Tascam 38 transport problem

janusz konar

New member
Sorry for being pain in the ass but i need to ask you again about my maschine.

Just take a look at a picture, it looks like pinch roller is putting more pressure on one side of capstan. In result, as you can see, tape is not rolling even and it is rubbing one side of the guide. I had this before, but I thought it was because of old/melted pinch roller. Now I have changed pinch roller along with capstan belt and after turning it on, it seemed ok, so we started doing some alignment/ calibration. Ater a while (1h maybe) we have notieced out of phase signal between two output tracks on a oscilloscope (picture no 2) We were plaing back tone from the test tape. I looked at headstock and notieced the problem went back

For us it looks like the metal part that is holding pinch roller is not 100% still. It seems to be little bit loose on its mounting. Not very much like maybe 0.5mm. In result capstan and pinch roller is not 100% parallel while prssured. Im not sure you can see it on a picture, but even without pressure it is not parallel, I think.

What wonders me, is why was it ok for a while, and then went back to previous state.

Do you have any idea? Im guessing it is not recomended to use maschine in this state?

Im depressed :)
 

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some ideas:

1) Any misalignment in the headblock (unlikely)
2) Check that the pinch roller doesn't wobble. Take a close look at it when turning
3) One possibility is that the pinch roller arm is slightly bent or has play, so you have a pinch roller that engages the capstan not fully flat
4) Check the tape path carefully to try to find the misalignment.
 
The only thing I'm noticing is that the pinch roller is sitting way too low in the first picture.

The tape should be travelling midway between the top and bottom of the roller so I'm suspecting that your replacement roller is the wrong one or is perhaps mounted upside down, by accident.

Cheers! :)
 
3) One possibility is that the pinch roller arm is slightly bent or has play, so you have a pinch roller that engages the capstan not fully flat

For me it looks like it. If so, can this be fixed somehow?


The only thing I'm noticing is that the pinch roller is sitting way too low in the first picture.

The tape should be travelling midway between the top and bottom of the roller so I'm suspecting that your replacement roller is the wrong one or is perhaps mounted upside down, by accident.

Cheers! :)

Yes, I also notieced that, but I think pinch roller is not symetrical, so it can be mounted only one way.

Thanks
 
Do you have the collar bearing that sits on top of the roller on the shaft ?
As mentioned roller sits mighty low.Maybe upside down?

Gary
 
Look at the picture, #7 (collar bearing) should come out when you remove the pinch roller. Do you have it ?

T38 pinch.png
 
Is the tape rubbing on the top of all the guides? I wonder if the alignment problem is the actual spools? The tape looks as if it is high on heads too.

Alan.
 
Look at the picture, #7 (collar bearing) should come out when you remove the pinch roller. Do you have it ?

View attachment 79921

Yes, i have this part. I think that rollor itself is alright, I tried to mount it other way, but didnt work



Is the tape rubbing on the top of all the guides? I wonder if the alignment problem is the actual spools? The tape looks as if it is high on heads too.

Alan.

Tape is rubing the guide on a picture only
 
Hmm....What about tape tension guide height adjustment on the take-up side ?
Maybe time for a full mechanical alignment from scratch.

Gary
 
Some news:

Is I discovered, the problem appears only while playing test tape. I played normal tape and it was alright.


????
 
Some news:
Is I discovered, the problem appears only while playing test tape. I played normal tape and it was alright.
????

Can you photograph the test tape? I'm curious in case it's got some weird centrepiece like the Zonal tape I have. That one was rather high, but it only rubbed a bit more than usual. It didn't do this.
 
Can you photograph the test tape? I'm curious in case it's got some weird centrepiece like the Zonal tape I have. That one was rather high, but it only rubbed a bit more than usual. It didn't do this.
 

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Sorry for being pain in the ass but i need to ask you again about my maschine.

Just take a look at a picture, it looks like pinch roller is putting more pressure on one side of capstan. In result, as you can see, tape is not rolling even and it is rubbing one side of the guide. I had this before, but I thought it was because of old/melted pinch roller. Now I have changed pinch roller along with capstan belt and after turning it on, it seemed ok, so we started doing some alignment/ calibration. Ater a while (1h maybe) we have notieced out of phase signal between two output tracks on a oscilloscope (picture no 2) We were plaing back tone from the test tape. I looked at headstock and notieced the problem went back

For us it looks like the metal part that is holding pinch roller is not 100% still. It seems to be little bit loose on its mounting. Not very much like maybe 0.5mm. In result capstan and pinch roller is not 100% parallel while prssured. Im not sure you can see it on a picture, but even without pressure it is not parallel, I think.

What wonders me, is why was it ok for a while, and then went back to previous state.

Do you have any idea? Im guessing it is not recomended to use maschine in this state?

Im depressed :)

It pic #1 the tape is to high up on the tape "guide" (see it crinkled?) so that seems to me that the table height needs to be lowered on either the take up side are the supply side are maybe even both...;)
 
Yeah, it looks like the centrepiece might be pushing it up. Spooling it onto a regular metal reel might be wise. By hand if necessary.
 
What is centrepiece?

Okay. A normal reel has a completely flat top like this:
reel_wo_centre.jpg


Or seen from the side:
reel_wo_centre-side.jpg



Some reels, like the one your test tape has been wound onto, have a central hub as well:
reel_w_centre.jpg


Seen from the side, you can see that the hub protrudes. About 1mm each side on my Zonal reel:
reel_w_centre-side.jpg


...this can cause problems. Adjusting the height of the reel tables in the deck to compensate is one option, but it's tricky to do and if it's adjusted for funny reels like that, it is very possible that it will no longer work properly with normal reels afterwards.
 
Great illustration Tape Wolf and I never noticed if I ever had different type hubs like that as long as I used my 38 back in the day. and I definitely see how that can present a lil problem for sure, so if janusz konar does a reel height adjustment he should do it with the type reels (hub) that he records with mostly right ?
 
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