Tascam 122 mkii at hyperspeed. Capstan caps already replaced. Other issues too

[jase_h]

I bought a 122 mkii which runs at hyperspeed. The motor is loud and the counter flies by. The most common remedy for this issue is to replace the electrolytic capacitors on the capstan motor board, which I've done

I seem to have created 2 additional problems during my attempt to fix it:

1) the eject button "bottoms out" far before it's able to push the door lever. The lever can be actuated manually to open the door (by reaching into the machine), but the button hits a piece of metal before it can push in the door lever
2) it's not possible to close the door with a tape in it. The heads seem to be stuck in the "up" position and thus the cassette hits the heads when trying to close the door

 

[SkywaveTDR]

That is why I say to people that you can not fix only one part but must service the entire machine which also included resoldering many bad joints on control and audio boards. There are also the cheap trimmer they used that crack and need to be replaced. I use Bourns Cermet trimmers that have a base of ceramic and this will not decay over time like Phenolic or plastic does. Now you need to do the rest of the deck which is the mechanical tear down.

 

[jase_h]

By "trimmer" are you referring to the trimpots? Is there one/some in particular that's troublesome, or are they generally bad? A full service is ideal, but doesn't make a heap of sense economically

 

[SkywaveTDR]

Trimmers on the top of the control board for the Mk II. People are getting them restored here all the time and there is a waiting line for those I do and sell. There is a alignment procedure but they usually do not get out of position unless the trimmers at the top get turned or damaged.

 

[SkywaveTDR]

So if the decks motor is still in high speed, does that mean full tilt which is to say the FG is lost or do you mean a 122 Mk II is going at 3.75 IPS? The motor was designed to work in other models like 238 and higher speed decks. There is a jumper that needs to be closed and one opened if they are set for 3.75 IPS which the 122 do not have. If it is going full tilt then that means that no FG is getting received either from bad mechanical settings or that there are foil patterns open due to leaked Electrolyte from bad SMD caps. I sometimes have to solder thin wire over traces that are dark and compromised. This then establishes a redundant path and then it does not matter if at some later time the foil pattern becomes open.