1969 Blaupunkt car radio tuner cord....

[AircooledEd]

Good evening Ladies & Gents

I wonder if anyone can help me out here? I am the proud new owner of a late 60s VW complete with what appears to be the original am Blaupunkt radio. It works, but after 41 years the tuner indicator drive cord has rotted and snapped.

Although able to open the chassis and recover all the debris, I am unsure how to re-string this to function correctly.

I'm no radio man (helicopter engines and airframes is my daily grind), but this falls squarely in the realms of non-electronics so I guess if some kind soul would enlighten me to the basics I may just get it cracked!

I suppose that the spring is positioned mid-run, to compensate for temp./humidity changes in string tension. One anchor point is clearly on the tuner shaft, and winds the string as the shaft turns. I haven't worked out where or how the other end anchors - is it a closed loop to the other end of the spring?

I'd love to have the satisfaction of seeing this installed and working in the car, so any guidance will be gratefully received. Perhaps a picture of a similar single tuning shaft installation correctly strung?

[AircooledEd]

Must add - set is 'Hildesheim' part number 7 639 000 I've found a picture on a site but the stringing (correct term??) is not shown very clearly.

Thanks

['LIVEWIRE?']

Do you know the model name/number? There should be a label, either on one of the side panels, or the rear, with a Blaupunkt part no beginning 76--------, and possibly a name.
Failing that, can you post a picture of the radio on here. If I can identify it, I MAY have a service manual showing the cord drive, and possibly even an original drive cord to suit it.
In most car radios the tension spring is positioned so that, with the pointer at one end of the scale, the spring is at, or near the other end, usually on the lower run of the cord.

[AircooledEd]

Livewire;
thanks for your reply. The model is 'Hildesheim' part number 7639000.
Radiomuseum.org shows a picture but as mentioned above, the cord terminations are unclear to my novice eye. Am I correct in the assumption that if anchored to opposing sides of the tuner control shaft, as one side winds 'in' that the other naturally plays out, moving the cord and so the indicator?

['LIVEWIRE?']

Somehow I missed your post #2 about the part no. Anyway I've had a quick look, but don't seem to have that manual, but you're basically right about the cord stringing. The no. of turns around the tuning shaft, and the direction(CW or CCW) are both important for correct operation of the cord drive, which is usually arranged so that the tuning runs from the LF end of the band in a L to R direction.

[AircooledEd]

Right, I'm getting somewhere!

I've included a picture to hopefully clarify where I'm stuck- beneath the brass tuning shaft, and driven by a small gear formed on it is a Nylon gear retained on a spindle by a circlip.
This gear has two slots, is this the anchor point for the drive cord? I imagine it is a fairly generic set up?
The principle is now fairly clear, but the execution not quite so crystal.....

All assistance is gratefully received, especially if no assumption of prior knowledge is made!

[AircooledEd]

Good evening all,

I'm after advice on how my Blaupunkt Hildesheim car radio tuner drive cord should be anchored to the drive gear. I think I understand the routing and tension spring arrangement, and that the cord should run to opposite sides of the gear, but how it should lay and attach elude me at the moment. A picture of a similar, single tuner spindle arrangement would really help me out here if an image of the specific model isn't available.

['LIVEWIRE?']

I've been trying to find a service manual for the Hildesheim or a similar model, without success so far, but, in the meantime, AFAIK, the cord is routed around the tuner spindle(no. of turns and direction critical) , over any pulleys present at either end of the dial, then anchored to the spring at each end, with the spring at the opposite end of the cord run to the pointer, so that, as the tuning knob is turned, the pointer travels(e.g.) R to L as the spring, on the lower part of the cord run, travels from L to R. Hope that's clear!

['LIVEWIRE?']

I haven't been able to find a Hildesheim 7639... manual, but have found one for a Mannheim 7639300, and one for a Wolfsburg 7637060(Series Y 1100 001).
The dial cord stringing in either of these should be similar, so I hope the attachments will help in sorting this out. I have some original Blaupunkt Pointers and cord tension springs. Send me a PM if these are wanted.

[Herald1360]

I think the scanner settings might need a tweak! Maybe greyscale only or even black/white would work better.

['LIVEWIRE?']

Yes, Chris, you could be right. I'll have another try, but, of course, have to bear in mind the limits imposed by the forum's software. Those scans WERE in Black & White!

['LIVEWIRE?']

Hopefully THIS scan of the Mannheim 7639300 dial cord diagram is more readable!!

[Herald1360]

Sorry if I seemed picky......

The new scan- no not really any clearer. Maybe a link to photo hosting site?

Realistically, don't bother on my behalf- I've no direct interest as such. Maybe time for another thread on getting the best out of the limitations on posting file limits.

Cheers

['LIVEWIRE?']

Aircooled Ed-having made two unsuccesful attempts to post a picture of the dial cord stringing, should you still need this info,and want to PM me your address, I can print off copies of the diagrams I have, and post them to you.
Mike

[Station X]

The file size limit for a jpg image is 200K which should allow good resolution of an A4 document.

Rotating the image so that it's landscape rather than portrait before uploading it may help.