Grundig TK248 Tape Recorder Repair

It's a common problem with this type of Tape Recorder that they won't rewind properly.
As found out on the internet that is due to a rubber roller which hardens up over time.
In this clip, I show how to re-install the new roller, demonstrate the workings and dig into the electronics to replace some faulty electrolytic capacitors.
Enjoy!

[@AverageJoe2020]

The construction of that machine is wonderful, They really put a lot of thought into the servicing of it in future times, Reminds me a little of a Bang and Olufsen music centre I had years ago, that was nice to work on. Best regards, J.

[@AstraWerke]

Its been a huge surprise to me how much forethought they put into the design - compared to my other Tape Recorder where you have to desolder every wire connected to the PCB (and there are a lot) in order to get it out... Brilliantly engineered!

[@Lazarus7000]

Rubber rollers are indeed recoverable in some circumstances. Two separate mechanisms lead to their downfall, age-hardening and polishing through wear. These collaborate with one-another to make slippage. Firstly the roller that has deformed because it is pressed against something in a rest position (or equipment was not returned to a rest position upon decommissioning) can be boiled until it rounds out again. Rollers that are polished should be very carefully re-surfaced with 400 grit sandpaper. The absolute minimum of material is to be removed, you are just trying to create the vaguest whiff of texture. Rubbers of all sorts that have aged can be treated with the delicious-smelling MG Chemical Rubber Renew. (Of course like most delicious-smelling industrial chemicals you shouldn't actively smell it but in using it you will definitely note a pleasant, minty aroma). Of course at the end of this it might still not work, but this is the procedure I developed with input from technicians more learned than I. Sometimes it is important to preserve original rollers because replacements are unavailable, or other reasons, and it is good to know what to do if this is the case.

[@DBAGNIS-mchSound]

Hello, I have the same recorder. One channel does not record and I found a 100uf capacitor burst near the recording keys. What capacitor voltage did you use?

[@leathandrubb]

HI THERE ONCE AGAIN MY FRIEND.I HAVE DONE THE CAPSTIAN BELT WOW!INSTEAD OF GOING ROUND THE BACK OR THE CAPSTIAN FLYWHEEL I PULLED THE BELT OVER THE TOP OF THE FLYWHEEL AND WHILE KEEPING THE BELT SUPPORTED NEAR THE MOTOR FED THE BELT OVER THE 7-1/2 (19 CM)GROOVE.WOW-WEE!THANK YOU FOR YOUR HELP.NEXT IS PUTTING BACK THE TAKE UP SPOOL BREAK STRING.

[@AstraWerke]

Glad you got things back in order. Tape decks drive me nuts every now and again, too - the only thing worse is re-doing the dial pointer string on a radio. Good luck with the rest!

[@user-dh8jh1po3f]

Молодец!

[@allalone7563]

i have one and it plays a little fast. how can i drop motor speed?

[@paulhorn2665]

Adrian becomes Techmoan :-)

[@Gajodareactividade]

HEllo, Adrian. Thank you for this video. I have this machine myself, and I just changed the belts. Yes, belts, plural! The kit I ordered had a 80mm belt, that I thought was from the motor spinner to the gray wheel. I see that the big belt gives a "turn" on the left side of the wheel, but I can't put it that way, it will always touch some metal part in the middle.... Did you replace a belt already? Thank you!

[@AstraWerke]

Hi there. I am glad I didnt have to replace the belts yet. I found a manual on how to change them - it is in German, but it might turn out alright via Google Translate. Here's the link: www.gummimeyer.de/Service-Riemenwechsel-TK248.pdf It appears some parts have to be removed in order to install the belt. Best of Luck to you Adrian

[@Gajodareactividade]

Thanks for our tip! I figured out that the other belt is for the counter. Well, I can tell that belt replacement is really a pain in the..... Anyway, your video helped me really the position of the belt. Keep on!

[@AstraWerke]

That's what I make these videos for - glad I could help!

[@Jukedome]

Hi please can you advise how you did this? Was there any dismantling required?

[@Jukedome]

I have just got one of these and I have ordered a rubber roller. I have also noticed the left reel is a little stiff causing staggered play at the slower speed. Will the roller help this or is it just for the winding functions?

