17th Apr 2020, 2:11 pm | #81 | |
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Re: Kolster Brandes 666 Valve radio restoration.
Quote:
Check voltages to R14 just to confirm that the centre tap is intact.
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17th Apr 2020, 2:21 pm | #82 |
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Re: Kolster Brandes 666 Valve radio restoration.
I have to do other stuff now.
Assuming you get 300VAC on each half of the secondary winding. Insert JUST V6 and power up the radio via a test lamp if you have one. Check that V6 lights up. Check that the capacitor box C19, C20 and C21 doesn't get hot. The test lamp should be dim. Measure the DC voltages across R10, R11, R12 and R13, and report back.
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17th Apr 2020, 5:10 pm | #83 |
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Re: Kolster Brandes 666 Valve radio restoration.
Update
Checked the valve tube inserts and the furthest apart would be anode 1 and 2 as found when tested orintated at 90 degrees Inserted volt meter probe into valve tube prong holder and checked the voltage to R14 Tap from transformer Each gave a individaul reading of approx 3OOV Inserted the 6v Tube valve and with the lamp limiter connected in parallel on live Proceeded to power up the set , The lamp limiter bulb glowed slightly and the R6 Valve illuminated Checked the C19 for over heating found to be o.k Porceeded to check the voltage following results acquired R13 reading of 610V R12 reading of 294V R11 reading of R178V R10 , not managed to acquire a reading yet , tried but possible pronging at wrong point , will need look again tomorrow bit closer Have attached couple of pictures Clive Last edited by real0real; 17th Apr 2020 at 5:25 pm. |
17th Apr 2020, 5:19 pm | #84 |
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Re: Kolster Brandes 666 Valve radio restoration.
You've certainly got some HT which is good, but the readings look a bit strange.
Are you measuring ACROSS each resistor in turn? ie one meter lead to each end of the resistor being tested?
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17th Apr 2020, 5:49 pm | #85 |
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Re: Kolster Brandes 666 Valve radio restoration.
I was checking for voltage current where the common would be earth and pronging positive postive of resistor wire of each resistor to get a voltage reading flowing through , not actualy checking the resistance of each across the resistor terminal ends ,
One thing i noticed as in picture attached R11 and R12 resistors appear to be connected together Last edited by real0real; 17th Apr 2020 at 6:00 pm. |
17th Apr 2020, 5:55 pm | #86 |
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Re: Kolster Brandes 666 Valve radio restoration.
Forget about resistance and current. What you need to measure is DC Volts. Measure the voltage ACROSS each of the resistors in turn.
In most cases voltages are measured with respect to chassis, but that's not what I'm asking you to do at present.
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17th Apr 2020, 6:27 pm | #87 |
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Re: Kolster Brandes 666 Valve radio restoration.
Will have a look at again tomorrow and see if i can check these , i think the R13 Resistor may be little tricky as unable to visibily see both ends , have attached picture of
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17th Apr 2020, 6:58 pm | #88 |
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Re: Kolster Brandes 666 Valve radio restoration.
What exactly is that lamp you're using in your limiter? What wattage rating is it? It looks like some sort of decorative job rather than an ordinary GLS tungsten filament typoe.
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17th Apr 2020, 8:06 pm | #89 |
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Re: Kolster Brandes 666 Valve radio restoration.
60 watt bulb / vintage style bulb
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17th Apr 2020, 8:14 pm | #90 |
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Re: Kolster Brandes 666 Valve radio restoration.
It looks like that bulb is glowing at almost full brightness indicating faults, probably with the electrolytic capacitors. (they never seem to be more than an orange glow), https://images-na.ssl-images-amazon....AC_SL1000_.jpg
You may get a better indication of what is happening if you used a standard 60 watt bulb. Normally at this stage you would expect to see a slight burst of bright on the bulb and then it would die down to barely visible. Similar to when the set did not have the rectifier plugged in. What ever you do do not plug the set in with out a lamp limiter, something is likely to go bang. Mike Last edited by crackle; 17th Apr 2020 at 8:27 pm. |
17th Apr 2020, 8:27 pm | #91 |
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Re: Kolster Brandes 666 Valve radio restoration.
