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Help Needed with my Yamaha CT-7000 Tuner

79.77.33.4
Posted on October 2, 2009 at 09:51:12
john53
Audiophile

Posts: 3
Location: Lancashire
Joined: October 2, 2009
 I bought a ct-7000 from belgium via a hi-fi forum and it arrived yesterday.

Unfortunately in transit several of the bulbs no longer work and the center tuning meter appears to be stuck in one position.

Where can I buy replacement bulbs, I am based in the UK, and could someone post me some instructions on how to fit them please?

What would you suggest about the meter, It could have been jarred in transport.

Any help gratefully appreciated.

Thanks


John
RE: Help Needed with my Yamaha CT-7000 Tuner, posted on October 2, 2009 at 13:00:02
Marantzguy
Audiophile

Posts: 2412
Joined: June 21, 2002
 Hi, John:

Have you searched through the Vintage Asylum archives for my previous posts on these topics?

I may be perhaps the only person who can answer both questions since I own three of these fine sounding tuners.

Basically, the lamps are incandescent types and are mounted through little boat-like cushions, which pull straight up off of parallel contact pins. They are not soldered at all, so do not let that fool you.

The lamps have extended wire leads coming off of them and those leads need to be threaded through the tiny little openings in the "boat" modules and then pushed right back onto the twin contact pins and seated properly. Sansui used a similar scheme in some of their finer tuners.

The original lamps should be rated 12 volts @ 60 mA and may still be available from most good electronics parts sources.

It is normal to find one of these tuners with a lot of lamps burned out, since they ** ARE ** incandescent types.

As for your meters:

They often stick in one position because typically, the old orange-red paint becomes fragile over time and simply flakes off or becomes swollen enough that the needles strike against the innermost surface of the meter housings.

I contributed something to this very forum long ago on the repair routine.

Basically speaking, you need to remove the meters from the tuner and gently open up the housing. The tops are held in-place by clear pieces of sticky tape. Just remove the top surface "cover", put a thin piece of protective paper beneath the needle while you scrape off the remaining paint with your finger nail. Watch out that paint particles do not fall right into the delicate movement or you may ruin the meter itself! Clean off the naked metal surface of the needle with alcohol, let it dry, and then repaint it with fluorescent type enamel hobby paint. Let dry and reassemble the meter housing and reinsert into the tuner.

Did this make sense?

Good luck!
Richard Links
Berkeley, CA

RE: Help Needed with my Yamaha CT-7000 Tuner, posted on October 2, 2009 at 13:15:31
john53
Audiophile

Posts: 3
Location: Lancashire
Joined: October 2, 2009
 Thanks Richard

Are the lights supposed to be coloured or plain?

Do these look correct to you?

http://www.rapidonline.com/productinfo.aspx?tier1=Electronic+Components&tier2=Optoelectronics&tier3=Miniature+Lamps&tier4=T1+Wire+ended+filament+lamps&moduleno=29267&catref=41-0225#techspec

Thanks
John
RE: Help Needed with my Yamaha CT-7000 Tuner, posted on October 2, 2009 at 14:46:20
Marantzguy
Audiophile

Posts: 2412
Joined: June 21, 2002
 Hi, John:

Yes, those are probably as close a match as you are going to get.

The lamps are clear, however.

I do not recall how the ones were mounted which illuminate the meters or the other front panel functions, such as "tune", etc. I believe that those may be soldered directly to a very small circuit board.

It has been a while since I worked on my tuners!

The main weakness in the CT-7000 has more to do with inadequate ventilation around the main power supply circuit board, however. Most, if not all of the original electrolytic capacitors should be replaced with fresh equivalents in that area. I also did much of that work myself fon the tuners I own. When operating properly, you will be amazed by the quality of sound it offers, on a par with the Marantz 10-B tuner, of which I also own several examples.

Enjoy your tuner!

Good luck!

Richard Links
Berkeley, CA

RE: Help Needed with my Yamaha CT-7000 Tuner, posted on October 2, 2009 at 14:50:37
john53
Audiophile

Posts: 3
Location: Lancashire
Joined: October 2, 2009
 Thanks Richard - You have been a great help.
John
RE: Help Needed with my Yamaha CT-7000 Tuner, posted on October 2, 2009 at 15:07:43
Marantzguy
Audiophile

Posts: 2412
Joined: June 21, 2002
 Hi, John:

Happy to assist you!

BTW, there are little "fuse-resistors" on the power supply board in the CT-7000 tuner. If you lose a function, in your troubleshooting routine, examine these little blue/gray resistors (about 4.0 ohms?) for faults. You can replace them with 3.9 ohm flame-proof 1/4 watt I believe or equivalent.

Richard Links
Berkeley, CA

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