Grundig Concertboy 1100 - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Leon Crampin · 18th Jan 2020, 11:52 pm

The 'speaker coupling capacitor is indeed 1000uF 10V.

If you let the smoothing capacitor fail dead short on our 250V (sometimes) mains, the selenium bridge rectifier may be damaged before the 400 mA fuse blows.

Leon.

rojosuiza · 19th Jan 2020, 9:13 am

Good to hear, that the radio runs again.

Something called 'Desolv-it' seems to be doing just that… Some cleaners might even desolve the plastic itself...

Sinewave · 19th Jan 2020, 10:48 am

Quote:

Originally Posted by Leon Crampin

The 'speaker coupling capacitor is indeed 1000uF 10V.

If you let the smoothing capacitor fail dead short on our 250V (sometimes) mains, the selenium bridge rectifier may be damaged before the 400 mA fuse blows.

Leon.

Perhaps the one with the wooden front had the slenium rectifier? This one has a silicon rectifier.

Though this year at the rallies I'll be looking out for a woody grille 1100.

Sinewave · 19th Jan 2020, 10:56 am

Quote:

Originally Posted by rojosuiza

Good to hear, that the radio runs again.

Something called 'Desolv-it' seems to be doing just that… Some cleaners might even desolve the plastic itself...

It jogs my memory that it's happened before. It seems a quick wipe is alright, but leaving it to soak around any thing which was printed or painted (however that badge was done) will dissolve the emblem.

As this is a concerning factor to consider when restoring vintage gear, I was doing some searching for a data sheet for this spray. It appears that this is a natural solvent.

Photo attached of the can.

paulsherwin · 19th Jan 2020, 12:09 pm

Foaming cleaner can remove some lettering on aluminium or plastic. I once damaged some text on a Technics cassette deck front panel that way. It's easy to get caught out, as most surfaces survive perfectly well.

You may be able to reconstruct the logo by printing it on a waterslide transfer.

Leon Crampin · 19th Jan 2020, 1:21 pm

My black sets all have Se rectifiers, although different types are fitted and the board is drilled for at least 2 pin outs. One black ITT rectifier looks like a Si bridge, but is definitely Se.

If run within limits, Se rectifiers are usually OK, with the notable exception of devices made by AEG. These are definitely change on sight and have caused damage in many cases by their failure.

Leon.

Sinewave · 19th Jan 2020, 1:44 pm

Quote:

Originally Posted by paulsherwin

Foaming cleaner can remove some lettering on aluminium or plastic. I once damaged some text on a Technics cassette deck front panel that way. It's easy to get caught out, as most surfaces survive perfectly well.

You may be able to reconstruct the logo by printing it on a waterslide transfer.

Where I haven't had any issues are on the aluminium strips (where the volume and tone controls are) where the lettering appears to be printed, perhaps it's an ink which can't be dissolved very well or not at all.

Hmmm, I'm going to have to restrict the use of this stuff to just 'casing' where there is no lettering at all. In the meanwhile it might be worth trying to find an alternative cleaner.

Sinewave · 19th Jan 2020, 2:17 pm

Quote:

Originally Posted by Leon Crampin

My black sets all have Se rectifiers, although different types are fitted and the board is drilled for at least 2 pin outs. One black ITT rectifier looks like a Si bridge, but is definitely Se.

If run within limits, Se rectifiers are usually OK, with the notable exception of devices made by AEG. These are definitely change on sight and have caused damage in many cases by their failure.

Leon.

There's a BU8-04 in mine, perhaps it was replaced in the past?

paulsherwin · 19th Jan 2020, 2:22 pm

That does look like a replacement, though it may be a factory mod introduced late in the production run.

Leon Crampin · 19th Jan 2020, 3:41 pm

Definitely a replacement. The overrun capacitor on UK mains probably destroyed its predecessor. Check that the fuse is correctly rated at 400 mAT (delay).

Leon.

Sinewave · 19th Jan 2020, 4:55 pm

I'd better check that out.

I ought to get some contact adhesive tomorrow to put the aluminium strips back on.

Sinewave · 26th Jan 2020, 8:27 pm

It's all back together working and sounding great as ever. I haven't twiddled with any alignment. I'll need to get a datasheet and perhaps make some check at some point.

Sinewave · 2nd Feb 2020, 11:56 pm

Well Radio 3 tonight is certainly putting the 1100 through it's paces tonight with a good jazz session.

18th Jan 2020, 11:52 pm	#21
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,870	Re: Grundig Concertboy 1100 The 'speaker coupling capacitor is indeed 1000uF 10V. If you let the smoothing capacitor fail dead short on our 250V (sometimes) mains, the selenium bridge rectifier may be damaged before the 400 mA fuse blows. Leon.

19th Jan 2020, 9:13 am	#22
rojosuiza Tetrode Join Date: Mar 2018 Location: Amsterdam, Netherlands Posts: 68	Re: Grundig Concertboy 1100 Good to hear, that the radio runs again. Something called 'Desolv-it' seems to be doing just that… Some cleaners might even desolve the plastic itself...

19th Jan 2020, 12:09 pm	#25
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,931	Re: Grundig Concertboy 1100 Foaming cleaner can remove some lettering on aluminium or plastic. I once damaged some text on a Technics cassette deck front panel that way. It's easy to get caught out, as most surfaces survive perfectly well. You may be able to reconstruct the logo by printing it on a waterslide transfer.

19th Jan 2020, 1:21 pm	#26
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,870	Re: Grundig Concertboy 1100 My black sets all have Se rectifiers, although different types are fitted and the board is drilled for at least 2 pin outs. One black ITT rectifier looks like a Si bridge, but is definitely Se. If run within limits, Se rectifiers are usually OK, with the notable exception of devices made by AEG. These are definitely change on sight and have caused damage in many cases by their failure. Leon.

19th Jan 2020, 2:22 pm	#29
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,931	Re: Grundig Concertboy 1100 That does look like a replacement, though it may be a factory mod introduced late in the production run.

19th Jan 2020, 3:41 pm	#30
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,870	Re: Grundig Concertboy 1100 Definitely a replacement. The overrun capacitor on UK mains probably destroyed its predecessor. Check that the fuse is correctly rated at 400 mAT (delay). Leon.

19th Jan 2020, 4:55 pm	#31
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Grundig Concertboy 1100 I'd better check that out. I ought to get some contact adhesive tomorrow to put the aluminium strips back on. __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

26th Jan 2020, 8:27 pm	#32
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Grundig Concertboy 1100 It's all back together working and sounding great as ever. I haven't twiddled with any alignment. I'll need to get a datasheet and perhaps make some check at some point. __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

2nd Feb 2020, 11:56 pm	#33
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Grundig Concertboy 1100 Well Radio 3 tonight is certainly putting the 1100 through it's paces tonight with a good jazz session. __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.