E.A.R. DeLuxe record player.

[ms660]

The red outer reservoir section of the smoothing capacitor can isn't in circuit so far as I can make out.

Lawrence.

[parlourtw73vs]

Graham, the pos. lead from the Dubilier cap. goes to one lead on the green resistor with the pale band in the centre. It's quite difficult to discern but I believe the other lead on the green resistor goes to the yellow terminal on the hunts can which i think is the 20uf section. Do you still wish me to connect the -ve terminal of the Dubilier to the main chassis or remove it all together. I've posted 2 images to hopefully illustrate these connections. If the latter I'd appreciate any instructions that can be given me in determining the measurements requested by techman.

[Techman]

I've just found your post where you got the valve heaters working - post #52.

The loud hum you got when the valves warmed up would be because the reservoir section of the smoothing can was disconnected and also the negative connection of its replacement, the large 'yellow' Dubilier capacitor, was completely isolated, so the capacitor wasn't doing anything.

You now need to remove the negative lead of that capacitor from under the screw holding the output transformer in place and extend that lead and connect it to a suitable tag on the main amplifier chassis that actually connects directly to that chassis - perhaps the negative tag of the silver can if it has one (NOT any of the three positive tags).

It's worth pointing out that this Dubilier capacitor hasn't had any volts on it for a very long time and I would really advise using a lamp limiter to first power up, but seeing as you don't have one then just do as I would do and with my meter set on the 600 volt DC range, clip the positive lead to the positive side of the Dubilier cap, perhaps where it connects to the green resistor, and the negative lead to the main amplifier chassis. Plug in and switch on and check the voltage on your meter. As the valves warm up that voltage should drop. It wants to be at least 200 volts, with hopefully very little hum from the speaker.

If it all seems good, don't leave it powered up for any length of time, but un-plug from the mains and feel the case of the yellow capacitor to make sure it hasn't started to show any warming, which would indicate leakage. Also check the metal can of the large silver one in the same way. If these capacitors become very leaky, they will eventually get so hot that they go off with an awful bang and you don't want to be stood over it if they do.

[Station X]

There is only one place the negative lead of a smoothing capacitor should go to in this player and that's the main chassis. It will do no harm to try it.

As Lawrence says, one section of the smoothing can has been disconnected and a partial attempt made to connect the Dublier cap in its place.

[parlourtw73vs]

Thanks so much Graham and Techman. As it's getting a little late now and near my bedtime I'll sign off for tonight and do as you suggest tomorrow morning. After re-routing the lead from the Dubilier cap. I'll take photos of the meter readings and upload them for you to study. Cheers, Malc.

[parlourtw73vs]

OK, I've disconnected the -ve lead from the Dubilier cap, extended it and secured it to the main chassis metalwork by means of the nut and bolt securing it to the cabinet. The extended lead is in direct contact with the metal chassis. As Techman has suggested I've clipped the probes from my DMM to the pos. lead of the cap and the -ve lead to the chassis. The meter is set on the 600v dc range. I haven't yet powered it up as I've taken a photo which I'll upload with this post which hopefully will show all in position and would like verification that all is correct before switching on the mains. When I get the OK I'll take a shot of the resulting voltage and report any changes. Malc.

[Station X]

That's fine, but make sure that the positive probe doesn't touch anything other than the point you're measuring.

I did note from the picture in post #122 that the soldering at that point looks dodgy? If so it would be a good idea to resolder it.

[parlourtw73vs]

I first replaced the valves and then switched on the power. The meter showed an initial voltage of almost 400 but after a few seconds it started to drop and after 10-15 seconds it stabilised at 244v. The valves lit up but unfortunately there was still a loud hum, to be honest it seemed possibly a little lower in volume but I can't be sure about that. I rotated the volume control from low to high and back but this made no difference to the volume of the hum. I left it on for about 2 minutes and then cut the power. The hum died instantly, it didn't slowly die away and I then felt the yellow cap for any warming. There didn't appear to be any discernible increase in temperature. I hope this gives you a clue as to what is going on and await your next observations. Malc.

[Station X]

244VDC is good. The reason the voltage drops after initial switch on is that as the valves' heaters heat up the valves draw current causing a volt drop in the series resistors. This is normal.

The next thing to do is check the voltage on the control grids of the pentode sections of the valves. ie on pin 3. You should see no DC voltage at all or a very low voltage here. Also check the cathodes on pin 2, expect around 25VDC here. All measurements made with respect to the main chassis.

Remember that when looking from UNDER the chassis, valve pins number clockwise from the gap.

[ms660]

Make sure that blown Plessey cathode bypass capacitor is disconnected first.

