Dansette Bermuda MK II ??

[martinpinner]

The tracks are now not connected. No continuity but an open circuit.
Reading on pin 9 is now 3.46 volts.

[Station X]

What is the DC voltage across the 100k resistor? ie one meter lead to each end of the resistor with the power on.

[martinpinner]

96.7 Volts. The last few times when the power is on it is very crackly with a metallic noise that goes away after a few minutes!!.

[peter_sol]

Either there is a short to earth (ground chassis) on pin 9 or the valve is faulty disconnect the 100 k resistor from pin 9 and check voltage connected and not connected may have a conductive PCB
Martin it will be easier if you fault find logically as this is going on and on very slowly.

[ms660]

With the 100k resistor connected and the grid coupling capacitor and tone control capacitor still disconnected it might be a good idea to check the voltages on all the pins of the UCL82 again (except pin 5) this time use pin 4 as the reference point for measuring.

Lawrence.

[martinpinner]

I shorted the circuit in the house for the second time this week
I must have had wires/components touching again when I switched the power on.
I have blown a circuit breaker and the board needs to be replaced .
I am out of action at the moment and not see if I will continue with it.
Let you know when I am connected

[Station X]

Originally Posted by martinpinner

I have blown a circuit breaker and the board needs to be replaced.

Wow! Even I've not managed to destroy a consumer unit.

[martinpinner]

My neighbor is an electrician and just fitted a circuit breaker - I now have sockets upstairs again. I have made the assumption that I might have had some wires or components touching that may have shorted the circuit as the PCB board and controls are not fitted but loose. However,I am not sure if anything made contact if it would cause this to happen. This was the second time this week it has happened. I am therefore worried that it might be something else and unsure whether to switch it back on. I have just noticed that with latest one I had the probe attached to the chassis but inadvertently put it in the 10A slot of the meter - not sure if this would have given the problem.

[Station X]

Originally Posted by martinpinner

My neighbor is an electrician and just fitted a circuit breaker - I now have sockets upstairs again. I have made the assumption that I might have had some wires or components touching that may have shorted the circuit as the PCB board and controls are not fitted but loose. However,I am not sure if anything made contact if it would cause this to happen. This was the second time this week it has happened. I am therefore worried that it might be something else and unsure whether to switch it back on.

If your neighbour is an electrician he should have the necessary test equipment to test your installation and should have done so before replacing a circuit breaker.

If you are worried about turning the supply back on, then I suggest you have a qualified electrician check things before you do so.

I have just noticed that with latest one I had the probe attached to the chassis but inadvertently put it in the 10A slot of the meter - not sure if this would have given the problem.

Having the test lead in the 10A socket would have effectively put a short-circuit across the meter leads. Depending on where you put the probes, this could have caused the circuit breaker to trip.

[martinpinner]

The 10A probe(black) was attached to the PCB chassis and the red probe in the VMA

[Station X]

When measuring voltage the meter, which will have a very high resistance, is connected directly across the circuit being measured, for example a battery. The meter's high resistance means that very little current is drawn from the battery.

When set to the 10A range your meter will have a very low resistance. For this reason it is connected IN SERIES with the circuit being measured. For example battery positive to meter positive lead, through meter, meter negative lead, lamp terminal, through the lamp filament, other lamp terminal, meter negative lead and back to the meter.

If you connect a meter on the 10A range across a supply capable of supplying a lot of current, then the fuse in your meter will blow and any other protective devices such as circuit breakers may trip.

It is rare to measure current when restoring a vintage record player. Far easier to measure the voltage across a resistor, which will give an indication of the current flowing.

[martinpinner]

Thanks for the explanation. The meter fuse did not blow just the circuit breaker.
It was probably my error that caused it but still a little hesitant about switching on.
If I do I will come back with the readings that had been requested before it happened.

[Station X]

A direct short circuit across the mains should trip the circuit breaker, not blow it.

If you shorted the mains within the player, the 3A fuse in the mains plug would probably blow before the circuit breaker tripped.

If a new circuit breaker has been fitted I don't see that it would do any harm to plug in your player and switch it on. The worse that could happen is that the circuit breaker would trip and you'd have to reset it.

What concerns me is that you may have an unrelated fault with your house's mains wiring and it's that which caused the circuit breaker to "blow" rather than trip.

[dalgwcobl]

I seem to remember that some Garrard auto-slim changers of that era had an overarm which you could 'park' at the back of the deck to make it easier to load single records on the short spindle. You lifted it up then swung it back towards the rear and down again. This enabled the changer mech to return to off at the end of the record. Can't remember which models did this, but I certainly remember this feature. Dynatron actually used a modified (by Garrard) model 6300 changer on which you could lift up and remove the overarm completely. On the model HFC32 it was fitted to, you couldn't shut the lid with the overarm in place - it came in a separate carton, for playing a stack of records.

[martinpinner]

Originally Posted by peter_sol

Either there is a short to earth (ground chassis) on pin 9 or the valve is faulty disconnect the 100 k resistor from pin 9 and check voltage connected and not connected may have a conductive PCB
Martin it will be easier if you fault find logically as this is going on and on very slowly.

Pin 9 with 100K resistor disconnected is -1.0 volts and when connected 3.40 Volts.

[martinpinner]

Originally Posted by ms660

With the 100k resistor connected and the grid coupling capacitor and tone control capacitor still disconnected it might be a good idea to check the voltages on all the pins of the UCL82 again (except pin 5) this time use pin 4 as the reference point for measuring.

Lawrence.

Measurements are:
Pin 1 1.31 Volts
Pin 2 19.90 Volts
Pin 3 19.30 Volts
Pin 4 -0.00 Volts
Pin 6 222.00 Volts
Pin7 99.00 Volts
Pin 8 1.18 Volts
Pin 9 3.40 Volts

[ms660]

You need to find out why both control grids have a +ve voltage on them, it could be the valve or it could be some other form of leakage. If I was investigating this I would remove the UCL82 and connect it's heater only, by using a couple of croc clip fly leads or whatever, then measure all the voltages on the valve holder again.

Lawrence.

[martinpinner]

Originally Posted by martinpinner

96.7 Volts. The last few times when the power is on it is very crackly with a metallic noise that goes away after a few minutes!!.

This is coming from the can housing the capacitors.

[martinpinner]

Are the heaters are on Pin 4 and 5.

['LIVEWIRE?']

The heaters of all B9A (9-pin) valves are always pins 4 & 5. To measure the voltage present , your meter should be set to a suitable AC voltage range