Philips Type 701 A/X - UK Vintage Radio Repair and Restoration Discussion Forum

Sinewave · 20th Jan 2019, 2:56 pm

We have this valve radio sitting in my aunts garage, I'm not sure what to do with it.

Lacking VHF it may be difficult to use as there's very little on the other bands, certainly of which I wouldn't listen to.

It was working when it was last switched on, so it should still be working.

Floor standers aren't usually my thing, so I'm wondering if this is worth me taking on as a retoration project or passing it on as it is? There are some nice Mullard valves inside.

Any thoughts/information welcome.

Cobaltblue · 20th Jan 2019, 5:00 pm

The Mono knobs are lovely sets but not so lovely to work on.

The lack of vhf can easily be overcome and you could use a Bluetooth module and stream from your phone.

Console sets do tend to sound pretty good I would be inclined to suggest keeping it and restore if you have space.

Cheers

Mike T

Sinewave · 21st Jan 2019, 5:17 pm

I am indeed tempted to take it in.

The bluetooth module you mention, does it transmit over one of the radio bands?

Cobaltblue · 21st Jan 2019, 5:24 pm

Hi Sinewave

No you can use the Radios Gram input.

There are loads of these for sale.

https://www.ebay.co.uk/itm/12V-Car-W...ZLT:rk:12:pf:0

Just an example not a recommendation some have VHF radios also built in as well.

Cheers

Mike T

60 oldjohn · 21st Jan 2019, 5:45 pm

Or there are these, https://www.vintage-radio.net/forum/...d.php?t=137154 FM output on the MW band. Its a long thread, best start reading at #15.

John.

Sinewave · 24th Mar 2019, 9:37 pm

Well, I caved and rehomed it.

I've not powered it up yet.

Here it is

Mike. Watterson · 25th Mar 2019, 2:25 pm

Quote:

Originally Posted by Sinewave

It was working when it was last switched on, so it should still be working.
Any thoughts/information welcome.

Only in a manner of speaking. It may have original paper dielectric capacitors (aka waxies), they have about a 10 to 15 year life.
The Electrolytic HT caps will need gently reformed via a current limited DC source or can burst.

Sinewave · 26th Mar 2019, 10:13 pm

I don't think I've a way of reforming caps here.

Do you think I'd be alright if I brought it up gently with my variac?

buggies · 26th Mar 2019, 11:12 pm

I had no reforming device when I rejuvenated my first amplifier but did have a variac. It was easy to remove all the valves and wire a 1N4007 in series with a multimeter on mA range across the rectifier valve holder anode and cathode pins.
Bringing up the variac slowly I could stop when the current was a couple of mA and see what happened.
With the same simple setup you can also measure voltage on the valveholder grid pins to see which coupling caps are leaking.

Mike. Watterson · 27th Mar 2019, 10:05 am

I use a 30V DC PSU. I take out valves and put it across each cap with current limiting set.
Even a 12V PSU and 1K resistor will do to start reforming. Measure current. If it drops to less than 1mA then you can try HT. A valve rectifier allows the HT to rise slowly. You can measure voltage and turn off for a few minutes when HT has risen to over 100V. Then try again a little longer.
I've also a modified double socket on a short cable that has the sockets in series. Then a different incandescent lamp can be put in as a limiter.
If an electrolytic gets hot it's not reformed. If in doubt, cut wire to it and measure current. If it's more than 1mA after an hour or two, then it's too leaky. The other problem is Electrolytics drying out. Symptoms are hum (HT) or lack of gain (Cathode decouplers) or no FM (4uF approx Discriminator cap, +Ve usually to 0V!).

Mike. Watterson · 27th Mar 2019, 10:14 am

Quote:

Originally Posted by buggies

With the same simple setup you can also measure voltage on the valveholder grid pins to see which coupling caps are leaking.

It should be zero on the control grids and HT on screen grids.