Lawrence.

[parlourtw73vs]

OK, just to clarify, when checking the voltage on pin 3 do I use the positive probe to touch the pin and clip the -ve probe to the metal chassis and also which setting should I use on my DMM? I will also remove that blown cap, do I need to remove the other Plessey cap and presumably I am checking both valves at pin 3?

[Techman]

Yes, you may actually see your meter register a slight negative (-) voltage on the grid pin 3, which would be good.

As a beginner, always start on a high range and work down just in case you make a mistake and catch the wrong pin. The expected voltages should be fairly low, but you never know!

[ms660]

Originally Posted by parlourtw73vs

OK, just to clarify, when checking the voltage on pin 3 do I use the positive probe to touch the pin and clip the -ve probe to the metal chassis and also which setting should I use on my DMM? I will also remove that blown cap, do I need to remove the other Plessey cap and presumably I am checking both valves at pin 3?

Re: Pin 3 measurements, yes, all voltages unless otherwise stated are measured with respect to chassis (aka WRT chassis) For pin 3 measurement set your meter to the 2 volt DC range.

You can leave the other Plessey electrolytic in circuit for the moment.

EDIT: Post crossed.

Lawrence.

[parlourtw73vs]

I've carried out the checking as requested. Firstly I cut one lead on the blown cap to take it out of circuit, upon switching on I noticed that after the valves had warmed up the hum was now considerably less but still not responding to movement of the volume control. After taking the readings on valve no1, this is the one on the left looking from above the chassis, I got a slightly alternating figure of between 0.023 and 0.028. When I took the reading of valve no2, the one directly above the blown capacitor, the reading changed from 0.00 to the single figure 1 on the left of the meter display. These readings were taken with the DMM set to the 20v dc setting.

[parlourtw73vs]

I notice in Lawrences post he suggests using the 2v dc setting, will this give a more accurate reading? If so I'll redo them. I have a couple of errands to do now so will be gone for 2 or 3 hours but will get online again as soon as I'm back. Malc.

[Station X]

You do not say which pins you're taking the readings on. If pin 3 the readings are fine. Worth rechecking on the 2V range though. As Techman says work down through the ranges starting from the highest range, then you won't be caught out.

[parlourtw73vs]

I've made a mistake in identifying pin3 on valve2, then nearest to the blown cap. Upon going to check the readings on the 2v dc setting I realised the valves were installed in a "mirror image" configuration and so these are now the revised readings on pin3 on both valves.
on valve 1 .260
on valve2 it is now .132
I've double checked my identification of the pins and am confident I've probed the correct ones. When taking the readings they fluctuated a bit and the figures I've given are approx. a mean between high and low on each valve.

[snowman_al]

Apologies,
I know the last thing this thread needs is another contributor giving advice...

But it concerns me (and others I feel) that the OP is now working on not only high voltages, BUT also a 'Live' chassis situation. Or did I miss something?

We should at least tell him to ALWAYS keep one hand in his pocket and wear some High Voltage rubber gloves. It really is easy to be distracted or just need to move the chassis and...

So may be a simple chart of the layout would help the OP locate the readings being asked for. Then record them on a simple table like:

V1 pin 1 =
V1 pin 2 =
V1 pin 3 =
V1 pin 4 = na
V1 pin 5 = na
V1 pin 6 =
V1 pin 7 =
V1 pin 8 =
V1 pin 9 =

V2 pin 1 =
V2 pin 2 =
V2 pin 3 =
V2 pin 4 = na
V2 pin 5 = na
V2 pin 6 =
V2 pin 7 =
V2 pin 8 =
V2 pin 9 =

I think I am inline with the diagram being used and the orientation as per the picture.

Sorry but I had to share my concerns.
New boy is off now. Alan

[Station X]

Mirror image or not, the pins still number clockwise from the gap.

Readings are a bit higher than I'm used to, but nothing to worry about at present.

What voltage are you seeing on the cathodes?

[parlourtw73vs]

I realise that taking these readings is second nature to most of you but as I haven't done this before I'm constantly rechecking myself as I go along, but even so still confuse myself as in the foregoing. Thanks for the concern Alan, but I am aware that there are high voltages involved and that the chassis is also live so I'm always using just one hand on the insulated probe and keeping the other hand away from the chassis. I also like your idea of giving readings on the various pins of each valve laid out as you suggest. When looking at your lists why are pins 4 & 5 on each valve listed as na? Does that mean they are irrelevant and I don't need to check them? Also Graham, which pins are the cathode? When taking these readings do I still clip the -ve probe to the chassis and use the +ve probe on the 2v. setting?