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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 3rd Oct 2017, 4:15 am   #1
Bazz4CQJ
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Default JVC HR-D120 VCR Won't Start

I just tried to switch on my beloved D120 (1982?) initially there was no sign of life, then some panel lights came on for a few seconds, then went off and the machine was quite dead. I could not honestly say how long since it was last used. I did not think it had been very long, so did not bring it up on the Variac.

My knowledge of the workings of VCR's is nil; any ideas on how to proceed in getting it going appreciated. I do have the service manual, looks incredibly complicated .

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Old 3rd Oct 2017, 8:10 am   #2
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Default Re: JVC HR-D120 VCR Won't Start

A long long time ago....

Weren't these the ones with the Fisher Price front Seem to recall there was an STK regulator in the power supply that was troublesome. Memory is hazy after all those years... STK5382 or 5384 was it ?

Anyhow, check all the PSU voltages, both switched and unswitched rails.
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Old 3rd Oct 2017, 9:35 am   #3
kevinaston1
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Default Re: JVC HR-D120 VCR Won't Start

Electrotanya have the service manual, nearly 50MB.

I have just looked at my original JVC manual; no STK devices, all discreet transistors in the power supply, apart from a 12V regulator - it could be that there were variants of this model.

I could scan the power supply page if this helps.


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Old 3rd Oct 2017, 10:39 am   #4
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Default Re: JVC HR-D120 VCR Won't Start

Is this the one with a 1uF cap in the primary? If so then you have cracked it.
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Old 3rd Oct 2017, 10:48 am   #5
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Default Re: JVC HR-D120 VCR Won't Start

Don't these have a linear PSU with a conventional mains transformer though?

Fergy equivalent was the 3V35 ISTR.
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Old 3rd Oct 2017, 3:00 pm   #6
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Default Re: JVC HR-D120 VCR Won't Start

^
Yes and yes. Capstan motors/carriages and reel sensors were all stock faults at the time.

Must be another model I was thinking of if these haven't the STK in them. We had 100's of these (Fergies and JVC's) on rental back in the day.
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Old 3rd Oct 2017, 3:12 pm   #7
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Default Re: JVC HR-D120 VCR Won't Start

Back to basics.

Is there a sensible resistance reading (tens of ohms) between the L and N pins of the mains plug? If not, try exercising the mains rocker switch on the back panel.

Check any fuses (including "circuit protectors" that look like tiny, 2-legged transistors) and look for dry joints on hot-running components in the power supply section.

After that, you'll need to look at the manual and check voltages of the power supply's outputs.

These manuals look scary but are usually easy enough to follow if you take your time, particularly if you have an original with coloured printing rather than an nth-generation photocopy or scan.

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Last edited by Nickthedentist; 3rd Oct 2017 at 3:19 pm.
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Old 3rd Oct 2017, 4:52 pm   #8
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Default Re: JVC HR-D120 VCR Won't Start

Thanks for those comments. As mentioned in the OP, I do have the original service manual, and as you might expect from Panasonic, it seems to be quite a good one... once you've found your way around it.

This does have a linear PSU; a transformer with two secondaries feeds a board which looks to have 6 DC lines out of it, and they have put specific test points on all of them. This uses mostly discrete transistors except for one "three leg" regulator which is a TA78012AP, which are still available. There is a relay on the board, so the mains switch on the rear of the VCR actually switches the AC to the transformer primary, and some DC outputs are permanently on, the others come on when the front panel switch or remote control are operated and I recall the relay then clunks in. I've never been inside a VCR before, so don't know how this compares to other machines. The manual also has a drawing of the board and component layout, so as long as that is not in some totally inaccessible position within the chassis, this might not be too bad to work on. There's a 0.022uF on the transformer primary.

Yes, the D120 is the 'Fisher Price' model .

