Pioneer Rt-1020L Wrong Playback Speed

elegey

New Member
:banana:My Rt-1020L is playing a little too fast at 7 1/2ips. Any suggestions regarding the fix for this problem would be welcome. I have the service manual for this unit. It is a 60/50HZ unit. The ac line voltage is set at 120 VAC. Line frequency at 60HZ. Thanks for your help.
 
I ran into this same problem with my TEAC A-4300 SX. Is this a belt driven unit ?, If so, is there a double pulley on the motor ? One may be for 50hz and the other for 60hz operation. I am not familiar with Pioneer designs but that is how my TEAC A4300 SX works.
 
I think this deck has a variable speed control, with a switch in it. If so, the first thing to do is clean the switch and control. if that doesn't work, there should be an adjustment on the capstan motor speed control board.
 
I ran into this same problem with my TEAC A-4300 SX. Is this a belt driven unit ?, If so, is there a double pulley on the motor ? One may be for 50hz and the other for 60hz operation. I am not familiar with Pioneer designs but that is how my TEAC A4300 SX works.
Hi Orzric, Thanks for your reply. The drive belt is set for 60HZ on the smaller diameter motor pulley. Also the Capstan Motor is a hysteresis synchronous type, it operates at the main power supply frequency. I checked the service manual and I can not find any control to fine tune the capstan speed. If you have any other ideas let me know. Tanks
 
I think this deck has a variable speed control, with a switch in it. If so, the first thing to do is clean the switch and control. if that doesn't work, there should be an adjustment on the capstan motor speed control board.
Hi dr*audio. I can not find any variable speed control, with a switch in it for this unit.The capstan motor is a hysteresis synchronous type, which operates at the main power supply frequency. The speed does require a fine adjustment. It is enough for a person to notice the pitch is wrong. The problem is how to perform this fine speed adjustment. Thanks for the advice, and any help is much appreciated. Thanks
 
Unfortunately, a line locked motor such as this has no way to adjust the speed. Have you checked it with a speed calibration tape and a frequency counter? If so, the only things you can look at are the capstan belt, lubricating the capstan motor bearings, cleaning and lubricating the capstan bearings, including the rear bearing, and checking the play on the rear bearing (not enough play will create drag.)
Also check the tension on the supply reel. If it's too high, it will slow the deck down.
Check that the tape isn't sticking to the heads. Ampex back coated tapes will do this. Eventually they can stop the transport dead. Make sure the heads don't have any sticky residue on them. This can cause a good tape to slow down.
If you have a wow and flutter meter you can check for wow and flutter. A bad capstan bearing would show up with high wow or flutter.
 
:banana:My Rt-1020L is playing a little too fast at 7 1/2ips. Any suggestions regarding the fix for this problem would be welcome. I have the service manual for this unit. It is a 60/50HZ unit. The ac line voltage is set at 120 VAC. Line frequency at 60HZ. Thanks for your help.

I though he said it was running to fast so sticky heads is not the problem.
 
I though he said it was running to fast so sticky heads is not the problem.
Thanks for the info, you are right, the unit is ruuning a bit faster than it should at 7 1/2ips. I found an adjustment pot on the capstan servo board, but that concerns more torque adjustment, and I do not believe that will cure the problem. The unit is definetely running a bit faster than it should at 7 1/2ips
 
My mistake. Perhaps it was wishful thinking. I had a look at the 1020L schematic and I see no pot on there at all, it's just a line locked motor as far as the schematic is concerned. Check the take up tension. If it's too high it could speed the deck up. There is nothing else you can do if it's fast. The motor has to go at the speed dictated by the line frequency. The capstan could be machined to the wrong tolerance. If you can calculate the correct diameter, you could get a machine shop to turn it down.
 
Thanks dr*audio for the advice. Vintage TX gave me another hint. This unit as far as tape speed goes, it comes in 3 different kinds of adjustable pulleys. The RLA-345-O-slightly small drive pulley in diameter, RLA 346-O-standard-size drive pulley in diamenter(standard speeds). RLA347-O-slighly large drive pulley in diameter. My unit is a 50-60HZ unit and 110-240VAC, so I assume it is an European Model. I suppose I need to see if I can obtain the right pulley for the unit. The one in the unit is making it go slightly fast at 7 1/2 ips. So I suppose I need the RLA-347-O which is slightly large drive pulley, larger diameter must mean lower speed. Am I right. Thanks for the help. It is much appreciated. We may be able to help other people in the forum with this discovery.
 
