Murphy A851G no sound to speakers. Tone arm fault on Garrard deck.

[Edward Huggins]

Yes, that new BSR will easily fit in your Garrard headshell. BUT you are going to need to re-wire by soldering the 4 connecting wires to push-on connectors (were these supplied?) that will slide on to the 4 pins at the rear of the cartridge. First you will need to cut off as close to that circular Sonotone connector the 4 wires fitted to it. Then bare the 4 cables. Then solder the 4 connecting pins to these bared wires. Then push the 4 pins to the RH+ (Red), RH+(White), LH- (Blue/Black), LH-(Green) pins on the cartridge body. This is very delicate work. Use tweezers to slide them on and a x12 glass will help.

[Gazworth]

https://www.amazon.co.uk/DollaTek-Ca...65&sr=8-8&th=1 would this be a suitable replacement for the 50uf capacitor? also would it be worth replacing the 3.3k resistors?

[PaulR]

That is a motor run capacitor. I would buy something like this https://www.ebay.co.uk/itm/Rubycon-4...8AAOSwAadfczoX

47uf is a "preferred value" and much more common these days than 50uf. The slight difference in valve won't make any difference. If the resistors are within 20% of the marked value and don't look burned I would leave them alone.

Regarding the cartridge the one you already have looks like a Sonotone 9TA HC. There were highly regarded but may have deteriorated over the years. It is probably better to get the amplifier working and then see how well the existing cartridge works before changing it.

Edit

Looking at the circuit diagram there are three 50uf capacitors in the amplifier. Two of them are in a large aluminium can and smooth the rectified current in the power supply. Dual cans like this https://www.cricklewoodelectronics.c...Capacitor.html are available and might be easier to fit than separate ones. The other 50uf is connected to the cathode of one of the valves. A lower voltage 47uf can be used here. It looks like the one fitted is a 25v one.

In addition there are some .01uf capacitors that should be changed. These are used to allow the signal through from the anode of one section of a valve to the grid of another whilst holding the HT at bay. If they leak the voltage applied to the grid of the valve would damage the valve and possibly other less easily replaceable components. Get 450v or higher replacements for those. More information about this is shown here https://www.vintage-radio.net/forum/...d.php?t=131732

[Gazworth]

Originally Posted by PaulR

That is a motor run capacitor. I would buy something like this https://www.ebay.co.uk/itm/Rubycon-4...8AAOSwAadfczoX

47uf is a "preferred value" and much more common these days than 50uf. The slight difference in valve won't make any difference. If the resistors are within 20% of the marked value and don't look burned I would leave them alone.

Regarding the cartridge the one you already have looks like a Sonotone 9TA HC. There were highly regarded but may have deteriorated over the years. It is probably better to get the amplifier working and then see how well the existing cartridge works before changing it.

ahh i see, so this is the one i would need to replace with the one you have advised?

[Gazworth]

Originally Posted by Edward Huggins

Yes, that new BSR will easily fit in your Garrard headshell. BUT you are going to need to re-wire by soldering the 4 connecting wires to push-on connectors (were these supplied?) that will slide on to the 4 pins at the rear of the cartridge. First you will need to cut off as close to that circular Sonotone connector the 4 wires fitted to it. Then bare the 4 cables. Then solder the 4 connecting pins to these bared wires. Then push the 4 pins to the RH+ (Red), RH+(White), LH- (Blue/Black), LH-(Green) pins on the cartridge body. This is very delicate work. Use tweezers to slide them on and a x12 glass will help.

very good, simple enough i can get the parts from work tomorrow thank you for you knowledge

[PaulR]

I have just edited my last post to make it clearer. You could replace that can with ones like to one I suggested but you might find a dual can easier. It depends on the room available. The other, white, one can be replaced with a lower voltage one.

