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Old 12th Nov 2021, 1:11 pm   #1
sparkimark
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Angry Dansette conquest auto sound output

Hi all
just dug out my old dads Dansette conquest auto and surprise surprise everything works!........... except the sound!
both Valves lit up, amp had sligth hum, so purchased a new medium output tc8 cartridge and great all working, well for about 3 minutes. After that the sound gradually deteriorated.
if left for a while, worked well again for about 3 mins, good sound good output then gradually deteriorated
Any help would be appreciated
thanks in advance
Mark.
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Old 12th Nov 2021, 2:06 pm   #2
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Default Re: Dansette conquest auto sound output

Hi Mark and welcome to the forum.

I am not sure which amplifier this uses but I suspect its the one with the 6V6 output.

It's likely that the coupling capacitor on the grid of the 6V6 is electrically leaking.

It will probably be a 0.01μF if you show some pictures of the amplifier we will soon know.

Don't keep using it like this as it can do some expensive damage

Cheers

Mike T
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Old 12th Nov 2021, 2:55 pm   #3
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Default Re: Dansette conquest auto sound output

Another two valve amplifier (also fitted to the Conquest Auto) is the 14-4 type, part schematic enclosed, the mains transformer and rectifier circuit is missing but that shouldn't be any big deal (half wave selenium rectifier etc) C4 is the output valves control grid coupling capacitor.

Lawrence.
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Old 12th Nov 2021, 4:13 pm   #4
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Default Re: Dansette conquest auto sound output

The EBC91 and EL90 circuit will be the one. These were fitted to the earliest of the Conquest Autos. The DC voltage after the rectifier should also be checked and should read about 220V. NB: Do remember that the TC8M cartridge you have fitted is as the original - but - it will permanently damage Stereo LPs.
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Old 13th Nov 2021, 1:59 pm   #5
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Default Re: Dansette conquest auto sound output

hi all,
thanks for the advice, im only playing 78's
im trying to attach a pic of the amp but im not too computer literate so struggling, but bear with me
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Old 13th Nov 2021, 5:17 pm   #6
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Default Re: Dansette conquest auto sound output

Looks like the 14-4 amplifier:

https://www.vintage-radio.net/forum/...ad.php?t=97373

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Old 26th Nov 2021, 2:05 pm   #7
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Default Re: Dansette conquest auto sound output

Hi All,
pardon my ignorance guys, but im really not sure what it is i need to replace here. ive put in a couple of brand new valves, but same issue. is there anyone who can give me guidance please. im able to solder ok , im just not sure which componant to replace or where to purchase a replacement.
Or is there anyone out there that would be willing to carry out a repair for me?
Thanks in advance
Mark
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Old 30th Nov 2021, 8:50 pm   #8
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Default Re: Dansette conquest auto sound output

Before going any further please can you confirm what valves are fitted in your player.
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Old 6th Dec 2021, 11:33 am   #9
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Default Re: Dansette conquest auto sound output

Hi, I have fitted an EBC91 and a EL90 as per previous advice in this listing.

Regards.
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Old 6th Dec 2021, 2:00 pm   #10
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Default Re: Dansette conquest auto sound output

If the original valves were of the same type, then this is a 14-4 amplifier as per the circuit in post #3.

Do you have a multimeter?
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Old 7th Dec 2021, 12:18 pm   #11
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Default Re: Dansette conquest auto sound output

I believe the valves are of the same type, but were purchased following advise from a previous post.
yes i have a multimeter
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Old 9th Dec 2021, 4:49 pm   #12
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Default Re: Dansette conquest auto sound output

Check that, with the fault present, there's no positive voltage present on the control grid of the output valve.
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Old 11th Dec 2021, 6:07 pm   #13
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Default Re: Dansette conquest auto sound output

hi, youve lost me now, do you know of anyone who would be willing to repair it , if i was to remove it from the player and send it to the repairer?
regards,
Mark
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Old 11th Dec 2021, 6:20 pm   #14
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Default Re: Dansette conquest auto sound output

The output valve is the El90. Its control grid is connected to pin 7. Pins number clockwise from the gap when looking a the valveholder from UNDER the chassis. Measure the DC voltage between pin 7 and chassis. Start with your meter set to it's highest range and switch down the ranges until you get a sensible reading which should be close to zero volts.

In fact you could usefully check the voltages on all pins of the valve except pins 3 and 4 which are the heater connections. Post the results here for analysis.

If you want someone to repair the player for you should post in the Repair and Restoration Services Wanted section of the forums.
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