The later reel to reel decks from Teac were called the X series. Both 7 and 10.5 decks were made, in single and auto reverse models. All are excellent performers, but do have common issues at this point.
7” models (X-3, X-7, X-300, etc)
Generally speaking, these decks are fairly reliable, and other than the pinch rollers and belts turning to goo, due to the rubber that Teac used, a good basic maintenance is hopefully all that is required. Still, there are other common failures in these decks:
Motors- Many later Teac decks used a 24 volt DC motor, which is the same motor (but different speed control board) as the Pioneer RT-901 and RT-909. These are simple servo controlled DC motors that use carbon brushes, and it’s not uncommon for these motors to fail once high hours have been put on them. Without pulling the motor apart, it’s impossible to tell in what condition the motor is, and the price of used motors has skyrocketed on ebay, usually around $250-400 USD.
Trimpots on the main PC board. I’ve had several decks in that had a number of bad trimpots on the main PC board. There’s no reason for these to fail, and the decks that came in showed no signs of internal corrosion, indicating that they were stored in a damp environment. Still, if one trimpot is intermittent when adjusting it, then there’s a good chance that others will follow suit, and all of the trimpots on the main PC board need to be replaced, and then the entire deck needs to be calibrated.
10” models (X-1000, X-2000)
Teac made the 10” X series in several different models, including auto reverse models and a ‘pro’ model that is 15 IPS and ½ track, although most of the decks sold were the auto reverse X-1000R and X-2000R ones.
When working, these are excellent decks, however they are more complex than the 7” models, and there’s more to go wrong with them. They are dual pinch roller models, and both need to be changed if they are originals.
In addition, the pinch roller bearings tend to seize up due to the old grease hardening up, and the old grease needs to be taken out and new lubricant applied. Even if the pinch roller bearings are moving freely, it’s a good idea to service them regardless.
Motors- the 10” Teac X series uses the same motors as the 7” models, and they are just as prone to fail as any other model.
Belts- a special warning regarding the belts used in the 10” X series.. the belt MUST be the exact OEM Teac belt, due to the width and thickness of the belt. Most ebay sellers sell generic belts from a cross-reference book, and that book is incorrect! The generic belts available are either too wide or too thick, causing undue stress on the motor, and cause the tape to drop away from the heads in either the forward or reverse direction (or both).
Logic/Transport board problems. There are custom chips used in the 10” X series made only by Teac specific to these models, and these are hard to find. Failure of the chips is rare, but I have seen decks where both chips failed simultaneously. A proper diagnosis is required here before changing the expensive chips., as failure in other areas of the deck can cause the transport to malfunction, or not to operate completely.
Tape tension circuit- this is a circuit not used in the 7” models of the Teac X series, and there are 4 trimpots that adjust the tape tension within the deck. These trimpots can drift in value, causing improper transport and tape operation, or it can cause premature head wear if the tape tension is excessive. While changing the trimpots isn’t difficult, the calibration after replacement requires a tentelometer tool, which is difficult to find. ADJUSTING THE TRIMPOTS AT RANDOM CAN CAUSE DAMAGE TO THE DECK!
Teac 3X , 4x and 5X series (semi pro models)
Teac made a number of semi pro ½ track high speed decks, in 2 track, 4 track and 8 track models (32, 34, and 38 respectively), and many were sold to home recording studios in the late 1970s and 1980s. Outside of the belt, pinch roller and motor problems (they use the same 24 volt motor as the X series), the 3X models have their own unique set of problems.
The more deluxe decks with direct drive capstan motors and a better tape handling transport, are the 4X and 5X series. These also had XLR input and output connectors as an option for more pro use.
Motherboard solder joints.- This is a rampant problem in all of these series, so much so that no deck leaves the shop here without a complete resoldering of the motherboard. Teac used double sided PC boards in these decks, with automated wave soldering done. The feed-through connections between the top and bottom PC board traces crack over time due to the expansion and contraction of the motherboard, causing dead channels, and intermittent audio. Each channel has about 20 solder connections that need to be resoldered on both the top and the bottom of the motherboard. To do the job right, the entire audio card cage needs to be removed from the deck, and that’s labor intensive.
Bad record/play relays. There are two relays per audio channel that switch the playback and record heads depending on whether you’re recording or monitoring a prerecorded audio channel. Over time, the relay contacts corrode and cause distortion or intermittent audio. While these relays don’t fail as often as the motherboard solder connections, if one relay is found to be bad, I change all of them on all channels. Different models used different relays, with all of the original relay part numbers being long discontinued, so some cross-referencing needs to be done to ensure you get the correct relay to replace the bad ones with.