Akai 4000D speeding replay - UK Vintage Radio Repair and Restoration Discussion Forum

chocolatetony · 7th Jan 2019, 4:10 pm

I have a reel to reel AKAI 4000D which has developed a reel odd fault !

It plays back faster than it records , this happens on both speeds
I dont understand how this can happen as what ever controls the capstan speed must be common to both record and play

I have owned the machine for many years and the fault has just happened ,this has encouraged my wife to speak against the machine and get rid !, I have no intention of doing this it if can be repaired at reasonable cost

Any ideas ?
Chocolatetony

toshiba tony · 7th Jan 2019, 6:53 pm

I'll tell you what, Tony, this is an odd one. And yes, as far as I am aware, there can be no difference in speeds between record or play. I will look at the manual when I get home. You need to ascertain which is out, what is it like on previous recordings made on this machine?

chocolatetony · 7th Jan 2019, 10:13 pm

Yes, will do this. That will tell me if the 'record mode' is slow or the 'play mode' is fast. Logic tells me this problem should not exist, but it does.

Diabolical Artificer · 8th Jan 2019, 7:29 am

After reading this yesterday I got to thinking, how do you know it is faster on PB than record? Do you have a tacho or speed app or something to track speed on the two function's, or is a gross difference? Or do you mean something else, on PB the track is too fast?

Tony's post is about essentially the same thing. Whenever you have a fault like this on a R2R, change the tape after a good clean of the tape path, especially the capstan roller. Andy.

toshiba tony · 8th Jan 2019, 9:33 am

Andy and Tony, briefly perused the service manual, nothing yet!

julie_m · 8th Jan 2019, 9:51 am

Measure 1.9 metres of tape, and time how long it takes to pass through the machine in both play and record (should be 20" without capstan sleeve fitted, or 10" with).

It's difficult to think what could be at fault here, except the motor and its associated capacitor.

Ted Kendall · 8th Jan 2019, 12:50 pm

Could this be a fault which has developed recently, so making all pre-recorded material sound fast? I'd be inclined to look at the take-up tension - tensions are high on these machines to start with and if the clutch is binding it could compete with the pinch.

TIMTAPE · 10th Jan 2019, 4:27 am

Not sure if already covered but many Akai machines have a stepped motor pulley for either 50 Hz or 60hz mains operation. Could the 50/60 setting have been accidentally changed?

I have also had Akai machines where the capstan belt stretches enough to ride up on the flange between the two pulleys.

Also what degree of speed change between record and playback are we talking about? 1%? 5%? In musical terms, a tone? A semi tone?

Diabolical Artificer · 10th Jan 2019, 7:32 am

"Akai machines have a stepped motor pulley for either 50 Hz or 60hz mains operation" good point Tim.

Andy.

7th Jan 2019, 4:10 pm	#1
chocolatetony Retired Dormant Member Join Date: Jan 2019 Location: Bournville, West Midlands, UK. Posts: 2	Akai 4000D speeding replay I have a reel to reel AKAI 4000D which has developed a reel odd fault ! It plays back faster than it records , this happens on both speeds I dont understand how this can happen as what ever controls the capstan speed must be common to both record and play I have owned the machine for many years and the fault has just happened ,this has encouraged my wife to speak against the machine and get rid !, I have no intention of doing this it if can be repaired at reasonable cost Any ideas ? Chocolatetony

7th Jan 2019, 6:53 pm	#2
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: akai 4000D speeding replay I'll tell you what, Tony, this is an odd one. And yes, as far as I am aware, there can be no difference in speeds between record or play. I will look at the manual when I get home. You need to ascertain which is out, what is it like on previous recordings made on this machine?

7th Jan 2019, 10:13 pm	#3
chocolatetony Retired Dormant Member Join Date: Jan 2019 Location: Bournville, West Midlands, UK. Posts: 2	Re: Akai 4000D speeding replay Yes, will do this. That will tell me if the 'record mode' is slow or the 'play mode' is fast. Logic tells me this problem should not exist, but it does.

8th Jan 2019, 7:29 am	#4
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,658	Re: Akai 4000D speeding replay After reading this yesterday I got to thinking, how do you know it is faster on PB than record? Do you have a tacho or speed app or something to track speed on the two function's, or is a gross difference? Or do you mean something else, on PB the track is too fast? Tony's post is about essentially the same thing. Whenever you have a fault like this on a R2R, change the tape after a good clean of the tape path, especially the capstan roller. Andy. __________________ Curiosity hasn't killed this cat...so far.

8th Jan 2019, 9:33 am	#5
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Akai 4000D speeding replay Andy and Tony, briefly perused the service manual, nothing yet!

8th Jan 2019, 9:51 am	#6
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Akai 4000D speeding replay Measure 1.9 metres of tape, and time how long it takes to pass through the machine in both play and record (should be 20" without capstan sleeve fitted, or 10" with). It's difficult to think what could be at fault here, except the motor and its associated capacitor. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

8th Jan 2019, 12:50 pm	#7
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: Akai 4000D speeding replay Could this be a fault which has developed recently, so making all pre-recorded material sound fast? I'd be inclined to look at the take-up tension - tensions are high on these machines to start with and if the clutch is binding it could compete with the pinch.

10th Jan 2019, 4:27 am	#8
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,969	Re: Akai 4000D speeding replay Not sure if already covered but many Akai machines have a stepped motor pulley for either 50 Hz or 60hz mains operation. Could the 50/60 setting have been accidentally changed? I have also had Akai machines where the capstan belt stretches enough to ride up on the flange between the two pulleys. Also what degree of speed change between record and playback are we talking about? 1%? 5%? In musical terms, a tone? A semi tone?

10th Jan 2019, 7:32 am	#9
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,658	Re: Akai 4000D speeding replay "Akai machines have a stepped motor pulley for either 50 Hz or 60hz mains operation" good point Tim. Andy. __________________ Curiosity hasn't killed this cat...so far.