Tandberg 420 issues
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tapetech
Repair Professional
"Rolling levels" and diminished highs is tape skew and low "inter-capstan tension". Tape skew is the tape moving side to side, exiting the proper tape path.
It's a common defect in the 300/400 series. Make sure the capstan shafts are spotlessly clean. If so, then it's time for major servicing:
-check that the head carriage moves freely (by hand). Dried grease is the problem.
-new belts and new pinch rollers will likely be needed.
-see if the counter belt is driven off the take-up hub or supply hub. If take-up, then a new different belt needs to be installed with it attached to the supply hub. This increases back-tension.
-clean/lube the capstan bearings (if worn out, then the deck is dumpster fodder)
Best for a pro shop to do this work. The transport should be aligned with an M300 gauge for best performance. Aligning the heads and electronics with test tapes will be needed as well.
Marrs Comunications can supply the belts. Terrysrubberrollers.com can put new rubber on the pinch rollers.
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It's a common defect in the 300/400 series. Make sure the capstan shafts are spotlessly clean. If so, then it's time for major servicing:
-check that the head carriage moves freely (by hand). Dried grease is the problem.
-new belts and new pinch rollers will likely be needed.
-see if the counter belt is driven off the take-up hub or supply hub. If take-up, then a new different belt needs to be installed with it attached to the supply hub. This increases back-tension.
-clean/lube the capstan bearings (if worn out, then the deck is dumpster fodder)
Best for a pro shop to do this work. The transport should be aligned with an M300 gauge for best performance. Aligning the heads and electronics with test tapes will be needed as well.
Marrs Comunications can supply the belts. Terrysrubberrollers.com can put new rubber on the pinch rollers.
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+1
Not sure why but the 420A has given me more trouble with tape skew than any other 300/400 series model, even though I've worked on more of the other models. Probably based on too small of a sample, so I try not to hold it against the 420A, but I've seen this same issue on three straight now and had a couple of 440A's a 340A, and some 330's in the same period that had no signs of tape skew even though they all have the same mechanical tendencies more or less.
John
Not sure why but the 420A has given me more trouble with tape skew than any other 300/400 series model, even though I've worked on more of the other models. Probably based on too small of a sample, so I try not to hold it against the 420A, but I've seen this same issue on three straight now and had a couple of 440A's a 340A, and some 330's in the same period that had no signs of tape skew even though they all have the same mechanical tendencies more or less.
John
No, you had it right... tapetech's the expert, and anyone that's seen my house lately will confirm that I'm a Tandberg nut.
John
John
Beyond that, call on JDurbin, our resident Tandberg Nut.... errm... Expert. Yeah, that's it...
Marc
petehall347
the brandy coffee man
bit of a dumb question after the fantastic advice .but have you tried different tapes ?
BMWCCA
Addicted Member
Just got a 420A today of local CL and it was exhibiting the same issue.
I took off the tape door cover and noticed that if I applied a bit of pressure to the supply reel drive, the skew issue went away. Figured it must be feeding faster than the take-up reel could handle it. The I noticed that if I went quickly from "wind" to "play" the problem went away for a moment. After fiddling with it for a while I realized if I hit stop before I hit play, the problem wasn't evident. I'm assuming there's some drag on the take-up side that remains after jumping from "rewind" or "wind" to "Play" that is mechanically absent with the intermediate stop at "stop". I'm also assuming that's probably a mechanical lever being slow to shift due to dry lubricant. I'll take it apart later but for now I'm enjoying the new toy.
Bought it from the original owner's daughter and she had saved the Operating Instructions manual, Tandberg Inspection Card with seven signatures verifying performance and test results, Operating Supplement for the 440A and the 420A, and the 420A Technical Data and Description brochure. If this is information would prove useful to anyone, let me know and I'll scan it.
tapetech
Repair Professional
My recommendations in post #3 apply to your deck as well. Also, if you apply more back tension (BT) and that fixes the problem, that does not necessarily mean the BT is too low. If you are applying more BT than spec, then that can cause speed defects towards end of tape.
-check that the head carriage moves freely (by hand). Dried grease is the problem.
-new belts and new pinch rollers will likely be needed.
-see if the counter belt is driven off the take-up hub or supply hub. If take-up, then a new different belt needs to be installed with it attached to the supply hub. This increases back-tension.
-clean/lube the capstan bearings (if worn out, then the deck is dumpster fodder)
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