Midistudio 688 problems

andrej]

New member
hi! i got this machine not long ago... it's great and i'm really into it, but, it has a not-so-slight problem: it stops all the time! when i press play, it plays for a couple of seconds and stops. i press play again and the same thing happens. after several repeats (an pressing the transport buttons is annoying, because the buttons are somewhat old and hard to press), then it plays okay for some time. this happens especially when the tape is near the beginning or the end. the same goes for rewind, forward and record. it resets the counter when it stops, just like it does when it reaches the beginning while rewinding, this might be a clue about what's happening, possibly a transport problem. the battery is certainly not the problem, as i changed it and memory works.

now, tips for you about the battery.

the machine is complicated, i opened it up. you need to be extra careful. you can't remove the battery from it's holder, nor can you find a suitable battery. it's 3v, lithium (not lithium-ion! it's not rechargeable) big and kinda spot-welded to it's holder. so, i removed it and it's holder by desoldering it and replaced it with a battery holder from a computer motherboard (cmos maintenance). the pin distance is suitable, you just need to bend one pin a LITTLE. the original one has 3 pins, while the computer one has 2, so you have to connect 2 of the pin terminals together on the copper side of the pcb. with a wire a normal cmos maintenance battery (found in most pc-s) is also lithium, 3v and suits the machine perfectly. it's also commonly available, cheap, and easily changeable because of the new socket you installed (though you'll only change it once a decade), so it's perfect. don't forget to backup your scenes to cassette before changing the battery, as disconnecting it will erase them.

i tried to help, so, can anyone help me?
 
Haven't worked on one of those for a while, but if memory serves, theres a take up reel sensor that works off the tape counter. This is to keep the machine from eating tape. In other words, if the take up reel isn't working, or if the machine THINKS it isn't working--STOP. Most of the time it's just the belt going from the mechanism to the tape counter. You might want to change any/all belts if you're going to get into the machine. I would "pop the hood" and make sure there are no broken or sloppy/worn belts. Good Luck!
 
that helped a lot! i'll try and see this weekend, since it's a bi*ch to disassemble.

i've never replaced belts. are they standard, or i need to find tascam ones? how to find 'em and the degausser, cleaning packs, etc?
 
Many electronic parts places carry belts. Not sure about your area. If you can get the old ones out in one piece, they can measure them and get you replacements. Sometimes they come out looking like bubble gum if they're really bad. If you go this route, keep in mind that they are probably stretched out a little so get them slightly smaller than what they measure. If you can't find them locally, just call Tascam or a Tascam service center and get the belt kit for your unit. As far as cleaning, use head cleaner or isopropyl alcohol on the heads and capstans. Use rubber cleaner/rejuvinator (again found at electronics stores) on pinch roller/belts. That's another thing to check also. Make sure your pinch roller(s) are not shiny and hard. They should look and feel like rubber. If they more resemble plastic, you should replace them if they can't be cleaned/rejuvinated with rubber cleaner. Normally, degaussing is not as big of a deal as cleaning, but if you find it necessary, you should be able to get a degaussing wand at an electronics store also. They are getting tougher to find since the cassette has kind of gone by the wayside. Hope all this helps and good luck!
 
hi! i got this machine not long ago... it's great and i'm really into it, but, it has a not-so-slight problem: it stops all the time! when i press play, it plays for a couple of seconds and stops. i press play again and the same thing happens. after several repeats (an pressing the transport buttons is annoying, because the buttons are somewhat old and hard to press), then it plays okay for some time. this happens especially when the tape is near the beginning or the end. the same goes for rewind, forward and record. it resets the counter when it stops, just like it does when it reaches the beginning while rewinding, this might be a clue about what's happening, possibly a transport problem. the battery is certainly not the problem, as i changed it and memory works.

now, tips for you about the battery.

the machine is complicated, i opened it up. you need to be extra careful. you can't remove the battery from it's holder, nor can you find a suitable battery. it's 3v, lithium (not lithium-ion! it's not rechargeable) big and kinda spot-welded to it's holder. so, i removed it and it's holder by desoldering it and replaced it with a battery holder from a computer motherboard (cmos maintenance). the pin distance is suitable, you just need to bend one pin a LITTLE. the original one has 3 pins, while the computer one has 2, so you have to connect 2 of the pin terminals together on the copper side of the pcb. with a wire a normal cmos maintenance battery (found in most pc-s) is also lithium, 3v and suits the machine perfectly. it's also commonly available, cheap, and easily changeable because of the new socket you installed (though you'll only change it once a decade), so it's perfect. don't forget to backup your scenes to cassette before changing the battery, as disconnecting it will erase them.

i tried to help, so, can anyone help me?
As a Troubleshooter and audio repair technician who probably worked about a hundreds of those tascam 688 series,every time you open one of those units and make an attempt to fix it with out any success,you compromise the unit to a point that no technician will be able to repair it and give you a reasonable service fee.Belts are measured with special belt measuring tools,the unit is tested not by the consumer users manual but by using the units service information,its a very thick book by the way.frequencies have to be calibrated with signal generators and a scope and so forth.If you carefully look at the bottom of the unit it says "refer to qualified technician only".
Save the unit,save some money,Ship it to a qualified service technician.No other way around it.
 
hmm, got it to work. i taped a piece of folded paper onto the edge of the cassette - over the erasure window (it still had that tab for recording), and now that problem shows up rarely.

