Kolster Brandes 666 Valve radio restoration.

[real0real]

Hi Mike
Have removed valves and noted so cant get them mixed up ,
Will try and get the coil resistance of each winding tomorrow , as a bit late here this evening

Clive

[real0real]

Hi Mike
Have measured the restance on transformer ,as long as i have traced the correct wires (as several exiting the transformer ,getting the readings of with the meter set at 2hms resistance
One coil larger outer coil 0.046 hms resistance
Inner coil of 0.190

----------------------------------
Checked apeaker resistance cross the plug terminals with volt meter set at 200k
2 pins 1.7
secound 2 pins 0.4

Have attched picture

[Station X]

2hms?

In the picture your meter is switched to the 200k range (200,000 ohms). It would be better to use the 2000 ohm range and get greater accuracy.

Also don't touch the probes with your fingers as you'll be measuring the resistance between them as well as the winding resistance.

[real0real]

Hi
Re-checked the speaker plug and set to 2000 ohms

picture attached of results

[Station X]

1707R and 451R respectively.

Pretty good!! Service Sheet says 1700R and 450R.

[real0real]

Good news ,

[crackle]

Can you confirm you have the manufacturers service manual?

Fit a new mains cable and, set the fuse/voltage selector to 250v.
Have you made a lamp limiter yet? If you have then use a 60 watt bulb in series.
With ALL the valves removed you could test the voltages from the mains transformer for a final check.
It would be worthwhile at this stage to replace the mains cable for a modern one.

CHECK THE METER LEEDS AND PROBES ARE IN GOOD CONDITION.

With the meter set to 600v~ (AC) and the negative connected to the centre tap of the transformer (R14 and C19 junction), switch on the mains to the transformer.
You should measure 300v AC on each of the rectifier anode sockets.
If it is a little less then it is is because of the lamp limiter reducing the voltage a tiny amount, but don't worry about that.
IF THE LAMP LIMITER COMES ON VERY BRIGHT AND STAYS BRIGHT FOR MORE THAN A SECOND OR 2 THEN SWITCH OFF AS IT IS INDICATING A FAULT.

BE VERY CAREFUL WHEN MEASURING AROUND HERE AS THERE IS 300 ON EACH ANODE BUT BETWEEN THE 2 ANODES THERE IS 600 VOLTS WHICH WOULD BE POTENTIALLY DEADLY.

If it passes these tests together with the 1.7k ohm reading for the field coil and 450 ohm reading for the speaker transformer primary then it looks very much like the restoration will be, hopefully, just a matter of replacing the capacitors and a few resistors..

Mike

[real0real]

Hi Mike
i Have not Downladed service data manual as yet as like to confirm which model i have as few listed is the Radio model i have the KB666 refs m13088 not with the following A/B/C type model
I have ordered a original KB666 Manual i found listed on Ebay awaiting delivery (not sure if this one would have full data required though)

[crackle]

Its the same service manual for all models.
Mike

[real0real]

O.K have just purchased and downloaded , will have a study of tomorrow will try Rig up a lamp limiter change power cable and give it a test (with valves removed)

[real0real]

Hi
Slight query about power cable lead , as mentioned earlier the old mains cable appears to have colors of yellow and Blue , was suggested that the Yellow wire was possibily originaly red live wire and has faded , i looked at chasis of radio and yellow/red wire is going directly to fuse and blue wire soldered to the on/off switch , but this is opposite way to picture shown in following link where the live (brown wire is soldered to switch and nuetral going to fuse ?

http://www.kbmuseum.org.uk/kb_images...6_chassisU.jpg

(i would of thought live possibly go to fuse first as in a wiring a plug live wire is fused )

any thoughts ? should the live definatley go to on / off switch ? or fuse just like to double check before switching on

have attached couple of pictures showing how this radio was wired , used a pen to point to yellow/red and blue leads under chassis so can see

[Herald1360]

The KB circuit shows one side of mains to switch and other side to fuse then voltage selector. It doesn't specify which is which and the set doesnt care. We might prefer a double pole switch and / or fuse in the live side but given what is actually there, switch in live and fuse in neutral is the best option.

In any case, don't rely on the switch alone when doing anything involving touching the works directly!

[real0real]

If solder new mains lead cable wires as same as in picture on the KB Museum website this would be correct just double checking as noticed switch looks bit different aswell

[crackle]

The reason I wired neutral to the fuse/voltage selector was because it is possible for the fuse carrier to come apart exposing the fuse. It seemed more sensible if that was the case to have the neutral wired to the fuse which is handled by persons rather than leave a potential live fuse.
What Chris said about relying on the switch is sensible as these switches are prone to sticking sometimes, and although you may hear a click the contacts may still be connected.

Mike

[real0real]

Hi Mike
should i wire it up as you have done ,live to switch and neutral to fuse

[crackle]

In my view yes, as explained above.
The assumption about the faded colours of the old cable is just an assumption, unless someone can produce old documentation to show the colour codes of cables back then.
The radio does not care which way it is wired, but I believe the safety factors are the consideration here.
Mike

[real0real]

O.K , will continue , i read in manual must have the speaker plugged in aswell when powering up , should take me possibly 1 possibily 2 hours to get everying ready to test as rig up a lamp limiter aswell keep you updated

[real0real]

Hi
Just powered up the Radio , not see the light limiter bulb light up , and the radio dial bulb has illuminated o.k , picture attached

[crackle]

Originally Posted by crackle

With ALL the valves removed you could test the voltages from the mains transformer for a final check.
It would be worthwhile at this stage to replace the mains cable for a modern one.

CHECK THE METER LEEDS AND PROBES ARE IN GOOD CONDITION.

With the meter set to 600v~ (AC) and the negative connected to the centre tap of the transformer (R14 and C19 junction), switch on the mains to the transformer.
You should measure 300v AC on each of the rectifier anode sockets.
If it is a little less then it is is because of the lamp limiter reducing the voltage a tiny amount, but don't worry about that.
IF THE LAMP LIMITER COMES ON VERY BRIGHT AND STAYS BRIGHT FOR MORE THAN A SECOND OR 2 THEN SWITCH OFF AS IT IS INDICATING A FAULT.

BE VERY CAREFUL WHEN MEASURING AROUND HERE AS THERE IS 300 ON EACH ANODE BUT BETWEEN THE 2 ANODES THERE IS 600 VOLTS WHICH WOULD BE POTENTIALLY DEADLY.

If it passes these tests together with the 1.7k ohm reading for the field coil and 450 ohm reading for the speaker transformer primary then it looks very much like the restoration will be, hopefully, just a matter of replacing the capacitors and a few resistors..

Mike

have you tried the final mains transformer test above.
But only do it if you feel confident in what you do and have identified the correct pins on the empty rectifier socket.

[real0real]

Hi Mark
I Would be confident enougth to do this , but uncertain of how to do
the negative connected to the centre tap of the transformer (R14 and C19 junction) unsure of which terminal points these would be ,if it is essential for this test to be done would try to do
could it be possible to upload / pointed out on picture of correct terminals somehow as unsure
I have attached picture of meter settings 600 v ~ i think this would be correct setting to do this test but checking as not 100% sure ,

Clive