Tascam 48 Counter and RTZ problem

R

Rufer

New member
My Tascam 48 is having some problems with the counter when using the RTZ function and fast rewind. The counter appears to be tracking appropriately when in play. The most obvious problem is when the counter is a few hundred counts beyond zero. When I press the RTZ button the counter will appropriately start to rewind back toward zero. However when the reels begin to build up speed the counter doesn’t seem to count down at the same rate. Finally when the reel speeds really get going the counter stops counting down all together (the number gets stuck) and the reels only stop when I press stop.

Does anyone have any ideas what the problem could be? Anywhere I should look? It was working fine for many months and the problem happened suddenly.
 
I'm sorry to say, but it does not sound like a simple problem. I sincerely hope I am wrong.

Assuming you are certain that the tach roller is not slipping or binding up (i.e. when the counter problem occurs, and you stop the deck and manually take the tension off the tape by turn a reel to slacken the tape, does the tach roller spin freely?), get ahold of a frequency counter...if you don't have one see if you can get ahold of one or a good digital multimeter...often times they have a frequency counter built-in, but it has to be a good one because it is going to have to read down to 12Hz...check the specs of the meter to make sure it can do this.

Connect the + probe to the 'L' terminal of the "ACCESSORY" connector on the back of your deck...connect the - probe to terminal 'TT' (I think...). 'L' is where the tach roller outputs tach pulses for a syncronizer...'TT' is the main unit ground.

When you put the deck in PLAY mode your frequency counter should read 12Hz. Now put the deck in SPOOL mode...frequency counter should read about 72Hz.

If you get that far then your tach is working but something is screwy with your counter display or something in between...that's beyond me for sure, though you could always try my favorite standby...open 'er up and disconnect and reconnect pertinent connections cleaning with deoxit as you go...might be a bad/oxidized connection that worsens with load/temperature or something.

That's all I can think of for now...maybe it is much simpler than all this...
 
Maybe it's just the small rubber grooves the tape run across on the roller are worn or sticky, preventing the roller to be accurate when it speeds up ?:)
 
Vintage Texas said:
Maybe it's just the small rubber grooves the tape run across on the roller are worn or sticky, preventing the roller to be accurate when it speeds up ?:)
Click to expand...
That would be my guess too. It sounds very much to me like some kind of mechanical slippage problem, but I don't know the specifics of how the counter works on that machine. IIRC the 38 takes its count from one of the reel tables, while the TSR-8 uses a roller.
 
The 48 uses a relatively small tach roller...it is downstream from the pinch roller...the design of the tape gives the tach roller quite a bit of tape wrap though which is why I suggested checking to see if the tach roller is binding up or something...yeah, if the rubber is hardened, and the lube is sticky in the tach roller bushing...yeah...
 
Thanks for all of your suggestions. I believed I'd been keeping all of the rubber parts clean--the tach roller appeared and felt to the touch to be in good shape too. Nevertheless I busted out the Caig and gave the roller a good cleaning and soak. I'll have to devote more time to confirm but in the few minutes I had this morning, I fired it up and the counter appears to be working appropriately.

I feel thankful (and dumb) that this seems to be such a simple solution--I really did think I was good about the regular maintenance.

May this forum and contributors be around for a while.

Thanks again.
 
:D:D:D

We're all happy it was relatively simple, Rufer! ;):cool::p

Let us know if anything changes with what you know of the situation (i.e. if it turns out its still acting up).
 
Eh so cleaning the rubber did not fix the problem. The tape tech I use emailed some possibilities off of the top of his head. I believe one of his ideast that "the rewind back-tention might be low, causing poor tape contact with the idler." is correct.

I can actually see the idler spinning as RW gets up to speed but at some point you can see the tape not spinning the idler and skimming over top when it's going really fast.

Is this an easy adjustment? It's nice of the tape tech to give me the emailed response--he's done a lot of work for me in the past and I've paid quite a few dollars for him to get the machine up and running. I don't believe he feels I'm obligated to have him fix it.
 
Anytime is a good time to bust out a Tascam reel-to-reel manual. :D

For your 48 look on page 7-10 and 7-11 which has section 7-4-4, Tape Tension Servo. That's the page that has the info about adjusting tape tension. The trimmers are behind the splicing block. Just remove it and you will see them. You also have to remove the lower dress panel. The procedure specifies to use a Tentelometer to measure the tape tension, but there is a bit that you can do visually without the meter and usually that can catch anything that is way out of spec, like REW back tension that is low enough to allow the tape to ride off of the tach-roller. :eek:
 
You must log in or register to reply here.
Back
Top