SANSUI FR 4060 running half step fast

[EmperorNorton]

Hey folks

Bought a new 23.6"belt for this Sansui turntable I found  few months back.  Put a few drops of oil in the tube under the platter and its runs very nicely apart from the fact that it plays a half step fast.  I played Ella and Louis 'April in Paris' on CD which is in B flat but when I play the LP it in B.  Probably not noticeable to 95% of the population but I'd like to sell it as 100% perfect.

One person I read online said that making the platter a little bigger with DymoTape (which might be scrce these days) would do the trick. Might just try a couple layers of all purpose duct tape.   

Any thoughts from the turntable gurus?

Thanks in advance.

Mike

[Sir Thrift-a-Lot]

In theory that should work, but in practice I hate it as a "solution" (FWIW, I'm no guru).   I would think that the motor has something in the circuit which is drifting out of spec.   If that's the case, you may end up adding tape every few months as it continues to drift until it finally fails.   If it were me, I would start with recapping the power supply then doing whatever the manual says to fine tune the speed.   I would be very surprised if there isn't a a trim pot somewhere on the power supply.

Is it off in 45 RPM as well or just 33?   That may help to narrow down the issue.

I just checked, there is a service manual on VE.

[EmperorNorton]

Its slightly off at 45 also.

I have read that there are not speed adjustments on his model.   

there is  slight chance the belt is too wide but, while it is obviously not a long term permanent fix,  I am planning to sell it and don't want to invest any money into it by taking it to Vince for(possible) repair.  If it is an issue with the belt and not the motor,  I'd reckon adding a bit of very hard material, like the DYMO Tape mentioned in one of the forums I read, would last a long long time.   Duct tape, probably not so much.

I suppose I can sell it as-is, giving the buyer  heads up about the speed issue, obviously.

Decisions, decisions....

[scorpio333]

I took a look at the service manual...it it 90% about the automatic arm movement. In the troubleshooting section:

Problem: Incorrect speed
What to do:
Improper capstan
Improper setting of capstan
Dirty capstan
Stretched belt

You could try and clean the capstan, but in my opinion it's the belt. The correct belt is likely unobtanium in the exact tolerances it needs to be. This is likely why the tape on the spindle is the best available fix. While it's not the most elegant fix, if it were mine I'd add the tape.

[rgpit]

According to the specs it has a synchronous motor so the speed should be controlled by the 60Hz 120 VAC input. If it is set for European 50Hz frequency it would run fast being powered by 120VAC 60Hz. Check and set if it can be re-wired or switched to 60Hz setting.

I think putting tape on the platter is a bad idea. It will add a lot of wow and flutter to the output signal.

[Sir Thrift-a-Lot]

I think putting tape on the platter is a bad idea. It will add a lot of wow and flutter to the output signal.

I agree.   I'm not sure that the 50Hz/60Hz is the culprit, because that would be about an 18% difference, and I'm sure a half step is far less than 18%.   That said, I like the notion that brown power could be the culprit.  Lots of fancy tables use outboard speed controls.   Do you power condition?   Do you have a gauge to say exactly how many volts you are running at?   Perhaps you could measure the speed at peak usage and late at night when usage is down and see if there is a difference.   There is a great app for Android called RPM Speed and Wow which you can use to measure.   If you are one of those iGuys I am sure they also have a similar app.

[MacGeek]

If the motor speed is controlled by the 60hz frequency, it doesn't seem a voltage drop should affect it (unless maybe it's extreme).  Might be a motor cap or two going out of spec.  Bad caps almost always seem to be the culprit when my tape machines run fast.

[OldiesButGoodies]

If the motor speed is controlled by the 60hz frequency, it doesn't seem a voltage drop should affect it (unless maybe it's extreme).  Might be a motor cap or two going out of spec.  Bad caps almost always seem to be the culprit when my tape machines run fast.

That would also be my 1st component-of-interest.   Be it cassette decks or turntables, bad caps in the motor electronics make them behave in wacky ways - I have seen turntables rotate in the opposite direction.   Are the 0.22 and 0.033 uf caps measuring ok? 

[scorpio333]

Emp, do you know which capstan you have? Those tables shipped with two different capstans, one for 50 and one for 60hz.

Not arguing against the idea the caps are to blame, but what if they're not? Found a few posts about those early 70's Sansui's, none mention caps. Most mention the tape idea, hanging the belt with a weight to stretch it a tad, and one that puts nail polish on the capstan to thicken it up a bit. Either way, Im interested in hearing what solves it.

[EmperorNorton]

Might just drive out bethel park way, but in the meantime , perhaps order a
Little bigger belt, this one seem pretty tight.  I'm new to this stuff but it seemed tight.

[Sir Thrift-a-Lot]

Emp, do you know which capstan you have? Those tables shipped with two different capstans, one for 50 and one for 60hz.

Again, that would be a 17% difference, which would translate to almost a step and a half in musical terms.   If Emp is correct about it being a true half step off, the 50/60 issue couldn't be the cause.   I suppose it could be the belt, but feel caps are far more likely.   Plus, it's a good thing to do to a 40 year old piece of electronics anyway.   If you spend a few bucks and a couple hours on caps and it doesn't correct it, you still haven't done any harm.

[scorpio333]

Emp, do you know which capstan you have? Those tables shipped with two different capstans, one for 50 and one for 60hz.

Again, that would be a 17% difference, which would translate to almost a step and a half in musical terms.   If Emp is correct about it being a true half step off, the 50/60 issue couldn't be the cause.   I suppose it could be the belt, but feel caps are far more likely.   Plus, it's a good thing to do to a 40 year old piece of electronics anyway.   If you spend a few bucks and a couple hours on caps and it doesn't correct it, you still haven't done any harm.

How dare you kill an argument with MATH!!! 

[Sir Thrift-a-Lot]

Emp, do you know which capstan you have? Those tables shipped with two different capstans, one for 50 and one for 60hz.

Again, that would be a 17% difference, which would translate to almost a step and a half in musical terms.   If Emp is correct about it being a true half step off, the 50/60 issue couldn't be the cause.   I suppose it could be the belt, but feel caps are far more likely.   Plus, it's a good thing to do to a 40 year old piece of electronics anyway.   If you spend a few bucks and a couple hours on caps and it doesn't correct it, you still haven't done any harm.

How dare you kill an argument with MATH!!! 

It seemed like nobody heard me THE FIRST TIME I said that, LOL.

[scorpio333]

Might just drive out bethel park way, but in the meantime , perhaps order a
Little bigger belt, this one seem pretty tight.  I'm new to this stuff but it seemed tight.

Wife and kids are in Disney til next Friday and I'm mostly home getting some work done. Just give me a heads up if you want to bring it out this way.

[EmperorNorton]

Update time.

Picked up a Sanyo turntable today.  It was belt drive so I put the Sanyo belt on the Sansui and the speed is now 34 RPM .  My conclusion is that the belt they sent me for the 4060 is too small.  Plan to find  local place that sells belts and take the Sanyo belt and find a belt jut slightly larger than the Sanyo belt.   

Thanks for everyones suggestions.