as for fixing it, i live in montenegro, and, i believe that the nearest tascam service center is in germany. it's at least 20 kilos in weight, so - shipping it to them and back and paying for the fix would probably be more expensive than the unit itself, or even a new digital 8-track...

you said you used to fix them, did you work for tascam? there are service and repair companies for audio stuff around here (serbia, montenegro, etc.), but i doubt they know anything about this machine more than i do. it's really not a common tape recorder, or even a common cassette multitrack. are there any other companies that fix them?

you said you had a service manual for it, do you still have it? can i get it from anywhere? i have considerable electronics knowledge, enough to follow it, (and i have access to some pro equipment and know how to use it). the belt size is probably written in the service manual, right?

i try to have a professional approach, and when i don't have the layout, i take pics while disassembling it.

and what if the only problem is the small belt to the counter? i also need to change the transport microswithches. what do you think, how much would that cost, including shipping? i'm a high school student, i don't make money often, and i don't make a lot...
 
would love to see those pics andrei. keep us posted. I have 2 688's as well and I will have to change the belts and battery sooner or later! good job on finding the manual.
 
hahahahaha. i'm late a bit, but i lost the pictures back then, when you asked. today i got to repairing my midistudio, so, i took some new ones. i'm replacing the transport tactile microswitches and I'm ordering a SERVICE manual to see if I can fix the stopping problem. 688 doesn't have a counter connected by a belt, but a phototransistor-based counter, i presume(there are some 4-pined transistors with an opening on the top). that's why i need the manual. the drive belt is okay.

as for changing the battery:

1: undo the screws on the sides
2: undo the screws on the bottom front hand-rest
3: remove the hand-rest
4: remove the little aluminum thingies (under the hand-rest) that hold the sides
5: remove the sides
6: unscrew the right panel (with the cassette mechanism and digital control and displays): the screws are on the bottom, the right and there are 2 screws inside the cassette compartment
7: remove the panel by pulling it towards you and then up
8: disconnect the cables connected to the panel. use a camera or a camcorder to remember the layout
9: the battery is on the circuit board side of the panel. to unsolder it and replace it with a battery retainer from a motherboard, you need to remove its daughter-board. consult the pics.
10: solder according to the pics and put it back together. watch the polarity

DSCN2043-1.jpg


DSCN2046.jpg
 
tascam 688

i have one of these and recently figured out how to use it, however the meters at the top do not work at all (the dB readings). Is this my lack of knowledge on using the 8 track or is there something wrong with it? I was told it was in good working order so i hope that there is nothing wrong with it. thanks
 
Tascam 688

@andrej] that's a sweet machine you've got there. I wonder if you found it on ebay, if so, how much you paid for it (plz, tell us how you got it anyway)?
I'm hopping to get my hands on one of those (there's currently one on eBay Germany going for 89€, but it says it has a defective recording head, which is IMHO a hard-to-find item, so I'll keep looking for a working one).
 
i got it from a guy on a serbian musical forum for 350eur. they are EXTREMELY rare around here. forget about that one with the defective head.
 
Hey, Andrej: I am new, and have a 688 that was in my closet since 2002, and I pulled it out last week. Through googling I found your thread and another on replacing the belts. I just wanted to thank you for the photo/post. It was a pain, and I broke a ground wire in the process, and I am no circuit board solderer, but I got the battery holder in, crossed the two connections on the board, and it seems to work fine, thanks to your pics. Between the two posts, yours and Heatmizers, I easily saved $3-400 in repairs and parts, and got it done in two days. Thanks again. M
 
i have one of these and recently figured out how to use it, however the meters at the top do not work at all (the dB readings). Is this my lack of knowledge on using the 8 track or is there something wrong with it? I was told it was in good working order so i hope that there is nothing wrong with it. thanks

Get an owners manual, it will help you figure out how to get the meters to work, or if they really are busted.
Select Scene 12, push recall, and throw in an old cassette tape and see if anything shows up in Groups 1/2
 
Thanks for good advice.

hi! i got this machine not long ago... it's great and i'm really into it, but, it has a not-so-slight problem: it stops all the time! when i press play, it plays for a couple of seconds and stops. i press play again and the same thing happens. after several repeats (an pressing the transport buttons is annoying, because the buttons are somewhat old and hard to press), then it plays okay for some time. this happens especially when the tape is near the beginning or the end. the same goes for rewind, forward and record. it resets the counter when it stops, just like it does when it reaches the beginning while rewinding, this might be a clue about what's happening, possibly a transport problem. the battery is certainly not the problem, as i changed it and memory works.

now, tips for you about the battery.

the machine is complicated, i opened it up. you need to be extra careful. you can't remove the battery from it's holder, nor can you find a suitable battery. it's 3v, lithium (not lithium-ion! it's not rechargeable) big and kinda spot-welded to it's holder. so, i removed it and it's holder by desoldering it and replaced it with a battery holder from a computer motherboard (cmos maintenance). the pin distance is suitable, you just need to bend one pin a LITTLE. the original one has 3 pins, while the computer one has 2, so you have to connect 2 of the pin terminals together on the copper side of the pcb. with a wire a normal cmos maintenance battery (found in most pc-s) is also lithium, 3v and suits the machine perfectly. it's also commonly available, cheap, and easily changeable because of the new socket you installed (though you'll only change it once a decade), so it's perfect. don't forget to backup your scenes to cassette before changing the battery, as disconnecting it will erase them.

i tried to help, so, can anyone help me?



This is good info about battery. Thank you. luckily I did not need to replace mine after testing.
 
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