Dansette Conquest auto mk2 (Actually a mk1).

[Cobaltblue]

You seem to have two faults.

Have you checked the output Transformer Primary for continuity and is it connected? (There doesn't Seem to be any HT on the anode of the Pentode pin 6)

secondly you don't seem to have any HT (I would expect 80 to 100V) on the triode anode pin 9.

Cheers

Mike T

[Skintin]

took a reading across the rectifier and its reading 249.0 v dc

[Station X]

Across the rectifier is not the place to measure HT. Measure the DC voltage on the smoothers. Chassis to each of the 32uF tags.

[Skintin]

If 1 have done it right then I get 241.0V across one of the 32uF tags and 228.0V across the second. The 25uF is reading 88.0V

[ms660]

Switch off...

Lawrence.

[Skintin]

Switched off.

[Skintin]

What should they be reading? Just in case my measurements were wrong!

[ms660]

The voltages on the two 32uf capacitors are OK for the moment, the voltage across the 25uf shouldn't be any higher than around 10 volts according to the schematic I'm looking at, if it was indeed 88 volts across that capacitor the capacitor will be under a lot of stress and could go bang if left switched on.

That capacitor bypasses the cathode resistor of the output valve, tag 2 of the valve holder is the cathode connection, tag 2 should read 390 ohms or thereabouts between it and the chassis, with the power off of course.

Lawrence.

[Clydeuk]

Apologies if I'm wrong here but in your pictures the transformer only appears to be attached with one screw and is overhanging the chassis on the other side. Unless this attaches somewhere else when the chassis is in situ it suggests to me that it has been replaced at some time as I doubt the manufacturer would have attached it with just one fixing.

Your readings suggest there is no HT at pin 6 of the ECL82, this comes via the output transformer and since you appear to have HT at the capacitor I'm thinking either your transformer primary could be open-circuit or wired incorrectly.

[Skintin]

the reading I'm getting is 0.446 across tag 2 and the chassis

[Edward Huggins]

Originally Posted by Station X

OK. The only Dansette I can see with the combination of electrolytic capacitors you describe, an ECL82 and a solid state rectifier, as shown in your pictures is a Dansette Monarch.

No, it's a Dansette "Conquest" Mark 1 version. The Dansette "Monarch" used the same amplifier, but using two 8" x 5" speakers. Edward

[TonyDuell]

I am puzzzled as to how you can have 88V across the 25uF capacitor, which is connected between the cathode of the output pentode and ground, but not have 88V on any pin of the ECL82.

[Cobaltblue]

Originally Posted by Skintin

the reading I'm getting is 0.446 across tag 2 and the chassis

No idea which tag Tag 2 is but if that reading is in Ohms it sounds like the secondary.

Can you take a reading on the ohms range with everything switched off between the ECL82's pin 6 and the + connection of C7 the 32 ufd smoothing capacitor.

It doesn't matter which way around the meter is connected.

Looking at your pictures again the Red wire to the output transformer looks to be HT from C7 and the Blue Wire to pin 6 of the ECL82

You should be able to follow the wires between these two points back to the output transformer just to make sure they are all connected.

Cheers

Mike T

[Skintin]

The reading across pin 6 and the positive side of the 32uF is 293 ohms

[Station X]

That indicates that the primary winding of the output transformer is intact and you should see a voltage on the anode of the ECL82 ie pin 6.

The current path is C7/rectifier -> output transformer primary -> pin 6.

What resistance do you measure across C6, which is in parallel with the cathode bias resistor? Expect about 390 ohms.

[Skintin]

Good morning chaps.

Graham. How do I do that? I can see C6 is the 25uF in the smoothing cap, but what is the cathode bias resistor?

[peter_sol]

You have not answered the question about pin counting from under the valve holder clockwise starting from the gap.
If you could give the voltage readings again please.

['LIVEWIRE?']

Answering 'on Graham's behalf!', the Cathode bypass resistor is R11 (390 ohm) connected between pin 2 of the ECL82 and chassis (in the diagram in Graham's post #35). As shown on that diagram 10volts should be present across R11, and thus also across C6 (the 25uf capacitor across which you have said 88 volts was measured). As Cobalt Blue (Mike T) has said double check that there is a connection between C6 +ve and pin 2 of the EC82, so that you measure 390 ohms across C6, with the power switched off. If not, check for such things as breaks in the printed circuit tracks, dry solder joints, etc. before replacing any components.

[Skintin]

hi livewire

I have measured across the R11 390 resistor and getting 460 ohms.

[Skintin]

Voltage readings for the ECL82 valve

1. 0.966mV fluctuating. (Control grid of triode section).
2. 12.5V fluctuating (Cathode of pentode section).
3. 24.4mV fluctuating (Control grid of pentode Section)
6. 0.2mV fluctuating (Anode of pentode section)
7. 153.0V (Screen grid of pentode section)
8. 6.6mv (Cathode of triode section)
9. 1.72mv fluctuating (Anode of triode section)