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Author Topic: technics rs-1500 maintenance help  (Read 9349 times)

Offline wailinfree

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technics rs-1500 maintenance help
« on: March 30, 2013, 06:29:59 AM »
Hi
I recently dug out my RS-1500 I got second hand in 1984. It was hardly used by the previous owner. I used it some but not extensively. It was stored in a rack mountable anvil like case so it's not gunky just dusty. I probably hadn't fire it up in some 20 years or more.
I took a chance and fired it up using a homemade variac type of device and brought it up to power slowly. I didn't hear anything explode so I may be ok for a bit although I would rather do some preventative maintenance before anything does go bad.
I believe I have a link to download a service manual but haven't printed it out yet.
Can someone recommend what preventative maintenance I should do.
I'm assuming open it up and check all the Caps especially in the power section
Any advice would be great.
This is my first post. I have been lurking since I recently broke out my echoplex again. It seems like every one is very helpful around here
Thanks in advance
Wailin

Offline ironbut

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Re: technics rs-1500 maintenance help
« Reply #1 on: March 30, 2013, 11:12:31 AM »
Hi Wallin,
Welcome to the forum.

For the most part, I've found that these machines are very durable and not too many need to have caps replaced to work correctly.
Many of the issues that folks have had with them are related to switches, pots and other "friction" connections.
It's not that unusual for the switch on the headblock which toggles between the 1/4 and 1/2 track playback heads to need a little work. Many times that just requires that you "work" the switch several times. In some instances, some cleaning is required. If you're super careful, a tiny squirt of contact cleaner into the back of the switch will work but in extreme cases, the switch needs to be removed for cleaning.
Another common issue is the tape counter. The 2 tiny belts that operate it often become hard and the counter itself can get noisy (screechy to be precise).
Personally, I don't use the counter very much so I've simply cut the old belts off. Replacing the belts (if you can find them) is not a trivial matter and requires the removal of the capstan motor and reversing roller.
Other than that, just check to be sure the brakes, pinch roller pressure and tape tensions are all at spec (I usually adjust the brake tension lower than the factory spec since I play lots of really old acetate tapes which are very fragile) and take care of issues as if they come up.
If you plan to use the machines for use with important tapes, I suggest taking it to a professional shop at least once, to have everything checked over, adjusted and cleaned. That will give you a baseline for the machines performance.
The investment of a couple of hundred bucks will go a long way to protect high dollar tapes or ones that contain your creative output.


steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline wailinfree

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Re: technics rs-1500 maintenance help
« Reply #2 on: March 31, 2013, 06:59:08 AM »
Thanks so much for your response and Bob's response to my PM
I fired the 1500 up again last night all seems to work except the rewind doesnt rewind at the speed it used to. Its very slow . So I amy have to at least poke my head in there and see if there are and caps that I can see that are visually bad. I plan on rereading BoBs repair diary again to see if he had this issue and which cap to look for to see if its bad
If anyone knows please chime in
I wish I knew of a good repair shop around here to take it to. Its way too heavy to ship unless someone can help me with  how to pack. i dont have a case except a rack I store it in?
Anyway Ill need to print the service manual and do all the other checks you suggested and see where Im at
I do hopefully want to use this to send my masters tio and see if it will warm up the difital mix some
Thanks again
Wailin

Offline Soundproof

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Re: technics rs-1500 maintenance help
« Reply #3 on: April 05, 2013, 12:09:28 AM »
I've downloaded the service manuals at HiFiengine.com, but can't find a guide to lubrication of a Technics 1506.

Any tips or links? My 1506 works excellently, but has developed a soft grinding noise during playback that I think is due to a need for lubrication. (The noise is not there during wind/rewind).

Stein Leikanger
TD124/Beogram 3000, Technics 1506, Beolab 5000 amplifier, Helsinki Gradient 1.5 speakers.
http://www.hifisentralen.no/forum/index.php?action=dlattach;topic=62965.0;attach=290514;image

Offline ironbut

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Re: technics rs-1500 maintenance help
« Reply #4 on: April 05, 2013, 02:02:42 AM »
Hey Stein,

Most of the rolling elements of the tape transport have sealed bearings.
For example, the capstan and reversing roller both have a front and rear sealed bearing.
While it's possible to disassemble, clean and lubricate these bearings, they should be replaced with similar bearings. Trying to clean and/or lubricate them without removing and taking them apart is generally a waste of time.

