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Old 3rd Jan 2021, 5:47 pm   #1
JamieEC
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Default JVC HR-7700EK / Ferguson 3v23 Issues

Hello,
I was messing with this machine today and suddenly the whole mechanism lost power it seems. The bulb no longer lights and it won't take a tape. I have tested the reset pin on the CPU as suggested in the manual and it looks good. The bulb connection is giving < 1v. I am going to continue to troubleshoot back from this, but if anyone has any quick suggestions / ideas or common faults with these, that would be appreciated.
Thanks
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Old 3rd Jan 2021, 6:03 pm   #2
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

At least 30 years since I last repaired one, is the Clock lit up ? From memory, there's a few fuses in the Power supply, and of course check the Cassette Lamp, when they go O/C the clock lights, and you get E to E but not a lot else Its been a long time sorry.

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Old 3rd Jan 2021, 6:06 pm   #3
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Yes sorry shouldve stated, the thing powers up, all the clock etc work.
It might be some issue with the lamp circuitry then, as the clock etc lights and tuner works.
Do you know the voltage the lamp should be at?
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Old 3rd Jan 2021, 6:08 pm   #4
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

12 Volts from memory, not gone o/c has it ? But I dont think think you can measure 12v across it as its a earth return, we did short them out for a quick test!!
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Last edited by its ur aerial; 3rd Jan 2021 at 6:23 pm. Reason: forgot some thing
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Old 3rd Jan 2021, 6:17 pm   #5
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

I don't think so as it was not reading 0v, but I will double-check
where does it usually go open? To me it feels just like the bulb is gone. Will it not take a tape with no bulb?
I am going to test it independently with a bench supply.
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Old 3rd Jan 2021, 6:18 pm   #6
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

At the time, they were a mind numbingly complicated bit of kit, but surprisingly very few suffered with difficult faults, I did do a two week training course on the 3V23 back in 1982 but 38 years has passed away.
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Old 3rd Jan 2021, 6:21 pm   #7
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

It was dead common, the lamp it self just fails. Stops every thing, except the clock and the E to E signal.

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Old 4th Jan 2021, 5:31 pm   #8
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

These machines are fairly interesting to me, because they were one of the first 'high end' VHS decks right?
I really want to see the 2x speed play
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Old 4th Jan 2021, 7:33 pm   #9
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Looks like the bulb is good, do you know if there is a 12v test point or if there is anything else which uses the 12v rail?
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Old 4th Jan 2021, 8:23 pm   #10
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

After some probing, looks like 12v rail is dead.
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Old 6th Jan 2021, 7:06 pm   #11
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Scratching my memory here, but I am sure you cant read 12 v on that lamp because, as I previously mentioned I am sure its basically part of a earth return, there are also several fuses in the PSU, have you checked all these?
I cant find a Circuit on the Web so cant advise much, have you got a manual , you really could really do with one.
The other thing worth trying is manually loading it up till its fully laced then applying power, and see if it unlaces and ejects, this might give a few more clues .
Failing this theirs a American Website, thats name escapes me, which has down loads of all the old Practical Television Mags, they must have done a article on the 3V23 at some time .
I will try and contact a old Ex RR Bench Engineer Colleague, he might remember more than me.
As I stated before although they were as complicated as Apollo 11, apart from the Mechacon Board, it was unusual to get a really tricky fault.
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Old 6th Jan 2021, 7:09 pm   #12
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

I have gotten the 12v rail working!
Now a couple of mechanical gremlins, do you know how you would run this machine without a tape? I have tried covering the 2 light sensors but it just laces then delaces straight away.

I found a service manual online, which has helped me immensely. That has full schematics.
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Old 6th Jan 2021, 8:18 pm   #13
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Again thinking from a not very good memory, if you fool it into loading, with out a tape you will need to turn one of the spools, and I cant remember if its the Supply or Take up Spool to make it think its has a tape, it will be the spool that operates the Tape counter. Back in the day we used to get a damaged Cassette, remove the tape, but keep the Spools and Housing.
If its not counting pulses from the Counter, it thinks the Tape has broken, hence it stops.
Why was there no 12 Volt then
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Old 6th Jan 2021, 8:20 pm   #14
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Just remembered, it the Loading belt worn, slipping ?
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Old 6th Jan 2021, 8:26 pm   #15
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Brilliant! Will try that
I have already replaced the load belt as that was the initial issue with it.
I have no idea on the 12v, I had it down to the rectifier not outputting the 12v, but I unplugged to test then reconnected and it was working
Maybe it was a bad contact or something.
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Old 7th Jan 2021, 6:33 pm   #16
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Some times its not obvious the Loading belt is slipping, it just slips before its finally finishes lacing, so try giving it some assistance to engage fully, make sure there is no grease on the belt or hard grease on the Worm Gear.
I spoke to my Ex RR College, and like me cant remember a no function one that was not the Cassette Lamp, but he did vaguely recall a micro switch fault on the Cassette Carriage. Not one I remember though
And also apparently I was correct, you wont measure 12v across that Lamp, it is in a earth return.
Back in the mid 90`s I meet some one who was part of the 3V23 Design Team, and he informed me they were really designed to show case how sophisticated they could make a VCR back in 1980, well it was certainly not for their Pic quality
Only one other common fault was no clock display, caused by dry joints to a tiny XTALS on a PCB at the RH side
Good luck with it.

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Old 7th Jan 2021, 6:44 pm   #17
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

I have had it playing! very briefly, it looks like the rw/ff is not working correctly so I need to look into this.
I love all this info, very interesting and stuff you can't find elsewhere
I measured the 12v directly from the power supply and it was bad, I will bear that in mind about the lamp, it looks like it has been replaced already on this.
You can tell about the design! it does feel like they have just seen how many features they can put on, was impressed by the meter showing how much tape is remaining, surprised there is no real time counter on this because I always thought they were similar.
Appreciate all the help
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Old 7th Jan 2021, 7:17 pm   #18
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Many years since I've seen a 3V23, very heavy, and the bucket brigade idea to give you sound in double speed play too!
But just fill me in, why can't you meter across the lamp? For presence of voltage or the bulb for being o\c.
Have dementia now but this is just jumping out at me, ta.
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Old 7th Jan 2021, 7:38 pm   #19
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Quote:
Originally Posted by JamieEC View Post
I have had it playing! very briefly, it looks like the rw/ff is not working correctly so I need to look into this.
Check the idler tyre and the take-up/ supply spools as they all have rubber components which could do with a clean. You might get a little more mileage out of them by removing the tyres and simply turning them inside out. Also wouldn't hurt to give the tape path a thorough clean.

Yes, I remember the time-remain dots. They used to do a merry dance on ours - quite distracting! Though we never got it, or the eventual missing clock repaired as the machine was already 15+ years old, by then. One day it just stopped accepting cassettes but you could hear the familiar power-up 'whizz' of the capstan motor at random intervals. Off it went to VCR heaven!

Quote:
Originally Posted by toshiba tony View Post
But just fill me in, why can't you meter across the lamp? For presence of voltage or the bulb for being o\c.
Good question!
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Last edited by John123; 7th Jan 2021 at 7:58 pm.
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Old 7th Jan 2021, 8:20 pm   #20
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Default Re: JVC HR-7700EK / Ferguson 3v23 Issues

Quote:
Originally Posted by JamieEC View Post
was impressed by the meter showing how much tape is remaining, surprised there is no real time counter on this because I always thought they were similar.
Forgot to add: There's a good thread on how the different types of tape counters work, here .
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