Grundig Top Boy 600 transformer replacement. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Jimwall · 27th Apr 2021, 1:53 pm

Images

Station X · 27th Apr 2021, 2:11 pm

This appears to be the problem area. Just a simple matter of resistance and voltage readings.

simpsons · 28th Apr 2021, 9:01 am

Good Day SA

Well Jim, a primary transformer resistance reading of infinity means that the connection from the lugs where mains is supplied to the windings is open circuit.

First, DO NOT use the 17 volt transformer you have as a spare. The radio circuits are not designed for this voltage.

Second, you have 2 choices. Either source a replacement transformer or find where the "break" in connection from the lugs to the primary winding is.

Should you need a replacement, you will need to measure the transformer size/"box" it sits in and ask members if they have a suitable one. I have some Grundig transformers myself and if the right size I am sure that the p&p can be worked out.

However, do examine the transformer under a magnifying glass to see where the break or thermal fuse is located.

Of course, if using a battery is OK with you then so be it.

Chris

Jimwall · 3rd May 2021, 6:05 pm

Thanks Poppy dog for feedback I don't see any thermal or other fuse on the housing or the xformer and the impedance.high Still is not readable on my meter on the ac input to the primary winding. Now the secondary winding is 3 ohms and all the rectifiers fuse zener diodes look good on the rectification circuit the DC side works fine and sound is good! So is the xsformer shot?thanks

Richardgr · 3rd May 2021, 6:29 pm

Often it can just be fatigue of the thin wire that is soldered to the lug, and it breaks after it exits the windings. If you are lucky, you will spot the break and be able to fabricate a repair.

Jimwall · 4th May 2021, 5:48 pm

Thanks gents for the advice I will check the xsformer at the weekend and see if I can see any broken wires/tracks.

27th Apr 2021, 1:53 pm	#21
Jimwall Tetrode Join Date: Sep 2020 Location: Johannesburg, South Africa Posts: 85	Re: Grundig Top Boy 6000 transformer replacement. Images Attached Thumbnails

27th Apr 2021, 2:11 pm	#22
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Grundig Top Boy 600 transformer replacement. This appears to be the problem area. Just a simple matter of resistance and voltage readings. Attached Thumbnails __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

28th Apr 2021, 9:01 am	#23
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Grundig Top Boy 600 transformer replacement. Good Day SA Well Jim, a primary transformer resistance reading of infinity means that the connection from the lugs where mains is supplied to the windings is open circuit. First, DO NOT use the 17 volt transformer you have as a spare. The radio circuits are not designed for this voltage. Second, you have 2 choices. Either source a replacement transformer or find where the "break" in connection from the lugs to the primary winding is. Should you need a replacement, you will need to measure the transformer size/"box" it sits in and ask members if they have a suitable one. I have some Grundig transformers myself and if the right size I am sure that the p&p can be worked out. However, do examine the transformer under a magnifying glass to see where the break or thermal fuse is located. Of course, if using a battery is OK with you then so be it. Chris

3rd May 2021, 6:05 pm	#24
Jimwall Tetrode Join Date: Sep 2020 Location: Johannesburg, South Africa Posts: 85	Grundig Top Boy 600 transformer Thanks Poppy dog for feedback I don't see any thermal or other fuse on the housing or the xformer and the impedance.high Still is not readable on my meter on the ac input to the primary winding. Now the secondary winding is 3 ohms and all the rectifiers fuse zener diodes look good on the rectification circuit the DC side works fine and sound is good! So is the xsformer shot?thanks

3rd May 2021, 6:29 pm	#25
Richardgr Heptode Join Date: Oct 2019 Location: Täby, Sweden Posts: 708	Re: Grundig Top Boy 600 transformer replacement. Often it can just be fatigue of the thin wire that is soldered to the lug, and it breaks after it exits the windings. If you are lucky, you will spot the break and be able to fabricate a repair.

4th May 2021, 5:48 pm	#26
Jimwall Tetrode Join Date: Sep 2020 Location: Johannesburg, South Africa Posts: 85	Re: Grundig Top Boy 600 transformer replacement. Thanks gents for the advice I will check the xsformer at the weekend and see if I can see any broken wires/tracks.