The easiest bearings to replace are the ones on the tensioners. Always buy quality bearings. I like Japanese bearings like NGK.
Take note that there are thin spacers with the bearings on the tensioners. Since these are spacers, you need to reassemble them in the right place or the bearings won't be aligned.
Another spot that can be lubricated are the pinch rollers. Those will also have spacers which should be reassembled correctly. Just a thin film of medium weight oil on the pinch roller shaft is all that's needed. If you put too much on them, the oil will migrate to the rubber rollers which is a very bad thing.
The rest of the bearings will need a puller and a press to replace them.

Luckily, most of the time the bearings that get noisy are the ones on the tensioners. Folks using too much head cleaner on those bearings will "wash" the lubricant right out of those bearings and ruin them.

You need to spend a little time locating exactly where the noise is coming from.
Sometimes it can turn out to be the tape counter mechanism or the pulleys that work with it.

It could also be the reversing roller. There's a "spider" spring under the center cap which pushes the center cap outward. A felt washer under the spring keeps it from making direct contact with the metal roller housing. Sometimes that gets a little out of alignment and makes a noise but it's generally kind of a ticking sound.

Another rolling bearings that can be lubricated are for the reel motors. Those motors need to be removed and disassembled. Just be careful not to use more than a "film" of oil on the motor shafts. The contacts adjacent to the shaft in the motor need to be clean for the servo to do it's job.

Hope that helps. Again, locate the origin of the noise before you start pulling motors and bearings. The precision of the way a machine moves the tape across the heads is what makes the difference between a good machine and a great one. Getting all this stuff to work together properly isn't a trivial matter.




steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline docb

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Re: technics rs-1500 maintenance help
« Reply #5 on: April 05, 2013, 11:24:51 AM »
If you don't hear it during fast wind it is quite possibly the pinch rollers, capstan or reversing idler that needs to some attention. The pinch rollers are easy to service so start there. Just take them off, clean them and the shaft and then lube the shaft and reassemble. I like a moly based lubricant there but any good light oil should be fine. For cleaning the rubber of the pinch rollers I use Formula 409.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline rubli

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Re: technics rs-1500 maintenance help
« Reply #6 on: April 17, 2013, 07:00:28 PM »
hello, I am new to this forum, and apologize if this has been asked before.
I got a RS1506 for repair, after changing some transistors, the mechanism is working, with the exception of the tape speed switch, which I will be checking later. my concern is that the head switch is broken.
can I remove the head assembly without messing up the tape adjustment ? do the heads connect via a connector ?

any hint will be appreciated

regards

Alexander

Offline ironbut

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Re: technics rs-1500 maintenance help
« Reply #7 on: April 18, 2013, 01:14:01 AM »
Hi Alexander,

Welcome to the forum.

Those selector switches are a common issue. Usually just need to be shot with some cleaner and worked.
Regarding the headblock, you can safely remove it by removing the 3 silver screws. The black ones are for adjusting the heads.
Once the screws are loose, just pull the headblock straight out. It has a multi pin connector on the back.
It shouldn't effect the heads unless you bump one of them. The guides immediately before and after the heads are also connected to the headblock so much of the alignment is self contained.
Installing the headblock is just the reverse.

It would be instructive if you could describe the problem you repaired and the transistors that you replaced to remedy the problem. In other words, what was the machine doing (or not doing) and which parts needed to be replaced.
I'm always interested to hear of problems encountered especially if they've been fixed.

steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline docb

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Re: technics rs-1500 maintenance help
« Reply #8 on: April 18, 2013, 12:03:25 PM »
I put up a video that we did a few years ago. Sorry for the poor quality, but it should get the message across:

http://www.youtube.com/watch?v=HfB8Y4dpRoM
« Last Edit: April 18, 2013, 12:39:34 PM by docb »
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline rubli

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Re: technics rs-1500 maintenance help
« Reply #9 on: April 19, 2013, 07:15:31 PM »
Hi Alexander,

Welcome to the forum.

Those selector switches are a common issue. Usually just need to be shot with some cleaner and worked.
Regarding the headblock, you can safely remove it by removing the 3 silver screws. The black ones are for adjusting the heads.
Once the screws are loose, just pull the headblock straight out. It has a multi pin connector on the back.
It shouldn't effect the heads unless you bump one of them. The guides immediately before and after the heads are also connected to the headblock so much of the alignment is self contained.
Installing the headblock is just the reverse.

