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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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12th Nov 2021, 1:11 pm | #1 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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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. |
12th Nov 2021, 2:06 pm | #2 |
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Location: Exeter, Devon and Poole, Dorset UK.
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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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12th Nov 2021, 2:55 pm | #3 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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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. Last edited by ms660; 12th Nov 2021 at 3:12 pm. Reason: extra info |
12th Nov 2021, 4:13 pm | #4 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
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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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Edward. |
13th Nov 2021, 1:59 pm | #5 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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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 |
13th Nov 2021, 5:17 pm | #6 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Dansette conquest auto sound output
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26th Nov 2021, 2:05 pm | #7 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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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 |
30th Nov 2021, 8:50 pm | #8 |
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Location: Ipswich, Suffolk, IP4, UK.
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
6th Dec 2021, 11:33 am | #9 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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Re: Dansette conquest auto sound output
Hi, I have fitted an EBC91 and a EL90 as per previous advice in this listing.
Regards. |
6th Dec 2021, 2:00 pm | #10 |
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Location: Ipswich, Suffolk, IP4, UK.
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
7th Dec 2021, 12:18 pm | #11 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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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 |
9th Dec 2021, 4:49 pm | #12 |
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Location: Ipswich, Suffolk, IP4, UK.
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
11th Dec 2021, 6:07 pm | #13 |
Diode
Join Date: Nov 2021
Location: Walton on Thames, Surrey, UK.
Posts: 7
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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 |
11th Dec 2021, 6:20 pm | #14 |
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Location: Ipswich, Suffolk, IP4, UK.
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |