Grundig Top Boy 600 transformer replacement.

[Jimwall]

I found Grundig Top Boy 600 in a stall in Jo'burg now this man from the Congo says it worked like a dream!
I gave him R100 rand and dissapeared into the gloom!
Anyway I cleaned it up and voila it worked OK on the battery side 4d types =6 volts sound was good! On the AC side 220v i am not getting Any secondary voltage
So does any one know if I can replace the transformer with anything generic and what voltage should I be getting on the secondary winding?this is FM/am LW radio only

[poppydog]

That looks bit like the top boy 600 board, are you sure you have got the mains/bat switch on the back of the radio in the correct position for mains?


poppydog

[Leon Crampin]

There may also be a fuse in the transformer secondary circuit.

Leon.

[Restoration73]

Many transformers used by Grundig had an internal thermal fuse on the mains side that might have failed, it will be in series with the winding. If a replacement is not available
you could use a slow fuse 50-250mA which would offer some protection.

[simpsons]

The first thing to do is to download the Grundig 600k schematic.

Grundig used similar circuits for many models and as poppydog has said, looks pretty much what you have got.

Should the main battery switch, also mentioned, be in the right position, check the fuse which is clearly shown in your photo using the ohms range on your test meter. This is on the low voltage ( secondary) side of the transformer. If OK, then:

Test continuity using the ohm range on your test meter) from mains input, to the transformer tags. Then, the resistance across the primary (mains input). Next, the resistance across the secondary. The primary will be in thousands of ohms, the secondary just ohms.

Report back as although transformer failure isn't unknown, it can happen although more likely the rectifier diodes.

Chris

[Jimwall]

Thanks for the input gents firstly the main fuse is still OK the output into the xansformer is fine 220v ac I will pull out the transformer and check if any protection fuse is there and then check the ohms on my meter on the winding s I have downloaded the schematic and I will revert back with any questions and hopefully answers but the radio has good output on the battery power ! It is just sad that in Rsa we don't use LW bands anymore

[MotorBikeLes]

If it does have an internal thermal fuse, they just slip in and out so can be replaced easily. If you can get one. I used to keep a few, but don't think I still have any.
Les.

[Jimwall]

Update s!second are I did check for all the switches fuses rectifiers and the secondar y windings was a couple of ohms .so the voltage was supposed to be 7.5 volts ac...but zero are reading on my meter my primary still measured 220v ac!the radio still plays on d type battery 4x1.5v DC_so does this mean the xansformer is shot?I may look for a second hand one
Any ideas on what current ratings will be? Cheers

[poppydog]

I would have thought if you have got low ohms on the secondary then the transformer is ok??

poppydog

[poppydog]

I have got a working top boy 600 here and there is 2.1k on the live and neutral of the mains plug pins and 2.4ohms on the secondary of the mains transformer.

poppydog

[simpsons]

Hmm. Something strange here.

With the mains switched off, remove the internal fuse. Measure the resistance across the secondary of the transformer. It should read 2.4 ohms as poppydog has advised. If not it is open circuit. If OK, with the fuse still removed, apply mains and measure the secondary voltage on the hot side of the fuse.

The secondary AC voltage should be around 7.4 volts and if present then further advice is required but this is a very simple power supply so no worries.

Chris

[MotorBikeLes]

You need to measure the resistance of the PRIMARY winding. Something in the range of 1500 to 2500 ohms makes sense. If it has a thermal fuse fitted, that will be in the primary, NOT the secondary. Some Grundigs had a specific transformer according to region, so it could be one single 240v winding only.
Of course the primary COULD have two 110v windings, either in parallel, or series depending on 110v or 220v region. Many Grundig transformers simply had the fuse in a slot, and could be removed and a replacement fitted.
Les.

[Cruisin Marine]

I have never heard of a Grundig HOT boy, surely the thread title should be HIT BOY?

[simpsons]

Thanks MotorBikeLes. I had had misreads Jim's last post believing he had understood earlier suggested checks.

Jim, when we speak of fuses, it isn't just the one in the plug or on the chassis but also the one fixed to the transformer. This is called a thermal fuse and isn't obvious.

It might just look like a "black blob" but when open circuit or as it is sometimes said "blown," then the AC supply will not reach the transformer windings.

This is why you need to check the resistance across the primary and as poppydog has given the readings, you should be able to confirm that your transformer has the same.

Chris

[Jimwall]

Apologies it is a grundig top boy 6000! anyhow I seem to have infinite resistance on the live and neutral pins there is 220volts ac on the primary windings the secondary windings is around 3 ohms so I have an anotheàr 220ac to 18v ac transformer with no in a spares box and measuring without a load and the live and neutral was about 500 ohms and secondary about 25 ohms so my multimeter is working fine and the spare transformer had about 17 volts ac which is good! I will now take the secondary wires off the grundigs PCB and see if any values change so the scenario is high impedance on the primary input and zero volts on the secondary windings

[Boulevardier]

Originally Posted by cruisinradio

I have never heard of a Grundig HOT boy, surely the thread title should be HIT BOY?

Yes, no such Grundig radio as a Hot Boy. Thread title needs changing or future searches will never find it.

[Jimwall]

To clarify I cannot see any thermal fuse on the transformer

[Cobaltblue]

The OP has clarified that this is a Grundig Top Boy 6000 so I will amend the title accordingly.

Cheers

Mike T

[crackle]

How about a photo of the radio and its model name. To be honest there are lots of hits for a Grundig Top Boy 600, but I cant see any for a Grundig Top Boy 6000.

Mike

[Jimwall]

Oh dear it is indeed a Top Boy 600 my apologies to all.anyhow I did check again the rectification circuitry as l have a polar tracker T3000 and all seemed well