PM5109 service manual needed.

[Turbon]

Hi.

There are manuals for the more advanced Philips generators on the net but I can't find one for this. Could someone point me to a free one please. It belongs with the others at elekrotanya or an similar place.

Regards

[tautech]

Add Fluke before the model number and you should get a few hits to choose from.

[oldway]

I did not find the service manual but it is a relatively simple test gear that should be able to repair even without this documentation.

I have a PM5109 in good condition and I could make some measurements to help you repair your own.

This is probably a RC bridge of Wien oscillator with double potentiometer to vary the frequency.

On the printed board, there are 3 separate blocks: the symmetrical power supply, the oscillator and the output amplifier.

[HighVoltage]

Look or ask at the vintage radio forum in the UK
There are some people active that are in to older philips gear.

[Turbon]

Thank you for your suggestions and answers. It ain't broken but I find the distorsion a bit high so I would need the schematic to see what to tweak to get it down. Most for fun as I do have some fixed frequency oscillators for more serious measurements if needed.

Regards

[oldway]

What do you mean with "I find the distorsion a bit high" ?
How much too high ?
PM5109 is not a very low distorsion sinus generator.
In low distorsion mode, <0.7% from 10Hz to 100Khz and <0.03% from 300Hz to 20Khz.

http://www.davmar.org/Spec/PM5109-spec.pdf

One of the worst faults of this test gear are bad contacts of the double wirewound potentiometer for frequency adjustement.
It can produce high THD on some frequencies.
It is not a good solution: most of the RC generators use a variable capacitor instead of a potenciometer, that's a lot better.

[Turbon]

Hi oldway.

I can't get lower than 1,2% at 1kHz/10mVrms checked with ARTA. Sure there are uncertainties in the chain. Lousy cables but they shouldn't add anything at these frequencies. Loopback with the E-mu 0404 is about -120dB. The Kenwood HM-250 adds a bit up to -90dB and with the PM5109 I get about -75db. The notch filter in the HM-250 drifts a lot. I started an hour ago and after a few minutes I have to center it again at 1kHz- the dial is now at 1,5kHz. The output voltage of the PM5109 is quite stable, it has decreased by 50uV during the session.

Regards

[oldway]

You should first find out if the distortion derived from the oscillator or from the output amplifier.

It's easy to find out by measuring the distortion to the input of the amplifier.

There are 2 amplifier input wires, a green (common) and another yellow (signal)

Simply measure the distortion of the signal at this input.

[Turbon]

Thank you oldway, my time for today in the cave is about filled . I'll test as you suggest in the next session.

I will test the pm5109 for it self as the hm-250 in between seems to add a bit before I test as you suggest.

Regards

[oldway]

Before concluding that the PM5109 is defective, you should first be sure that the distortion is really too high.

Your Kenwood HM-250 seems not trustable.

You should first solve it and confirm with another distortion meter.

Regarding the PM5109, we must first check and adjust the power supply voltages to +/- 20V.

Here are some pictures of the PM5109.

With my HP 331A, I measure a THD as low as 0.002% at 1Khz with low distorsion selected.
With fast setting selected, THD is 0.46%

[sandor626]

I found it
 https://nvhrbiblio.nl/schema/Philips_PM5109.pdf