Tascam midistudio 644 or 688 service manual

[rohmal]

Dear Sir,
If any one having reference to above service manual, please can you tell me the variable pot resister part No.s on the cassette record/playback PCB marked TEAC R/P PCB (starting with R and following with 3 digits after on the circuit) referring to adjust RECORD volume and PLAY BACK volume. If it is 644 the PCB has symmetrical 4 channels on the board markedTRAK-1 to TRAK-4 where your recording/playback head and erasing head wires will lead to and if it is 688 there are 8 channels on the PCB starting with TRAK-1 to TRAK-8 with both your heads wiring leading to it. If some one with the schematics can let me have a scan of a single complete channel lets say TRAK-1 in Adobe PDF file format( of the cassette tape record/play back amp section) I'll be able to solve my problem. A big thanks if anybody can provide the required so I can put my unit back to work as a paper copy is really expensive and cost only a little less than the units bought price at my end of the world.. If any one can make a readable scan copy in A4 paper parts of the TEAC R/P PCB circit of a 644 or 688 schematic in pdf format and email to me I can pay you a reasonable fee by PayPal to cover your effort.
Thanks.

 

[John Mackenzie]

I am awaiting delivery of service manual from USA. Expensive !! When I get it, I shall attempt to send you details you need.
John

 

[rohmal]

Thank You Dear Sir John,
I'll help you to repair your unit. Do not hesitate to ask any help. I am a retired Electrical Engineer. I can give you the leads where to check, what to check and how to check. Today I dismantled my unit and found really nothing much wrong as you said it was not really in record mode. I set the inputs to the channels the way I required and started recording. It all happens well and do record also with less volume when I play back after(Than the levels I usually set at recording). I have to see if I can bring the record level up or to see if the transistors/ IC's on that board are less efficient or any voltage defective to them as all 4 channel inputs fed with reasonable volume levels seem to be low on play back from tape. A pre-recorded tape from other source plays nicely with good volume on the unit, so it has to be a recording amp/oscillator problem common.

 

[John Mackenzie]

Hi Rohmal. I know you are a competent engineer. I have also worked as an AV TEC and computer TEC for most of my life, now retired. Silly question , but have you cleaned and demagnetised the heads? Levels from tape need to be set as you wish, and are not the same as you see when montoring recording. It is a complicated business , but worth the effort to keep experimenting. Thank you for all your offers of help. I can hardly wait for my service manual to arrive, just to see if I still have the skills needed !!

 

[rohmal]

Dear Sir John, It is wonder full news that you will get a spare unit of same. If you receive it listen to it's history from the owner and we can decide what to do. Most probably you can interchange the boards and see for a quick repair. My one is recording now but input level I set want be the out put I get back. It is low when compared but listenable. I'll write to You when I get back home. I do vintage Hi-Fi repairs as a hobby and a side income. I am retired and is 58 years old now. My wife is a medicinal doctor and is still working for the government health service. I have a daughter of 24 years attending to the university now on final year doing soft ware engineering. I have a small place near the university of my own and I stay the week days with my daughter there and go home at the weeks end. I have a collection of Hi-Fi stereos including old reel tape recorders, Cassette decks, amplifiers, equalizers, mixers, microphones and junk I use to listen/repair. I kill my time over them. I live off 25km away from Colombo in Sri Lanka. So write any thing you want to me. You can reach me at rohanamallawa@gmail.com.
I,ll send some photos of my unit when I go home in the evening

 

[John Mackenzie]

Hello rohmal. I am still waiting to hear back from the man who offered me the 688. He actually lives in London, but the unit is in his fathers garage, only about 1 hours drive away from me. Just trying to arrange a time for collection. I live in Scotland, in the Scottish Borders region. I am also a retired AV/Computer technician, age 67, and have the same interests as you with repairing old Hifi things. i have always been a musician and home recording fanatic. I have a daughter too, who is a Lawyer, here in Scotland, and I have a son who is a mechanical engineer and lives in Malaysia. I am looking forward to conversations with you in the future. I did notice, when examining the circuit boards in the 688, that there was a potentiometer marked "REC LEVEL" in there. I can't remember if there was only one of these, or if each channel had a separate control. I will check later, as I am just going out to feed our horses.
Thanks again, you have been excellent help to me.

 

[bgencarelle]

I would like to say, bump!

 

[John Hodge]

Tagging onto this to see if I can get some help on my 644 Midistudio. I finally acquired a new capstan motor and am in the process of getting this back together, but I have a small part that I cannot determine where it goes. I have been informed it may be a type of leaf spring to give some resistance to the capstan metal flywheel that the belt drives. Here is the pic, so if you can tell me where it goes and orientation I would be appreciative. John

 

[bgencarelle]

I will bump this as well.

 

[John Hodge]

I am awaiting delivery of service manual from USA. Expensive !! When I get it, I shall attempt to send you details you need.
John

John, did you get your 644 manual?

 

[SkywaveTDR]

Regardless of if you have the manual or not, you can not do the job unless you have the high speed play tapes make by Teac to set the levels. I understand it was a proprietary format so not a lot of other people have these tapes available. These tapes are designated MXT-###.

 

[Tracy Ellenbecker]

the tension wing goes inside the flywheel, wings to inside surface. There is a small white washer that goes on next to keep the tension wing off the bushing surface.

I just took mine apart to replace the belt. I do have a question as to which pot adjust overall tape tension. Looks like a R15 and a R22 on the mech cont pcb

 

[Laszlo]

Regardless of if you have the manual or not, you can not do the job unless you have the high speed play tapes make by Teac to set the levels. I understand it was a proprietary format so not a lot of other people have these tapes available. These tapes are designated MXT-###.

Just found a list of TEAC test tapes: http://www.gennlab.com/teac_cass.html
It includes the original numbering..

 

[SkywaveTDR]

This is great. I have stored it away. Any idea of Teac YTT reel tape numbers?

 

[SkywaveTDR]

The spring part above is found in decks to allow a push back of the flywheel to the rear so that it meets with the thrust plate bearing. There should be a small amount of movement but this spring will generally keep the flywheel and capstan shaft from moving front to back as small as it is. They are on Pioneer RT909 decks too as well as other decks of the newer designs.

 

[Francisco Muñoz]

Any one have the 688 service manual?

 

[Clockgate]

I have a copy. Send me your email address and I will forward it to you.

 

[Max Bley]

@Clockgate could I grab that off you too?