[Gazworth]

here are photos of what i have done, replaced the 50/50uf, also replaced the two caps as suggested, i havnt soldered the can in yet as i want to make sure what i have done is correct before firing it up. anything else? i do have parts to do the rectifier behind the can but is it worth it? if not ill leave it? if all is right ill get on tidying it up.

[Station X]

I'm quite surprised that components are being replaced without, as far as I can tell, a single voltage reading being taken.

Apply power and measure the voltage from each tag of the smoothing capacitor to chassis. You'll soon know whether the rectifier is any good.

[PaulR]

It is a bit difficult to see what your proposed connections are, but there doesn't appear to be anything connected the the top tab in the photograph. I am assuming that the tabs with the coloured spots atr the positive connections of the two 50uf capacitors and the third is a common negative. If so the coloured tabs should be connected to the leads that previously went to the positive tabs of the old capacitor with the 3.3k resistor between them and the negative tab should be connected to the chassis. Compare your connections with the circuit diagram if you are unsure.

Graham is quite right, of course, some voltage readings should have been taken before we got carried away with replacing components. However, we are where we are. Connect up the 50+50 uf capacitor then be prepared to do some voltage checks. As I mentioned in an earlier post it is possible that faulty components have caused the output transformer to fail but let's hope not.

[Station X]

Originally Posted by PaulR

....there doesn't appear to be anything connected the the top tab in the photograph.

I missed that one. That tag should be wired to chassis.

It looks like there are two bare wires connecting the positive terminals to the 3.3k resistor, but it's not clear how well wrapped they are at the resistor end.

I believe the red tag denotes the reservoir section and the yellow tag the smoothing section. The red tag should be connected to the rectifier.

[Gazworth]

i read the can when i removed it to check it and it was reading 29uf. also reading the old 50uf caps i removed showed they also has a very low reading to what they should be so im confident they did need replacing.

onto the can connections yes the 2 i have connected up already match the way in which the original can was connected, i can run a ground from the tag if thats required, this is why i asked before i went to switch it on.

[Station X]

Yes a wire from the negative tag to chassis is needed. The original can was probably connected to chassis via the case and clip.

[PaulR]

If you are confident on the connections you have made you can go ahead and apply power. I would use a lamp limiter just to be safe. If you don't want to make a "proper" one as shown on this site you could simply put a bulb holder with a 100w incandescent bulb in the mains circuit using choc-a-bloc connectors. Don't be tempted simply to twist the wires together. You will need a multimeter to take voltage readings.

[Gazworth]

Originally Posted by Station X

Yes a wire from the negative tag to chassis is needed. The original can was probably connected to chassis via the case and clip.

brilliant, yes that makes perfect sense now ill make sure to do that right away.

[Gazworth]

UPDATE - grounded the can correctly and double checked everything, applied connections for the new cartridge, all connected, powered up and all looked well but still no sound from the speakers. only other thing i can think is gone is the transformer. im somewhat less clued up on this than you guys and ive learnt much. all suggestions appreciated.

[Station X]

DC Voltage readings on the smoothing capacitors?

See post #28.

[Gazworth]

been very busy so havnt had much time to check anything else until now, ive gotten to this, the image where the voltage is reading 37v is with the resistor and cap in circuit, the other image where its 150v is with them OC, on initial power up it read around 215v, by my understanding something further up the circuit is dragging down the voltage, looks like a lengthy time of checking components

[Station X]

Is your meter set to a DC Volts range?

There are two tags on the smoothing capacitor. What voltage do you see on each tag?

I'd put my money on a duff rectifier.

[Edward Huggins]

Graham, may well be right. This uses the same amplifier as the BUSH SRP31D and rectifier failure on these is a known very common problem. Test the voltages in and out of this. If it's down, a replacement fix (diode+resisitor) is easy and cheap.

[Gazworth]

Originally Posted by Station X

Is your meter set to a DC Volts range?

There are two tags on the smoothing capacitor. What voltage do you see on each tag?

I'd put my money on a duff rectifier.

yes set to DC.

just read both sides and both sides read between 65 and 75v DC