The bulb does illuminate quite bright a lot brighter than the link you showed when plugged in direct to mains, think it glows quite well as lamp limiter element wire is much longer and thiner and easier to see, in a way possibly better than shorter element bulb where the element wire would be thicker and harder to see, not have much choice at the moment of trying to get a different bulb at moment as everywheres closed due to corona virus did have a look for one as wasnt that keen on using this type at first
Last edited by real0real; 17th Apr 2020 at 8:43 pm. |
18th Apr 2020, 12:28 pm | #92 |
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Re: Kolster Brandes 666 Valve radio restoration.
Hi
Update , Have rechecked the voltages for the following the DC voltages across R10, R11, R12 and R13 (used crocodile clips each side of the resistor) R13 Getting a reading of 20.2V R12 Getting a reading of 125V R11 Getting a reading of 55V R10 Getting a reading of 0.564 (volt meter set at 2v) Do these appear o.k ? Clive Last edited by real0real; 18th Apr 2020 at 12:41 pm. |
18th Apr 2020, 1:05 pm | #93 |
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Re: Kolster Brandes 666 Valve radio restoration.
No, the voltage across R10 is too low, it could be due to a component short such as C7.
Best way is to measure the voltages with respect to chassis (aka WRT chassis) To do that connect the meters -ve probe (Black) to the chassis then measure the DC voltages along the divider chain R10, R11, R12 and R13.... So, WRT chassis: Voltage at the junction of R10 and R11? Voltage at the junction of R11 and R12? Voltage at the junction of R12 and R13? Voltage at the other end of R13? Lawrence. Last edited by ms660; 18th Apr 2020 at 1:12 pm. |
18th Apr 2020, 1:13 pm | #94 |
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Re: Kolster Brandes 666 Valve radio restoration.
FWIW, assuming an unloaded HT of 350VDC, I calculated the voltages across the potential divider resistors as follows:-
R10 100V. R11 66V. R12 125V. R13 20V. Of course these voltages could be pulled down by leaky screen grid capacitors in the set. Low reading on R10 suggests C7 may be electrically leaky. It would be worth while measuring the resistance of the resistors in the chain.
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18th Apr 2020, 1:37 pm | #95 |
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Re: Kolster Brandes 666 Valve radio restoration.
Update
Retested R10 as before and this time getting a reading of 87 volts noticed there is paint on resistor possible the clip never contacted properly , is this figure closer to reading i shoud be achieving Not full enderstand how / what the procedure to test the resitors in a chain if this needs to be done |
18th Apr 2020, 1:42 pm | #96 |
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Re: Kolster Brandes 666 Valve radio restoration.
That figure is better. Can you confirm that you measure the same voltage across C7 please.
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18th Apr 2020, 1:49 pm | #97 |
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Re: Kolster Brandes 666 Valve radio restoration.
That voltage is more like it.
Time to replace some capacitors. EDIT: Post crossed. Lawrence. |
18th Apr 2020, 1:52 pm | #98 |
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Re: Kolster Brandes 666 Valve radio restoration.
Which takes us nicely back to post #28.
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18th Apr 2020, 1:56 pm | #99 |
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Re: Kolster Brandes 666 Valve radio restoration.
Hi.
Just Checked C7 and can confirm same reading of approx 87V. |
18th Apr 2020, 1:59 pm | #100 |
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Re: Kolster Brandes 666 Valve radio restoration.
That's good. Personally I'd replace C1 before proceeding, but I do have capacitors in stock.
Probably best if you buy all the capacitors needed now and get back to us once you've replaced C1. I don't recommend replacing all the capacitors in one go as it's all to easy to make a mistake. Others may have different opinions.
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