Hi all,
I’ve just started to get into Valve equipment and am really enjoying it. I work as an electronic technician by day and at night in my garage I’m trying to learn the principles of valve equipment and how to repair and restore these beautiful old radios. Unfortunately, we only touched lightly on valve technology at Uni in the late 1990’s.

Last weekend I purchased what will be one of my first valve projects, a beautiful old Philips ‘radioplayer 3852’ it was purchased new in the mid 40’s and has sat in a garage for the last 30 years before I purchased it. Unfortunately the owner plugged it in to test before I purchased it and she reported that it light up but had no sound. I hoping that this didn’t cause any damage.

The first thing I did when I got the radio home was replacement of all electrolytic and paper/wax capacitors. I slowly powered it up but unfortunately all I heard was a ‘deep buzzing’ from the speaker and I thought I heard a ‘sizzling’ sound coming from the transformer..... I’m not sure what could be causing this. I’m confident all the caps are correct after checking and re-checking. Would I be correct in assuming that after 70years all the valves would be dead and need replacement? Is there anything initially I should be checking for? I plan to check the resistors tonight to make sure something’s not shorted or open. Would anyone know where a good place would be to find a schematic doc for this type of radio?

Thanks all, and I hope I’m able to contribute something of interest to the forum soon.

G'day AA,

Welcome to the forums.

Would I be correct in assuming that after 70years all the valves would be dead and need replacement?

This is a common assumption and I once held the same view. Usually, the valves will have survived the test of time. They often last far longer than they were originally designed. More often than not a valve is damaged by another fault in a circuit than simple wear and tear.

Condensers, and in some cases, resistors most often require replacement, especially electrolytics and the black AWA ones. At this stage of the game it is more or less mandatory for every set before power is applied and before accounting for other faults.

I thought I heard a ‘sizzling’ sound coming from the transformer..

Could be a number of things including a faulty transformer, or possibly a problem with the rectifier valve.

The usual sequence for troubleshooting -- after dealing with capacitors and looking for any shorts caused by perished insulation, etc -- is to start with the power supply and ensure that all voltages are correct.

I always bring the mains voltage up slowly and progressively via a Variac on any equipment that has not been used for a period of time, with all the senses alert to potential problems.

Suggest applying the sniff test to the transformer. If it's dodgy there will be an unmistakeable odour about it.

I cannot find a schematic for a 3852. Let us know the valve line-up in that set.

Might be a 3652 in that era (1946)?.

If it is 1940's it is liable to have a 5Y3 as a rectifier and it could have rubber wire, this deteriorates and I have replaced a lot in the last few months.

One hopes that you have not left the old electolytic's "in circuit" as they can present as a short, or explode. Modern electrolytic's rarely quote a surge value and I will not use less than 500V on a 5Y3, or 80. Not all caps are what they should be and I have had one 500V type let go at 480V (on an 80). Before heater valve conduction, with a filament rectifier like 5Y3 / 80 you will get a voltage surge close to twice EMF, prior to conduction.

If it has a 5Y3 the filaments should be floating and not going to ground as they carry B+. We need info on the valves to see what we have.

I have put UX-201-A valves back into service, that predate the number changes in 1930.

One has to be careful with a Variac as too low a voltage can poison the valve cathodes.

I, as normal practice & procedure, hook an analogue meter to B+; That is how I quickly spotted the B+ issue & hit the kill switch.

We need to find out what it is.

If its a 5Y3? make sure there are no short circuits in the filament, dial lights & heaters, remove the 5Y3 and check the voltage between chassis & pins 4 & 6 NOT ACROSS them unless the meter can handle more than 1KV. See if it still crackles. Report back. Transformers often growl if there is a short. Run it a little while & see if you get smoke, or it gets hot. With the rectifier still out of the set.

Marc

Hi all,

Wow! thanks so much for all the input, you guys are great!

I had another look at the radio last night and I think I have solved the sizzling sound by substituting the original rectifier tube with a known good valve from my other radio. The radio is now just making a constant ‘bleeeeeeeeeeeeeeeeeeeep’ sound, it’s almost turned into its own signal generator.... I didn’t leave the radio on for long as I didn’t want to risk any damage.

The valve line up is as follows: 6J8G, 6U7G, 6B6G, 6U6G, 5Y3G. I’ll take some voltage measurements tonight and report back my findings. Just worth noting as I didn’t mention before that this radio uses an external field coil located on the speaker so all my tests have the speaker connected. All caps inc electrolytic have been replaced >500V.

I've just been surfing with Dr.Google trying to find a schematic for this radio Philips radioplayer 3852’ but to no avail I have found an image of an identical looking radio the 'Philips radioplayer 3362' the only visible difference is that this radio is a table top cabinet type compared with mine being in a large wooden console. Would anyone have a digital copy of a Philips radioplayer 3362 diagram handy?

The valve line up is as follows: 6J8G, 6U7G, 6B6G, 6U6G, 5Y3G

I think that's 6V6 rather than 6U6.

The only Philips sets I can find with that line-up are models 3252A and 3552. The 3552 (dated 1946) has a 7 pin speaker socket.

The radio is now just making a constant ‘bleeeeeeeeeeeeeeeeeeeep’ sound.

Possibly positive feedback where it should be negative.

Audioaaron: "Would anyone have a digital copy of a Philips radioplayer 3362 diagram handy?"

If you unhide your email address (via Control Panel), I'll send you schematic and notes.

Hi GTC,
yes you are correct, it is a 6V6G valve. Sorry I can't read my own hand writing...

Many thanks for offering to send me a schematic, I've un-hidden my email address.
Thanks again!

Okay, sent.

The original scans are not the best so you'll probably need to use the PDF reader zoom button.

A lot of Philips radio's used feedback from the secondary of the OP transformer. When I rescued the 132L I have here, it had been disconnected. Judging by what I found, it was obvious why.

The primary of the OP transformer had been reversed & didums had no idea as to the fault when he changed the transformer & drilled a hole through the cone (stuffed it). Most of the sets where this reversal takes place: Oscillate.

Disconnect the secondary wire not going to earth & if that shuts it up, fair bet its reversed.

Marc

Look what just turned up!!

Philips 3852 Circuit Diagram.

Fantastic! many thanks MonochromeTV

This is the exact CD. I'm looking forward to having the radio up and running soon *hopefully* Unfortunately I've been spending most of my spare time converting my mother-in-laws super8mm films from the 50-60's onto DVD's, only another box to go.....

Thanks again

Hi all,

If you have a spare 20-30 seconds please feel free to have a look at the video I uploaded to youtube of this radio fault. I'm tearing my hair out with this one... but I'm sure someone will know exactly what this strange beeeeeep sound is. I've substituted all the valves with known good ones from a couple of other sets but no change.

This was an all original radio when I received it as in previously 'un touched' I have replaced all the capacitors electrolytic and paper/wax. I've checked the resistors and all still seem within spec. The output transformer on the speaker looks in great condition and is all original so I don't believe anyone has had a tinker in the past with this.

https://www.youtube.com/watch?v=MoctEps6mpA

Thanks all, any thoughts or suggestions as to what I check next would be great.

If that was on my bench, I would be progressively isolating each stage until the noise stopped. Now that you have the schematic, that shouldn't be too difficult.

It seems from the video that the hum is able to be controlled via the volume pot. If so, then the source is prior to the audio stage.

BTW: have you checked your power supply voltages against the schematic?