Harman Kardon T60 110v/60hz @ 220v/50hz

[nicama]

Greetings One and All!

A friend of mine brought his Harman Kardon T60 table asking me to revitalize it. The TT was bought in the US in early 80s. It's made for 110V/60Hz AC, and equipped with the quartz-locked motor.

So far the TT has no shell+cart and the belt. The shell&cart are coming shortly, and the belt is ordered and is on its way down here.

In order to make the TT compliant with our 220/50 AC standard here I purchased a step-down transformer, and switched it on to the TT.

Fortunately the motor starts spinning, quartz locking button works, autostop works as well, and the rest functions seem to work fine.

Though I don't have an original stock T60 belt, I've found a similar flat belt, that I manage to put over the motor spindle and the subplatter. Well, now I got platter spinning!

But, being unable to test the TT sonically (the shell hasn't come yet), I decided to test the RPM by means of strobe disc, once I'm not sure that 60Hz motor, even quarz-controlled, will run at the proper RPM of 33,3 under 50Hz AC.

Unfortunately I've found that the strobe 33rpm/50Hz marks don't stand still, but move rather noticeably. T60 has an adjustment knob, but turning it to its both limits didn't help either, the marks kept moving one and the same direction.

According to the manual, there are resistors on the main board, which will adjust RPMs for 33/60, 45/60, 33/50, and 45/50. I didn't try to adjust them yet, and am unsure whether it will help or not.

Also, once the belt I tried seems to be somehow tighter than needed, this fact may also influence on the actual RPM, but I'm not quite sure.

That's how it goes, and now I need suggestions on what to do further on. Maybe I need to order a tachometer to adjust motor's RPM thoroughly, don't I?

I appreciated if someone would give any ideas on the possibility of using the 60Hz AC quartz-locked TT attached to 50Hz mains in general, and HK T60 in particular. Anybody's experience shared or just opinions are welcome too.

TIA
Nick

[LPfan]

A quartz locked motor is supposed to be a dc motor, so the mains frequency should not be a problem. Are you using a 50Hz strobe disk or trying to adjust by strobe marks on the platter side? The later shall not give correct indication of speed as those markings shall be for 60Hz only. Download a 50Hz disk from here and check with that.

Regards,

LPfan

[nicama]

Are you using a 50Hz strobe disk or trying to adjust by strobe marks on the platter side?LPfan

I'm using two record clamps. One has all 33/50, 45/50, 33/60, and 45/60 marks, the other one has 50 Hz marks only. The platter itself is markless.

When the disk spins, neither any of 60 Hz nor 50 Hz marks are still.

Again, the belt I'm able to use now is not the proper one. But on the other hand I don't believe this matters, since the gear ratio should depend on the pulley and subplatter diameters only, shouldn't it.

Nick

[Alec124c41]

There is a simple way of determining the speed at which the platter is turning. Put a bit of tape on the edge of the platter, and time it.
At 33.33 RPM
100 rev takes 3 min. flat
50 rev take 1 min 30 sec.
25 rev take 45 sec.
This method not only tells you if the speed is correct or not, it tells you how much it is off.

Cheers,
Alec

[nicama]

LPfan, Alec, thank you for your comments!

Yesterday I experimented with T60 adjustments, and found that the diameter of the belt really matters. I took another flat belt, the older one from my Dual 505. It is tighter than previous one I tried, and the platter started spinning at a higher RPM. So that the tighter the belt is the higher RPM the platter spins at.

Moreover, it looks like the stock T60 belt is wider than those I tried. This factor is obviously important as well.

When I turned the quarz lock off, I was able to adjust the motor speed to get an appropriate platter RPM at both 33 and 45. But I believe that such an adjustment makes no sence, if the stock belt is available.

Anyway the TT needs its stock belt to operate properly, hope it'll come in a week or so.

Once I found that HK T60 was nearly not referenced here at VE, I'm going to drop few lines here with my impressions of it as soon as all parts get together.

Nick

[Van_Isle]

The quartz lock on these turntables are famous, it seems, for not locking in correctly as the turntable ages. Some have had success with recapping the speed control board. First however, try a complete cleaning of the pots for the 33/45 speed selector and speed control (the external adjustments) and the speed control trimpots inside the turntable on the speed control board.

Then once the correct belt shows up, center the speed adjustment control and adjust the trim pots as per the manual's procedure under the "Quartz Lock Off Adjustment" section. That should give you the maximum +/- adjustment possible.

Don't worry about a tachometer ... use your stoboscope's 50Hz scale, since that is what your AC power is at, feeding the light you are using on the stroboscope ... your step-up transformer is taking care of the 60Hz to the turntable but that has no relationship to the stroboscope pattern to be used.

As far as I know the only way to adjust the speed with the quartz lock engaged is to change the motor pulley, as is discussed in the service manual ... and that is an impossible dream since Harman Kardon threw out all their spare parts a number of years ago. I've read that the turntable sounds better using the manual speed adjustment anyway (can't confirm that as the quartz lock on my T-60 runs slow!).

The only other thing that might help is the info on the quartz lock and motor mounting in the T-60 service bulletins that are posted in the library.

Sounds like with the step-up transformer you might be able to combine that with the Van Alstine external power supply mod into a tidy little package.

See here: http://www.audiokarma.org/forums/showth ... p?t=350805

With regards to belts, I am running a 25-inch belt on mine. I did have an email conversation with the longest-standing US HK dealer who swears the correct belt for a T-60 is a FM25.75, which is not the same belt that 99% of the online stores list for this table. I haven't tried one to see if that fixes the quartz lock.

What headshell did you order?

Anyway, I hope that helps ... and enjoy the table!

