Philips PM3305 Oscilloscpe

[Diabolical Artificer]

Bummer, I have days/weekends/weeks like that sometimes where the Gods have micturated into ones handbag, I sympathise Rob. Hopefully you'll bounce back. A good clean of the switches might not go amiss, failing that could you not use your Teks square wave calibrator? Some scopes can be a bit hard to drive, stick with it,you'll get there. There's a few good videos about a different model to yours - https://www.youtube.com/watch?v=iPYzzsRXaMY, but they are very comprehensive,t here's also a video on your model here by chris who's over on UKVRR - https://www.youtube.com/watch?v=3m8FOXPAt-s.

Good luck, Andy.

[ppppenguin]

While I don't know the PM3305 I've looked it up and it strikes me as a somewhat outdated and complicated digital scope. Unlike analogue scopes where once you get above a certain level something like an old Hameg or whatever can be a good bet, older digital scopes can be positively horrible.

For a compact digital scope for simple work I'd have bought the cheapest RIgol such as this: https://www.rigol-uk.co.uk/product/rigol...illoscope/ I have one of these: https://www.rigol-uk.co.uk/product/rigol...illoscope/ but I still find my analogue Tek more intuitive to use. All of these Rigols are good scopes and great value for money. Possibly if I used the Rigol more, I'd get to be more familiar with it and use it more intuitively.

[Murphyv310]

Hi.
A beginner with limited knowledge should always start with an analogue scope. I agree with Jeffery an old Hameg or Hitachi are ideal. Dont run before you can walk. Buying expensive new kit can be a mistake if you give up and then you never recoup your losses.

Take me for example. I passed my foundation and intermediate amateur radio exam. Did I go out and buy a £2500 transceiver and an expensive cobweb antenna? No I bought a very tidy Icom IC-706 for £300, made a 2 meter Slim jim, then I bought a £50 yagi and modified a Silver Rod for 10 meters. So if I did give up I'd sell the radio for what I paid for it, the antennas would get me something but the loss would be small. I'm not giving up as I'm more than happy in the hobby having QSOs into Europe and the US.

[Bushbaby]

Hi All
Thanks very much for your advice.
Angie (my better half) helped me to move some equipment around in the workshop whilst I hobbled out there. At present I'm only checking 2 of the 'scopes I have, the Philips 3305 and the Tektronix 935a. The latter I'm please to say is working well although having not been used for a while I did notice that some of the adjustment control e.g. voltage adjusters needed to be switch right around several times to get them fully working - but they are now.
I have retried the 3305 with the probe I found set in 1x setting. The probe calibrate on the 'scope is indicated at 1.2V P to P x1. I now realise the noise I was getting yesterday may have been from not setting up correctly which I overcame today. However, it does appear that there is a problem with the second channel. I've attached some pics and you should be able to see that these are the same settings for both channels. Channel A appears to be spot on. Channel B has a much lower signal and for some reason cannot be adjusted? Is this a fault do you think and is it worth getting repaired or living with just one good channel?

Best Regards

Rob

               

[Murphyv310]

Try pressing the AC DC switch in on channel 2

[ppppenguin]

Incidentally, never use x1 probes unless you know exactly what you are doing. They impose a large capacitative load on the circuit under test. Usually around 100p.

[Murphyv310]

Hi.
Rob is trying to fault find hum on a guitar amp, the X1 probe will be fine on this.
100pf won't be an issue on 50 or 100hz ripple.

[Bushbaby]

I've just hobbled out to the workshop as I wondered if the ac/dc switch was depressed It would be on my mind all night if I didn't check!!). It was depressed and I thought it had a fault BUT I pressed it in and out about 3 or 4 times and the signal imprved and is exactly the same as Channel A. Its obviously because its not been used for a while.

[ppppenguin]

Hi.
Rob is trying to fault find hum on a guitar amp, the X1 probe will be fine on this.
100pf won't be an issue on 50 or 100hz ripple.

I agree it won't matter for that sort of usage and the extra sensitivity may be useful. Need to beware of high HT when scoping valve kit. Both the scope's own maximum input voltage and the probe's rating. An x10 probe can help to protect the scope.

[Diabolical Artificer]

That's looking better. As advised in my previous post Rob go in and give the switches a clean, it should be one of the first things you do with any gear that's not been used for a while.

Andy