Grundig TK747 Reel To Reel Plays at wrong speed

This is a mid 70's Grundig that is running a little slow.

[@leeboleebo6228]

I know it's 02,45am here in UK but I love to watch your videos

[@alexandrustatie3974]

To increase the belt tension some rubber/foam window gasket could increase the size of the old square rubber mounting of the motor. Great videos, you helped me in the past to figure out the fault of my receiver, multi-button input resistor ladder caused by oxidised buttons that developed their own resistance. Thank you 👍

[@gabrieleorioli1760]

That deck is actually well engineered. Many cables are fitted on connectors and not soldered, the boards are neatly placed, the transport is simple enough. I like it.

[@UHF43]

Good old Grundig.

[@enricoself2256]

I would say the tables brakes are not very effective, the supply spool still rotates a bit after play is stopped leaving a slack of tape...

[@chillidogkev]

I wouldn't trust any important tapes on that unit unless I was very careful with the tape transport and being on hand to smooth out that whiplash in the tape slack every time.

[@sunspot42]

I wonder if it’s not quite working correctly. Maybe something is still a bit gummed up with dried lubricant?

[@dhpbear2]

Interesting the lengths they went to to make it 'low-profile'. That has to be the THINNEST 7" tape deck ever!

[@SergZak2023]

Thanks, Dave. Very interesting repair. I remember a next-door neighbor that was originally from Ethiopia swearing by Grundig electronics. At that time here in the US, all I knew were the typical brands sold here more commonly. Grundig was alien to me.

[@12voltvids]

Grundig was some under the Normandy name plate here. I have one that was my father and mother in-laws. Have to service it some day.

[@chriscutress1702]

Great job. Fantastic to see an old relic get a further chance to continue entertaining it's owner.

[@butcharmstrong9645]

Super interesting fix. I really don't know squat about electronic repairing but it still interests me to watch someone else do it. Specially if the repair person is as good as you sir.

[@robsmart8734]

Thank you for turning out so many videos, Dave. Man that’s a lot of work

[@12voltvids]

Tell me about it. And remember I don't have a production company doing it for me. I am the production company.

[@groovejet33]

@@12voltvids Ive said it before, we all expect professional productions these days, and dont think about the effort involved to film & edit a video.

[@gabrieleorioli1760]

I am a simple man, for I see a 12voltvids video about tape stuff and I almost instantly click the like button.

[@frankowalker4662]

I have the same model in my mini studio, they sound great. Thank you for this walk through, I might need it one day. :). Also, in all the years I've had it, I never knew it had a stand. LOL. I use the mounting holes on the back so it can be secured to the wall. Edit: Subbed, BTW. :)

[@danmackintosh6325]

9.50 the sound puts me in mind of Aussie50's (rest his soul) MOT/washer motor execution videos, that resonance & wow in speed when the bearings start to die lol

[@SDsailor7]

Note to self: never get a Grundig. what a nightmare to work on.

[@duncan-rmi]

I have a wem copicat tape echo from the 70s that also uses combined mains trafo/motor. actually it's a 110V model, which has somehow found its way back to the UK; I need to fix it up & re-export it, I guess.

[@ReduktorSzumu]

Good job.

[@waynesharp1690]

Nice. Just got myself an old grundig TK14L reel to reel.

[@goodun2974]

I have read that 3 in 1 oil contains a rust-inhibiting polymer that coats the metal with a solidifying film, making it less than ideal for motor bearings and the like. My tapedeck-specialist technician friend uses synthetic Mobil 1 instead.

[@SergZak2023]

Dave uses the 3-in-1 *Motor Oil* in the blue/red/white container specifically meant for motor bearings. This Motor Oil is formulated differently than the much more common 3-in-1 multi-purpose oil in the black/red/white container

[@ch2o2]

well done, I'm getting lots of flashbacks here :) Generally speaking, it should be said that GRUNDIG products (especially televisions) from this time stood for solid and highest quality (at least in Europe). Funny detail: did you notice that even the flat ribbon cables in the device have the German colors ( black-red-yellow)? :) I've repaired a lot of such devices but it's now that I really notice it. Allow me one small complaint: After stopping (after Play or Fast Forward), the left tape runs far too much and is braked too little... one cannot imagine how long the tape runs on there without really braking when larger, heavier reels are used. Apart from this: great job!

[@akella728]

i have a tape deck "TONIKA-310" with the same motor. creepy miracle

[@zx8401ztv]

I bet it hasnt been cleaned and lubed for donkeys years. What a difference!, it sounds bang on speed wise 😀 Good solid quality motor, no shit in a grundig. Grundig made great products, shame its dead but there are plenty of units out there. I call all clips ' Ping ' for the obvious effect.

[@SDsailor7]

That Grundig looks totally different than the Akai,s and Teac,s and the Sonys that i have seen.