[@AstraWerke]

No, the roller is for ffwd and rev winding only. The reels have a drag mechanism - basically a piece of string wound around it, tensioned by a spring. You can try to reduce the drag by over-stretching the spring a tiny bit, but you have to be very careful as the mechanism is quite delicate and sensitive to adjustments.

[@AstraWerke]

If you take the top cover plate off, you'll see them immediately.

[@Jukedome]

@@AstraWerke Thank you thats worked , the autostop seems to not be working I can hear clicking sometimes but its not working properly.

[@AstraWerke]

@@Jukedome I'm glad it worked out :D Regarding Auto-Stop, I have to be honest and say I have no clue how exactly they work. They seem to create a circuit between the mechanism and a metal strip at the end of the tape, so maybe there's a relay somewhere that disengages the driving wheels, but that's more speculation at this point

[@Jukedome]

@@AstraWerke I have found the left hand post is wired and when metal touches it's supposed to cut the mech. However the wire isn't connected very well so I will resolder this and see.

[@leathandrubb]

HI THERE AGAIN.MY REWIND WAS GREAT BUT SOLVED MY FAST FORWARD NOT GOING TO THE END OF THE TAPE BY FITTING A FRESH CLUTCH PAD TO THE MOTOR PULLY.HOWEVER MY CAPSTAIN DRIVE BELT HAS COME OFF AND LOOKS VERY HARD TO FIT IT ON THE CAPSTAIN FLYWHEEL AGAIN.DO YOU KNOW HOW TO DO IT.

[@AstraWerke]

I had to replace the main drive belt on a TK149 before and it was a nightmare, as the whole mechanism for coordinating the drive pulleys and tone heads has to be taken apart and, since everything is under spring tention, is very hard to get back together. I don't know how to do it on the 248 but I suggest if the drive belt has only slipped off the pulleys to try and manipulate it back into place using tweezers or dental hooks. Patience is the number one virtue here.

[@NewNova88]

What's the tool you used at 1:23 ? I don't have anything that can remove that small thing !

[@AstraWerke]

It's a pair of snap ring pliers. They come in different sizes and designs for inside and outside rings - in a pinch, you could try levering the ring up with a flat screwdriver - being careful not to launch it across the room.

[@NewNova88]

@@AstraWerke Thanks for the fast answer ! For now, I ordered the diverse wheels and belts that it needs. I'll try getting a pair like you have, it can be useful to me. I'll not try to lift it up with a screwdriver, I have a bad case of unlucky attempt and breaking stuff, and even if I manage to remove it, I have to place it back without breaking everything. And then I need to figure out why the tape I have with the unit is silent. Maybe the tape is blank, or the head is dead. It doesn't seem used, but rusty. I cleaned it with isopropyl alcohol 70% and it was brown/orange like rust. Now it looks okay. Also need a way to plug something into it. Mine is not a TK-248 but a TK-246. But they are very similar, mine is just like a lower version. Great video !

[@aramkarakuzu2029]

Adrian I have same unit which wire feeds amplificator

[@user-dh8jh1po3f]

Хороший аппарат!

[@user-pc9rz3gy3c]

Мне болбше Танберг нравится, особлыво ламповый, бо всё просто и железно..

[@reamonntreacy]

Where did you get the roller?

[@AstraWerke]

Ebay :D

[@reamonntreacy]

thanks

[@gabrielgabriel8769]

Me puedes mandar alguna direccion??

[@pharofirst8386]

I have philips 3549 a 4 traks One 1 and 3 dosen t work But 2/4work properly How can I fix this problem Thanks

[@AstraWerke]

Might be as simple as a dirty switch (contact cleaner will take care of that), could be a broken cable (see if any cables are loose) and in the worst case will be a defective play head, which would be a very expensive and laborious issue.

[@pharofirst8386]

@@AstraWerke i cleaned the head and every thing is ok Excuse me i have another question from a friend Grundig tk 40 work properly Suddenly the green light stops and no sound But play and rw ffis ok Thanx for advicec

[@AstraWerke]

@@pharofirst8386 I never worked on a TK40, but if it's an issue that comes and goes, it might be a dirty contact on the play/stop switches. If it went silent and never came back, its probably something more serious: The green light going off suggests a loss of High Voltage which means either a fuse is blown or the transformer burnt through.

[@pharofirst8386]

@@AstraWerke thank you very much