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Old 11th Apr 2020, 7:44 pm   #21
real0real
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Default Re: Kolster Brandes 666 Valve radio restoration.

Cleaned chassis up a little earlier today
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Old 11th Apr 2020, 8:17 pm   #22
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Default Re: Kolster Brandes 666 Valve radio restoration.

Looks like it's lived in a smoker's house! The "patina" on the chassis looks familiar.....

How bad does it smell?
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Old 11th Apr 2020, 8:28 pm   #23
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Default Re: Kolster Brandes 666 Valve radio restoration.

It's going to be a beauty .... please listen to and take the counsel offered by Mike 'Crackle' and co - check, check, check ... and replace ... then power-up via a lamp limiter. (The electrolytics within the 'boxed' psu smoother/res unit will either be shot or require re-forming etc. etc.). Nice find!
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Old 12th Apr 2020, 12:45 am   #24
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Default Re: Kolster Brandes 666 Valve radio restoration.

Better picture
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Old 12th Apr 2020, 11:29 am   #25
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Default Re: Kolster Brandes 666 Valve radio restoration.

Hi
Thanks for the advive on using a lamp limiter , have looked at videos on youtube to see how this works so will rig one up prior to plugging it in to test ,any recommendation on what is the best bulb wattage to use
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Old 12th Apr 2020, 11:52 am   #26
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Default Re: Kolster Brandes 666 Valve radio restoration.

I use a 100 watt bulb in my lamp limiter and I know many people use 60 watt bulbs. In my case, it was what I had lying around at the time.

Gus.
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Old 12th Apr 2020, 2:57 pm   #27
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Default Re: Kolster Brandes 666 Valve radio restoration.

That is a very attractive set and the chassis is in good original condition with only a couple of replacement capacitors. This is one that would deserve the extra effort of restuffing the capacitors.

There is a substantial amount of work to be done on capacitor replacement and checking resistors. Do not be tempted to switch it on until the restoration is complete as it will cause expensive damage.
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Old 12th Apr 2020, 5:33 pm   #28
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Default Re: Kolster Brandes 666 Valve radio restoration.

Lets start talking specifics then. Using the manufacturers service information.
The components in the chassis all look original to me, so I am certain there are many capacitors that need to be replaced, BEFORE APPLYING ANY POWER.
C1 is the audio coupling capacitor, it must be changed, it will be electrically leaky and as a result it will allow DC voltage from the anode of V4 to leak onto the grid of the output valve causing it to possibly burn out the output transformer primary, and may even damage the mains transformer secondary and also the loudspeaker field coil.
This is not the only capacitor which must be changed.
The big rectangular card box contains all the smoothing capacitors, C19 C20 & C21 these are electrolytic types it is very unlikely they will be serviceable and will all probably need replacing. If they are not replaced and are faulty then the rectifier valve could be damaged, or the mains transformer and speaker field winding fused.
It is always nice on a radio of this age and quality to make a good job of re-stuffing the old capacitor cases with the new capacitors. it is normally easy to fit the new capacitors in the old cases because the new ones are always smaller.
Of course the choice is yours to re-stuff or not, it is your radio after all. But taking time and care over doing this will help preserve the originality and hence the value of the radio.
There is probably information available on this forum and elsewhere on the internet giving details on how to re-stuff a capacitor.
The above mentioned capacitors are not the only ones which need replacing, but it is a start.

Mike
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Old 12th Apr 2020, 6:03 pm   #29
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Default Re: Kolster Brandes 666 Valve radio restoration.

Very nice too.
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Old 12th Apr 2020, 8:44 pm   #30
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Default Re: Kolster Brandes 666 Valve radio restoration.

Hi
To get this overhauled in a shop would possibly cost a arm and a leg , and out strip value of radio and my budget , i am trying to contact someone locally through a friend of a freind who may be able to check a few things as i have limited knoledge in electrical stuff , if no joy may just plug in using lamp limiter, i believe these radios were built to last , and appears as if has been stored in dry place as none of caps show any sign of decay and hopefully should just switch on
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Old 12th Apr 2020, 9:10 pm   #31
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Default Re: Kolster Brandes 666 Valve radio restoration.

" i believe these radios were built to last , and appears as if has been stored in dry place as none of caps show any sign of decay and hopefully should just switch on"

Am I REALLY the only one thinking this is not going to end well..

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Old 12th Apr 2020, 9:10 pm   #32
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Default Re: Kolster Brandes 666 Valve radio restoration.

This is an 86 year old radio. The capacitors were not built to last.

We can be fairly certain that the capacitors were starting to degrade 70 years ago.

The waxed paper capacitors absorb dampness even in relatively dry rooms.

Modern electrolytic capacitors may require 'reforming' if they are left on the shelf for 5 years.
The old electrolytics will require reforming or replacement.

You can get new capacitors delivered to your door in a few days if you use online suppliers.
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Old 12th Apr 2020, 9:31 pm   #33
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Default Re: Kolster Brandes 666 Valve radio restoration.

Running the set as is is likely to lead to permanent damage to the set as well as a risk of electrocution and fire.

