Grundig transistor 865 - basic info links please

[bugbear]

I have done the obvious search on the forum, and have an unusual problem.

Too many threads, too much info.

My late father had one of these radios, and I grew up with it.

I have now bought one from eBay, but it needs some love. The exterior case is battered, dirty, slightly corroded, and the trim is lifting. I've done many restorations/renovations on woodworking tools, and think all this is within my skills.

There is no "indicator vane" in the tuning window

The sound is poor - slightly distorted, and very uncontrolled boomy bass.

Can anyone point me at:

* how to open the case (I know that sometimes screws are hidden under things, that "just pull off", but I don't want to pull the wrong thing)

* a service guide (esp with voltage check points)

I will defer any electronic "debugging" until I've acquired a good deal more familiarity with the inside. I have fixed my hi-fi power amp, and have basic electronic knowledge and equipment.

BugBear

[paulsherwin]

This is the export variant of the Yacht Boy 210 sold in Europe and the UK. You will find much more info on that, both here and on the wider net.

https://www.radiomuseum.org/r/grundi...210_n_210.html

You can buy service data for both the 865 and Yachtie for £1.99. The proceeds help fund this forum.

https://www.service-data.com/section.../1/865-mariner
https://www.service-data.com/section.../yacht-boy-210

These radios do have odd sound equalisation. The treble control can be pulled out which will reduce the bass boost and make the set sound much better to modern ears.

[bugbear]

I have purchased the 865 service manual and (conveniently) it includes instruction for getting inside.

I'll open her up, and see what I find.

I'll be back with further annoying questions, probably in 8-10 days.

BugBear

[Freya]

If you short out C617 on the volume / tone board it will give you a flat frequency response.

[paulsherwin]

I think they sound fine with the tone control in the 'low bass' position, but opinions do vary.

If you have low volume distortion, the first thing to check is the output transistor quiescent current as outlined in the service info. A surprising number of Yachties left the factory in Portugal with this set incorrectly.

[bugbear]

Thanks to all; I am visiting friends this weekend (so no work on the radio) AND I've lent my soldering iron and meter to another friend.

So there will be a pause...

BugBear

[bugbear]

OK; I managed to start a basic inspection over the holidays, gaining access as per the instructions in the service manual.

There are "some issues".

1) The main one, from a functional POV is that the tuning indicator (notable by its absence from the tuning window) was lying in the bottom of the case. The cord is 70 cm long, in two pieces. There is a loop at (only) one end, and a spring. The needle is intact, but glued to the cord. I'm guessing I need a new cord, and that replacing this is a "normal" part of working on old radios; even the service manual (only 6 pages) speaks of it. Guidance would be very welcome.
[img]https://farm5.*****************/4897/32694788678_901a117852_c.jpg[/img]spring

2) The tip of aerial has come off (broken off?) during cleaning. My current plan involves quite a lot of Araldite. Is there a way to remove the aerial?

3) One of the screw holes for the base has split open. My current plan involves reinforcing with araldite (around the split, simply glueing the split would never hold).

4) The speaker "tags" have become detached from the insulated support; they appear to have been simply "clipped" in place by bent sprigs of wire on the reverse side.

I was hoping to use some fine copper wire wrappings to hold them in place, then re-flow the solder on the windings for a permanent (enough) job.
[img]https://farm5.*****************/4864/32694789378_e5b6d796a7_c.jpg[/img]speak_term

5) The speaker dust cap appears to have been made of foam, and it's ... gone. I was going to leave this well alone.
[img]https://farm5.*****************/4830/32694793148_5c5a8cbf18_c.jpg[/img]speak_cone

6) Generally speaking, the interior looks corroded and dirty. But (to be fair) it's 50 years old. I'm pretty confident about cleaning and tidying the case/exterior. I don't know whether attempting to clean the inside would risk more harm than good.
[img]https://farm8.*****************/7903/32694792868_93d19031bb_c.jpg[/img]overall

I would very much welcome both specific comments on my numbered issues, or any general advice.

BugBear

[bugbear]

Some progress;

1) 0.6 mm Dial cord is on order (diameter measured via a pixel counted macro shot)

2) It turns out the tip of the aerial is a threaded fitting. It had come unscrewed. I have screwed it back on.

4)
[img]https://farm5.*****************/4864/46616672511_b9f0e97d4f_c.jpg[/img]speaker_tag_wired
[img]https://farm8.*****************/7924/32742606198_1df7d0cf96_c.jpg[/img]speaker_tag_soldered

[crackle]

It looks like that brass tag holding the speaker connection terminals on is about to give way as well. Maybe use a fine screw and nut to fix it on.
The copper wire you have wrapped around the terminals should hold very well when soldered.
Does the speaker diaphragm move in and out when you push it gently, with out any scraping noise?

[bugbear]

Originally Posted by crackle

It looks like that brass tag holding the speaker connection terminals on is about to give way as well. Maybe use a fine screw and nut to fix it on.

Good thought - I'll have a rummage in the "magic coffee jar"

The copper wire you have wrapped around the terminals should hold very well when soldered.
Does the speaker diaphragm move in and out when you push it gently, with out any scraping noise?

It seems OK. I'll check it on some fly-leads before re-assembly. (it worked before)

BugBear

[bugbear]

Progress. I have installed the new tuning cord.

I didn't have a long spring, but my magic coffee jar yielded two shorter springs. This turned out to be an advantage, since I could tied the cord ends to the springs under no tension, and then (at the last) hook the two springs together.

I also discovered that a crochet hook is pretty much MADE for the job of tieing knots in fine cord. I practised on linen button thread before moving onto the actual cord. (the knot I used was variant anchor knot, locked with nail varnish)

https://www.youtube.com/watch?v=ckkC5rPDAjY

To fix the tuning indicator in the right place, I affixed some masking tape to the backlit white plastic, and made pencil marks at 1cm intervals.

I then reassembled and tuned to radio 4, FM. I noted where (on my pencil marks) 94.1 (on the scale marked inside the outside case) lined up.

I could then disassemble, and put the indicator in the pencil mark position noted. And more nail varnish.

Onto fixing the distortion!

BugBear