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Old 19th Feb 2018, 3:48 pm   #81
martinpinner
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Default Re: Dansette Bermuda MK II ??

In my post 66 I show a photo of the sufflex capacitors fitted and questioned if number 5 should also be making contact with the PCB circuit below.I have just been on a "stickie" for a Bermuda Mk 11 with a sound problem and there is a photo of the PCB board showing the capacitor being connected to the circuit below. Could this have an effect on the sound? See photo.

Also, checks were done on the valves to check voltage and resistance but as I had sound before I took the deck off and replaced the capacitors mentioned whether I would need to do this.

With regard to auto changer it is now operational but the pick up arm only takes it just onto the record but not far enough to get onto the "lead in". It also returns before it reaches the end of the record. Is this still a mechanical issue (trip pawl) or is there an adjustment that can be made somewhere.
Martin
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Old 19th Feb 2018, 4:06 pm   #82
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Default Re: Dansette Bermuda MK II ??

It looks to me like you've got three tracks bridged there.

Have you traced out the PCB tracks and compared them with the circuit diagram?
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Old 19th Feb 2018, 5:17 pm   #83
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Default Re: Dansette Bermuda MK II ??

My post 66 shows my board and that has the capacitor on only one circuit.It is not bridged on the circuit below even though may look like it is.

I am still a Novice at this especially with circuit diagrams.If you are able to assist it would be appreciated - the circuit was posted on 41.
Martin
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Old 19th Feb 2018, 5:21 pm   #84
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Default Re: Dansette Bermuda MK II ??

Looking at all the photo's so far the schematic doesn't tally up with what's on the ground, in particular the tone control, in the player it's a three wire connection, not so on the schematic, one of those connections (the wiper) is connected to the anode of the triode pin 9) via a capacitor, that capacitor goes from pin 9 to what appears to be a spare tag on the output transformer, from that tag a blue wire connects to the wiper of the tone control.

You can see that capacitor and the blue connecting wire in the posters own photo's and the one he has just uploaded from a completely separate thread, needs reverse engineering along with anything else and the schematic amended accordingly.

Aside from the above, I think the capacitor (C5) that was being referred to is in fact C8 when numbering the capacitors from left to right on the schematic.

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Old 19th Feb 2018, 5:40 pm   #85
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Default Re: Dansette Bermuda MK II ??

The long track running along the bottom of the PCB goes to pin 2 of the UCL82 ie the cathode.

If the Dansette diagram is to be believed, the only components connected to that pin should be the cathode resistor and the feedback capacitor. In the picture appended to post 66 there's what appears to be a ceramic capactor connected to that track, It may be the feedback capacitor or it may be part of a tone control circuit wired differently to the circuit.

As Lawrence says, reverse engineering is needed.
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Old 19th Feb 2018, 5:56 pm   #86
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Default Re: Dansette Bermuda MK II ??

If that capacitor (C8) is joined to that bottom print track the other end should go to a white wire that goes to the 10k resistor on the control panel, if that's so then it's the feedback capacitor from the cathode of the pentode.

Lawrence.

Last edited by ms660; 19th Feb 2018 at 5:58 pm. Reason: ammended
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Old 19th Feb 2018, 5:59 pm   #87
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Default Re: Dansette Bermuda MK II ??

Picture of a similar 14-14 amplifier. No sign of the Mullard Mustard.
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Old 19th Feb 2018, 6:19 pm   #88
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Default Re: Dansette Bermuda MK II ??

And another one, this one appears not to have a three wire feed to the tone control, just the single blue wire and the other end of the blue capacitor would appear to connect to the anode of the pentode as per the schematic, I would think that one end of the tone pot track is grounded at the control panel, I think there was some production variants for sure:

https://www.vintage-radio.net/forum/...1&d=1392465351

Thread for the above here:

https://www.vintage-radio.net/forum/...d.php?p=662046

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Old 19th Feb 2018, 6:33 pm   #89
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Default Re: Dansette Bermuda MK II ??

This amp supposedly has no output apart from the noise generated by the stylus in the groove.

I can't see that a problem with a feedback or tone control capacitor is going to cause that.

