• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Numark TT500 Pitch control options

propagandazoo

New Member
I have two Numark TT500 Turntables and the pitch is not working correctly on both.


The fader that seems to work the best has a change in ohms from 14 to 5 when measured with 10K ohms on millimetre and moving fader. It does not register centre position but more noticeably changes pitch.

The other one registers no ohm changes. so I guess the contact of the brushes is negligible. And will certainly need changing.

However, the pitch faders are discontinued:

https://www.reddit.com/r/AskElectronics/comments/g2cjyj
https://instrumentalparts.com/slide-pot-pitch-fader-tt500/

This forum had a thread whose solution is not available anymore:


How would you approach this problem?
 
Last edited:

rjenkinsgb

Well-Known Member
Most Helpful Member
How many pins are there on the connector?

The PCB is not part of the "pot"; also the 0105 is almost certainly a manufacturing date or batch code - the value is the "10KB", 10 K Ohms, linear scale.

This should be suitable electrically, if it's a conventional three terminal pot:

The hard part is finding the right size and value with the same shaft type as the original..
 

propagandazoo

New Member
How many pins are there on the connector?

The PCB is not part of the "pot"; also the 0105 is almost certainly a manufacturing date or batch code - the value is the "10KB", 10 K Ohms, linear scale.

This should be suitable electrically, if it's a conventional three terminal pot:

The hard part is finding the right size and value with the same shaft type as the original..
NB: part - VRS103610010 -

I think I may have found a suitable replacement. Based on this very loose Ebay write up in Italian. Been searching a lot today...


I have ordered one to test Has the same number of pins to solder into the PCB, it is same length, same manufacturer - Fingers crossed.

If it works will update and add info - regards.
 

B4dg3r

New Member
How many pins are there on the connector?

The PCB is not part of the "pot"; also the 0105 is almost certainly a manufacturing date or batch code - the value is the "10KB", 10 K Ohms, linear scale.

This should be suitable electrically, if it's a conventional three terminal pot:

The hard part is finding the right size and value with the same shaft type as the original..
Hi I also have the same issue and have also been drawing a blank on sourcing replacements.
How many pins are there on the connector?

The PCB is not part of the "pot"; also the 0105 is almost certainly a manufacturing date or batch code - the value is the "10KB", 10 K Ohms, linear scale.

This should be suitable electrically, if it's a conventional three terminal pot:

The hard part is finding the right size and value with the same shaft type as the original..

Hi, I am also experiencing the same issue, i've looked everywhere but seem unable to trace replacement pots for these turntables.

I've attached a drawing of the dimensions of the pot alongwith a photo of the carbon tracks inside them.

The main issue that I find when tracing replacements is the fact that they are two gang with a centre tap on the pot, ive tried to clean them with contact cleaner, small eraser to remove deposits etc but nothing has worked.
and to be honest im not wanting to skip the turntables due top this issue.

Any help from anyone will be gratefully received - Thanks Badger (jim)
 

Attachments

Nigel Goodwin

Super Moderator
Most Helpful Member
The issue is probably simply that the pots were specially made for Numark - so the only place they would have been available would be from Numark.

A great many pots were custom jobs, and at one time there were plenty of manufacturers offering such services.
 

B4dg3r

New Member
The issue is probably simply that the pots were specially made for Numark - so the only place they would have been available would be from Numark.

A great many pots were custom jobs, and at one time there were plenty of manufacturers offering such services.
Hi Nigel and thanks for the response,

In your experience or maybe through speaking with others that have experienced issues with non obtainable pots, is there a way of reapplying carbon to the tracks to see if they can be revived or would it be a case of finding another pot that has a centre tap and then modifying it to carry out the same task?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hi Nigel and thanks for the response,

In your experience or maybe through speaking with others that have experienced issues with non obtainable pots, is there a way of reapplying carbon to the tracks to see if they can be revived or would it be a case of finding another pot that has a centre tap and then modifying it to carry out the same task?
Historically there used to be a considerable number of wholesale companies supplying spares to the service trade, and often such companies would have contacts with various manufacturing companies, and quite possibly even the ones who originally manufactured the un-available parts. So if there was any reasonable sort of demand, they would get the manufacturer (or another one) to make some suitable replacements.

