Tascam 122 MKII Problem

[MercuryFire]

Hi,

I just purchased a second hand Tascam 122 MKII Tape unit. The guy selling it sold it for a dirt cheap price because it has a problem with Play/FF function. I can rewind a tape with no issue, but pressing play does nothing. When I press FF it makes a slight noise for about few seconds (like it wants to move) but also does nothing. Does anybody know what is the issue and can it be fixed? And if so, what is required?

I appreciate your help.

MF

 

[SkywaveTDR]

It would be an educated guess but I suspect the cam belt has stretched. I am using cam belts that can not stretch anymore so once I put the belt in they are fixed for good. I also oil the cam motor bearing, clean and regrease the mechanism and spray the feedback pot. I also have had the joint made by 3D printing so that if you have a broken one we have that part that for years no one had available. The 3D printed part is much more robust. This is the part that goes on the feedback pot and is often broken by people that take them off the pot shaft. It has a nylon fork section that once broken can not be fixed. Due to construction of the Mk II with the control PCB on the rear of the Transport block it is not the easiest unit to work on but I have successfully fixed many of them. The capstan motor has the same issue in all the MK models. The Mk II has a 4 terminal pot in the pitch control board that fails due to falling apart inside and for those that fix these small pots I am told this is one that can not be fixed. So in the many hours it took to come up with a solution I found a great plastic conductor pot and a series of mods both electrical and mechanical that have to be done but the result is a much more long lasting and strong part assembly. The fast wind system is driven by a driver chip and reel motor and reel tables. It often works independent of the cam system so it leads some people to think all is OK but it really is not. It is just somewhat independent.

 

[MercuryFire]

Thanks for your reply SkywaveTDR, but for someone like me who has no idea when it comes technical terms nor knows what those parts are, can you please direct me to a site that 1) shows the parts and what you mean and 2) where can I buy these parts in order to get them fixed? Is it a DIY job or do I need a qualified repairer?

 

[SkywaveTDR]

I am not aware of a web site that shows you parts and what they are as all decks are different inside. The service manual has a parts list that tells you the name of the parts- if you are going to work on decks you are best advised to get the manual that you are working with. Hi Fi Engine may be free but can have some of the worst scanned documents that will just add complexity to the repair. I get my manuals in paper from Stereomanuals.com where real manuals are had in great reproduction.
Some belts can be ordered at Consolidated Electronics if you know the size. He does not know what belt goes on what model.
The gear C part is available on E bay or from me. Ams Oil can be bought at any Automotive store or I have even seen it at Ace Hardware in the motor oil section. The oil I have is 0 W30.
Lubriplate grease 105 is had from hardware or from online. Stores always want to make profit on what they sell so the best deals are online. A 10oz tube can be as low as $7.00.
Denatured alcohol is had at Home Depot or any Paint store. It can be had for as little as about $15/Gal can. Smaller cans are usually there too.
If you are a DIY type repair person you will need to learn the terms for the parts such as what a capstan shaft is and a Flywheel or a motor pulley. Some You tube people call them the wrong terms indicating right away that they are not smart enough to even find out what the part is actually called- not everything is a spindle.
There are not that many parts in a cassette deck to make it hard to understand what they are. Just as on Open Reel decks the tape does on a reel table. This term is also the term used in the cassette deck as well as Capstan Shaft, Pinch Roller, Brakes, and so on. Some better decks have reel motor as they are direct drive- these were the expensive one. Most decks make use of a reel drive from a central motor called the reel drive motor. This energy is transferred to the reel table by a gear in some cases or a Idler that has a rubber tire on it. Tire being made of rubber sometimes crack and fall off. The reel drive is used both is winding tapes as well as providing take up when in play mode. If take up stops or the reel motor has a dead spot on the commutator then the motor usually needs to be replaced. A crack Tire can also give irregular reel drive in play but is much easier to resolve than a new motor. In tape deck repair one has to look and see what is really happening rather than jump to conclusion with no proof. Repair is nothing more than observing what is wrong and going after the cause of it. Once that part is fixed or replaced then the deck works again. Many people change pinch rollers on decks all the time- this is a waste and most pinch roller can be cleaned and reconditioned with Naphtha. Some people are Part changers not Technicians and so they waste a lot of time changing parts to find out they guessed wrong again.

