HK CD491 Odd Behavior...

[corona blue]

Hi everyone-

My trusty CD491 is kaput! Wondering if any of you have seen this with your machines or if any bench techs on the forum might know:

Upon power up, the usual "WAIT" message appears. Once the voltage is stable everything lights up normally. Then within a few seconds, ALL the transport lights begin flashing in unison and are non-functioning. It almost looks like some kind of error code! Anybody seen this before?

My local audio "repair specialist" didn't have a clue or seem to care much except when it came time to clip me for the $25 inspection fee. Business must be good!

So I'm kind of on my own here. I'm sure it must be fixable. I've got the service manual, but did not see any mention of this problem. I'm wondering if it failed some kind of transport self-test? Maybe it just needs belts?

Any help greatly appreciated...

Allen

 

[tapetech]

Sounds like a stalled cam-assist motor. Clean the cam switch contacts, then turn the cam-assist gear by hand for several revolutions. If that doesn't fix it, then remove the motor, apply about 6 volts DC to it and spray in a little Deoxit. Let it run for a few minutes and re-install.

Best long-term repair is to install a new motor. I have a part # if you need it.

 

[dr*audio]

And get another tech. This one sounds worthless.

 

[corona blue]

Thanks for the help guys. I will try TapeTech's advice in the next day or so and report back.

Thinking about it now, it DID seem to be weak on FF and RW just prior to all of this... so maybe a gummed up motor? Whether bad motor or bad belts, I figure I should change belts regardless, right? Do you recommend just going to HK for the correct belts?

Thanks in advance,

Allen

 

[diepbtt]

Thanks for the help guys. I will try TapeTech's advice in the next day or so and report back.

Thinking about it now, it DID seem to be weak on FF and RW just prior to all of this... so maybe a gummed up motor? Whether bad motor or bad belts, I figure I should change belts regardless, right? Do you recommend just going to HK for the correct belts?

Thanks in advance,

Allen

The idler ruber ring is worn out you should replace it also when you repair the control motor.

 

[dr*audio]

Thanks for the help guys. I will try TapeTech's advice in the next day or so and report back.

Thinking about it now, it DID seem to be weak on FF and RW just prior to all of this... so maybe a gummed up motor? Whether bad motor or bad belts, I figure I should change belts regardless, right? Do you recommend just going to HK for the correct belts?

Thanks in advance,

Allen

I doubt HK will have the parts, but check with them first. If they don't have it, check with Fred Marrs of Marrs Communications. He gets his belts from the factory in Japan that made them for the original manufacturers.

 

[Jon_Logan]

Thanks for the help guys. I will try TapeTech's advice in the next day or so and report back.

Thinking about it now, it DID seem to be weak on FF and RW just prior to all of this... so maybe a gummed up motor? Whether bad motor or bad belts, I figure I should change belts regardless, right? Do you recommend just going to HK for the correct belts?

Thanks in advance,

Allen

The FFW and RWD problems would be different than the Cam assist motor issue TapeTech was talking about. These are Sankyo transports, similar to the ones Nakamichi uses on their BX line. The cam assist motor has a worm/leadscrew that engages a cam. The cam has three leaf switch followers that let the uCon know where the transport is. Sometimes that motor develops a dead spot in it's rotation. If you force it off the dead spot by hand, it may begin to turn and allow the transport to regain it's bearings.

The wind torque problems would be the next thing to fix.

 

[jimbo2k]

The deck I loved to hate

I have had three of them and they are frustating. Cant seem to keep them running.Had a CD401, then a CD 491. Swapped it in for a CD491 in black.Neither HK nor the authorized waranty center i ran at the time could keep them working, A friend gave me a Champaign gold one with a bad power transformer and for years I tried to find one. Tossed it in the garbage about a year ago. Shoulda held onto it for parts. Jim

 

[dr*audio]

I have had three of them and they are frustating. Cant seem to keep them running.Had a CD401, then a CD 491. Swapped it in for a CD491 in black.Neither HK nor the authorized waranty center i ran at the time could keep them working, A friend gave me a Champaign gold one with a bad power transformer and for years I tried to find one. Tossed it in the garbage about a year ago. Shoulda held onto it for parts. Jim

Man, I would have taken that! Ow. Got any left?

 

[corona blue]

The FFW and RWD problems would be different than the Cam assist motor issue TapeTech was talking about. These are Sankyo transports, similar to the ones Nakamichi uses on their BX line. The cam assist motor has a worm/leadscrew that engages a cam. The cam has three leaf switch followers that let the uCon know where the transport is. Sometimes that motor develops a dead spot in it's rotation. If you force it off the dead spot by hand, it may begin to turn and allow the transport to regain it's bearings.

The wind torque problems would be the next thing to fix.

I think Jon here really has nailed it...

I spent some time on it today... I cleaned and gave it some deoxid...

What I found is that the cam drive seems to "oscillate" back and forth slightly. When I manually moved the head/roller sled upwards (without a tape) something freed up and the cams aligned. I had it kind of working ok there for a minute! The transport lights went out and I was able to use the transport functions. Oddly, the transport operated without a tape in the unit... don't remember it doing that before(?). But the idler does indeed seem to be worn out. The unit will not FF or RW though the shuttle motor works fine... and when pulling tape in play the speed is inconsistent... again seems like the idler.



It's just not making adequate contact with the plastic wheels.

The capstan loop seems to be fine.

I'm just wondering if there is maybe too much ripple on the motor line thus making it oscillate. Just a guess. I haven't poked around to look at rail voltages yet.

Are things like the idler wheel even available??? Is this a lost cause?

Thanks for the help everyone.

Allen

 

[dr*audio]

Are things like the idler wheel even available??? Is this a lost cause?

Thanks for the help everyone.

Allen

Try HK first and if they don't have the idler and the belt, contact Fred Marrs.