Tascam midistudio 688 - no play, no record - belt changed - motor hot - need spare parts

[Ray Fite]

Hello to all,

I've got a problem with an old midistudio 688 - motor is getting hot

The midistudio can do fast foreward and backward. But there is no reaction when i press the "play-" or the "rec-button". "pause button" does work fine. The tonehead rolls to the tape. But then no play or record is possible.
The counter works when in fast-forward or in fast-backward-mode.
I changed the belt, because it was described as the first solution - and the old belt was really sloppy. First I hoped that that was the only reason for the malfunction. But it wasnt.

I checked the two switches that are used to control if a tape is in / the tape is secured to overwrite. These switches are working.

I checked a while during the device was open, and I realized, that the motor that turns the capstan is getting really hot. Now my questions:

Can it be that the motor is turning to slow - so that there is somewhere a speed-sensor that does not allow running the play function if the motor is to slow?

Does anybody know a place where I can buy a replacement motor?

Is it possible that just the Play and Rec Button switches are damaged?

Is there something else I should check to get the midistudio 688 to play?

Thanks in advance for your answers

Greetings
Ray

 

[Jack Saturn]

Sounds to me like the voltage regulator inside the motor has overheated. This is a very common with Tascam machines that use this particular motor. Since the motor spins whenever the machine is powered on, if the machine gets left in idle when not in use, the motor can prematurely burn out.

I run a business working on 4-track machines and have refurbished a great number of these motors. If you feel comfortable de-soldering it and removing it from the tape mechanism, I'd be glad to discuss working on it for you. Are you in the USA? -Jack

 

[Ray Fite]

Hi Jack,
thank you for your reply -I'm from Germany - so not just around the corner....- I found an old stock new motor - it arrived two days ago - Also I bought ten 2-Pin switches to exchange the Play,Rec FF REW Pause and Stop - Still five switches left - I used some contact cleaner for the tape-recognizing and rec-recognizing switches on top left side of the tape-drive.
Now the play and rec- function are working again. But due to the hot motor the tape runs too slow. So I'll have to change the motor - with the new one - Does anybody have some tips how to remove the small drive wheel from the old electric motor? I worry that I could damage the component.
Does anybody know if the hot motor/voltage regulator of the motor thats not working is due to a wrong voltage of the input-cables? I don't want to crush the new motor with too big voltages and get the same problem after some hours playing?


Greetings
Ray

 

[Jack Saturn]

Where did you manage to source a NOS motor for this machine? That's a true rarity!

You mention wanting to remove the "small drive wheel" from the capstan motor. Are you referring to the plastic pulley on the shaft? If so, it's safe to use a plastic pry tool or flathead screwdriver to gently nudge it off. This won't do damage to the motor, as the shaft is held in place internally by two bearings.

The voltage regulator overheating is not due to the external wiring or anything else inside the machine. As I mentioned, it is due to overuse, likely from the machine being left turned on for extended periods of time — perhaps by a previous owner? Provided the new motor you sourced is correct and in good condition, it is safe to install it. (And always be sure to power the machine off when not using it!)

 

[sweetbeats]

No need to desolder anything…the capstan motor in the 688 is mounted with screws to the transport chassis.

 

[Ray Fite]

I found the motor here - I think this was big luck....

https://reverb.com/de/item/87249155-original-mabuchi-1600-3200-rpm-for-tascam-4-track-8-track-recorders

But they had only one...and the sending to Germany cost 20€ ! - But what can I say....


Today I exchanged the motor. It is fixed with 3 screws but I had to desolder the cables of the old one and resolder it to the new. And ... the machine is back -It plays tapes, that are recorded with my old tascam 488, but I don't manage to record to channels 5,6,7,8 - Maybe I use the wrong settings - But on channels 1 to 4 I can record with a microphone. You can hear all 10 inputs thru the MONITOR-Button on headphones. I use SCENE 10 and I panned the 1,3,5,7,9 to odd and the 2,4,6,8,10 to even. The channel-switches for the channels 1 to 8 are blinking. You hear a louder humming the more channels you activate. But nothing is on tape 5,6,7,8 after recording. Do you have any tips? Is there a cable-bundle loose? - Yet I only opened the right side of the machine - Any Ideas?

 

[Jack Saturn]

Checked out the Reverb listing — the motor you got is described as "used," which is not rare, but the one you got looks to be in good external condition. So glad to hear the machine is back up and running!

As for troubleshooting recording on channels 5-8, the Tascam 688 is overcomplicated that the problem could be in a number of different places. You could have bad capacitors or broken solder joints on particular input channels, or there may be quad switches elsewhere in the machine that have gone bad.

I rarely use the preprogrammed scenes when I test a 688, so I'm not familiar with scene 10 specifically. In order to troubleshoot, you should start out by manually assigning all tracks to input Mic signal, test all of these, then move on to Line, etc. Once you've made a complete list of all the scenarios in which signal isn't passing, you can start to narrow it down.

 

[sweetbeats]

Apologies for my short-sighted comment about desoldering…I was thinking the earlier guidance was the motor itself needed to be desoldered, like a motor with embedded contacts that were both electrical connections and mechanical mounting. Yes, as noted, the wiring is solder connections, the motor is fastened by screws.

 

[Ray Fite]

Hi jack, thank you for your tip to use an own scene. I copied the SCENE 10 to an empty SCENE 15 and did all the settings new (switched on the switch-field "Main to Groups" in a diagonal way 1->Grp1; 2->Grp2 and so on) and what is important to put the inputs new on the map. So you have to choose the inputs and set these inputs (e.g. I wanted to record through a microphone -so I choose MIC)- And now that's important even if the dots in the matrix are in the right place, you have to press the channel-number twice to first delete the input and then to reset the input again. After this procedure all my channels worked fine.
Now my Tascam 688 works
Hope this helps someone else too.

Greetings Ray

 

[sweetbeats]

The “Scene Display Panel”, while a powerful part of the 644/688 functionality, can also be confusing for some. I created a YouTube video offering guidance on the Scene Display Panel some years ago, which may also, in addition to the information above, may be useful:

 

[Ray Fite]

Some problems still exist.
- the input 9 is way too silent - The input is 10dB lower than the other inputs. You can't see a meter-peak although the mic-trim-poti is set to full
- the left headphone-jack works only on the left channel - right channel is missing.
- the switch of the dbx 1-4 on the back is broken - you can't change the value to stop dbx -
-the input peaks of the line channels 1-10 are different. When I use the same input source all show different peak values.
Channel 1 0 dB
Channel 2 +2 dB
Channel 3 +6 dB
Channel 4 0 dB
Channel 5 -2 dB
Channel 6 +1 dB
Channel 7 +2dB
Channel 8 +2 dB
Channel 9 -10 dB
Channel 10 0 dB
Does anybody know how to fix this?

Greetings Ray