 

[SkywaveTDR]

As to your second question, the deck like the 122 Mk II or III have SMD surface mount devices on them. These are cheap garbage parts that are only designed to last a short period of time. Much shorter than the same parts in through hole design. While an Electrolytic capacitor might last up to 50 years, there SMD parts fail in a much shorter time. I doubt that they are good for 10 years. I dislike them as there is no history that they are anything other than parts put on throw away cards. In the case of the capstan servo with coils attached there is no new part and so you need to fix it. This requires the talent of removing the SMD parts without pulling up the foils on the circuit board. It can be done and I did one the other day with no damage. There are some things such as working with soldering tools and solder suckers and solder wick that you will need to develop a talent to use. The use of a solder gun is not applicable in tape decks. The solder station with a small fine tip usually is and I use the Weller Brand station and they have digital readout models now but I hesitate to buy a product with LCD readout as they usually limit it's life in that the displays fail all the time. LED readouts are much more reliable and no readout is even better- no one looks at them beyond setting anyway. In buying equipment to do this work there are many deals on E bay but then there are also wrecked equipment thieves are trying to sell- usually the cosmetic condition of a product can give idea of the care that was given to the unit. Until you get good at doing all the required work on a deck it is best handled by a good technician who has all that he needs to do the correct job. Your deck will work a lot better after a proper servicing in comparison to a minimal servicing. It only needs a belt is a line I hear taking in a unit- if it only needs a belt then go change it I tell them. What they mean is they want it fixed for cheap- we don't work for cheap anymore- most shops are $100/Hr and some are even more.

 

[MercuryFire]

Thanks Skywave. I am in Australia, so will need to search for all those things ad find a proper Tascam servicer here.

 

[SkywaveTDR]

I wish you would have said so earlier. I will do all I can to help you but I just found out the flat rate small box went to $8.30 and so maybe the First class postage may have also gone up. The gear C in that case would be cheaper from the E bay seller as he has E bay shipping discount while I have to pay sometimes $21.00 to get a box to Australia.

 

[MercuryFire]

Ok, will look for these parts on Ebay.

 

[KevinW]

I also have a 122MKii that I am working on, previously owned by my late father who purchased it new in 1987. The loading belt had dissolved into black goo, and I purchased a new one from Bob at vintage audio. It now operates well except for the pitch control. I read with interest your comments on the pot that becomes open. Well, that is exactly what has happened to this one. It appears that there is no easy replacement of this pot. I have searched ebay and found a seller in Spain that appears to have parted out 2 machines but has not replied regarding the pitch control board. If anyone reading this post has a recommendation for replacing this pot, I would greatly appreciate it.

 

[SkywaveTDR]

Forget old pitch control boards as the same old put that was cheaply made will break anytime soon. I would not put that cheap stuff in there. I do put a much better plastic conductor parts that requires an extension but put on it as well as the circuit mod to allow this pot to work like the old one. The old one has a 40% tap and I think that this is used in some way but not sure why. I have had to come up with mods that get the good linear pot to work. This is not a simple part replacement and I know it is unfortunate but that this was caused a long time ago when they did not use a good part in the first place. This pot is said to be able to do 1,000,000 rotations. It does not get dirty either.

To test motors a 54K resistor can be put in that will allow the deck to run at regular speed. I test the motors when I have to fix them that way independent of the Pitch control board.

 

[KevinW]

Just a quick update. I actually opened the pot by carefully drilling the rivet tips off. With the use of a jewelers magnifying visor, I discovered what actually happens to these pots. The wiper is a tiny metal piece that is held in place by a notch on an inner wheel. I suspect that if the unit is left for an extended period, (in this case more than 20 years), one initial turn can dislodge this piece from its position and then contact is broken. In any event, I was able to return it to it's position. I also applied a tiny bit of crazy glue, applied using a pin to this wiper. It now works perfectly. I was staring at this pot on my desk for 2 months and thought what do I have to loose? I reassembled it with a bit of crazy glue on the rivets as I inserted them. Up and running again! It is a really nice unit.

 

[-mjk-]

Nice work, @KevinW!

 

[SkywaveTDR]

Crazy glue is not a substance that will hold for long. Every time I see it it is on a failed glue job. It was made for medical purpose as in skin.
Epoxy is a much better long term solution. Well as long as you are happy. When I see parts that are like these costing maybe a dime, I say that is not going back in. I use a 1 million rotation plastic conductor Linear pot.