If you mean the pulley on the motor shaft, no, larger diameter means faster speed. A larger pulley on the motor makes the flywheel turn further with each rotation. So you probably have the slightly larger pulley and need a smaller one, or you could get the pulley turned down by a machine shop. You could ask them to take a small amount off at a time and then you could try it.
 
If you mean the pulley on the motor shaft, no, larger diameter means faster speed. A larger pulley on the motor makes the flywheel turn further with each rotation. So you probably have the slightly larger pulley and need a smaller one, or you could get the pulley turned down by a machine shop. You could ask them to take a small amount off at a time and then you could try it.
Thanks dr*audio. You are right about the pulley diamenter. I will try to find a machine shop in my are so that they can turn down the pulley. Another solution is to find the original slightly smaller pulley for this unit. Question is... do you know where I can buy one of these pulleys? I know Pioneer Parts is out of stock. I have to find a machine shop in my area, I wish I knew how much to take off this pulley. Thank you very much for the very wise advice.
 
I don't know a source for the part. The speed thing is the ration between the size of the 2 pulleys involved. I don't know if it's the diameter or circumference, but since they are directly related to each other, I don't think it matters. You need to measure the speed accurately using a speed calibration tape and a frequency counter. Then you can calculate the percentage the speed is off by. Then you measure the diameter of the motor pulley and I believe you want to reduce it by the same percentage.
 
dr*audio thanks again for the advice. I will measure the frequency with the test tape and frequency counter and then I will be able to calculate the percentage the speed is off by. Very clever advice. This is the 2nd unit I buy from Ebay ,paying top dollars, just to find out I got ripped off. The unit was supposed to be in perfect condition. First thing bad, both VU meters are mechanically broken, then the Playback board was all broken, including the copper traces gone, It took me many hours just repairing this board. It is working ok, now. Next is the speed problem. Enough to give up. Thanks again for your care and prompt replies. Take care. Elso Legey, I will let you know the result of the test.
 
You need to measure the Pinch Roller tension if the speed is fast or slow. For this measurement, you need the proper spring scale.
I wouldn't touch any adjustments before taking all tension measurements. Don't forget all tension points are interrelated.

Ron
 
You need to measure the Pinch Roller tension if the speed is fast or slow. For this measurement, you need the proper spring scale.
I wouldn't touch any adjustments before taking all tension measurements. Don't forget all tension points are interrelated.

Ron
Thanks jblmar, I think you suggestion is very well taken and it makes a lot of sense. Let me think what I will decide to do with this unit in the next two days, I will let you know. Your contributions to this Forum are most welcomed.
 
Unfortunately, a line locked motor such as this has no way to adjust the speed. Have you checked it with a speed calibration tape and a frequency counter? If so, the only things you can look at are the capstan belt, lubricating the capstan motor bearings, cleaning and lubricating the capstan bearings, including the rear bearing, and checking the play on the rear bearing (not enough play will create drag.)
Also check the tension on the supply reel. If it's too high, it will slow the deck down.
Check that the tape isn't sticking to the heads. Ampex back coated tapes will do this. Eventually they can stop the transport dead. Make sure the heads don't have any sticky residue on them. This can cause a good tape to slow down.
If you have a wow and flutter meter you can check for wow and flutter. A bad capstan bearing would show up with high wow or flutter.

I love the point about Ampex tapes. The earlier tapes evidently used whale oil for the lubricant, and the new synthetic oil that went bad causing the tape to stick so bad it could stop the entire transport.
 
Thanks jblmar, I think you suggestion is very well taken and it makes a lot of sense. Let me think what I will decide to do with this unit in the next two days, I will let you know. Your contributions to this Forum are most welcomed.

The 1020L is a very well built machine. Worth getting up to speed.

Ron
 
The 1020L is a very well built machine. Worth getting up to speed.

Ron
Hi jblmar, I did check the speed accuracy of the unit at 7 1/2 ips with my Teac Test tape with the 3KHZ tone. Result, the unit is definetely running faster, I got about 3.215KHZ average using my Fluke Frequency counter. I also checked the Take-up reel torque Resistor tap, intact from the factory, it has never been moved, the same goes to the capstan solenoid assembly.( no screws have been turned, still have the original factory laquer ion them. I did apply pressure to the pinch roller by placing my finger on the pinch roller itself, and I could get the speed frequency to go to 3.02KHZ, withing the tolerance. Should I move the solenoid in and out, or should I try to do some trimming with the pulley and/or flywheel. Thanks for your help. We will conquer this situation. Yes the RT-1020L is well built and I love its sound quality. Thanks again. When I got the right speed accuracy, in the pinch roller test, the tape started squealing.
 
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