E.A.R. DeLuxe record player.

[Station X]

Pins 4 and 5 are marked as na (not applicable), as they have the AC heater voltage on them. All other pins are DC.

I described how to measure the cathodes in post #129.

In post #136 I suggest switching down the meter ranges.

In post #133 Lawrence says that all voltages are measured with respect to chassis unless otherwise stated.

[parlourtw73vs]

I've taken all the measurements of the various pins on both valves and have tabulated them as per Alans' suggestion. I've posted an image of the readings and hope they mean something to you.

[Station X]

Not good. No anode voltages pin 6 or screen voltages pin 7.

This is clearly a measuring error though as you have cathode voltages on pin 2 indicating that the valves are drawing current.

Repeat these measurements on the 600 VDC range. (pins 6 and 7)

[Station X]

Pin 9 of V1 (anode of the triode) doesn't look right either. Check this on the 600VDC range. If no joy suspect the resistor on this pin.

Your technique should be to start on the 600 VDC range and work down towards the 2VDC range until you get a sensible reading. The "1 ." readings you're seeing indicate an out of range voltage.

[Techman]

The slightly positive grid voltages on pin 3 of the valves is likely to be due to them suffering from a bit of grid emission, of which these old valves have a bit of a tendency, rather than leakage of the coupling capacitors. As said, no need to worry about it at the moment and it can always be verified by disconnecting the capacitor from the pin 3 connection later on.

I'll repeat this again as a reminder - you MUST start taking each voltage reading on the highest range (600 volts) of your meter and then work down if necessary - a fault condition may cause a much higher voltage reading than you were expecting. If you keep using a lower range when the voltage is higher and out of range, you'll eventually destroy your meter and you'll have to buy another, so be warned!

Why not just google your valve type (UCL82) and print out the data sheet to work from, it'll tell you all you need to know as regards the pin configuration and maximum voltages etc.

[parlourtw73vs]

Your absolutely right Graham, I've made a mistake in my original readings. The new readings are :-
valve1
pin6 209 @ 600v. meter setting
pin7 214 " " " "

valve2
pin6 208 " " " "
pin7 215 " " " "
Interestingly, the hum which has lessened considerably is now reacting to the volume control. At minimum vol. it is barely audible and it increases smoothly to maximum. This wasn't happening before, any idea what may have happened here?
In defence of my earlier readings, it is very crammed all around the underside of the valve bases and I was probably being a little too careful in trying to not contact any other components when placing my probe on the pin. In consequence I possibly didn't use a firm enough pressure, I was much more positive this time.

[Station X]

Looking good. Have a go at V1 pin 9 now.

[Techman]

I agree, it's looking good and you're certainly getting there now!

I thought that the hum level would gradually get less over time as that add on capacitor and the other one in the silver can started to recover, but remember to 'feel' them for any signs of warming after you've first unplugged the unit from the mains - live chassis, and all that!

The green resistor will run very hot in normal operation, hence why the solder joint to it had decomposed. I even suspect that when it was originally connected to the 'red' tag on the silver can, that because its lead out wire is so short, there would be excessive heat both transferred and radiated to the bottom of the capacitor can, thus causing its eventual failure. I think it was also quite close to that other capacitor that had 'blown'. When you eventually tidy the job up, I would like to see that hot resistor mounted away from other sensitive components and wiring, even if it means extending its wire leads slightly - or you could buy a new replacement with longer leads, but no need to worry about that for the time being.

[parlourtw73vs]

Sorry, missed your post on pin9 of valve1 Graham. I've redone the reading and this time it is showing 95.7 @ 200v. setting. I did start at 600v on each reading and only reduced it as I observed the figures to be preceded by zero's until I got what I thought was the correct result. Again this time the hum has remained at the same level no matter the position of the volume control, is this a meaningless comment, I only mention it because of the variance from one session of readings to the other.

[Techman]

Any hum affected by the volume control will be governed by how the pickup input wiring is situated. All other hum unaffected by the volume control will be down to HT smoothing, so keep an eye on those two capacitors for any warming of the cans.

[Station X]

The hum has probably decreased because the smoothing capacitors have reformed. Do you have a cap to temporarily fit in place of the Plessey one you removed?

[parlourtw73vs]

Techman your comments are a great encouragement to me, I did wonder if it was the large capacitors reforming. I've been feeling both the large capacitors, particularly after taking the large batch of readings from the valve pins, both had very slightly increased in temp. the metal can slightly more than the yellow dubilier but nothing like the warmth radiating from those wire wound resistors as you commented. I feel as though I'm making progress, but more importantly I think I'm beginning to understand the circuit and how the components are relating to it.

[parlourtw73vs]

Techman, I've disconnected the input wiring from the amplifier at the moment but have kept the wiring to the motor intact as I presumed that would have an effect on any readings I would make on the chassis.

[Techman]

You said you'd made the negative connection of the 'add-on' Dubilier capacitor by using a chassis mounting bolt. Old chassis mounting bolts are notorious for 'crusty' connections unless they're thoroughly cleaned - I did advise a good solder connection to a tag already connected to chassis. The above could be why you seem to be getting varying hum levels.

[Station X]

Forgot to say that V1 pin 9 is OK. If you replace that Plessey cap you may have a working player.

[Techman]

Originally Posted by parlourtw73vs

Techman, I've disconnected the input wiring from the amplifier at the moment but have kept the wiring to the motor intact as I presumed that would have an effect on any readings I would make on the chassis.

You shouldn't be getting any particular hum which is affected by the volume control then, unless there's a dodgy connection somewhere.

Yes, the wiring to the motor should be left intact.

You're doing well!

[parlourtw73vs]

Graham, in post 58 I uploaded a photo of some capacitors which I have, If you'd be so kind as to have a look there and inform me if any one of those would be suitable. From reading many of the posts on this forum I understand that some components can be replaced by others not necessarily of the same rating but I don't have the knowledge to effect such a substitution myself.

[Techman]

Just a reminder to everyone to keep refreshing the page, as the posts have been coming thick and fast, so it's very easy to miss some - probably time for a quick re-cap of the last few posts just to see what's been suggested.

[parlourtw73vs]

Techman, when I made that connection of the -ve lead from the Dubilier cap to the chassis I stripped the insulation back ,formed a loop and placed it in direct contact with the metal chassis. I then put a star washer on top and then tightened down the nut. I'm pretty confident that there will be a sound connection there but fully understand your concern if I'd merely wound it round the bolt.

[Station X]

I can't remember whether it was the 25uF or the 50uF Plessey cap which blew. Either way temporarily replace it with one of the 47uF caps you have. Observe polarity, remembering that the silver stripe on those caps denotes the NEGATIVE lead. The polarity of the Plessey caps is obvious. Red POS and Black NEG.