Bush SRP 31D not producing sound.

[Glowing Bits!]

One thing we will do first of all is forget the heaters lighting up and the bulb lighting up, this only shows that the power supply is outputting 6.3v for the heaters/bulb.
The one to worry about at this stage is the high voltage part of the circuit.
Disconnecting the pickup wires should not cause a problem at the moment.
I may have gone too technical on my last message/post, I'm hoping (and now praying) you have found the service data sheets for this set, they are available at the top of this website, without a schematic, we're working in the dark.
Simply put, get the multimeter, stick it on a DC setting (the highest, failing that, the next setting down), place the black lead of the meter on the chassis, place the red lead of the meter on both contacts on the rectifier, one should give a reading somewhere near to 200 volts DC, if there is no DC reading, the rectifier could be stuffed!!!
Please get back to me with the reading this time.

[Spencervs]

Where should the black lead go? Am I right putting it on the chassis to earth it? Or does it not matter?

[Glowing Bits!]

The black lead should always be on the chassis.
My way to do things is to find a small hole on the chassis and stick the black probe (lead) through it, this makes it have a permanent connection, it frees up a hand!
Multimeters usually have a high value resistor in them to make them work, this is why the black lead should go on the chassis, without it on the chassis, there's no connection, thus no readings can me made/taken.
Once you've started getting into the swing of things when using the meter, this set will no longer look scary to fix, it'll get easier and hopefully be more enjoyable in the future, everybody has to start at the beginning, as we all did!

[Spencervs]

Hi guys, sorry I'm late in replying, I graduated recently from uni so have been away! Tonight though I had a better measure of my rectifier with a better multimeter and I found the rectifier's red wire to the valves is at 215-220 DCV and 482 ACV. As for the grey wire, it was around 220-230 ACV so I believe the rectifier is ok?

I do have a copy of the service manual for the Bush SRP31 but it isn't for the SRP31D, does this matter? what should I look at next?

[AC/HL]

The circuit for the SRP31D isn't available via VRSD, but it is here -
https://www.vintage-radio.net/forum/...ad.php?t=86032
However, as long as you note the different pin numbers for ECL83 and ECL86 it is virtually identical.
The main difference is that the ECL86 requires 5.6v bias, created by a 120 ohm bias resistor, and the ECL83 12v and 270 ohm respectively. Both produce 3 watts.

Are both the bulbs still lighting brightly?
The HT is correct at 215V (ignore the AC reading, you can't measure DC volts on an AC range), and the valve heaters sound OK, so the fuse bulb shouldn't be lit.
Also the slight hum and hiss from the speaker would suggest that the amplifier is working to some extent.

[Spencervs]

I checked it again and the fuse bulb doesn't light up now but it is a new bulb I acquired from my older record player. The main bulb still fluctuates brightnesses I have noticed.

I looked at the diagrams you linked me to and noticed the numbers for the pins... I assume that is for the ECL86 (it was the little circle on the bottom with the dots and they were numbered 1-9) and as Glowing Bits suggested I measured the DCV of pin 6 on both the valves. I found they were at 215 exactly... does this mean the valves are in the clear? what should I measure next?

[AC/HL]

You should get 5-6v on both pin 7s. That will indicate that the output valves are conducting normally.
The fuse bulb is rated at 6v 500mA, the one that is bright is probably a torch bulb, unless something has changed between now and the earlier posts.
If you unplug the co-ax plug at the rear of the deck, and touch the inner of the socket, do you get any noise?

[Spencervs]

I just looked at the valves again and was in some confusion as to the numbering! I think I worked it out based on the diagrams you gave me but if I did then pin 7 on both valves produce no voltage according to my meter and pin 6 produces a normal 215-220v. Am right in saying that on the circuit diagram the pin numbers go by the big gap at the bottom then clockwise from that? because in the machine, the big gap is at the top hence the confusion, so I have here a diagram of what I think are the points as they are on the diagram and how I am assuming they are in the player...

[Nickthedentist]

Originally Posted by Spencervs

I just looked at the valves again and was in some confusion as to the numbering! ...so I have here a diagram of what I think are the points as they are on the diagram and how I am assuming they are in the player...

In the machine itself, looking from underneath, they're numbered consecutively in a clockwise direction starting at the "gap", see the little piccy here: https://www.vintage-radio.net/forum/...2&d=1342476743

Nick.

[AC/HL]

From underneath, the pins are numbered clockwise from the gap, whichever way up it is.
You should have the same voltages on both valves (power output)

Pin 3 - 190v
Pin 6 - 210v
Pin 7 - 5.6v
Pin 8 - 0v

Disregard the other pins for the moment

[Spencervs]

OK, I see. I just tested those pins now and have the same values for both valves:

3= 194v
6= 211v-213v
7= 5v-6v
8= 0v

So I guess that the valves are ok? if so then what else could go wrong in the machine?

[AC/HL]

Right, power supply and output stage OK.
Next stop low power stages.
The triodes have different voltages.
V1 - Amplifier
Pin 1 - 0v (and hopefully a loud buzz)
Pin 2 - 1.5v
Pin 9 - 125v

V2 - Phase splitter
Pin 1 - 0v (and a different buzz)
Pin 2 - 25v
Pin 9 - 170v

[Spencervs]

right I got the results of the test!

V1

1= loud buzz (same as when you touch the bare tone arm wires) and 0v
2= 1.2v
9= 122-123v

V2

1= 4.1v and no hum (although I tested it a few times and once it was 0v and a very quiet hum but you had to listen for it)
2= 25.6v
9= 166.8v

[AC/HL]

There definitely shouldn't be a voltage at V2 pin 1. If there is, I would expect pin 2 to be much higher than it is, and pin 9 much lower!
However, your amplifier would seem to be working sufficiently to produce some sound, especially as you replaced the cartridge, the most common cause of no sound in equipment of this age.
You need to investigate the 4.1v. Quickly move backwards & forwards between pins 1 and 2 to check whether they are both consistent.

[Spencervs]

Just double checked it again and pin 1 shows 3.8v and pin 2 showed 23.8 although it varied slightly. Pin 1 did make a connecting sound but still no hum is it possible a resister has blown?

[Spencervs]

I have taken the liberty of photographing the machine inside so that you may see what it looks like. I know I took a photo before but that was one I had of an older SRP31 that was spare.

I was having difficulty getting into my SRP31D (the nut was on to tight) and so I took a photo of the other machine which I assumed would be the same. Turns out it isn't as the SRP31D has had a service since its making in 1964! Hopefully the pictures will be useful in determining what could have gone.

[AC/HL]

I've just checked the circuit, and the voltage on pin 1 of V2 is probably correct, which explains why the cathode voltage is also correct.
So the DC conditions in the amplifier are OK. Did you check for noise at the co-ax connector as in post 27 ?

[Spencervs]

Without the risk of sounding foolish, what exactly is the co-ax connector?

[Spencervs]

Haha, sorry about that! I noticed the error of my ways and understood you meant the RF port to go into the amp! Tested it and no joy and also the amp has taken to making a nasty fwooosh noise when it's turned off which it never did before as well as hum and hiss when on.

[Station X]

See if you get a buzz when you touch the centre tag of the volume control.