14th May 2016, 9:43 am | #41 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
R11 has risen in value, but that can be sorted later.
You have 12.5V on the cathode which isn't too bad given the higher value of R11, yet you apparently have 88V across the 25uF cathode bypass capacitor which is the same point! Check both readings. You have no volts on the anode pin 6, yet in a previous post you showed the output transformer primary was intact. Check the anode reading again too.
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14th May 2016, 9:50 am | #42 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Suspect R10, 18K? open circuit or C5, smoothing cap, short circuit or possibly latter causing former.
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14th May 2016, 9:54 am | #43 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
If R10 was open circuit surely there'd be no voltage across C5 or on the screen grid of the valve?
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14th May 2016, 9:58 am | #44 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Just to be sure I have showed were I'm getting the 88v from.
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14th May 2016, 10:01 am | #45 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
OK. Check the voltage on all the other soldering points on that PCB track. You can see that one of them is on pin 2 ie the cathode.
It's difficult to tell from the picture, but some of the soldering doesn't look too good.
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14th May 2016, 10:05 am | #46 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
ok graham bare with me, I'm hobbling around on crutches at the moment
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14th May 2016, 10:13 am | #47 |
Octode
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Yes sorry Graham I am getting confused.
No voltage on the anodes of both sections of the valve it seems. But Pentode taking current as cathode near enough. |
14th May 2016, 10:13 am | #48 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Check the voltage with the unit off or on?
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14th May 2016, 10:14 am | #49 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
I'm beginning to doubt whether that is C6. Why? Well there are three other connections to the PCB track. There should only be two ie R11 and pin 2.
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14th May 2016, 10:18 am | #50 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Voltage readings are always taken with the power switched on and the unit plugged into the mains.
Resistance readings are always taken with the power switched off and the unit unplugged from the mains.
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14th May 2016, 10:32 am | #51 | |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Quote:
C6 should have two connections ie R11 and pin 2. C5 should have three connections ie R10, R6 and pin 7. Looking at the soldered side of the PCB valve pins number clockwise from the gap.
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14th May 2016, 10:35 am | #52 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Indeed Peter. That makes good sense.
What we need now are fresh voltages for each pin of the valve (correctly numbered of course) and for each of the three caps in the can.
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14th May 2016, 10:44 am | #53 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
hope this helps...just managed to master arrow pointing on my mac!
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14th May 2016, 11:01 am | #54 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
a new photograph with readings on
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14th May 2016, 11:02 am | #55 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Even allowing for the dubious build quality of most Dansettes, especially with the Margolins' metal saving use of any form of discernable chassis, that Mains transformer looks as if has swung out (on that one bolt) by 90 degrees? It looks like, but may not be, the original. Assume it measures well on its secondary? Edward
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14th May 2016, 11:10 am | #56 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
for the caps measurement
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14th May 2016, 11:28 am | #57 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
You're measuring the wrong points.
Put the NEGATIVE lead of your meter on the tag at the three 'o' clock position in your picture. That's the chassis/ground. Then apply your meter to each of the other three tags of the cap in turn. You should use the same ground when checking voltage readings on the valve.
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14th May 2016, 11:34 am | #58 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
i have took some more readings. placed the neg onto the chassis as pictured and took the following readings.....
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14th May 2016, 11:38 am | #59 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
Much better!
Did you measure the voltage on the valve pins with respect to ground? It appears you have low voltage on pin 9, the anode of the triode and I can see a vacant hole on the PCB track leading to it.
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14th May 2016, 11:39 am | #60 |
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Re: Dansette Conquest auto mk2 (Actually a mk1).
cheers graham...i changed it to your setting and get the same reading as the photo albeit a little higher but nothing dramatic
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