It would be instructive if you could describe the problem you repaired and the transistors that you replaced to remedy the problem. In other words, what was the machine doing (or not doing) and which parts needed to be replaced.
I'm always interested to hear of problems encountered especially if they've been fixed.


hello

thanx for the tip.

as for the power supply failure.. the unit was completeley inoperative, I began to check the to220 transistors (and some alike) and found out that TR604 was faulty, replaced with a BD series transistor, and the machine begin to work. BTW I use a Atlas peak transistor checker (not expensive) , as I had the case with many transistors, that they check ok with the multimeter, but on the checker, they test as two diodes...

I will take apart the head switch, (it is broken), and keep on troubleshooting this unit, that according to my client, was sitting there for almost a decade

regards

alex

Offline rubli

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Re: technics rs-1500 maintenance help
« Reply #10 on: April 19, 2013, 07:21:20 PM »
I put up a video that we did a few years ago. Sorry for the poor quality, but it should get the message across:

http://www.youtube.com/watch?v=HfB8Y4dpRoM

thank you very much  this vaulable video, quality is superb !!!!!

regards

Alexander

Offline wailinfree

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Re: technics rs-1500 maintenance help
« Reply #11 on: June 07, 2013, 12:28:48 PM »
ok
I got he 1500 working ok I was thinking of sending it to J-corder to optimize the unit.
Can anyone recommend j-corders work
i was thinking of getting some performance upgrades
he offered a trade on a unit already complete for my 1500
any idea of how much i may be able to sell mine for?
its in great condition and does function but needs a little tender loving are to make it better
thanks for any help

Offline argibbo

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Re: technics rs-1500 maintenance help
« Reply #12 on: March 07, 2014, 09:14:50 AM »
Hi Everyone
I too have a Technics RS15-6, plus the additional 4442 headblock. I had a problem with mine. The top end began to disappear on playback after a few moments. It turned out that the tape tension was not being maintained over the headblock. The cure was to check and adjust the yoke that applies the pinch rollers to the capstan, and then to check capstan pressure. Both rollers must touch the capstan at the same time. All this is available in the service manual. Properly adjusted the tape runs perfectly.
Cheers
Andy

Offline mikkelbreiler

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Re: technics rs-1500 maintenance help
« Reply #13 on: December 23, 2015, 05:40:04 PM »
Another common issue is the tape counter. The 2 tiny belts that operate it often become hard and the counter itself can get noisy (screechy to be precise).
Personally, I don't use the counter very much so I've simply cut the old belts off. Replacing the belts (if you can find them) is not a trivial matter and requires the removal of the capstan motor and reversing roller.

I actually fiddled a little and managed to change the belt that goes onto the capstan without removing the capstan assembly at all, all you need is patience and looping the belt over the capstan, a thin piece of metal with a tiny l-shaped hook made from a straitened paper clip ought to do it. I used a piece of metal I had lying around anyway. A similar piece with plastic on it, usually used for keeping cables organised should work too.
In my opinion the less parts you disturb during any process of restoring the better, so I did not want to unmount any prt I did not absolutely have to.

Other than that, just check to be sure the brakes, pinch roller pressure and tape tensions are all at spec (I usually adjust the brake tension lower than the factory spec since I play lots of really old acetate tapes which are very fragile) and take care of issues as if they come up.
If you plan to use the machines for use with important tapes, I suggest taking it to a professional shop at least once, to have everything checked over, adjusted and cleaned. That will give you a baseline for the machines performance.
The investment of a couple of hundred bucks will go a long way to protect high dollar tapes or ones that contain your creative output.
A good mod for the tape path, which depending on your exact needs with fragile tape may be a good investment, is to make the fixed tape guides movable, by installing smaller rollers in their place. That includes the two arms pulling tape off the heads when play or record are not engaged.
This will lessen the tapes contact with fixed objects.
While one of the most easy and cheap ways to start is to push the lever on the right of the headblock pulling in the arms that keep the tape off the heads when winding (old style programme search when winding), this will mean more wear to the heads, but while the heads are less prone to pick up debris or scrape the surface it is actually just the slightly lesser of two evils - wear the heads or have the tape scrape the arms.
When I wind a fragile tape I either play at 38cm/s (15IPS) in the U-loop, or I let the tape go straight from supply to take-up reel and hold down the two upper tension arms, to engage the transport modes for fast forward or fast reverse.

-Mikkel