Just got Tascam 246. It worked but now will not turn on

M

Mstone

New member
Hello all! My name is Mathis, and I am new to this forum and home recording, but I got a Tascam 246 a few days ago (knowing it needed new tires and a new pinch roller. It was working fine, and I had it apart and it was working fine too. I kept it in the bottom half of its shell so it would not touch the floor. I took it apart a little deeper last night, but only taking off the row of inputs metal bracket on the front and the motherboard that is attached to those inputs by white wires so i could see if i could spray deoxit in that way into the pots because they need it.

Anyway, I got the new pinch roller in the mail today, got it installed, and the machine will not turn on at all! In the multiple times I tried, I did see the tape heads move up once, even though there was no tape in there. When I was taking out the old pinch roller, the whole assembly of them moved back without power, so maybe it was readjusting that. But no lights will come on or anything. I feel like there is something silly that is wrong with it or that i am doing wrong but I dont know what and i need some help. Thank you!
 
Okay now I am actually getting it to turn on but its flickering on and off and making an electrical sparky noise. So i think the cord is lose somewhere.
 
After some testing, it is having a problem with it moving the tape heads too far forward when it is in stop, rewind or fast forward. But not always. But when it does it cant move the tape to rewind or when stopped, it is sometimes difficult to put a tape in or take it out.
 
Hi. There is a motor in the transport that, via a small belt, and xyends and retracts the headblock assembly. When things are partially disassembled to replace the capstan belt, the gear mechanism that the control belt drives is separated. When you put it back together you have to make sure that the headblock is in the lowest position and then make sure the gear mechanism is aligned so it is also at the end of its travel that corresponds with the headblock lowest position state. This is all from memory...I ran into this on a 234 which uses the same transport assembly. With your 246 powered off and unplugged from the wall, find that motor with the small control belt (looks like a smaller black rubber band). Manually turn the motor pulley and observe what it moves; how it extends and retracts the headblock assembly. Hopefully you can figure out or see how when the heads are at their lowest position the gear mechanism is supposed to be at the end of its travel. My hunch is it’s off.
 
Oh okay. You know, that makes a lot of sense, since the seller of this machine replaced all the belts but did not seem to know enough, or didnt want to put in the effort, to replace the tires and pinch roller, and clean it up. I will try this for sure.
I actually ran into a couple other problems as well. First of all, I replaced the pinch roller but the hole in the center was slightly too large. I found a seller who sells a bunch of different sized ones but he only has pictures of them next to rulers to show their dimensions. The machine is playing tapes too fast. Would this cause that? Also, they are playing too quiet but that could be me. I tried but was not successful on trying to record onto a tape and play it back, but I was able to play a regular tape very quietly.
I had also replaced the tires that turns the spindles but I simply went to home depot to try and find a washer and I found one that fit, but it is round instead of flat. It seems to be about the right size though. They slip a little but not much, and I can turn the wheel with my finger and see it turn the gold motor shaft and spindles when it touches both. Do you think this is okay?
I will also be giving all the controls a good Deoxit session once it arrives in the mail, and replace a bulb on one of the VU meters when that arrives as well, Just to let you know where i am at. Thank you!
 
Be aware that many portastudio machines run the tape at double speed for higher quality. I believe the 246 is one of those.
 
Okay, I turned the gig white wheel with large holes in it, attached by a small band to a plastic motor pully, and it interlocks gears with a black plastic gear with an odd shape on it. This moves the assembly back and forth. Starting from furthest counterclockwise position, the heads are all the way out (would be in the tape). Then, after about 3 full turns, the heads go in. Then back out in another turn. Then 7 more turns and back in they go, and then they go back out in 1 full turn again. And then they stay out for the last 2.5 turns and thats the end of the wheel turning. Now I have to figure out which end is supposed to have the heads in instead of out.
 
And oh yes, it does. But it also has a speed switch to go to normal speed. A pitch control. I can only get the speed right however with the pitch knob all the way down.
 
Okay so I found that where it puts the heads in stop mode, when it has the heads in the tape still just a little is about 3 and 1/16th turns counterclockwise from the most clockwise point that the wheel will go. Sometimes in stop mode, it moved the heads back just enough to get the tape out. FF is 4 1/4 turns counterclockwise, and rewind is the same. So should it be at these points where the heads are not going in the tape? Or should it be at the end of its travel also?
 
