That's no problem being larger value, it's on the 12V B+. Might have been a production change to fix some ripple or interference when the motors were loaded down. In that diagram they show 2 100 uF's in parallel for total 200 uF.

Ok, I wasn't sure, I knew in old tube equipment, capacitor values weren't too critical but I wasn't sure about solid state stuff ( I know some solid state stuff like this capacitor value is more critical, than in tube circuits, which is why I asked.)

And I would think tube equipment would be more critical than solid-state...

How critical a capacitor value is depends on its function, and has relatively little to do with tube vs. solid state. Power supply filter caps need to be a certain minimum size. Signal-handling cap tolerance depends on function. Stage-coupling caps need medium-tight tolerances to assure low-frequency response. Caps for functions like tuned circuits require the tightest tolerance.

Tube and transistor circuits are similar in their sensitivity to passive component values.

Tube amplifiers generally may be sensitive to individual tube parameters, while most transistor circuits are generally insensitive to transistor parameters above a certain minimum, for example if current gain (beta) >=100. There are exceptions, for example where matched transistors and/or diodes are required to maintain proper bias in push-pull power stages.

Good clarification. Thanks!

I've always avoided working on anything with vacuum tubes including CRT TVs. Reason why is, back in the '70s my Aunt and Uncle up in Connecticut came home to find my cousin dead on the living room floor. He had been working on a tube-type guitar amplifier. So I've been a bit wary ever since.

Although one of these can nail 'ya too, about 80V + and - on the finals... one of my Pioneer SPEC-4 power amplifiers that decided to let the smoke out one day.

http://www.videokarma.org/attachment...1&d=1653176101

Hi. The PV-1730 was probably Panasonic's answer to the Sony SL-2700 Beta hi-fi. Like the 2700, it has direct drive reel motors and electronic servo-controlled back-tension. The same mechanism was incorporated into some Panasonic portable VCRs from the same time. The NV-180/PV-8000 being a good example.

Fivos

And the stereo Hi-Fi PV-9000 portable, can't leave that one out!:thmbsp:

Yeah. Quite amazing how they managed to cram the AFM circuits inside a unit that small in 1984.

Yes! But at the same time they didn't figure out how to keep the 8000 and 9000 VCRs from coming un-docked from the PV-A860 docking tuner charger power unit, until Panasonic came up with a modification kit a while later. Don't know how many of those I installed that kit in but it was a bunch!

http://www.videokarma.org/attachment...1&d=1653345370

Zenith and JVC in the 1980s had some pretty interesting Hi-Fi and Mono VCRs (one of them was a sideways loading front loading VCR) and most of those were also direct drive units as well. :thmbsp:

Was warranty service for JVC and Zenith, HR-D470 sideways load, and those did not have direct drive reels. DD capstan motors, yes, and the cylinder of course. Even the relatively sophisticated HR-S5800 and S6700 that you could use two together with a remote controller for editing didn't. ☺ The big industrial VCRs might have though, we didn't see many of those.

Matsushita owned a large stake in JVC but they sure didn't share any chassis or anything else.

I've had a few JVC (and JVC's Rebadged as Zenith) that did have direct drive mechanisms (mostly the really high end prosumer grade Hi-Fi units.)

Look up any HR model JVC and I betcha there's a belt from the DD capstan motor to the reel drive mechanism. Pretty sure you're thinking about the "prosumer" industrial models. But hey I've been wrong more than once!


Thinking about it, some of them (HR) had a centrally located DC motor between the reels for reel drive but still used an idler wheel to move one way or the other depending which direction the tape needed to go.

You're probably thinking of JVC's "BR" line. My 2¢!

The HR-D470 has a separate reel drive motor but it still uses an idler tire. There's no consumer JVC with direct drive take-up and supply "pancake motors" like the PV-1730 or SL-2700. Some Grundig European-market VHS VCRs from the mid 80s have a similar setup to the PV-1730, but those utilize the U-loading system like Betamax.

Yep!

I remember getting in those HR-D470s and the Zenith version too, where the backup supercap would leak and make a mess of things on the front timer board as I recall.

Some would need the star washer under a screw on the bottom deck board to ground. I installed that washer on every similar chassis JVC that came in with even the potential of needing that, just so it wouldn't come back on me.

