Are these JVC SR-V101 VCRs broken?

[lordsmurf]

Two decks, two problems.

Deck 1, Day 1

Seems to load, eject, play, FF, rewind.
But the image is bad -- really bad. Lots of grain, black specks, dropout comets, horizontal jitter (timing errors).
My assumption = bad heads

Deck 2, Day 1

Seems to load, FF, rewind.
When you "play" it shows an image for a second and then shows nothing. Tape still moving. If you FF while play, the image is on screen.
During troubleshooting, its discovered that the pinch roller is off the shaft (broken?). No obvious way to reattach.
My assumption = bad pinch roller

Deck 2, Day 2

So the fix appears to be obvious. Take the good roller from the #1 "bad head" deck. It's opened remove, swapped. Now deck #2 should have good heads and a good roller!
But the deck remains unchanged. Same problem playing tapes.
My assumption = bad mainboard

Decks 1+2, Day 3

Both decks opened,drums swapped. So now #2 should have good mainboard, good drum/heads, good roller.
Now the not-fun begins!

At first, neither deck would loads tapes.
Remember, even with no roller, #1 was still accepting/loading.
The pinch roller was re-attached several times on #2 before it would seat correctly.

Now #2 will not rewind or FF.
The LED counter does not work anymore, though the on-screen does.
And to top it off, it still plays with a 1-second picture, or FF-play shows picture.

Deck 2, Day 4

As it turns out, it's just the buttons on the VCR that do not work. The remote will allow FF and REW, but some thing really nasty happens. JVC VCRs start out by FF/REW while a tape is against the drum. Then it will suck the tape back into the cassette, and FF/REW in there.
This VCR will not completely suck the tape back in, and the reels make this horrible "missing" sound. The tape isn't actually moving, but the deck is grinding the heck out of the bottom of the tape.

I discovered something about the intermittent playback. With bluescreen on, the image will play audio and video for a second, then disappear. With bluescreen off, the image and audio are fine for 2-3 seconds, then turn shows video only for 1-2 seconds, then gets garbled for about 5 seconds. Turn it off right then, hit play, and it's magically fine.

I'm thinking the heads on both units are shot. Both not sure.

Now...

I've never had a JVC act like this.

So far, it seems as if I broke a broken VCR. <sigh>

Any ideas?

The service manual is attached.
Note: The 101 manual is very brief, and refers heavily to the 5901 manual for the mechanics.

[Quasipal]

As a VCR engineer I'm afraid what you did is not really the right way to go about fault finding as before changing anything you need to verify what the fault is and then when fitting new parts, use brand new ones, not ones from another unit. By using ones that have seen use, they will likely not work well when fitted to another unit with its own wear characteristic. With pinch rollers always fit new ones - they have a short life and become contaminated with tape lubricant, increasing tape skew and drift. With the correct tools you can refinish rollers to almost new - the rubber needs removing until the 'lubricant free' rubber is exposed, but if the central bearing is worn then that will either need replacing or a new roller.

As to the other issues, well as you can imagine I can't diagnose from afar. You mention worn heads. Worn head symptoms are usually accompanied by many warning signs like bands of missing information and don't usually just turn up. With practice you can see visually if a head is worn by using a 50mm f1.8 SLR lens (I use a Pentax one) and an LED torch with good close up ability - like the Lumintop Tool. You can then see the radius of the head and how the wear is occurring (radius change). Tricky to see but one you see what you are looking for its a doddle and saves wasting time when heads are not available. I have had machines with worn head symptoms but the radius was like new so I moved attention onto the main board and found failed bi-polar capacitors under the head.

Please don't mix and match parts from different VCR's as you may just be moving faults about and adding new ones inadvertently by moving stuff (like a Rubics Cube) and applying pressure to delicate plastic bits without realizing it. Each time you open and fiddle inside, more gets displaced - happens to me too - a trapped wire, tape door not aligned etc. Approach each fault separately and eliminate it. If the main board U/S then just move on to another machine, with modern VCR's fault finding on these is very hard and time consuming. But this is rare - only had it once.

As an offer, I can refinish the rollers to 'as new' using a machine of my own design and return them to you FOC if you would like. Just pay postage - I'm in the UK. Of course if you have new rollers fit those.

[lordsmurf]

After a few days off, it was time for Day 5 of my DIY fix attempt. Now, I knew I was tired this week -- I now suffer from chronic fatigue -- but I was more tired than I realized.

I had forgotten to attach a ribbon on BOTH decks.

I forget off-hand which piece was disconnected (tired again), but it's the one that controls both the counter and the alignment. The picture is now behaving, and the tracking is a solid "A-" (auto-tracks SP, can track EP/SLP though not auto). Audio fine.

So one down.

Now, if I can only get 1 from the 2, I'm satisfied. However, I'm not ready to entirely give up.

This 2nd deck now has two major problems:
- the pinch roller detached, and
- it grinds tapes when FF/rewind. Play is fine, and even FF/rewind is fine while the tape is snaked through the transport. It's when the tape sucks back in after 2-3 minutes, to rewind within the clamshell.

I have several other non-working JVCs, including a 3800. The roller looks the same. I can see a little black round doodad holding it in place on the 3800. That's missing on the 101. How is this removed? I've never tried to remove just a roller, and in the past have had a whole new assembly.

Quasipal, yes, I agree. What I'm doing isn't ideal. But I want to take some non-working decks and try to cobble together some "new" ones. Of the 6 non-working decks here, I've managed to repair 2 of them! I'm trying not to buy parts or more decks to do it. It's not the first time I've frankensteined gear to make new ones.