought at RadioShack back in the day. Plugged it in, no smoke, turned on, put a tape in and IT WORKS! Checked the voltages and it's bang on 5v everywhere it's supposed to be.

Some other symptoms I hadn't noticed before but make sense now: The power led was not lighting up. The VU meters on the front display weren't showing up at all, completely dark. If you look at the schematics it's clear both of these features need 5v to operate. Both of them now light up brightly.

I'm so psyched about fixing it. This deck is super clean and looks almost new inside and out, I was sooo disappointed that I might have ruined it, but I didn't! Although if I was less knowledgeable about electronics I'd be dead in the water and down ~$350. Now I can get on with the rest of the project. Gonna test the Panasonic for hours on junk tapes before I think of putting anything precious in there. I've attached some pix so you guys can see for yourselves. Hopefully this thread helps anyone who comes across the same sort of issue in the future.

Soon I might provide some comparisons between my two decks on VHS-C. Should be interesting considering my old one was made specifically for VHS-C tapes.

[lordsmurf]

Quote:

Originally Posted by dinoman64

IT'S FIXED!!!
I'm so psyched about fixing it. This deck is super clean and looks almost new inside and out,
Soon I might provide some comparisons between my two decks on VHS-C. Should be interesting considering my old one was made specifically for VHS-C tapes.

Excellent.

[timtape]

Quote:

Originally Posted by dinoman64

IT'S FIXED!!!

I found the ref no. 1000 schematic in the manual, it's lumped in with the "Video (main)" schematic. This area provides various 5v power sources for the whole machine, it contains a shunt regulator and 2 NPN transistors that output "REG_5V" and "DIGITAL 5V". Transistor Q1002 responsible for REG_5v was outputting only ~1.5 volts on the emitter, and transistor Q1001 responsible for DIGITAL 5V was outputting ~6.7V.

I replaced all the caps in the ref no. 1000 area, and removed the faulty transistor to find... A tiny bulge on the transistor! I found the source of the smoke! I replaced it temporarily (maybe permanently) with a TIP31 transistor I bought at RadioShack back in the day. Plugged it in, no smoke, turned on, put a tape in and IT WORKS! Checked the voltages and it's bang on 5v everywhere it's supposed to be...

Glad you fixed it. In addition before replacing the electro caps in that area I would have measured their capacitance and ESR to try and find out what might have caused the failure of the transistor. If operated within their safe operating parameters transistors very rarely fail. Electro caps inevitably deteriorate and may have caused the eventual failure of the transistor.

[billct97]

Quote:

Originally Posted by dinoman64

IT'S FIXED!!! Soon I might provide some comparisons between my two decks on VHS-C. Should be interesting considering my old one was made specifically for VHS-C tapes.

Great news and pictures! IIRC you were going to compare JVC and Panasonic with the VHS-C tapes. I'm still seeing better color on my JVC so I'd be curious to know if you see similar results. If not maybe it's a sign my AG-1980 has some flaws.