I can’t answer any questions about how many turns equate to what position of the headblock assembly. I would have to open up a machine with the same transport but I don’t own one anymore, so I’m sorry but I can’t help on that one.

As far as the idler tires, if you’re going to the trouble to replace them, you should get the correct parts. There is a pretty exhaustive tutorial on the idler tire replacement in these transports put together by DrZee...he found some square cross-section o-rings for faucets IIRC that worked well...search this forum for Tascam 244 idler tire.

An incorrect pinch roller diameter or bore will not directly effect the transport speed. The transport speed in PLAY is regulated by the capstan shaft. When you say you can only get the speed correct by turning the pitch control all the way down, do mean for a tape recorded at regular speed on a different machine, when you play it on the 246 and have the speed setting set to the low speed it is still too fast unless you turn the pitch control down?
 
Yes. I used a regular pre recorded cassette tape just so I could more accurately test the speed. I had to have it set to low speed on the switch, and pitch control all the way down. And the reason I ask about the pinch roller is because when I push on the pinch roller to push it more into the tape, it slows it down because it puts more pressure on the tape and capstan. So the roller should be sitting where it normally does when it plays, but I was thinking the thinner space between the central bore and the outside of the roller would equate to less pressure on the tape and capstan, therefore allowing it to move faster. With no pinch roller pressure, the spindles move at near fast forward speed and so does the tape.
And yes I read his tutorial on rhe pinch roller and idler tire replacements, and I went to home depot to look for what he was talking about, but I thought it might be better and more economical to look at the packages of washers and o-rings that they had. I think the ones I put on are working decent but i guess I cat really tell until I fix this head block setting issue.
And oh okay I understand. I will just have to play around with the positioning of it then.
So just, which part has to come off to be re aligned? It looks like the belt would just pop off without taking off any of the wheels.
 
Mstone said:
Yes. I used a regular pre recorded cassette tape just so I could more accurately test the speed. I had to have it set to low speed on the switch, and pitch control all the way down. And the reason I ask about the pinch roller is because when I push on the pinch roller to push it more into the tape, it slows it down because it puts more pressure on the tape and capstan. So the roller should be sitting where it normally does when it plays, but I was thinking the thinner space between the central bore and the outside of the roller would equate to less pressure on the tape and capstan, therefore allowing it to move faster. With no pinch roller pressure, the spindles move at near fast forward speed and so does the tape.
And yes I read his tutorial on rhe pinch roller and idler tire replacements, and I went to home depot to look for what he was talking about, but I thought it might be better and more economical to look at the packages of washers and o-rings that they had. I think the ones I put on are working decent but i guess I cat really tell until I fix this head block setting issue.
And oh okay I understand. I will just have to play around with the positioning of it then.
So just, which part has to come off to be re aligned? It looks like the belt would just pop off without taking off any of the wheels.
Click to expand...

So how do you know the pre-recorded tape is playing too fast? Just by ear? I think in addition to the pitch knob there is a speed adjust trimmer on the pitch control PCB. You first adjust the pinch roller pressure, then use a test tape with a known frequency tone and reproduce the tone and adjust the trimmer until the frequency measured at the output jack of the 246 is equal to the known frequency on the test tape. Yes of the pinch roller pressure is too low, the takeup torque may overcome the capstan shaft and the tape may be slipping past the capstan shaft. First, you need to install the correct pinch roller, and secondly you need to adjust the pinch roller pressure using a spring guage in accordance with the instructions in the service manual. You really, really, really ought to have the service manual for that machine if you are doing this kind of open-heart surgery and wanting/needing to make these kinds of repairs/adjustments. Do you have the service manual?

Regarding the idler tires, no offense, but if you had the info for which parts to get, and you chose to do something different for whatever reason, don't expect it to work right, or that you will be able to get it to work right. If somebody told me what parts to get, I wouldn't consider something else at the risk of it not working right. There's a reason the particular washers were recommended by DrZee. Its up to you whether or not it is worth saving a few dollars to have the headache of trying to get it to work right.

I think your first objective IMO is get a service manual, and second get the correct parts.

