Tape dragging

[mobydud]

Hey all, I'm having an odd problem with my Akai GX-630D. It plays wonderfully, then slows down to about half speed for a while. I thought I was having a problem with the deck itself, then noticed how dirty the pinch roller had gotten. Bought some rubber cleaner/rejuvantor and cleaned the pinch roller nicely. Also the heads, tension arms, capstan..the whole tape path.

Everything was great for almost a whole tape. Then musshhhhhh..slowdown again. It happens on the same spots on the same tapes over and over. So it would seem to be the tapes, right??

Now I don't know. I have some new tapes and they are doing the same thing! Slowing down very consistently in the same spots on the tape throughout repeated playbacks.

I'm at a loss..any suggestions?

Thanks much

 

[whitetrash]

If the player is slowing down when the same amount of tape gets spooled on the empty reel, then I would check the belts and or idler wheels for slippage. It sound like at a certain weight something that is worn, loose or just dirty can't get enough bite. Be sure to check all moving parts for dry lube as old lube will cause the problem you are having also by not allowing full arc.

 

[Vintage TX]

Hi Moby,

Sorry to hear you got problems
This model got a servo-pc-board with a small transistor on a heatsink.
You can reach this board with taking the right sidepanel off.
there is 2 adjustments pot there but don't adjust those !!
Behind those is the transistor, 90 % this one starts acting up after a good warmup of the deck and speed suddenly start slowing down or speeding up by itself.
Of course before you go ahead and replace it, check the tape-travelpath for worn pinch-roller or dirt on the tape-guides first.
Testing with several tapes like you did and same result, tells me the problem is the transistor in the power-supply
But double-check the travelpath first Moby.

let me know what you find

 

[mobydud]

Hi Tex, appreciate your help again as always

I looked over the tape path again, and at least to my eyes I don't see anything obviously wrong. There isn't any noticable wear anywhere on the arms, guides, rollers..etc. I used tape head cleaner on the path for this, and rubber roller cleaner ( for printers ) on the pinch roller. All is clean and shiny. I really had thought it was just a dirty pinch roller until the same thing happened consistently. Sounds like once again the resident Reel to Reel Guru knows far more than us mere peasants :

I was wanting to send this deck off to be serviced, looks like its a for sure thing now..maybe it's for the best anyways.

 

[Vintage TX]

OK, do this test first before ordering parts or start packing.
Turn the power on and leave it for 2 hours just sitting there with a tape on the machine but not playing.
After 2 hours press Play and see what it does.
IF it slows down directly or the speed is not correct in the beginning of the tape the servo-board transistor has problems.
May I ask what brand of tape you are using ?

 

[mobydud]

Ok Tex, I'll give it a try. The only tapes I have so far are NOS Realistic ( Scotch) ...ya I know, but I could drive down the road a ways and get the last few on the shelf:

Also a Maxell UD-35 on 10" Reel..well used from the look of it. It came with the deck. Other than that, pre-records from eBay, some in great shape, some not so great. The problem is most predictable with the Scotch tapes I recorded on new. All the way through..until the last few minutes of tape. Then mussshhhhh .

I will definitely be ordering new Quantegy tapes as soon as my *fun* budget allows. Part of the reason I suspected a tape problem in the begining was because I know these are not the best tapes..by a long shot! But I was surprised when my pre0records started doing it to..hmmmm,,we'll see. Thanx again,

 

[Vintage TX]

If you use only 7 inchs reels and at the end it starts dragging, what speed, 7-1/2 or ?
Test with Maxell 10-1/2 reel one time and see if Play function does the same as the smaller.
Because it is a direct-drive 2-speed motor it can only be 3 things, travel-path, power-supply or the capstan-motor.
Did you clean both tension-arms grooves really good ?
Old tapes can do what you are saying, even on bigger machines the result is worse.
But IF the power-supply got problems it will show up directly after you leave the deck on for awhile before testing.
Usally 10 inchs reels only make it thru 50 % of the tape before acting up.
The other Akai models with pitch-control can really start creating funny speeds by itself.

 

[mobydud]

Hi Tex, I'll give your warm up test a try tomorrow afternoon when I have some time. Going to be busy with work between now and then. As for tape speeds, yes almost everything I have is 7 1/2..and yes the big 10 inch reels make it about halfway through before speed changes up and down..and down..and up again. I'll look over the tension arms to be sure they are clean..but they didn't have anything on them when I cleaned in the first place. Maybe I rubbed a cotton thread down in there somewhere hmmm?

 

[Vintage TX]

Never leave 20 Q-tips crumbled up in the headstack
You will hear "Cotton-Eye Joe" ... ....


Good Luck with the testing !

PS/ When it start acting up, change speed and see if that changes anything.