What is wrong with JVC HR-7700EU VCR?

[Rolle68]

Hi.

I have been capturing using my JVC HR-DVS2 and happy with the results.

I saw HR-S7700 coming to sale for 5€(!) and bought it immediately. The seller said that it will not even power up (seller had newer used it and was selling it behalf of someone).

Since HR-S7700EU and HR-DVS2EU seem to be released in same year, I bought S7700 primary for possible spares for DVS2EU.

The S7700 actually powered up, so I cleaned the heads and tested it and got a picture.
The only thing is that the picture is not as good as in my DVS2 .
Should these vcr's perform similar?

Since I got the picture out, I am not interested in using it as spares anymore if I can get the picture "cleaned/corrected"

Attached very short captures (S-video / Osprey 260e).
Settings in both captures are similar:
BEST OFF
EDIT Mode ON
Digital 3R OFF
TBC ON

Does anyone have any clue what may be the problem?

My first tough was to recap the power-supply side (re-capping is no problem for me, kind of a hobby).

[lordsmurf]

Quote:

Originally Posted by Rolle68

I have been capturing using my JVC HR-DVS2 and happy with the results.
Since HR-S7700EU and HR-DVS2EU seem to be released in same year, I bought S7700 primary for possible spares for DVS2EU.
The only thing is that the picture is not as good as in my DVS2 .
Should these vcr's perform similar?

DVS2 is not that similar to 76xx/77xx lineage, but all should be quality, when in good condition.

Quote:

The seller said that it will not even power up (seller had newer used it and was selling it behalf of someone).
The S7700 actually powered up, so I cleaned the heads and tested it and got a picture.

Random sellers lie all the time, like the rest of general population.

Quote:

Since I got the picture out, I am not interested in using it as spares anymore if I can get the picture "cleaned/corrected"
Settings in both captures are similar:
BEST OFF
EDIT Mode ON

"Edit" is not some sort of "raw" mode, as many falsely believe. VHS reality is that no "raw" video signal exists, and everything must be processed in some way to turn it into an image. "Edit" is less processing, and that almost always mean more noise.

Different lineages of JVC VCRs (and Panasonic, and everything else) will process different.

The rub here is that your DVS2 may actually over-process on non-Edit modes, which can be seen on certain decks. It can be true of NTSC 7500 and 9500 (though other aspects of 9500 make it still very desirable, and I own one myself).

Quote:

Does anyone have any clue what may be the problem?

It don't see immediately a problem, just differences.

That 7700 looks similar to what I see from my NV-HS1000 (PAL) and AG-1970 (NTSC). (At least when my 1970 was working -- Panasonics are such a PITA to keep running.)

Quote:

My first tough was to recap the power-supply side (re-capping is no problem for me, kind of a hobby).

Health and/or age will rob you of that eventually. Enjoy it while it lasts.

[themaster1]

old capacitors on the power supply probably, i've seen worse. try to check 'em

[lordsmurf]

Quote:

Originally Posted by themaster1

old capacitors on the power supply probably, i've seen worse. try to check 'em

I don't think this will have any effect here, but I'd agree in checking these for due diligence.

[radiokom]

Quote:

Originally Posted by lordsmurf

I don't think this will have any effect here, but I'd agree in checking these for due diligence.

Because checking, in many cases, mean desoldering, checking and resoldering (at least with tools available for 99% at home) and you should access capacitor legs anyway, "recap and forget" is faster then checking. You should not worry about non standard capacitance - if there are 1200µf or 1500µf caps, replace with 2200µf, 83µf and 120µf you can replace with 100µf. However "low ESR" caps are recommended to use in switching power supplies, in real life any new capacitor is better than original (I mean well known brand capacitors from trusted suppliers). Now I recapped Panasonic NV-FS200 (before even switching it on). And it was good decision. 2 small capacitors visibly started to leak. So - to recap PS is my rule Nr.1, I do not need wonders.

[Rolle68]

Quote:

Originally Posted by lordsmurf

The rub here is that your DVS2 may actually over-process on non-Edit modes, which can be seen on certain decks. It can be true of NTSC 7500 and 9500 (though other aspects of 9500 make it still very desirable, and I own one myself).

Thanks, this is new information to me.

Quote:

Originally Posted by lordsmurf

It don't see immediately a problem, just differences.

I think that also the added text "jitters" (don't know the correct word ) more in 7700 than in DVS2, so may this be more than device model specific processing?

Quote:

Originally Posted by lordsmurf

Health and/or age will rob you of that eventually. Enjoy it while it lasts.

Sorry to hear

Quote:

Originally Posted by themaster1

old capacitors on the power supply probably, i've seen worse. try to check 'em

Quote:

Originally Posted by radiokom

Because checking, in many cases, mean desoldering, checking and resoldering (at least with tools available for 99% at home) and you should access capacitor legs anyway, "recap and forget" is faster then checking.

I will recap the PS and aim is to get caps filling the standards that originals have (checking serials from service manual and then searching similar from DigiKey etc.)

[Rolle68]

I replaced all electrolytic caps (17 pcs.) shown in service manual - "Switching regulator schematic diagram" that is used in 7700-model.

I think the effect was significant . Attached is a 7700 capture with identical settings as in the 7700.avi attached to the original post. The improvement is visible throughout the capture, but for example, it is worth comparing frames 17 and 18 between these two captures.

(My intention is to measure the capacitances of the old capacitors at some point and add the information to this thread.)

[radiokom]

Quote:

Originally Posted by Rolle68

The improvement is visible throughout the capture, but for example, it is worth comparing frames 17 and 18 between these two captures.

Are you kidding? Really?

[Rolle68]

Quote:

Originally Posted by radiokom

Are you kidding? Really?

Well, no and yes?
At least now the picture is more par to my expectations.
Attached comparisons from frames 17 and 18.

[radiokom]

Quote:

Originally Posted by Rolle68

Well, no and yes?
At least now the picture is more par to my expectations.
Attached comparisons from frames 17 and 18.

Strange. Hard to believe that difference is because of PS recap. Commonly PS recap is preventive action to avoid repair later. Or something was really wrong with those caps in PS. I assume there are no PS measurements before and after? It would be interesting to compare.

[Rolle68]

My intention is to measure the capacitances of the old capacitors at some point and add the information to this thread. I did not measure voltage levels from any points from the VCR before the recap. Only quickly measured resistances from few caps after desoldering and I got fully open results from some of them.

[radiokom]

Quote:

Originally Posted by Rolle68

My intention is to measure the capacitances of the old capacitors at some point and add the information to this thread. I did not measure voltage levels from any points from the VCR before the recap. Only quickly measured resistances from few caps after desoldering and I got fully open results from some of them.

Not only voltage measurements, but scope readings. Although personally I have never bothered with it - I just replace them and that is it. If after recap something is wrong, then I start looking for a reason. But if some caps are dead you get dirty output from PS and it could be an answer why picture changed after recap.

[Rolle68]

Quote:

Originally Posted by radiokom

Not only voltage measurements, but scope readings. Although personally I have never bothered with it - I just replace them and that is it. If after recap something is wrong, then I start looking for a reason. But if some caps are dead you get dirty output from PS and it could be an answer why picture changed after recap.

Well I don't have a scope so that's why I referred only to voltages. But as I wrote in first message, the seller said that device will not even power up and if that actually happened to him the PS has indeed been in bad shape. For some reason it powered up when I got the VCR...

[radiokom]

Quote:

Originally Posted by Rolle68

Well I don't have a scope so that's why I referred only to voltages. But as I wrote in first message, the seller said that device will not even power up and if that actually happened to him the PS has indeed been in bad shape. For some reason it powered up when I got the VCR...

Well then, it is clear. Another example of why PS recap is a must.

[Rolle68]

Finally got the caps measured.
These are the capacitors that deviated the most from their nominal values ​​(measured with a cheap "LCR-T4 ESR" meter):
C5308 / 100µF,16V, measured 64,3µF
C5309 / 100µF,16V, measured 64,6µF
C5303 / 100µF,16V, measured 59,3µF

[timtape]

If it's an ESR meter where are the ESR values?

