5th Dec 2016, 8:11 pm | #61 |
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Re: Tandberg 64x after changing capacitors
Thanks Lawrence, R224 measures right...also against the cap next to it. Also I have measured voltages between:
R224 -----C214 neg rod about 95-105 V R224 -----------R208 R224------------R214 C214 positive and R214 (if i remember correctly) There should be no break in the circuit..... |
5th Dec 2016, 8:17 pm | #62 |
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Re: Tandberg 64x after changing capacitors
I am lost now....shall i try a set of other ecc83s? or other caps/resistors in the c215 c216 area...? I am just guessing really.... its a real pain in the...
Could be something wrong at the connection point 22 or 27? Or actually only at point 27? It goes all the way around...not sure what voltage comes in at point 22....at point 27 there are two small resistors...could be some issue there..maybe i should measure them too... Last edited by Levente; 5th Dec 2016 at 8:35 pm. |
5th Dec 2016, 9:23 pm | #63 |
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Re: Tandberg 64x after changing capacitors
Don't change any valves. They are not the cause of your problem.
It will do no harm to measure resistors. I'm busy doing other stuff at the moment, but will look at the circuit later if Lawrence doesn't beat me to it.
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5th Dec 2016, 9:32 pm | #64 |
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Re: Tandberg 64x after changing capacitors
Well...I did write what's below a while ago but decided at the time to highlight,copy and hold it for a while, anyways for what it's worth here it is now:
As Graham has already pointed out, the two anode voltages for V6 are for all intents and purposes non existent, the anode voltages for V8 are existent (the last time you measured) So somewhere the voltage is disappearing between the anodes of V6 and the point where the HT feeds the anode load resistors for V8, that leaves the two anode load resistors for V6 (R208 & R214) their associated the HT feed resistor (R224) C214, a break in the printed circuit (or other poor connection) or a short. You have already measured the resistance values of R208, R214 and R224 and you say they check out ok. It would now help if you measured the voltages pertaining to those resistors, measured at the resistors themselves, such as shown below, I know you've already measured some voltages but it would be handy to see everything in a table as shown below: R208, anode end (enter voltage measurement) R208, HT feed end (ditto) R214, anode end (ditto) R214, HT feed end (ditto) R224, HT out end (ditto) R224 HT in end (ditto) Lawrence. |
6th Dec 2016, 12:07 am | #65 |
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Re: Tandberg 64x after changing capacitors
I endorse what Lawrence has said, but must admit I hadn't actually identified V6 as the culprit.
An extract from the circuit is attached. You need to measure the voltages as specified by Lawrence with respect to what you call C214 neg rod. This assumes that if C214 has been replaced, the new component is the right way round.
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6th Dec 2016, 7:53 am | #66 |
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Re: Tandberg 64x after changing capacitors
Thank you so much Lawrence and Graham....
Update: THE C210 WAS SHORT!..,,I am such an idiot, why did I do that, I don't know. Re soldered and I have measured the voltages again against the neg. rod of C214. I think something still not right? 1: 125 2: 0 3: 7 4: 0 5: 0 6: 90 7: 13 8: 0 9: 1 At the pin 5 should not be 12V~? Please bear in mind, you guys are dealing with an idiot here... |
6th Dec 2016, 9:36 am | #67 |
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Re: Tandberg 64x after changing capacitors
Some of those voltages don't quite make sense to me, for instance V6b's grid shows 13 volts but the cathode shows 0 volts.
V6a's cathode voltage shows it to be too high. Yes, pin 5 of V6 should be approx. 12 volts DC, pin 4 should be approx. 6 volts DC. I would check them again but with respect to point 27 on the board as that is the HT-ve line, sometimes referred to as chassis or ground/earth. Any low voltage measured such as less than 1 volt should be recorded thus: Eg: 0.7 volts.... Not .7 volts, it tends to eliminate any possible misinterpretation of the voltage recorded. Lawrence. |
6th Dec 2016, 10:10 am | #68 |
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Re: Tandberg 64x after changing capacitors
Also Sometimes it pays to measure each voltage twice just to make sure the meter probe is making good contact and that there's no misinterpretation with the decimal point if using a DMM.
Lawrence. |
6th Dec 2016, 10:38 am | #69 |
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Re: Tandberg 64x after changing capacitors
C210 was short circuit. It feeds the signal to V6B's grid which is now at too high a voltage.
I wonder if R212 (1k) has been damaged?
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6th Dec 2016, 7:59 pm | #70 |
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Re: Tandberg 64x after changing capacitors
I really appreciate your help and time guys on this...
