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Old 13th Jan 2017, 4:07 pm   #161
ms660
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Default Re: Tandberg 64x after changing capacitors

Yes, so far as I can make out, pins 2 are the grids.

Lawrence.
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Old 13th Jan 2017, 4:21 pm   #162
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Default Re: Tandberg 64x after changing capacitors

Okay...

The opposite tube of V5 (not sure is it the V7 or8? ) pin 2 has a very little hum, while the opposite tube of V6 has huge hum, same volume as the pin 7 of the V5.

Are these pairs such V5 is a pair of V7 (opposite of each other) and the V6 is pair with V8?
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Old 13th Jan 2017, 4:37 pm   #163
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Default Re: Tandberg 64x after changing capacitors

The valve opposite V5 (ECC83) on the other side of the switch is V7 (ECC82)

The valve opposite V6 (ECC83) on the other side of the switch is V8 (ECC82)

Can you confirm again the result of the hum test on pin 2 of V7 and on pin 2 of V8.

Lawrence.
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Old 13th Jan 2017, 4:41 pm   #164
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Default Re: Tandberg 64x after changing capacitors

Thanks Lawrence,

V7 pin 2 is very weak hum (same as pin 7 on V6)

V8 pin 2 huge hum (exactly the same as pin 7 on V5)

The result is like an "X" in terms of similarity between the tubes...none of the opposite tubes of each oother has similar readings but they have in an "X" shape...V5 readings equals of V8 and V6 equals of V7.
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Old 13th Jan 2017, 4:51 pm   #165
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Default Re: Tandberg 64x after changing capacitors

CORRECTION:

V7 has NO hum at all on pin 2.

V6 has less hum than the V5 on pin 7.

V8 pin 2 has equal hum to V5 on pin 7.

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Old 13th Jan 2017, 4:55 pm   #166
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Default Re: Tandberg 64x after changing capacitors

I have re done the test, and correcting on thing, the V7 has no hum at all on pin 2



V7 has NO hum at all on pin 2.

V6 has less hum than the V5 on pin 7.

V8 pin 2 has equal hum to V5 on pin 7.

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Old 13th Jan 2017, 5:20 pm   #167
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Default Re: Tandberg 64x after changing capacitors

Ok, the results up to the last test made sense but the last test seems to conflict with those previous tests...Never the less, you can do another hum test, same valves as last time, V7 and V8, this time it's pin 7 on each valve, you might have to turn up the output level control (volume) even further.

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Old 13th Jan 2017, 5:25 pm   #168
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Default Re: Tandberg 64x after changing capacitors

Okay,

V7 and V8 pin 7 has a very little hum, very high frequency hum but the same on each pin 7.

The other "hums" on V5 and V6 ver very loud on my previous test and sounded more like 60 cycles hums.

The V7 and V8 hums on pin 7 are much faster, more cycles than 50 or 60....barely hear-able...the V8 hum on pin 2 is a very loud hum, again like a 60 cycles hum...different to the pin 7.

Thanks Lawrence!
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Old 13th Jan 2017, 5:34 pm   #169
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Default Re: Tandberg 64x after changing capacitors

This:

"Okay...just tested it

The first tube I believe is the V5 pin 7 has huge hum..much louder than the C205 cap had...

Th other tube V6 pin 7 has no hum, just a tiny little noise when i touch it for a second...like an electrical tiny little pop, but definitely no hum there at all.."

Contradicts this:

"The other "hums" on V5 and V6 ver very loud on my previous test and sounded more like 60 cycles hums."

Lawrence.
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Old 13th Jan 2017, 5:37 pm   #170
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Default Re: Tandberg 64x after changing capacitors

Yepp...the V6 has a hum on pin 2, pin 7 has no hum.

