|
|
|
#1
12-06-2011, 12:13 PM
|
||||
|
||||
|
My latest project, a Grundig RF255U...
I got this beast at a hamfest over the weekend. It's my first German radio, and it seems to be a pretty nice one. It's a tube-type stereo unit, and was made in 1967. At $20 I think it was a pretty nice score, especially since it mostly works, but there are a couple of things that need attention.
The most obvious issue is the trashed veneer on the top, and there's also some missing from one side. It seems to just be pretty common quarter-sawn walnut veneer, so rather than trying to repair all the splits, I think what I'll do is strip all the old veneer off the top, saving a piece of it to patch the side if I can, then put a whole new sheet on the top. Any ideas what sort of glue was used on these things, and whether it's even reasonably possible to salvage a piece of the old veneer? But the more pressing matter is the fact that the dial cord has come loose. The string itself seems to be intact, and I can probably even figure out how to hook it back up. But in order to get to it, I need to take off the dial glass, which requires removing the tuning knob. And that's where I'm stuck... nothing I try will budge that damn knob. I can't find a set screw anywhere, but pulling on it seems to have no effect either (though I didn't want to yank too hard for fear of breaking something). Is there some trick that I'm missing? 
|
|
#2
12-06-2011, 02:41 PM
|
|||
|
|||
|
very cool score man! dont see many of these stateside. veneer is a pain to work with so i would reccomed just replacing it if possible. and for glue, you would be really suprised what some good old elmers school glue and a butter knife can do
 the dial string, if your not experianced with them, -dont mess with it if it still works. you will be very sorry!! they are a nightmare to re-string so, hows it sound?
|
|
#3
12-06-2011, 02:42 PM
|
|||
|
|||
|
aah i see your from central florida, cool beans, i was born in orlando and lived there my whole life untill a few years ago, i can guide you to tome really good gettin spots up there if you dont already know about them, lemme know just ask!
|
|
#5
12-06-2011, 11:39 PM
|
||||
|
||||
|
Quote:
And that's all stuff I've done many times before, except that all the veneer repairs I've done have been on old stuff that used hide glue. But I'm pretty sure this radio uses something other than hide glue, and different glues require different removal techniques, and some won't really let go at all. I was hoping to find out ahead of time what sort of glue I'm up against, in order to avoid having to spend a bunch of time experimenting with different removal methods. As for the dial string, yes, I'd love not to have to mess with it, they indeed are a PITA, and it really doesn't get any easier no matter how many times you do it... but, as I said before, the string on this radio has come loose, so in order to use the tuner I have no choice but to figure it out. If I can manage to get the damn tuning knob off, that is. The sound is hard to judge at this point, since I only had a staticky AM station to go by. I'll be able to get a better idea once I fix the dial string and/or make an adapter for hooking an external source up to the input on the back.
|
| Audiokarma |
|
#6
12-07-2011, 10:23 AM
|
||||
|
||||
Hi,
I may have the complete manual with stringing.  Do you want me to search for it?  Scans are free.  best regards, TV-Collector
|
|
#7
12-07-2011, 02:26 PM
|
||||
|
||||
|
That would be awesome. I'll certainly take you up on the offer if you can find it... it'd save me a whole lot of trouble.
I also took a quick swipe at the veneer with a heat gun today, just to see what would happen, and it does a decent job releasing the glue... I don't think I should have any problem saving an appropriately-sized piece for patching up the side, then it's just a matter of finding a good price on a new sheet for the top.
|
|
#8
12-08-2011, 11:45 PM
|
||||
|
||||
|
O.K. I check it out at the week-end!
best regards, TV-Collector
|
|
#9
12-10-2011, 08:06 PM
|
||||
|
||||
|
Some years ago I had one of those.
Sold it off to make room. Had a detachable right channel speaker. Sound was VERY GOOD!
|
|
#10
12-10-2011, 11:19 PM
|
||||
|
||||
|
Unfortunately I didn't get the additional speaker with mine. I'll have to keep an eye out for one (or at least an appropriate bare driver, and just build a replica box for it), but in the meantime, I can either use it in mono mode, or just hook two external speakers to it. I assume it should be able to drive a fairly efficient pair of bookshelf speakers well enough.
Speaking of which... what's with the oddball 5-ohm impedance it lists for the speakers? I've noticed that on other German radios, too. As far as I can tell, they use completely normal 4-ohm speakers, so where does the '5' come from?
|
| Audiokarma |
|
#11
12-11-2011, 06:38 AM
|
||||
|
||||
|
Don't know if the knob is a push-on kind, but if it is: if there's space, see if you can drip a little WD-40 into it with a toothpick or something and let it sit. Then loop a piece of strong cord or insulated stranded wire around the shaft behind the knob so you have the two ends coming out at you 180 degrees apart and long enough to loop around your hands and give alternating tugs. I had to do this on an RCA where one of four knobs would not budge.
Of course what we really need is a Grundig guru on here to say what kind of fastening the knob really uses.
__________________
Reece Perfection is hard to reach with a screwdriver.
|
|
#12
12-11-2011, 08:33 AM
|
||||
|
||||
|
That was one of the first things I tried. I used penetrating oil rather than WD40, couldn't get a whole lot in there though, since I didn't want to risk having any drip onto the paint on the back of the dial glass.
I actually made a sort of jig for pulling on the knob... took a few inch long section of 1/8" x 3/4" aluminum flat stock, cut a notch in the middle to fit around the shaft, then put a couple holes in the ends and looped some twine through those. I slipped that behind the knob and pulled on the twine. I succeeded in bending the aluminum, but the knob wouldn't budge. 
|
|
#13
12-12-2011, 11:35 AM
|
||||
|
||||
|
When I find seized knobs, I always use Reece's method (a long cord) and sooner or later the knob comes out.
Judging from the shot, the dial knob should be similar to other Grundig sets e.g. RTV370, RTV600, RTV400 etc, and it's a press-on knob. Marco
|
|
#14
12-12-2011, 03:05 PM
|
||||
|
||||
|
Alright, I threw all my retard strength into it and finally managed to get the gorram knob off, and did a proper inspection of the thing.
The dial cord is indeed broken, and I think most of it is gone. It appears to be two separate pieces, there's a length of thin wire with loops on the ends, and that's still intact, but then there was also a nylon(?) string, of which I only have a couple inches. Additionally, there may be some other piece missing, since I can't otherwise figure how the tuning indicator would attach to the string. I will definitely need a stringing diagram to figure out what's going on. I also made another less-than-pleasant discovery... one of the output transformers has been replaced with a (much smaller) Triad 'universal' one, and the circuit may have also been modified to accommodate it. There are a couple unpopulated spots on the board for resistors and capacitors, and the soldering there doesn't look factory original. So that sucks, looks like I'll need a full schematic too.  I don't know what the chances are of finding another original OPT, but I guess worst case I could just replace both of them with a matching pair. There seems to be a fair supply of Telefunken SE EL84/EL95 ones on eBay that should work well with the ELL80 and wouldn't look too terribly out of place, or Edcor probably has something functionally suitable as well.
|
|
#15
12-13-2011, 03:32 PM
|
||||
|
||||
|
Nick please send me a PM. I think I can help you.
Marco
|
| Audiokarma |
 |
|
|
Linear Mode