Here is what I have checked. The resistor you have mentioned Graham has 0.9 kOhm (no power on)..i think that survived the "stress" i have put on...luckily. I had a bit of difficulties finding which pin is where on that particular tube Lawrence and I think I have mistaken the order of the pins...coming home after work very tired and my eye is not set to read properly this time...I have rechecked now and this is how it looks like: pin1: 126V (anode) pin2: -002 (which I believe is 0.004V) (grid) pin3: 1V (cathode) pin4: -002 (0.002V) (heater) pin5: 13V (heater) pin6: 91V (anode) pin7: -096 (o.096V) (grid) pin8: 0.68V (cathode) pin9: 6V (heater centre tap) are these so far correct? Thank you. |
6th Dec 2016, 8:06 pm | #71 |
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Re: Tandberg 64x after changing capacitors
That's looking a lot better. To all attempts and purposes the grids are at zero volts.
I'll have a look at your other readings further up the thread in post #42.
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6th Dec 2016, 8:10 pm | #72 |
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Re: Tandberg 64x after changing capacitors
Yes, that valve (V6) looks all set to function so far.
Lawrence. |
6th Dec 2016, 8:15 pm | #73 |
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Re: Tandberg 64x after changing capacitors
Awesome...how about pin 4? should not be 6V? Shall I re measure all tubes against the neg rod of a capacitor?
Thanks guys. |
6th Dec 2016, 8:21 pm | #74 |
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Re: Tandberg 64x after changing capacitors
The heaters are OK.
You have 0V on one end of the heater, 13V on the other and 6V on the centre tap. That's fine.
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6th Dec 2016, 8:24 pm | #75 | |
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Re: Tandberg 64x after changing capacitors
Going back to post #42.
Quote:
Connect the meter's negative lead to wherever it was connected when you tested the ECC83's.
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6th Dec 2016, 8:32 pm | #76 |
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Re: Tandberg 64x after changing capacitors
Pin 4 of V6 should be 0 volts, you have a very small voltage reading there but that should be of no consequence so no problem, pin 9 should have the 6 volts on it which it seems to have so again no problem.
The voltage measurements should be referenced to HT-ve (ground/chassis etc) you can use the negative connection of one of the electrolytic capacitors as the reference point for your voltage measurements providing you are sure it's connected to HT-ve, point 27 on that board can also be used as that is definitely connected to HT-ve. The important thing when posting voltage measurements etc on the forum is that you have read the meter readings correctly, written them down and typed them up correctly and that the reference points (valve pins etc) are portrayed correctly in the post you submit, it can save a lot of confusion and time. EDIT: Post crossed with Graham's. Lawrence. |
6th Dec 2016, 8:39 pm | #77 |
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Re: Tandberg 64x after changing capacitors
Lawrence.
I think there may be an earth discontinuity problem here, as taking readings to what I assumed was the chassis gave totally wrong readings.
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6th Dec 2016, 8:49 pm | #78 | |
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Re: Tandberg 64x after changing capacitors
Quote:
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6th Dec 2016, 9:22 pm | #79 |
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Re: Tandberg 64x after changing capacitors
Hi Graham, Lawrence.
I did another reading. Reference point for to the neg rod was pint 27. Start with the two ECC 82s 1: 53V ----------- 1: 42V 2: 001V ----------- 2: 0V 3: 1V ---------- 3: 1V 4: 13V ---------- 4: 13V 5: 26V ---------- 5: 26V 6: 202V ---------- 6: 202 V 7: 6V ---------- 7: 6V 8: 30V --------- 8: 30V 9: 19V --------- 9: 19V --------------------------------------------------------------------------- Two EEC 81s 1: 142V ----------------- 1: 88V 2: 0.006V ----------------- 2: 0V 3: 2V ----------------- 3: 2V 4: 13V----------------------- 4: 13V 5: 26V ----------------- 5: 26V 6: 71V ---------------- 6: 73V 7: 0V -----------------7: 0.065 V 8: 0 V ----------------- 8: 1V 9: 19V ----------------- 9: 19V ----------------------------------------------------------------------------- and the 4 ECC83s 1: 133V--------128V------127V-------126V 2: 0.006V-------0V--------0V---------0.004V 3: 1V------------1V--------1V----------1V 4: 0V------------0V---------0V---------0.002V 5: 13V----------12V--------13V----------13V 6: 140V---------129V-------93V----------91V 7: 0.06----------0.01V-------0V----------0.09V 8: 0.06V---------1V----------0V----------0.64V 9: 6V------------6V-----------6V------------6V ------------------------------------------------------------------ On the ECCs 83 the pin 6 voltages declining from tube to tube (left to right on the panel) and the one ECC81 pin1 has only 88Volt. I have purchased this tube few weeks ago as brand new...the Ecc 82s readings are nearly identical.... Shall I test the unit how it sounds or is it tooo early? |
6th Dec 2016, 9:52 pm | #80 |
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Re: Tandberg 64x after changing capacitors
The ECC83 readings are good enough. Not quite as per the service sheet, but resistors may have changed value slightly
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