The one I'm thinking of, that I have currently, is the Prosumer grade version of the HR-U8000 S-VHS VCR, of course maybe I was thinking of the HR-U8000 S-VHS unit when I was thinking of one of the JVC VCRs I had (which I've had several over the years including JVC made Zenith VCRs) that was all direct drive...:scratch2:

And Yes I have also had the HR-U8000 S-VHS VCR as well, (which I got from the High School I went to when they retired it.)
Actually I had two of them, I also got one from a garage sale one time as well, the one I got from the school had its original remote and the one I got from the garage sale didn't, the one I got from my high school when they retired it had long since died and been junked out (including the remote) by the time I found the one at the garage sale a few years later.

That would be HR-S8000U...The one with the crappy switching mode power supply burns up in, melts the insulator sheet! Did not like it when I got assigned one to work on, at all! And no, not direct drive reels in that either.

Ok, I thought it did have them (I had opened it up only once when I had it and I saw several motors under there but didn't realize it wasn't direct drive all around).
Sorry for the confusion.
The unit I have now which I think is the sister to the wood-grained S-VHS unit I was talking about is the HR-D630U Hi-Fi VHS VCR from 1987.

HR-D630U not S-VHS, a higher end consumer model, with central reel motor and idler drive. Any others?

I didn't say it was S-VHS, I said it was the regular Hi-Fi VHS version of the S-VHS unit that JVC made that year because it had the same style front end layout.

Never mind...! I am done.

BTW.. If you still have the HR-S8000 I would advise unplugging it when not in use or it might burn your house down! No thermal protection and fuses wouldn't blow either. ☺

Nope, fortunately I don't have either of them anymore as they both suffered the burned up power supply issue you mentioned, although at the time I didn't realize that's what happened with them...

I'm sorry I didn't mean to confuse you with the descriptions of the VCRs I had. I was just describing what I thought they looked like.

I got my new (to me) analog ESR Meter today, installed some batteries and found some test leads for it (I had some spare test leads for it from an old $10 Harbor Freight DMM that died on me a couple of years ago) that worked with it perfectly and I tested those capacitors I mentioned that we figured out were part of the take-up and supply reel motor B+ lines and they all tested bad (they pegged out the ESR meter, at least I think so anyways if I'm reading it right, in reference to an ESR chart I downloaded from the internet.)

Alright so I actually figured out that if the meter pegs out the capacitors are good. So I figured out that C6-C8 were the actual culprits, they actually suffered from the notorious Matshuista(sp?) green corosion/leakage issue and that's actually the first time I've ran into that so far. :scratch2:

But I know Shango and J. P. Dylan have both discussed it in their videos quite often so that's the only reason why I recognized it once I found them with my ESR Meter. :thmbsp:

Now to gets some replacement capacitors and install them and put the VCR back together and I think I should finally have a functioning VCR again. :yes:

Well another update on the VCR, I did manage to find some capacitors for the VCR in my capacitor stash, and installed them, and put the VCR back together and it is partially fixed, the VCR is now powering on all by itself now when you plug it into the wall, and the take-up reel spindle is now spinning at a much faster speed than it used to when it is doing the self-diagnostic check.

But its still not spinning up the supply reel spindle and the video head drum isn't spinning up either in the self-diagnostic check, so I wonder if there's some more capacitors on another board that's involved with the loading/playback mechanism?

Also I noticed that when the VCR attempts to power up the display screen shows "camera" on the readout which I'm not sure if that's normal or not but I'm wondering if that's maybe something that might be something to do with what's going on with the VCR and why its acting up?

Is the input selector switch set to camera?

Looks like the PV-1730 uses the same motor drive ICs as the portable PV-8000 so this schematic might be useful although the board itself is obviously different.
Attachment 204340

Attachment 204341
EDIT: Because the resolution of the attachments is garbage, here's the links for the full-res png files:
https://drive.google.com/file/d/1Xge...ew?usp=sharing
https://drive.google.com/file/d/1LGu...ew?usp=sharing

No, it wasn't it was set to the Line Input mode (which apparently triggers the "camera" light on the VFD Display readout, which is the same thing that happens when its actually set to "camera" mode.)