Regarding the head base position, I'm attaching two pdf files to this post. One is the instructions from the 246 manual regarding the head base position adjustment. It was a little difficult to make sense of it, so I also grabbed the same instructions from the 234 manual which help to clarify. Refer to the 246 instructions as far as the adjustment trimmer identifier and location, but use the 234 instructions as a clarification on what you are supposed to do. You basically put the transport in PLAY and then STOP mode and power it off and then make a note of where the head base is sitting. You then turn the reduction pulley (the large white one with the 4 holes in it) by hand to see if you can get the head base to go lower. If you can, then on the 246 there is a trimmer R552 on the control PCB...you turn it on, put it in PLAY again and then STOP and tweak the trimmer to lower the head base position to the lowest position in STOP mode. You then repeat this a couple times to make sure its where it should be (i.e. PLAY, STOP, power off, note head base position, see if you can get it lower with the reduction pulley by hand and if you can, power up, press PLAY, then STOP, tweak trimmer, PLAY, STOP, shut it off and repeat the steps until the head base is in its lowest position when you hit STOP and power the machine off). If you can't ever get the head base to its lowest position in STOP within the sweep range of the trimmer then you will need to figure out what needs to be disassembled and what gear teeth need to be adjusted so the adjustment can be accomplished within the trim range of R552.
 

Attachments

  • Tascam 234 Head Base Position.pdf
    158.9 KB · Views: 1
  • Tascam 246 Head Base Position.pdf
    722.6 KB · Views: 5
Oh that is a better idea to listen to a single tone as a test tape. But yes I was listening by ear and the speed difference was VERY noticable. Lol. Roughly 1.5x the correct speed at the normal speed setting with the speed switch on low. Plus I can compare it to the same song playing from my phone. It was just a preliminary test though. I will do the tone test when I get things functioning more accurately.
Yes i do have the service manual, and i agree it is very hard to make sense of. Thank you for the uploads. I will use them and try this out. I will try the trimmer before the belt.
Then I can see what is up with the pinch roller after that.
And its okay. I know I wish I could have found the correct part for the idler tires, but i couldnt. Ill give it another look online
And i have never heard of a spring guage. Where do i get one of those? Thanks!
 
Mstone said:
Oh that is a better idea to listen to a single tone as a test tape. But yes I was listening by ear and the speed difference was VERY noticable. Lol. Roughly 1.5x the correct speed at the normal speed setting with the speed switch on low. Plus I can compare it to the same song playing from my phone. It was just a preliminary test though. I will do the tone test when I get things functioning more accurately.
Yes i do have the service manual, and i agree it is very hard to make sense of. Thank you for the uploads. I will use them and try this out. I will try the trimmer before the belt.
Then I can see what is up with the pinch roller after that.
And its okay. I know I wish I could have found the correct part for the idler tires, but i couldnt. Ill give it another look online
And i have never heard of a spring guage. Where do i get one of those? Thanks!
Click to expand...

You do understand when I say test tape I mean a cassette calibration tape right? Not your own cassette you record test tone on but a pre recorded precision tape with tone already on it? They are about $75.

If it sounds like its running 1.5x normal speed when on the low speed setting, there is definitely a problem because the pitch control covers (IIRC) +/- 12%...so that would mean your tape is running 60+% fast. You need to sort out the pinch roller pressure first...but even before that you need the correct pinch roller.
 
I mean couldn't i just use a tone generator on my phone to generate a specific frequency, record it, and play it back? Or record it on a different tape deck maybe so it wont be recorded by the machine at the same speed its being played back? Im not going to buy a $75 test tape. I will do some shopping around for a cheaper one maybe. It only really needs to be a consistent speed with itself and not regular tape decks anyway right? As long as it is un noticeably close to standard speed its fine.
And well then it may be running around 15% fast because at the lowest pitch setting it is almoat normal.
I got the exact correct washers with faucet adapters from home depot. Same dimensions, but they are slightly too thick so I am currently trying to find a way to shave them down just barely. You can tell in his tutorial that they may have been too thick for his also because he said he has a bit of warble in the machine, and looking at when I squeeze them in, they are almost round, but they are just too thick to be perfectly round. Only by a very small amount.
 
If you don't care about your machine being truly on spec you could record tone on another machine that you think is closer to its correct speed, but just be aware that if you then use that tape to set the speed of your 246 it will only be as accurate in speed as the deck you used to make the homemade test tape.

The $35 tape would likely be better than the homemade tape.
 
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