Sorry i think I got confused on the pin's....
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Old 13th Jan 2017, 5:41 pm   #171
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Default Re: Tandberg 64x after changing capacitors

I think I am gonna start again measuring the pin 2s and pin 7s on each tubes and report it back
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Old 13th Jan 2017, 5:48 pm   #172
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Default Re: Tandberg 64x after changing capacitors

V5
Pin 2= huge hum
Pin 7= huge hum

V7
Pin 2= NO hum
Pin 7= Barely hear able high frequency hum

V6
Pin 2= NO hum
Pin 7= Hum, but weaker compare to V5

V8
Pin 2= huge hum
pin 7= Barely hear able high frequency hum

I hope better this way as I got confused on pin 7 and V7 i think...sorry
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Old 13th Jan 2017, 6:23 pm   #173
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Default Re: Tandberg 64x after changing capacitors

Thanks Lawrence,

All the tubes a lit up visually okay.

V5s

pin 6 = 126V
pin 7 = -0.08V
pin 8 = 0 V

Thats what i measured just now....
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Old 13th Jan 2017, 6:44 pm   #174
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Default Re: Tandberg 64x after changing capacitors

I've deleted the last post I made, there was an error in it, I'll post again in a bit, I'm on dish washing and fire lighting duty

Lawrence.
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Old 13th Jan 2017, 6:46 pm   #175
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Default Re: Tandberg 64x after changing capacitors

)) that's okay..thanks man for all the help so far! Levente
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Old 13th Jan 2017, 8:05 pm   #176
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Default Re: Tandberg 64x after changing capacitors

Ok lets eliminate the possibility of one of the playback heads being open circuit or a discontinuity/high resistance in the wiring/connections to them, power off and do a resistance test, a resistance test between chassis and the junction of C205 and R201, then a resistance test between chassis and the junction of C206 and R202.

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Old 13th Jan 2017, 8:33 pm   #177
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Default Re: Tandberg 64x after changing capacitors

Okay, i have measured the two resistors and both of them are measuring 256 Ohms.

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Old 14th Jan 2017, 8:19 am   #178
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Default Re: Tandberg 64x after changing capacitors

...on the playback PCB all the capacitors had been changed besides these:

C201
C203
C202
C204
C215
C216
C219
C220

the C 201 and 203 are a brown drop tantalum? or ceramic looking caps, the C 203 and 204 a silvery looking with some pink liquid inside, some styrolfex or polystyrene types?

and the rest are Hunts caps, these are also covered with some ceramic hard casing...

shall I just go ahead and change all of these? I have removed two resistors out of the pcb to test them and they were gave me OK reading. R201 and R202. I can not remember the exact readings as It as months back, but i've put them back in place.

The oscillator board is also full of plystyrene caps, and one big one which I can not see what it is without taking it out..looks like some electrolyt of old Siemens or sthing...

i am just really guessing as I am totally lost...damn.

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Old 14th Jan 2017, 10:13 am   #179
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Default Re: Tandberg 64x after changing capacitors

Quote:
Originally Posted by Levente View Post
Okay, i have measured the two resistors and both of them are measuring 256 Ohms.
That appears to be ok.

More DC voltage measurements now with respect to chassis, all pins of V5 and all pins of V6, if their heaters are lit up then you don't need to measure pins 4, 5, and 9.

Don't change anymore components yet.

Lawrence.
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Old 14th Jan 2017, 10:33 am   #180
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Default Re: Tandberg 64x after changing capacitors

Weird readings....

V5
pin 1: 138V
pin 2: -0.64 HUGE buzz when I touch this on my headphone
pin 3: 1V
pin 4: 0.01V
pin 5: 12V
pin 6: 130V
pin 7: -0.08V
pin 8: 0.32V
pin 9: 6.63 V

V6
pin 1: 128V
pin 2: 0V
pin 3: 1V
pin 4: 0.01V
pin 5: 13V
pin 6: 96 V
pin 7: -0.06V
pin 8: 0,6
pin 9: 6.41 V

Levente

Last edited by Levente; 14th Jan 2017 at 10:39 am.
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