Anyways, I take it that the "Servo Board" also has some influence on the functionality of the VCR's loading/playback mechanism? If so could it be possible that there might be some bad caps on that board as well causing some issues?:scratch2:

Generally the servo circuit is what controls the speed and phase of the capstan and drum motors. This machine being fully direct-drive will have an extra servo board for the reel motors. Loading issues are usually caused by dirty mode encoder switches, gummed-up mechanisms or missing/low power supply voltages. Since you have the Sam's, have you verified that the voltages from the power supply are correct?

I did check the voltages and the seemed to be where they were supposed to be. I did notice though in the Sam's that there is a Voltage regulator transistor for the supply reel motor which (which seems to be the only part of the motor drive board that has a voltage regulator transistor), I wonder if that might of failed and that's what's causing the supply reel motor to malfunction, either that or some bad capacitors on another board somewhere in the VCR. :scratch2:

Also I was looking at the Servo/Control Board for this VCR in the Sam's and it seems that it does indeed control the take-up and supply reel motors as well besides the capstan and drum motors.
So again I think I might take a look at that board for some bad capacitors with my ESR meter.

Well I took the Servo Circuit Board out and looked it over closely and when I was checking some of the electrolytics on the board, I noticed what looked like a dip or low spot in the board around one of the plastic stand-offs and so I looked at it closely and sure enough the board has several cracks in it that go through to the traces and so I think that the reason why this VCR isn't working is because of the cracks in the Servo Board. :sigh: :no: :tears:

Unfortunately I think this VCR is a lost cause unless someone has a donor board from a junker VCR that they'd be willing to send me or know of one somewhere for sale... :scratch2:

You can measure the junctions of the transistor in the diode test mode of a multimeter. I don't know if this model is supposed to run the supply and/or take-up reel motor when you turn it on as we didn't have a PV-1730 equivalent model here in Europe. Does the front loading mechanism accept tapes?

No it doesn't accept tapes into the VCR when you try to load the tapes into the VCR, that's because (at least in USA models) the VCR has to be powered on in order for it to be able to load a tape into the mechanism, and if the VCR refuses to power on (goes into safety shut-down mode) then the VCR loading mechanism will not load tapes.

And as a little update, unfortunately I found several broken traces on the main control board of the VCR (the board that contains the Servo Circuit, Index Circuit, and the System Control Circuits) that were from some cracks that I found on the circuit board that were around a couple of the plastic standoffs that were for supporting the board against the case when you installed the board into the case.

I'm going to see if there's any way to repair those traces, if not I'll see if there's a board for this VCR available on feebay for sale.

It will more than likely be a single-layer board so severed traces will be easy to repair. Can you upload close-up pictures of the damaged traces?

Yes, thankfully it is a single layer board (traces only on one side) so yes I think it should be able to be repaired using the Shango method.

I'll post a picture of the broken traces when I get back from work later tonight.

Shango method... awaiting the results.

http://www.videokarma.org/attachment...1&d=1655600823

Used to get in PV-5000s and PV-6000s (portables) with cracked 3-layer boards a lot. Panny had placed a small rubber spacer between the board and the bottom cabinet panel. All it took was a bump while carrying it around to crack the board. Yes I repaired them, charged by the hour. Used the Ed method.

Have fun!

-

I meant Shango066 on YouTube. 😜

ah.. OK. I thought you were going to listen to Santana's "Shango" while you worked on it. :thmbsp: That was one of several albums I used to listen to while at work.

That's OK, I just thought that when one mentioned Shango on here it was kind of understood that one was talking about Shango066 on YouTube.

I guess I shouldn't assume things like that on here. 😅

OK, so I finally got the VCR Fixed! :thmbsp:

But of course now it has a timing issue related to the mode switch I think, because when I put the tape in, it loads the tape in normally like it would if you tried to play a tape but then when you hit play the tape loads against the heads and attempts to play but then unloads the tape back into the tape housing, and if I try to hit rewind or fast forward the tape will rewind for about a second before stopping and then loading the tape against the heads like its going to try and play but then the VCR shuts down and when you try to power it on again it shuts back down again after a few seconds (and the tape is stuck in fully loaded/playback mode the entire time.)

Is there some sort of way to figure out which mode the mode switch is in in reference to the mechanism? Like is there some sort of specific marking that will tell you which position is which on the mode switch (ie stop, play, Rew, FF, Eject, Pause, etc.?)