[nicama]

Van_Isle,

Thanks a lot for your exhaustive suggestions and info!

Now I realize that T60 is not as easy as it seemed to me in the beginning

Yes, I made some primary cleaning of external panels and knobs(pots), but didn't make it inside yet. Thanks for pointing me out there.

The belt I ordered at turntablebasics.com marked exactly as FM25.75, so that I expect it's the right one. It's clear for me how to adjust QL off mode, I read the manual carefully.

My strobe discs are quite sufficient for the task, I realized that yesterday. As to the motor pulley, I clearly saw, that there's no way to apply the approach mentioned in the docs, once it seems like the belt embraces the spindle itself. Please, correct me if I'm wrong. Anyway, you say that all the stuff had been thrown away... Being optimistic, I hope that the proper belt will make the trick.

And you're right, QL off mode would help in adjusting the RPM as a viable resort.

Fortunately, manuals are avalable here at VE, so that I may consult them along my way forward.

The headshell is the stock one, it's coming in a couple of days. My friend just forgot to attach it to the arm. Once the shell mount isn't standard, I doubt that I can find anything similarfrom the source other than HK.

And there's one more question. I found that the platter mat is hard and hazardously fragile. Would it be good to exchage it with a new one. What kind of material is best, cork, sorbothane, or acryl? Acrylic ISOMat is available on eBay, and its price is quite affordable.

Thank you again for the great comments and multiple source references on the topic!

Nick

[Van_Isle]

Nice to have the original headshell! I believe this ADC - style headshell works fine, should you want an extra:

http://www.lpgear.com/Merchant2/merchan ... HEADSHELLS

or

http://www.lpgear.com/Merchant2/merchan ... HEADSHELLS

From what I understand the slight difference (possibly) in angle between the "generic" and the HK shells can be compensated for during alignment (twisting the cartridge in the headshell). The key thing is to get a headshell with the proper length so you can set the overhang.

By the way, the HK overhang / alignment protractor is attached as the last page of the T-35C owner's manual in the library. Print it out to scale on some stiff card stock.

I lucked upon a used (and free) headshell at a local electroncs sales / repair shop ... not a HK unit and it isn't a ADC brand, but it is darn close.

I'm not sure exactly what you mean regarding the spindle. I have read of others speeding up a turntable through increasing the diameter of the spindle by applying a thin coating of solder to it (carefully when it is spinning) and then sanding it down by trial and error.

I am somewhat surprised that the HK turntables work at all with quartz lock given the "loose" mounting of the motor and the lack (as far as I am aware) of any speed feedback circuit in the design.

I'm not up too much on replacement platter mats .... others can advise better I am sure. The stock T-60 one is very hard ... it may have gotten brittle with age.

[nicama]

By the way, the HK overhang / alignment protractor is attached as the last page of the T-35C owner's manual in the library. Print it out to scale on some stiff card stock.

I'm not sure exactly what you mean regarding the spindle. I have read of others speeding up a turntable through increasing the diameter of the spindle by applying a thin coating of solder to it (carefully when it is spinning) and then sanding it down by trial and error.

I am somewhat surprised that the HK turntables work at all with quartz lock given the "loose" mounting of the motor and the lack (as far as I am aware) of any speed feedback circuit in the design.

I'm not up too much on replacement platter mats .... others can advise better I am sure. The stock T-60 one is very hard ... it may have gotten brittle with age.

Van_Isle,

Many thanks again for your useful comments!

Yesterday the shell with the cartridge mounted on it arrived. The cart is Stanton 881S with D81 stylus. Using some belt that I have (an old one from my Systemdek IIX) I managed to give T60 a spin, obviously with QL off and pots tuned up appropriately. I set Stanton at 2g VTF by means of eletronic micro scales, and the sound I got was quite reasonable to say the least.

Now I need to align the cart, adjust VTA probably, etc. Stanton's needle needs to be oserved as well. I'll definitely make use of a protractor you suggested.

And of course, I've seen how the pulley is attached to the motor's spindle. Well, I really got nothing to do about that.

There is some minor problem with the lift, but I need to take some time to play around it. Maybe I will need an advice on its tuning later on.

Nick

[Van_Isle]

If you check the vinylengine cartridge database, I think you will find that Stanton should be tracking at 0.75 to 1.25g .... rather than 2g.

Sounds like that cartridge is a real winner ... especially if it is the original version (not MkII):

http://www.vinylengine.com/phpBB2/viewtopic.php?t=21684

(and there are lots of other opinions and info on that one on the web)

Replacement stylus is available from LPGear:

http://www.lpgear.com/Merchant2/merchan ... e=STNS881S

[nicama]

If you check the vinylengine cartridge database, I think you will find that Stanton should be tracking at 0.75 to 1.25g .... rather than 2g.

Yes, I know that 1g is a "net" VTF, but with the brush attached if I get it right from the brochure, one needs to set 2g up at the counterweight (or at the scales as I did). Anyway I will verify a proper VTF with HFNR test record.

The stylus is the original one, I hope it's not worn. I read few opinions on the net, and found them quite encouraging, but after a brief audition I feel like a definite need to align the cart properly. Once the outer tracks played great, the inner ones were awful.

Thank you again for meaningful and useful info!

Nick

[AmCan]

Hey Guys,
Just wondering how things turned out with the speed of your T-60? My quartz lock is running slow and the variable resistors are running fast. I already did a recap and replaced the belt. It worked for a while but now it is dragging again. Do you think replacing the variable resistors might resolve the speed issue. If so, does anyone know what part to use or is this table done?

[Van_Isle]

Just to follow up - I ordered a 25.75" FBM from turntableneedles.com and my speed is now correct using the quartz lock. So .... it can be done!