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Old 3rd Oct 2017, 5:35 pm   #9
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Default Re: JVC HR-D120 VCR Won't Start

Hi. I have two of these machines. One HR-D110EG and one HR-D120EM. Check the capacitors and the voltage regulator of the power supply board on the back.
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Old 3rd Oct 2017, 9:53 pm   #10
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Default Re: JVC HR-D120 VCR Won't Start

Hi, It's been a while but I think that a common fault with this model was failure of the thermal fuse in the mains transformer primary (it certainly was with the Baird 8944 which was a clone of the 3v35/HR-D120), if I'm not mistaken there were pins on the the transformer which the thermal fuse was wired across so you could check its continuity - I'm not sure if this was deliberate or just an "integral" part of the transformer design.

Regards

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Old 4th Oct 2017, 6:22 pm   #11
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Default Re: JVC HR-D120 VCR Won't Start

It's working! I'd really like to claim that I'd undertaken some brilliant repair job, but in reality all I did was "waggle" every connector on the PSU board and then try it again (bringing it up on the Variac; the relay will kick in at ~140V). That's very pleasing . I wonder how much longer these machines will last? I still have some cassettes I need to digitise.

Thanks to everyone who offered their advice.

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Old 4th Oct 2017, 8:46 pm   #12
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Default Re: JVC HR-D120 VCR Won't Start

Well done!

Be prepared to look for dry joints if the fault rears its head again.

N.
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Old 6th Oct 2017, 11:52 am   #13
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Default Re: JVC HR-D120 VCR Won't Start

Congrats. Does the mechanism work? The most common problem with this JVC chassis is the leaf switch on the bottom that closes when the tape is threaded. If it fails, the loading motor will continue to run even if the tape is threaded and that will blow a fuse on the bottom PCB or it will just never go to play mode. This usually needs to be replaced.
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Old 6th Oct 2017, 2:40 pm   #14
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Default Re: JVC HR-D120 VCR Won't Start

yes, it seems good. The only thing that I note is that the display (I think that is LED, or a form of LCD I don't recognise) has some segments which are brighter than others, but that is a aging effect that has been evident for a while.

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Old 6th Oct 2017, 3:24 pm   #15
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Default Re: JVC HR-D120 VCR Won't Start

Probably a vacuum fluorescent display (VFD).

Some lasted much better than others.

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Old 6th Oct 2017, 5:00 pm   #16
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Default Re: JVC HR-D120 VCR Won't Start

Quote:
Probably a vacuum fluorescent display (VFD)
Could be; in any case, I doubt that the procurement spec called for a service life of 35 years on components for many domestic video recorders .

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Old 7th Oct 2017, 1:36 am   #17
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Default Re: JVC HR-D120 VCR Won't Start

Quote:
Originally Posted by Bazz4CQJ View Post
yes, it seems good. The only thing that I note is that the display (I think that is LED, or a form of LCD I don't recognise) has some segments which are brighter than others, but that is a aging effect that has been evident for a while.
It's a VFD. My HR-D110 has a nice and bright display but my D120's is very dim. Common problem with this type of display.
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Old 8th Oct 2017, 2:37 pm   #18
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Default Re: JVC HR-D120 VCR Won't Start

We used to go through a lot of transformers in these - I felt that replacing the thermal fuse was a no-no on a customer's machine.
I like the Fisher-Price comment!
Incidentally, mods, think this post has wandered into the wrong heading!
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Old 8th Oct 2017, 10:37 pm   #19
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Default Re: JVC HR-D120 VCR Won't Start

It won't be the first, or the last, to fade away into obscurity. If it's worth discussing it needs a new thread!
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Old 9th Oct 2017, 4:04 pm   #20
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Default Re: JVC HR-D120 VCR Won't Start

Quote:
Originally Posted by dj_fivos_sak View Post
It's a VFD. My HR-D110 has a nice and bright display but my D120's is very dim. Common problem with this type of display.
Overrunning the filaments for a few seconds often rejuvenates them.
At ones own risk of course.
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