Only full restoration including replacement of all paper and electrolytic capacitors will make this radio work properly when it will only receive MW and LW stations so will be of limited entertainment value. Even then it will not conform to modern safety requirements and will still constitute an electrical shock and fire risk.

You could put the chassis back together and use it as a display piece.

Perhaps your best option would be to put it on ebay along with the pictures of the condition and your restored case. It should attract plenty of interest and make a reasonable price.
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Old 12th Apr 2020, 10:07 pm   #34
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Default Re: Kolster Brandes 666 Valve radio restoration.

Few other radios i have collected
https://www.vintage-radio.net/forum/...hp?albumid=821
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Old 13th Apr 2020, 4:35 pm   #35
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Default Re: Kolster Brandes 666 Valve radio restoration.

If you plug it as it is some very expensive components costing £50 upwards will be destroyed. For the sake of a few tens of pounds worth of capacitors you could have a radio that will work well for another 80 years and look very attractive.

People here will guide you through the servicing and restoration, they will take you through step by step if you are patient with us.

If you don't know what you are doing and are not prepared to learn, ask questions, listen to advice given and do a decent job on the radio then you should sell it on to someone who can do a good job.
Mike
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Old 13th Apr 2020, 9:12 pm   #36
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Default Re: Kolster Brandes 666 Valve radio restoration.

Hi Mike
O.K understand what you are saying , and i could have a ago at replacing few components myself have done bit of soldering work before , i would not like to see it go up in smoke , wondering if possible you could possibily download picture ive attached and mark which ones would need replacing on picture i have uploaded (edit / draw on picture/point and re-upload , so then i can check on the radio for accesibility with a soldering iron , plus types of caps or anything ealse that may require changing ,and are the components available on Ebay ? , will take some better pictures of underneath of chassis tomorrow

Best Regards

Clive
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Old 13th Apr 2020, 10:43 pm   #37
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Default Re: Kolster Brandes 666 Valve radio restoration.

If you send me the full size image It will be easier to identify and mark.
I will PM my email address.
Mike
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Old 14th Apr 2020, 11:51 am   #38
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Default Re: Kolster Brandes 666 Valve radio restoration.

A potential difficulty is that the set has a cardboard capacitor box. It will need to be restuffed or removed and discrete capacitors fitted in its place.
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Old 14th Apr 2020, 8:05 pm   #39
real0real
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Default Re: Kolster Brandes 666 Valve radio restoration.

Quote:
Originally Posted by crackle View Post
If you send me the full size image It will be easier to identify and mark.
Hi Mark have sent few pictures

Best Regards

Clive
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Old 14th Apr 2020, 9:17 pm   #40
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Default Re: Kolster Brandes 666 Valve radio restoration.

Hi Clive
By the way the name is Mike.
Thanks for the photos. I will also post this reply on the forum so that others can also comment.
I have to say that you have taken on a mammoth task.
I have been restoring KB radios for the last 10 years and I admit to finding this set a little daunting.
To get this radio working reliably about 90% of the capacitors must be changed.
That's about 19 or 20 capacitors to change. They are nearly all "waxed paper" capacitors and these unfortunately had a very short life expectancy. The problem is the wax impregnated paper, which is used as the dielectric in the capacitor, over time absorbs moisture and the capacitor breaks down allowing DC current to pass through.
Normally a capacitor will block all DC current and only allow AC current (radio and audio signals are an AC current) to pass through.
If DC current passes through a capacitor then it is called "leaky" the DC current will cause unwanted voltage to leak into parts of the circuit where it will do a lot of harm.

I note you have removed all the valves, it is useful to identify where each came from and note the type number of the valve to compare against the chassis drawing in the service document.
Whilst the valves are out you can check the heater on each valve to see it it is OK, if the heater is OK then the valve will probably also be OK and serviceable. Valves are generally very reliable and seldom need replacing.
Some details of the valve pins can be seen on page 14B of the KB document. You can also check online for the valve base pin numbers. The radio museum page https://www.radiomuseum.org/r/kolste...ostat_666.html will give a link to each of the valve types. e.g. https://www.radiomuseum.org/tubes/tube_9a1.html


Anyway these are the steps I would take first to tackle the restoration of this radio.
Download the KB service document, if you haven't already, I recommend you print it out as I find it useful to find the components and to mark off what you have checked and replaced.
The transformers and the speaker energising coil need to be checked to see if they are serviceable, if any of these are damaged then it will become a very expensive restoration.
When carrying out resistance measurements it is essential to have a clean bright metal connection to the meter test probes. You should set the meter to the correct range depending on the expected reading. The resistances of the transformers and coils is all contained in the KB service document.
1, The mains transformer PRIMARY and SECONDARY windings need to be checked and the resistance of the windings noted.
2, The output transformer PRIMARY must be checked and again the resistance noted.
3, The Loudspeaker has an electromagnet field coil which also doubles as a choke in the HT circuit to help with the smoothing. The resistance of the field coil needs to be measured.

So lets start with checking the transformers and field coil.
Let us know the resistance of each winding.

Mike
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