tascam 688 - disassembly and (hopefully) repair)

cjacek said:
heat.... that's right. You can't put in previous tapes recorded with the bad belt (and expect correct pitch). That's why changing belts (and rubber components in general) every 5 to 10 years max is a good idea. Also, it's never gonna be dead on 15min for a 60 min tape. There are variations in tape lengths (due to cassette tape manufacturing) and also the machine itself, any analogue machine. Your best bet is tracking something and observing stability. I think it was a success. Keep us posted. :)
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sweetbeats said:
Heat, don't sweat it...I have ALWAYS found that 60 minute tapes run about 32 minutes a side and 90 minute tapes about 47.5 minutes...I think you've got it. Try a test recording.

And as for the old tapes? That pitch control is gonna come in handy now mate. :D
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Thanks so much for your encouragement and advice!

I laid down about 6 quick tracks of acoustic guitar and it maintained the same speed flawlessly. Now, only time will tell, but it is already apparent that this is a huge improvement. I couldn't get through one take let alone 6 tracks without having the pitch all messed up before.

To think how close I was to giving up...

Still getting a digital roland unit though :p :o. I'm gonna find a way to use them both together and try to get the best of both worlds. Thanks again!
 
heat, im glad you were able to fix your 688!

my unit is still on the fritz, i cant seem to nail this pitch problem. When my unit had the bad belt it didnt fluctuate at all BUT it just stopped all the time, now it doesnt stop at all but changes speed! haha, im going mad!

hows your roller?
 
If I may chime in ....... The pinch roller doesn't really affect the speed fluctuations so either there's still a problem with the belt (maybe placed wrong or...?) or indeed it's an electronic malfunction. That 688 is one big computer controlled behemoth.:eek: I still would try to trouble-shoot a possible belt issue until you know for sure that it's not. Did you clean the old belt's residue and centered the belt correctly? Does it ride correctly? Are you getting pitch changes with all new material?
 
moogmymellotron said:
heat, im glad you were able to fix your 688!

my unit is still on the fritz, i cant seem to nail this pitch problem. When my unit had the bad belt it didnt fluctuate at all BUT it just stopped all the time, now it doesnt stop at all but changes speed! haha, im going mad!

hows your roller?
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Thanks moog :). I'll have to try it more to be sure, but if not fixed entirely, it is certainly better than it was. Mine never stopped unexpectedly, but I've read plenty of threads on portastudios over the years and often, changing the belt cured a sudden stopping issue. It seems as though in your case, yu traded one issue for another :(.

My roller has a strip the width of the tape running across the center of it that was pretty shiny, but scrubbing it with cotton fabric soaked in diluted window cleaner took a lot of the sheen off and now it looks pretty decent. Not like new or anything, but decent.

I am confident enough that it will work that I picked up an rc 88 remote for it on ebay...that thing is pretty cool!
 
cjacek, thanks alot. Im going to rip that thing apart tomorrow morning. when i replaced the belt, the white spacer on the motor was GUNKED. it was literally enitrely black. I scrubbed it cleaned and im thinking by doing that it might be slipping across the spacer? im 98% certain i installed the belt correctly but..im def going to take a dive into the machine tomorrow.

i began to wonder if it might have had something to do upon reassembly? maybe somethings off center? thanks again.
 
hiya, i bought two motors, with shipping came out to about 17 bucks, theyre 7 bucks each. really fast shipping! plugged in and worked great. Exact same Mabuchi brand motors. the motor number is EG530KD-2B. which could be found here...

http://www.audiolabga.com/noimage_1.html


as for the belt, i purchased one from tascam about three weeks ago. Dealt w really shitty service getting it. Also, there is a site where you can order replacement belts for the machine i just seemed to have misplaced the link. ill post when i find it.
 
moogmymellotron said:
hiya, i bought two motors, with shipping came out to about 17 bucks, theyre 7 bucks each. really fast shipping! plugged in and worked great. Exact same Mabuchi brand motors. the motor number is EG530KD-2B. which could be found here...

http://www.audiolabga.com/noimage_1.html


as for the belt, i purchased one from tascam about three weeks ago. Dealt w really shitty service getting it. Also, there is a site where you can order replacement belts for the machine i just seemed to have misplaced the link. ill post when i find it.
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Cool. Glad to hear it is running well. Hey, that motor was cheaper than the belt! Not bad. Thanks for the link.
 
cjacek said:
heat... 688 still going good, at a steady pace?
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Yes indeed :)! So far, so good. I have more confidence in it now than I have in a while...and at least I know I can probably get a motor if need be. Having a remote for it now is so cool. Makes punching in much easier.
 
moogmymellotron said:
heat

ive been trying to track a remote down as well. how much did you find yours for? thanks
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Hey,

$39.95 + $5.50 shipping on ebay. NIB too! I had been checking almost daily for months and nabbed this one about 15 minutes after it appeared. I don't know if that's a fair price or not, but it seemed good to me. I know they pop up there from time to time. Not sure where this one was sitting for the last 15 years, but I'm glad the dude decided to part with it.
 
