Hi all,

a wild stab in the dark this, but I've just got some time on my hands and I thought I'd transfer all my old 4 tracks masters from tape to my Mac. I've had the Porta Two for a few years now and I've had no problems with it. I set the thing up and popped in a tape, pressed play and then after about a second the play button popped up again and it stopped, rather like it had reached the end of the tape.

I checked what was happening and noticed that the right hand spindle that is meant to move the tape was not turning. The capstain was, but the pinch wheel hadn't come out far enough to make contact, and that wasn't turning. It's almost as if the pause button had been pressed, and the pinch wheel had been retracted a short way, and the spindle had stopped spinning.

I opened the case up and checked the motor and belts, and everything looked fine ... very good in fact for something 20 years old. Apart from the fact the spindle wasn't working and the pinch wheel hadn't extended far enough.

Has anyone got any ideas as to what could cause this problem? I know a little about eletronics etc. but can't work out what could be wrong in this case. Is it worth trying to pick up another Porta Two (or similar)?

Help please?!

Stuart

If the belts are the original ones, I would change all of them. A belt can "look OK" and still slip under load.

I seem to recall that a motor brings the heads and pinch roller into place on Porta Two. If the belt for that starts slipping when the head moves into position, it could behave just as if the unit is in pause. Remember that, at a certain point, the spring that presses the pinch roller on the capstan and the spring which engages the takeup drive must have their tensions applied by this motor and belt.

Thanks for the reply MidiMagic,

I've taken the thing apart and removed the tape drive unit and inspected the underside to see what's going on, and I can honestly say that the belts look fine. I did this with the power connected and the play button down (for as long as it would stay there). Everything was spinning, except the drive spindle of course!

I suppose changing the belts is a good place to start, by that I mean the least expensive.

I had a word with someone I tracked down who claims to repair old Tascam gear (in the UK) and he said he was worried that it might be a cam that had broken, and that it would be difficult to replace. We'll see. I think I'll try and source an old Porta Two for repairs. Know anyone?

Stu

What causes the heads to move into place on this? Is it the play button pushing the head, or is it a motorized drive?

I was thinking a second belt did that. It's motor should NOT be spinning if the head is fully extended. If it is spinning, the cam is not turning. The belt may be slipping at the cam without turning the cam. This keeps the head and pressure roller from extending and keeps the take-up drive from engaging.

It's also possible that the pause circuit is stuck on.

I've got this exact same problem and have just gone through the same steps as Stu. I also removed each belt, cleaned them, and measured for replacements, but each belt seems to have both wheels properly turning with no sign of slippage. With no tape or mechanical resistance, the take up reel spindle doesn't even begin to turn in play mode, and when the head plate moves into its highest (play) position, there appears to still be a gap of more than a sixteenth of an inch between the pinch roller and capstan.

Here's my main concern:

There's a black metal arm under the head assembly, about the diameter of a paper clip, maybe an inch long, with sort of a "fish hook" shape (see picture). In the picture, you can see one end sticking up behind the rec/play head at a slight angle and the other end pointing toward the roller. There's a suspicious amount of play in that part. It's locked in a cutout behind the plastic head assembly, but there's no obvious tension on it in play mode or otherwise. The right (straight) end is free to drop up and down by almost a quarter inch. Is that normal or has it broken or jumped out of its correct position? It almost looks like maybe the right end once extended into the pinch roller housing or something.

Either way, even if I push the pinch roller carrier up a bit by hand until it begins spinning, I still get no takeup reel movement, so I don't guess it's just the roller gap.

Much much thanks to anyone who can help!

George
[attachmentid=3550]

Hopeful bump and addendum----

Actually, if I pushed the whole head plate assembly up far enough once play was engaged, I did indeed get the takeup reel spindle moving and the deck wouldn't automatically drop out of play after a couple seconds like it normally does. Apparently, the pinch roller hits first, but the idler tire (?) doesn't drop against the takeup wheel until it lifts up a bit more. Not sure if that's how they are on a properly adjusted one though.

Here's another picture if anybody wants it. The "tire" I'm talking about is on the wheel just above the takeup (I drew a red circle around it). As the head carriage raises up, all that stuff comes down and the tire starts driving the reel. I also drew a red line coming off a little peg to the left of the reel. As that metal plate in the center rises up, the peg will drop into that little notch in the side (drew a small circle there), but with no assistance it never gets far enough up there.[attachmentid=3554]

What the heck determines the amount of upward pressure on that head assembly and how do I increase it? OR, is there something which might cause the whole assembly to be too hard to lift after a couple decades, even though it has the correct pressure?