[@dhpbear2]

There appears to me no playback volume control; all the sliders are turned down!

[@12voltvids]

The line out is fixed level. The sliders are for the built in amp, and if you read the label that was stuck on it said audio amp NA.

[@oldnewstock]

Have the TK-745, these recorders aren’t hard to get running mechanically, it’s the electrics that get you. The fancy auto levels system for recordings has given me nothing but trouble, even when I’m trying to use it manually. Still haven’t figured out what’s causing it, and I’ve had the damned thing for almost 5 years.

[@larryshaver3568]

the belt adjustment mechanism[speed selector] may have hardened grease

[@larryhuff3383]

I have a Sony TC399 that started to run slow by about 3%. I’ve determined that the motor run capacitor is failing. I’ve ordered a replacement from DigiKey which should solve the problem. My test tape is one (on a three inch reel) that I made when I purchased the deck over 30 years ago. I recorded 440 Hz for speed checking and 12 kHz for azimuth alignment. The test tape is starting to unfortunately deteriorate and was curious to know if you make and sell test or alignment tapes. Commercial tapes seem to be pretty pricy for my occasional checking.

[@moshezaharia4666]

German electronics tends to be over engineered, but it works great and sounds amazing.

[@chillidogkev]

So the actual fix to the problem was that the motor was loose? Everything was slipping somehow? I see all the bearing lubrication done, but the torque of that motor would have hardly seen any bearing stickiness that would have accounted for the significant speed problem seen at the beginning. As always, highly enjoyable repair process to watch.

[@12voltvids]

Did you not see the part where the motor was slow and there was no belts on it? The bearing was causing the trouble.

[@chillidogkev]

@@12voltvids Yes. But although you commented on the dry state of the bearings, when you had the motor in your hands disassembled, everything seemed to be free moving and turning very easily. Hard to see then how just the bearing was the only culprit for such a dramatic speed issue. That was my feeling.

[@12voltvids]

@@chillidogkev well it was slow to get to speed and had low torque. It gained speed after running a bit but once cooled down it was very gummed up again. You did see the state of the old lubricant that came out of the bearing didn't you. It was all black.

[@bones007able]

I'm surprised the reels turn without a tape ....no end of tape switch on this one?

[@theoloutlaw]

What a very interesting R2R design. The ol' Germans made some good gear in their day.

[@mrpedrodrodriguezsr7628]

A European equipment with mixed Phillips and slotted screws ? How common is that ?

[@highpath4776]

Probably made loads of those slotted screws - which seem far more common in metal to metal parts, but the outer screws with Philips heads seem more common going into plastics.

[@mrpedrodrodriguezsr7628]

@@highpath4776 But I have never seen them combined in one product before , especially in European products !

[@alex1520]

the belts will probably perish before anything else gives out. I assume you gave the heads and tape path a clean+demag off camera :)

[@12voltvids]

Well belts always go bad especially if it sits around.

[@bernardholdsworth2171]

Hi and thanks for your video.i live in UK,i know nothing about electronics at all,my highest IQ is changing a plug...lol,but i bought a couple of weeks ago a TK747 just to try out,was told no lead with it but already had one,tried to power up on 240v here in UK,but no power,it was getting to the motor,but not beyond that.used electricians tester so it was getting power,stripped it down,motor etc like you did,still nothing,so the last attempt was to try 110v like you have over there,(this model has 110,120,220 and 240v plug switch at back)put it to 110v and used a transformeror, 'knock down box' we call over here,switched on and hey presto,power at last.Could this motor been 'blown' on 240v,i checked the 3 fuses on the motor board and they are all working,any clues?

[@SwedishRetroTechNerd]

Cool I never knew Grundig made stuff in the US!

[@12voltvids]

Where did you get that idea?

[@SwedishRetroTechNerd]

@@12voltvids Well ik Grundig was a brand from Austria and most American friends I have has said that Grundig didnt exsist there but now ik know it does : )

[@12voltvids]

@@SwedishRetroTechNerd well that's because people imported them.

[@chronos4244]

@@SwedishRetroTechNerd Grundig was a German brand, not an Austrian. Grundig died like all other German and European companies which were in this business.I say this as an German Grundig former employ back in the days, when this tape recoder was build. That's long time ago...very long time.

[@jantrammelant]

@@chronos4244 grundig was bought by philips. And then philips let it die. Grundig was the bigest reel to reel manufactor in the world. And they Made pretty good stuff.

[@afzaalkhan.m]

German build Quality

[@tacofortgens3471]

German Engineering

[@1pilotsteve]

Za Germans strike again..

[@lukasgayer5393]

Omg, these were terrible :) I had several in my R2R collection. The sound wasn´t half bad but the cheap approach was obvious. These were the 70´s and compact cassettes were gaining strength.