[Rolle68]

Quote:

Originally Posted by timtape

If it's an ESR meter where are the ESR values?

Below values of all replaced caps
Does some value stand out?
(ESR, Vloss and capacitance are measured values, Cap values = nominal values)

Capacitor	Cap values	ESR / OHM	Vloss / %	Capacitance / uF
C5006	68µF,400V	0,74	0,8	65,6
C5102	27µF,35V	1,3	1,4	26,8
C5201	220µF,6.3V	0,64	1,6	214,4
C5213	220µF,6.3V	1,6	2,4	242.4
C5203	2200µF,10V	0,09	1,2	1896,0
C5202	820µF,16V	0,14	1,1	755,0
C5206	180µF,25V	0,33	1,7	188,5
C5204	4.7µF,100V	2,3	1,8	5,1
C5205	10µF,50V	3	1,8	9,6
C5207	220µF,16V	0,45	1,4	198,0
C5208	220µF,10V	0,8	2,9	190,3
C5307	47µF,6.3V	4,3	6,8	43,1
C5306	100µF,6.3V	1,2	4,4	86,0
C5308	100µF,16V	1,5	6,4	64,3
C5309	100µF,16V	1,5	5,7	64,6
C5301	1000µF,6.3V	0,18	1,9	840,0
C5303	100µF,16V	1,5	7,9	59,3

[latreche34]

From the capture samples in the original post the recording appears to be grainy so the 7700 is just spitting out what's on the tape, The DVS2 is over processing it making it look dull but leaving the noise as is in transition areas like the pole and the edges of the picture, So I don't think the 7700 is faulty. The after recap sample looks like overprocessing to me (look at the pole, the noise is still there) capacitors cannot change things in only parts of the frame, they affect the whole frame, so there must be a setting difference in the original sample and the after recap one.

[Rolle68]

Quote:

Originally Posted by latreche34

From the capture samples in the original post the recording appears to be grainy so the 7700 is just spitting out what's on the tape, The DVS2 is over processing it making it look dull but leaving the noise as is in transition areas like the pole and the edges of the picture, So I don't think the 7700 is faulty. The after recap sample looks like overprocessing to me (look at the pole, the noise is still there) capacitors cannot change things in only parts of the frame, they affect the whole frame, so there must be a setting difference in the original sample and the after recap one.

Thanks for the analysis & comments!

The first conclusion is that I seem to appreciate over-processed images...
I'm still at the beginning of the learning curve when it comes to capturing, so I would really appreciate it if there were clear signs to tell when a capture is in order and when the capture has graininess or noise due to the poor condition of the vcr? (I tried looking at the post You referred at the capture and I think there is a difference between captures?)


I like to think that I work systematically and all settings have indeed been identical before/after captures and the only thing that has changed has been the replacement of the capacitors. I thought I would do a test where I capture 7700 in different image modes (BEST OFF, Digital 3R OFF TBC ON but with different Picture Modes?) and share the results here. It would be a great help if You could suggest a specific frame that would be most revealing?


Another thing: I got another DVS2 for a very reasonable price (primarily as spare parts ...and DV mailfunctioning of course), although I had to drive a total of 5 hours to pick up the device . This new DVS2 has a significantly grainier image with the same image settings than my old one. Since the DSV2 has separate power supply circuit boards, I transferred the power supply from my first DVS2 to the new one as a test and I have a few questions about these observations (when I have time, I think I'll make own topic about this to the capture thread).

[radiokom]

You can't get the result with the "like/dislike" method. First you need a properly calibrated VCR. It means you got your reference VCR from well known technician or shop. I have test tapes and experience with Panasonic but, until now, no experience with JVC. I bought a 7722 from vcrshop and then two mint condition 7711 (exactly the same, only black, 7722 is silver) in local sales in small towns in Germany. All 3 work identically, and the picture and sound is identical from both the test tapes and the other VHS/SVHS cassettes. It is possible to tell if your VCR is working properly if you have a calibrated the same model reference VCR to compare it to. Otherwise it is a waste of time. PS recap should be done of course.