Topic: Help restoring an old analog field recorder

[hexyjones]

I came accross an unusual JVC Cassette Field Recorder. Never saw this model before. Bout the size of a NAK 350 / 550.

The transport seems fine - a bit of resistance to rewinding - but that seems vary. Seemingly no problems otherwise and really quite solid.

The circuitry is nicely component-ized. 1 main board and 2 sub assemblies.

1 sub assembly connects to the main board with a piece of that flat-film/ribbon multi-conductor stuff - has a something like an IDE plug on 1 end(plugs into main board), the other connects to the smaller board on a series of large pins/solder.

Symptoms:

No sound on playback. However - it almost seems like I can hear tape noise and indeed I can hear the NR circuit go to work when I switch it on and off. If I crank up the headphone volume I can hear a little in one channel - no movement on levels.

When trying to record - I can only get signal on one channel (L) same on both mic and line setting(input is selected via a switch). I can monitor this on the headphones and the L channel level controls work. If I try to play this back - nothing - no sound. But if I put it in another deck - the L channel IS recording...

So this is a little funny...

Im inclined to start at the tape head...Question:

Can I direct the output from the tape head to another preamp and see if there is any signal? Will just running the transport produce any output from the tapehead?

Next - I'm suspicious about that flat film connector and am tempted to replace it with some actual wire...any known issues with that kind of connector?(especially in mid-70s era gear) Is it prone to poor/cold solder connections...? I was suprised to see this kind of material in a device this old. The socket end had some goo on it...I cleaned that off - but that didnt change anything...

At the moment, Im trying to work my way over to the input select switch on the side of the unit. I'd like to clean it, at least look at it.

Nothing seems intermittent or dirty...no crackles in the controls...

Running it off AC now - any reason to test it with Batteries?

I know its a long shot...but if anyone has any insights - they are appreciated.

My camera batteries are charging at the moment - pics to follow...

[kuba]

Running it off AC now - any reason to test it with Batteries?

I can't see any.

[hexyjones]

pics - not that they help that much...

[kev B]

Wow, that is an old unit. So is that Maxell. It still has the sticker label 

[Idle Wind]

a buddy of mine had a JVC like that - a KD-5 I think it was.
late 70s - early 80s.  It had some different NR - not
dolby or DBX but something proprietary to JVC I think.

I remember he wrapped it up as a birthday present to
smuggle it in to Radio City for the Dead in October 1980.

the story was it was a birthday present for his brother
who he was meeting at the show. (20 vinyl albums -
the size and weight of the box was right).

they used the same ploy to get it into Shea's Theatre
in Buffalo.  didn't get the stands in though, but managed
to raid the custodian closet and got two mop handles...

those were the days...

FWIW, we all thought the D5 and the 550 were superior
machines.  this was similar in quality (in our opinion, then)
to the 3 head marantz decks that were also around at
the time.

[Kyle]

a buddy of mine had a JVC like that - a KD-5 I think it was.
late 70s - early 80s.  It had some different NR - not
dolby or DBX but something proprietary to JVC I think.

I remember he wrapped it up as a birthday present to
smuggle it in to Radio City for the Dead in October 1980.

the story was it was a birthday present for his brother
who he was meeting at the show. (20 vinyl albums -
the size and weight of the box was right).

they used the same ploy to get it into Shea's Theatre
in Buffalo.  didn't get the stands in though, but managed
to raid the custodian closet and got two mop handles...

those were the days...

FWIW, we all thought the D5 and the 550 were superior
machines.  this was similar in quality (in our opinion, then)
to the 3 head marantz decks that were also around at
the time.

 

fantastic - bring on the old taping stories!!

[hexyjones]

yeah +t for the story!

I have owned both the D5 and the 550 - I hadnt seen this one before and couldnt resist...

I also just got a Marantz 340...records and plays fine - no ff or rew...

[sml42]

A common failure point for many old electronics is the electrolytic capacitors. Over time the electrolyte dries up, and the capacitor basically stops working. Typically it will fail after 10 to 20 years. If you are really set on restoring this old recoder, the first thing I would do is to swap out all the old electrolytic capacitors. A quick google threw up this link (dealing with old radios, but you get the idea): http://antiqueradio.org/recap.htm

Another common failure point is soldering to gold-plated connections. Particularly in old equipment, where the physics of gold / tin / lead interactions were not understood at the time. From the photos you posted, I can't see any gold plating, so you're probably clear. Google for more info if you're interested.

Hope this helps,
stephen

[SparkE!]

sml42 hit it right on the head with the comment about the electrolytic caps. (+t)  That's the best first step to take when refurbing old electronics.  The next group to replace is all of the rubber parts if you can find them.  The pinch roller is probably hard and slick and may have a flat spot in it if a tape was left in the machine. Belts get hard, loose and slick too.  Replacing all that will probably get you to the point where you have a working deck again.  Then it's just a matter of replacing the scritchy pots.  Sometimes you can resurrect the existing pots by cleaning them up with a bit of tuner cleaner, but be careful... Some of the older pots required the use of a light film of lubricant along the wiper path.  Some tuner cleaner formulations include a lubricant for that purpose, but keep that stuff away from the rubber parts.

[neutrino]

+T for taking on the restore challenge.

I'd break out your eye loupe and check for cold solder joints over each of those pcb's. Looks like you got a few spots with heavy flux residue that can become conductive over time.

Good luck and keep us posted.
dB-

[relaxing]

Another common failure point is soldering to gold-plated connections. Particularly in old equipment, where the physics of gold / tin / lead interactions were not understood at the time. From the photos you posted, I can't see any gold plating, so you're probably clear. Google for more info if you're interested.

Funny to hear it phrased like that - even through the late 1990's there were motherboard manufacturers making gold-plated sockets when the chip and card manufacturers had gone to tin connectors.   A delayed self-destruct feature.