Perhaps voltage measurements are required?
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Old 19th Feb 2018, 6:35 pm   #90
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Default Re: Dansette Bermuda MK II ??

Quote:
Originally Posted by Station X View Post
This amp supposedly has no output apart from the noise generated by the stylus in the groove.

I can't see that a problem with a feedback or tone control capacitor is going to cause that.
Me neither.

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Old 19th Feb 2018, 6:38 pm   #91
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Default Re: Dansette Bermuda MK II ??

Thanks to all. I will have a look at this when I am back home.
Martin
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Old 19th Feb 2018, 8:46 pm   #92
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Default Re: Dansette Bermuda MK II ??

Regarding the tone control circuit difference to what's in the schematic...

...So far as I can make out it's bass boost, treble cut, the track of the tone control is substituted for the pentode's control grid return resistor (680k in the schematic) The wiper of the tone control is connected to a capacitor that's connected to the triode's anode, so in one direction treble is cut due to the triode's anode being shunted to chassis via the said capacitor and in the other direction the bass is boosted as the said capacitor is now connected across the pentode's grid coupling capacitor thereby increasing the capacitive coupling to the pentode's grid.

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Old 26th Feb 2018, 11:37 am   #93
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Default Re: Dansette Bermuda MK II ??

Thank you for the posts. I removed the deck yesterday and started to look at the comments made. As I have lost amplified sound only since I removed the deck and replaced the 3 capacitors C5, 7 and 8 I wonder if it is something that I have done in relation to this. It is obvious that there are differences with circuits and possibly more with mine having a Garrard deck fitted.

Photo 1 shows the C7 capacitor(yellow) replaced.
Photo 2 shows the C5(vertical) and C8 (horizontal) capacitors replaced.

C8 is joined to a track with the other end on a track that goes to the white wire and the 10K resistor. My original question being should it also be bridged to the bottom track below.
The bottom track goes to pin 2 of UCL82 and the resistor as shown in photo 2 and the 320ohms resistor that I cannot see on the circuit - far left photo 3.

I hope that this makes sense.

Martin
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Old 26th Feb 2018, 12:11 pm   #94
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Default Re: Dansette Bermuda MK II ??

I think Lawrence answered your question in post #86.

EDIT.

I don't think a disconnected feedback capacitor would stop the amplifier working.

As mentioned in an earlier post, it looks like one end of the green Welwyn resistor hasn't been soldered. Has it been soldered? Can you measure HT at the smoothing caps?
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Old 26th Feb 2018, 1:29 pm   #95
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Default Re: Dansette Bermuda MK II ??

Sorry missed reading that post. Should both end of the capacitor be bridged?

Yes the Welwyn has been soldered. Not sure how to measure HT as the caps are in a can. Please advise.

I am being offered an Ecko 706 record player that has a sound problem. I cannot see much on the forum for these players. Is it worth accepting?

Thanks Martin
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Old 26th Feb 2018, 1:37 pm   #96
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Default Re: Dansette Bermuda MK II ??

Measure the DC voltage between the chassis and each of the other three terminals of the can.
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Old 26th Feb 2018, 1:52 pm   #97
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Default Re: Dansette Bermuda MK II ??

There are 4 terminals of which 3 give readings - 7.23, 7.21, 7.20.
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Old 26th Feb 2018, 2:00 pm   #98
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Default Re: Dansette Bermuda MK II ??

You don't give any units, so I'll assume volts.

Your readings are way, way too low.

Does the Welwyn resistor measure correctly using a DMM on an appropriate resistance range?

What is the AC voltage w.r.t chassis on each end of the 100R resistor?
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Old 26th Feb 2018, 3:29 pm   #99
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Default Re: Dansette Bermuda MK II ??

Yes the units are volts - tested with power off.
I am sorry but I do not understand all of the terminology - what is DMM and w.r.t.
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Old 26th Feb 2018, 3:40 pm   #100
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Default Re: Dansette Bermuda MK II ??

You cannot measure voltages with the power off. What you're seeing is probably residual charge on the capacitors.

DMM = Digital Multi Meter.

w.r.t = with respect to.
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