Unfortunately the spares trade has all but died out, and very few of those companies still survive :(

For an even more 'obscure' example, there was a small 10 inch colour TV called a Nikkai Baby Ten - they were mains or car battery powered, and a VERY popular choice with caravanners. Unfortunately they used a regulator module - three terminals (in, out and gnd) potted with epoxy to regulate the 12V car battery input to 10.5V, and these commonly failed. After a couple of years they were no longer available, and a friend of mine (Michael) designed and built a replacement module using a switchmode IC, and published the design in Practical Television Magazine. One of the previously mentioned component suppliers had this manufactured commercially, and sold it both to the trade, and to other component suppliers. My friend Michael was never paid a penny for his design though.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I've attached a drawing of the dimensions of the pot alongwith a photo of the carbon tracks inside them.
That's interesting - the fourth pin is a centre tap on the main track.

I cannot find a service manual for the TT500, but there is one for the TT200 on the elektrotanya site here:

That uses the same four terminal centre tapped 10K pot.

The tap is connected to the output of a 4000 series shift register used as an expander on the CPU; it selects either 0V or 5V feed to the centre tap !

If the TT500 works the same, it may? be possible to use a normal three terminal pot, either with an extra resistor added from what would be the centre tap terminal to the wiper (if it's an AC or PWM drive) or possibly a couple of analog switch or FETs sections to switch in an extra resistor at one end or the other of the pot, simulating the offset the voltage on the centre tap would cause.

Ideally it needs someone to see what the voltage or signal on that extra terminal actually is while the deck is running at various speeds, with a meter and if necessary an oscilloscope..
 

B4dg3r

New Member
That's interesting - the fourth pin is a centre tap on the main track.

I cannot find a service manual for the TT500, but there is one for the TT200 on the elektrotanya site here:

That uses the same four terminal centre tapped 10K pot.

The tap is connected to the output of a 4000 series shift register used as an expander on the CPU; it selects either 0V or 5V feed to the centre tap !

If the TT500 works the same, it may? be possible to use a normal three terminal pot, either with an extra resistor added from what would be the centre tap terminal to the wiper (if it's an AC or PWM drive) or possibly a couple of analog switch or FETs sections to switch in an extra resistor at one end or the other of the pot, simulating the offset the voltage on the centre tap would cause.

Ideally it needs someone to see what the voltage or signal on that extra terminal actually is while the deck is running at various speeds, with a meter and if necessary an oscilloscope..
Hi and thankyou for your response,
Sadly the information you have supplied is beyond my skills as I have only just started tinkering (for want of a better description) with electronics.

I will continue my search for a suitable replacement and also for a local (Aberdeen Scotland) electronics club or repairer that I can approach with the hopes of finding a resolution to this.
I have already mailed the mother company that own Numark in the hopes that they can inform me of the original supplier of the pots or if they can provide me with a copy of the original schematics to see if I can then source a replacement possibly from a different brand.

I may also purchase a carbon pen to see if I am able to lay down a new track - but fear that the resistance value may not be the same, but time and experimenting will tell.

I'll post back with any further questions or findings and continue to pick everyones brains if I may?

Thanks Badger (jim)
 

propagandazoo

New Member
Unfortunately I cannot source this alternative part either so back at square 1...

"Unfortunately Numark have informed us that they can now not source this part from any of the worldwide inventory"

Will keep updating...
 

propagandazoo

New Member
Hi and thankyou for your response,
Sadly the information you have supplied is beyond my skills as I have only just started tinkering (for want of a better description) with electronics.

I will continue my search for a suitable replacement and also for a local (Aberdeen Scotland) electronics club or repairer that I can approach with the hopes of finding a resolution to this.
I have already mailed the mother company that own Numark in the hopes that they can inform me of the original supplier of the pots or if they can provide me with a copy of the original schematics to see if I can then source a replacement possibly from a different brand.

I may also purchase a carbon pen to see if I am able to lay down a new track - but fear that the resistance value may not be the same, but time and experimenting will tell.

I'll post back with any further questions or findings and continue to pick everyones brains if I may?

Thanks Badger (jim)

I have found solution and it might work for you. See below
 

propagandazoo

New Member
Update. Solution

I bought two second-hand TT200 Turntables for cheap. Check pitch fader works if possible.

I de-soldered (very carefully making sure you suck up all excess solder with a de-soldering tool (and not too hot so you don't separate any on the metal from the PCB - there's plenty to solder to if you mess up by scratching the PCB back to metal - even using a little wire bridge if you are totally new to this) and completely took apart the pitch fader - using a pair of needle nose pliers and a point tool like a scriber to open and close tabs. Use a marker to make sure everything stays correctly aligned. Clean everything with contact cleaner. carefully remove any residue in housing. Be careful not damage brushes...

Damaged brushes probably mean you want to replace the track as well. I tried to use the TT500 track, but had to replace with TT200. Worked fine then. More work. So maybe just replace both brushes and track. Try to visually inspect the best brushes if applicable.

The only really difference between the pitch faders on TT200 and TT500 was the PCB - which I have a feeling may be true for all these TT turntables. Something that Numark support don't even know - as they like most modern businesses just want to make money on parts - and not waste resources on repairs.

When I get a chance I will try another model.
 
Last edited:

propagandazoo

New Member
That's interesting - the fourth pin is a centre tap on the main track.

I cannot find a service manual for the TT500, but there is one for the TT200 on the elektrotanya site here:

That uses the same four terminal centre tapped 10K pot.

The tap is connected to the output of a 4000 series shift register used as an expander on the CPU; it selects either 0V or 5V feed to the centre tap !

If the TT500 works the same, it may? be possible to use a normal three terminal pot, either with an extra resistor added from what would be the centre tap terminal to the wiper (if it's an AC or PWM drive) or possibly a couple of analog switch or FETs sections to switch in an extra resistor at one end or the other of the pot, simulating the offset the voltage on the centre tap would cause.

Ideally it needs someone to see what the voltage or signal on that extra terminal actually is while the deck is running at various speeds, with a meter and if necessary an oscilloscope..
Here is the pitch fader from the TT500 service manual that I managed to get from Numark...
 

Attachments

Nigel Goodwin

Super Moderator
Most Helpful Member
Interestingly that's labelled as a PWM pin - however, of course that's only one potential use for it, and it 'could' just be used as a normal I/O pin.

Be interesting to try replacing it with a pot without the centre connection, and see what (if any) difference it makes.
 

propagandazoo

New Member
Rather annoying that they make a 'big thing' about the control been easily interchangeable (as they tend to be short lived) - yet then make it obsolete.

Yeah I think it's just the reality of manufacturing now. Bet Technics mk7 don't last like the originals... Break quick. Limited parts = customer buys new. This clown world...

Anyway one turntable platter is now stuck rocking forward and back after trying to service the oil on the bearing. On inspection the oil definately needed servicing...

It was making quite a noise, so could have been early sign of component failure (as it did have intermittent starting problems before and a loud clicking) - but I thought worth a try lubing

Maybe I damaged the optical sensor when servicing, or maybe the IC chip just happened to die at exactly the same time I decided to service the oil.

I am hopefully going to get another one to test exactly what failed.

I really need to learn more electronics so I can test components properly - rather than cut and paste style... But then I think that with electronic miniaturisation- maybe wasted time for future realities.
 

EE World Online Articles

Loading
Top