Grundig R35 tuner/amp saved from the skip

[vinrads]

This is a very nice unit , after a few checks I plugged it in , what do you know it worked but distorted on the L/H side , the speaker was found to be burnt out , when connected to the bench spk's both channels worked ok , no DC on the spk's , the next problem was the tuning cap getting stuck part way round , turned out to be the small nylon cog broken , buer where am I going to find one of those ? as a temporary measure I fitted a rubber sleeve which worked ok .
New lamp holders were fitted behind the main dial ,two green led's were fitted on the sig strength and tuning meters .in pic one the broken cog is in the middle the one on the right is one I found on an scrap cd mech pity it's to small I estimate it needs to be 6mm dia. what looks like a cog on the tuning cap is a splined shaft which the cog fits on to , Mick.

[The General]

Nice find. I had one a few years ago, they sound very good when paired with good speakers.
Good luck with the little gear, maybe a brass gear from a model making supplier could be made to fit?
Mark

[vinrads]

I did a search on Ebay no luck there , what I need is someone with a bucket full of old clock parts. Mick.

[orbanp1]

Hi Mick,

Nice radio!
Probably a lot easier just to fit a "new" variable cap there as opposed to finding replacement a gear.

Regards, Peter

[vinrads]

Hi Peter not that easy, the vhf vary cap pot is fixed to the rear of the tuning capacitor ,and is driven from the spindle , for the amount of use it will get the rubber is holding up quite well , also there are several pre sets for vhf tuning . Mick.

[vinrads]

The tuner/amp was on soak all day, then lost sound in the l/h channel ,just a loud buzz , I quickly switched off , yep there was dc on the spk out , so that's why the spk burnt out , checked all nine transistors , all read ok , switched on again with a 25 volt bulb in series with the output , working ok again ,tried heat ,still ok freezing it still ok , two hours later click ,the bulb lit up , checked mid point , volts it was high .
Decided to swap the transistors one at a time ,starting with the output, eight transistors later the lamp was still glowing ,swapped the last transistor , switched on now both channels ok , so I replaced both the transistors GPS A 05's with equivalents , set up quiescent current, now on soak test again, fingers crossed, time for a . Mick.

[al_kaholik]

Your broken cog would be a very cheap and easy part for someone with a 3d printer to reproduce. Perhaps worth an ask around on here or a local maker space?

[Welsh Anorak]

I needed a cog for a tape deck and was going to try the 3D printer route when I found some sellers online that offer a selection of nylon gears for little money, and one fitted exactly.

[vinrads]

Hi Glyn that was my fist thought ,but had no luck there , the one need has very fine pitch teeth, Mick .

[orbanp1]

Hi Mick,

I am not sure how feasible the following idea is, but here is it.
If you can not find the right gear, how about using a "regular" varicap without the pot mounted on the back, and rigging up a separate pot, and driving it from the dial string - does it use a dial string?
Obviously you need room for that, a different, longer dial string, a good quality linear pot, and an appropriate diameter pulley on the pot.
Alternately, you could just mount that separate pot and tune it manually, independently from the main tuning. It would be adequate for finding stations and then entering them into the "program section".

Regards, Peter

[SeanStevens]

You could try this:

Push the good bit of the cog into Plasticine or blutack (cover with talc first)

Remove cog gently then fill with 'no more nails' to make a replacement part.

It will be fiddly!


otherwise

Find a pinion roughly the same size - make a rubber tyre to fit.


SEAN

[vinrads]

Thanks for all the suggestions , the rubber sleeve seems to be holding up well , Mick.