Technics 1500 tweaks

[KevO]

Greetings,

Some questions:

1) I removed the lower tape guides from the headblock and thought all was well. Tape path is running smoothly and packing perfectly. But I see the lower mounting posts are touching the tape. Do I need to increase the contact with the erase and record heads to eliminate this?

2) The tape lifters are quite grooved. Someone (Steve?) was using teflon tubing as a cover. What size? What source? Also, the lifters sit close to the tape while it is playing, does the tubing hit the tape while playing?

I was taking this to a tech for head alignment, but he talked me into doing it all myself. I have an o'scope for azimuth but need to handle the above first.

All assistance gladly welcomed!

Kevin

[ironbut]

Hey Kevin,

Happy New Years.
I haven't done the mod that removes the lower tape guides so I'll leave that for those who have experience with that.

Regarding the use of Teflon tubing on worn lifters, IIRC, the tubing I use is the FEP Teflon which I purchase from McMaster and Carr. There are other formulas of Teflon but I found that the FEP is a bit more compliant which makes friction fitting it on the lifters more secure.
The size I use is ID 3mm and the OD is 5mm (I think).
http://www.mcmaster.com/#tubing-%28made-with-teflon-fep%29/=kxeo6x

On my machine, there is no problem with the tape touching the lifter while in play and since the lifters are between heads, that shouldn't be a problem unless there is a need to lower the head height of the erase and/or the record heads for the tape guide removal (which is possible).
Be aware that these Teflon "sleeves" do wear rather quickly so you need to check them every few tapes you rewind to be sure that the groove doesn't get very deep and I rotate the "sleeves" every once in a while then pull off the headblock to replace them once an un grooved surface can't be found. I rotate them with a pair of needle nose pliers away from the area that the tape contacts them.
I cut the tubing to size with a razor knife just short of the length of the lifter shaft. There's a black rubber (?) spacer almost inside of the machine so push the cut sleeve against that. If the sleeve seems loose, squeeze it a little to close the inner diameter a bit and it will keep the sleeve from rotating when you don't want it to.
Also, be careful when push on or pulling off the sleeve. You don't want to bend the arm that the lifter is attached to inside the machine. It seems pretty strong but you don't want to find out the hard way. Replacing those arms would require the purchase of a parts machine!
I keep meaning to take one of those lifters to see if a ruby or pyrex sleeve can be bonded onto it. I'm sure it can but at what cost?
For now, I'm content to live with the tiny hassle of fooling with the Teflon sleeves.

[KevO]

Steve,

Thanks for the resource. You devised an innovative solution for the worn lifter rods. I read the lifters could be rotated, but you are correct that the part as a whole is so imbedded in the player that any damage would be costly. I won't risk it. Sleeves make sense.

Installing the Tape Path Upgrade has taken me out of my comfort zone, but I enjoy that. To a point.

I removed the 'C' tape guides because I do not have the tool to lock the outer ring once I adjusted them. It appears I will have to increase contact with the lower heads to stop the tape from contacting the lower mounting posts. Once the lower heads are moved outward the upper heads also need to move out.

The tech I spoke with warned against removing the the tape guides. Doc recommends it. I understand where Doc is going with this. Less scrape flutter. Better sound. Less tape wear too.

Moving the heads for greater contact is taking me a few more steps out of my comfort zone.

Maybe I should reinstall the lower tape guides.

Q: What is the tool that locks the slotted nut around the slotted screw? (lower tape guide)

The Manual calls it 'tool'. That is too generic to search for. And I can imagine the photos if I search for 'tool' ;-)

Maybe Doc will reply with some guidance on head alignment and if BH increased head contact to eliminate hitting the lower head block mounting posts.

Perhaps the heads on the 1500 I bought have always been in too far.....

Thanks
-Kevin



 

[docb]

I recommend the removal of the lower tape guides for me, because I tried it and liked it. For everyone else the idea seems to bring mental turmoil, especially any other tech. Thus I stopped recommending it for anyone - except me.

Re the lower guide adjustment - you don't need a special tool other than a teeny screwdriver to catch the slot in the outer threaded ring while you turn the inner threaded rod with another little screwdriver and vice versa. And possibly a BFH to straighten out the bent up mess that inner rod might be from some guy who screwed the whole thing down too hard and bent the crap out of it. That is very common. Many 1500s look like they were serviced by Axe Man from Resident Evil.


"Yes, I can lop, I mean lap, the heads for you..."

[KevO]

Doc,

Thanks! Yes the lower guides do seem 'off'. I find the lower guides flimsy too, so I would like to leave them off.

I decided to increase contact with the record and erase heads. Lo and behold, both were a bit loose and had moved away from the tape.

I increased contact and will now reevaluate see if the tape is above the lower mounting posts.

-Kevin

[Listens2tubes]

Hey Dan, why the hood when lapping?

[tandyman]

I take it he couldn't find the goggles to protect his eyes against flying metal.

[docb]

There was some rumor that the guide removal will increase head wear. How this was determined just a few months after we started removing guides is not something I have been able to figure out. I am not concerned about wear, but there are a couple of considerations I think worthy of discussion. One is that you really have to nail the alignment of the heads and remaining guides and also have the tension perfect to be sure that the tape won't shift around when passing over the heads. The other is that the head wrap will be a little different. I never noticed a sonic difference, but in theory you might have to recess and/or rotate the heads a bit to get exactly the same wrap - which of course makes the tape lifter and that support post potentially more intrusive to the tape path.

Regarding the hood, my experience over the last few years has been that aside from the truly expert and thorough technical guys like Mike Spitz, John French, Greg Orton, Jeff Jacobs, etc. a lot of other supposed expert tape techs that our customers have taken decks to for work might be better off wearing something that obscures their identity...

[KevO]

I have not moved the play head since Greg Orton installed it, but it may need to move forward. I reinstalled the lower guides and added the Teflon tubing to the lifters. The tape hits the Teflon during play. 1mm.

I will fuss with the heads some more, but I am way off my experience cliff here.

Do you move the heads quite forward (toward the edge of the mounting block) to make all this work? Wisdom comes from experience and experience from mistakes. So I am on my way.

My big mistake may be not taking this to a pro...... yet, I am pretty capable. Any tips or photos that will help me out? I am so close and have a tape to play...... but I do NOT want to ruin a tape.

-Kevin

[ironbut]

Hey Kevin,

It's possible that your machine is slightly different from mine so the teflon tubing might not work. There are differences in the electrical layout and even the actual components used in one RS1500 to another so the size and shape of the lifter levers could also be different.
Luckily, it's cheap enough to try so little is lost.

I actually have my lifters adjusted as high as I can so yours are almost certainly different.

[docb]

Everyone should have a work tape. That is simply a tape that is expendable, that you use when you are making adjustments like visual alignment of the tape path, brake and servo tension, etc.

[KevO]

I wondered if design changes were made over the years. I wouldn't doubt it.

You say your lifters are adjusted high, I can't find lifter/shifter adjustment in the manual. Looking at the part in the manual, I can't see any way to adjust it on mine.

I had the tape path packing tape perfectly without the lower guides. I am sure I can achieve that with the lower guides reinstalled.

I really liked your 'tubing' fix for the lifters. I want it to work. I'll try a few more things. Reread the documentation.

Knowing what you 'don't know' is a good thing. I can take it to the pro.

Thanks for the help.

-Kevin