Thanks!

Check the following:

That belt would be the third belt if it has motor driven head load.

- With the motor-driven head load, something is causing the head load to shut off before the take-up tire engages. Check the limit switch.

- Check to see if a spring on the take-up tire is weak.

- Is a rubber tire missing from the takeup spindle (the part that indicated tire contacts)?

- Are parts bent?

MidiMagic-

Thanks! You seem to know these things, so I'll try not to bug you too much.

I put it back together for protection, so I may be tomorrow or so digging back in to look at this new stuff.

I'm not real experienced with these things, but I'll try to locate that limit switch. I have 122 & 122mk2 service manuals but no Porta Two. I'm not sure on most of the takeup-specific suspects though, as the pinch roller never moves up enough either, so it seems like something affecting the whole assembly.

From what I remember, there didn't seem to be any rubber to the actual spindle part of the takeup reel, nor evidence that there once was any. I remember cleaning the plastic to make sure it hadn't gotten grease on it. The takeup tire however, was rubber over plastic (the plastic wheel has a groove in it).

You're not by any chance familiar with that bent black metal rod I pointed out behind the main head are you? I'm guessing that thing is normal now. I'm not sure it could be easily broken or even bent.

Thanks Again,

George

Update on this:

I dug it open again last Thursday and didn't get anywhere. Last night I decided to go at it again and (yikes) dissect as much of the gearing as I could to figure out how much stuff was responsible for moving the head plate up.

As it turns out, I must have somehow made the right assumption back before I had even looked that far into it. After getting a closer look at that black "L-shaped" thing, I can see that it's got the coiled spring center like it should be applying pressure to something, but it's fully extended. After trying to squeeze the short end back under the plastic and having it keep popping back out, I decided to pull the whole part out and look at the back. There's an obvious chip of plastic missing where the short end of the spring burst through at some point. The part probably could have been designed with a bit more reinforcement, or made out of a different material. That spring is hard as a rock. You really have to use some force to squeeze it shut, so I'd imagine as the plastic ages or it goes through temperature changes, it's at high risk. The screw that holds one end of that part down also sits right on the stressed out area which probably doesn't help much in keeping it from cracking.
[attachmentid=3557]
I wish Stuart (stuming) was still in here. I wouldn't doubt that his cracked too. I wonder if he threw it away or got it fixed.

I guess I won't really know if that's all it is until I can manage to repair or replace it, but the position it's in would seem to put a lot more upward pressure on that head plate. Sad part is, I messed with so much junk before going back to the metal clip that I've likely thrown a bunch of other stuff out of whack, gotten the belts dirty, and obviously destroyed the head alignment. I was hoping to avoid a service manual as I'm already figuring to need a 234 or 134 for most of my tapes (3.75ips). I figured maybe I could do the azimuth and a couple other things with no docs, but I guess the erase head in a multitrack cassette also needs to be perfectly straight and I have no idea how they go about that.

Thanks for the help MidiMagic. Maybe if someone else ever runs into this problem they can find this thread. I'll let you know if I can revive the thing. I may try to clean that part first and rebuild the chipped area with some JB Weld or something. Should that fail, I'll have to get the part number and hope Tascam can still sell it and the total cost isn't prohibitive.

Take Care,

George

[quote=Jidis,Sep 18 2008, 01:45 PM]
Update on this:

I had the same problem after pulling out my P2. I changed all (4) four belts, three below the mechanics, one was broken, the one that made the capstan turn. And everything started working except the fast forward. Why would this not work???

Sorry I'm just noticing this (I'm guessing RP is gone now ).

I'm noticing on two of the Tascams I've been restoring, that they have a couple hidden idler tires which don't show up in the service manual. They're both on the same assembly, but the manual just lists the whole part. Those drive the FF/RW and they dry up just like everything else. The two I hit were the 234 and the 122 (original). I'd suspect the Porta uses that same setup, but I hadn't gotten that far into mine.

I got replacements from Studio Sound Electronics. They have a PDF there that you can compare sizes to. The 234 took an IT-5, which was a perfect fit. The 122 appears to take something around the size of the IT-42, but I haven't tried to install those yet. Both machines used a pair of tires. The idler mechanism sits between and above the two reels and is removed from the rear, but count on doing some digging and keep close track of how everything was positioned (I usually snap pictures along the way).

Hope that's of help to someone.

George

PS- If you have to pop off an 'e' ring while doing this, shield it with your free hand or something. They tend to shoot off and head for the hills.