Heat and co.

So with some great help from Heatmiser I too replaced the belt on one of my tascams!:)

Unfortunately, it didn't cure another problem I have since a couple of weeks. Whenever I put the 688 on I can hear a loud humming/grinding noise which I think comes from the capstan. It's gone when I press play, but when I press stop rewind or forward it's back. It doesn't seem to affect any of the controls nor the speed, but it's annoying as hell. When I turn the 688 upside down/or press the capstan down a little, the sound dissapears. I'm afraid this problem is going to be a bit more tricky than changing the belt. Anyone??? :confused:

BTW, my old belt was still quite firm, but there was some melted rubber on both wheels
 
Bobby Darko said:
Heat and co.

So with some great help from Heatmiser I too replaced the belt on one of my tascams!:)

Unfortunately, it didn't cure another problem I have since a couple of weeks. Whenever I put the 688 on I can hear a loud humming/grinding noise which I think comes from the capstan. It's gone when I press play, but when I press stop rewind or forward it's back. It doesn't seem to affect any of the controls nor the speed, but it's annoying as hell. When I turn the 688 upside down/or press the capstan down a little, the sound dissapears. I'm afraid this problem is going to be a bit more tricky than changing the belt. Anyone??? :confused:

BTW, my old belt was still quite firm, but there was some melted rubber on both wheels
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How loud Hermann? Like a horrible mechanical "I'm about to fail" grinding noise or an annoying buzzing hum? One of my mixers developed a buzzing hum after a few years when it warmed up that I traced down to the transformer buzzing and rattling the metalwork that surrounded it. Pressing down on the metalwork above the transformer stopped it even though the transformer was still vibrating. Something to do with laminated transformers & magnetic fields I do believe. A bit of Blue Tac in the right place stopped it. Damned annoying though.

Dunno if this helps you track it down.

Buzzing Audio Transformers

:)
 
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hi guys, im in a similar ship. i just acquired another 688 ( i did manage to fix the first, running smoooth) this particular unit was missin one of the erase heads nuts and im assuming is completely out of alignment since tracks 1 3 and 4 do not erase, ODD thing is that they will if i enable all 8 tracks to erase.

has anyone ever had to align the heads? anyone bias the unit before? i have the service manual and im currently trying to research a way where i can align the heads since i lack the necessary jig that is required to follow the manual. anyhelp would be appreciated!

thanks
 
Bobby Darko said:
Heat and co.

So with some great help from Heatmiser I too replaced the belt on one of my tascams!:)

Unfortunately, it didn't cure another problem I have since a couple of weeks. Whenever I put the 688 on I can hear a loud humming/grinding noise which I think comes from the capstan. It's gone when I press play, but when I press stop rewind or forward it's back. It doesn't seem to affect any of the controls nor the speed, but it's annoying as hell. When I turn the 688 upside down/or press the capstan down a little, the sound dissapears. I'm afraid this problem is going to be a bit more tricky than changing the belt. Anyone??? :confused:

BTW, my old belt was still quite firm, but there was some melted rubber on both wheels
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Hey - just saw this...glad the belt change went ok. If you had residue on the pulley, then it was probably time for that old belt to go.

Sorry to say that your newer issue is beyond me. You've got some suggestions so far and I hope you are able to figure it out. Man, this thread makes these machines out to be a huge PITA, but they are worth it :).
 
I left the unit upside down for one night and in the morning it was fine :confused: I hope this will last...Anyway, changing the belt really made it better! I can feel the transport reacting a lot tighter when I push record,play etc. Two machines to go and I'll be happy.

On a side note: I can hear some frizzle/sizzle going on in the background when I put on my headphones (this is not a grounding issue). This is not affecting the recordings yet as far as I can hear, but I guess I need to do some recapping in the near future. Anyone done this to the 688??
 
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