A good plan, though I took guts of a £5 single use camera and replaced the 300uF with a 1uF 600V, added 2 x 1M in series; that's the +Ve terminal. I then put a neon with a parallel 0.1uF 250V (very low leakage type) in series with -Ve. The on/off is a spring loaded toggle. WARNING, a cap charged to 600V that has no leakage varies between unpleasant (10nF) to lethal (0.5uF an higher maybe?). Discharge the cap under test.
Unplug valves and set from mains. If in doubt cut "hot" end of a cap. Leaky Anode to Grid caps will wreck valves and can damage load coils, HT rectifier and even mains transformer. Leaky screen grid caps means no gain or no LO or no mixer depending on location.

20th Jan 2019, 5:00 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: Philips Type 701 A/X The Mono knobs are lovely sets but not so lovely to work on. The lack of vhf can easily be overcome and you could use a Bluetooth module and stream from your phone. Console sets do tend to sound pretty good I would be inclined to suggest keeping it and restore if you have space. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

21st Jan 2019, 5:17 pm	#3
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Philips Type 701 A/X I am indeed tempted to take it in. The bluetooth module you mention, does it transmit over one of the radio bands? __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

21st Jan 2019, 5:24 pm	#4
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: Philips Type 701 A/X Hi Sinewave No you can use the Radios Gram input. There are loads of these for sale. https://www.ebay.co.uk/itm/12V-Car-W...ZLT:rk:12:pf:0 Just an example not a recommendation some have VHF radios also built in as well. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

21st Jan 2019, 5:45 pm	#5
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,985	Re: Philips Type 701 A/X Or there are these, https://www.vintage-radio.net/forum/...d.php?t=137154 FM output on the MW band. Its a long thread, best start reading at #15. John. Last edited by 60 oldjohn; 21st Jan 2019 at 5:53 pm.

24th Mar 2019, 9:37 pm	#6
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Philips Type 701 A/X Well, I caved and rehomed it. I've not powered it up yet. Here it is Attached Thumbnails __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

20th Jan 2019, 2:56 pm	#1
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Philips Type 701 A/X We have this valve radio sitting in my aunts garage, I'm not sure what to do with it. Lacking VHF it may be difficult to use as there's very little on the other bands, certainly of which I wouldn't listen to. It was working when it was last switched on, so it should still be working. Floor standers aren't usually my thing, so I'm wondering if this is worth me taking on as a retoration project or passing it on as it is? There are some nice Mullard valves inside. Any thoughts/information welcome. Attached Thumbnails __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

26th Mar 2019, 10:13 pm	#8
Sinewave Octode Join Date: May 2016 Location: Oxfordshire/Bucks borders, UK. Posts: 1,604	Re: Philips Type 701 A/X I don't think I've a way of reforming caps here. Do you think I'd be alright if I brought it up gently with my variac? __________________ Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.

26th Mar 2019, 11:12 pm	#9
buggies Heptode Join Date: Jan 2009 Location: West Lothian, UK. Posts: 761	Re: Philips Type 701 A/X I had no reforming device when I rejuvenated my first amplifier but did have a variac. It was easy to remove all the valves and wire a 1N4007 in series with a multimeter on mA range across the rectifier valve holder anode and cathode pins. Bringing up the variac slowly I could stop when the current was a couple of mA and see what happened. With the same simple setup you can also measure voltage on the valveholder grid pins to see which coupling caps are leaking. __________________ George

27th Mar 2019, 10:05 am	#10
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Philips Type 701 A/X I use a 30V DC PSU. I take out valves and put it across each cap with current limiting set. Even a 12V PSU and 1K resistor will do to start reforming. Measure current. If it drops to less than 1mA then you can try HT. A valve rectifier allows the HT to rise slowly. You can measure voltage and turn off for a few minutes when HT has risen to over 100V. Then try again a little longer. I've also a modified double socket on a short cable that has the sockets in series. Then a different incandescent lamp can be put in as a limiter. If an electrolytic gets hot it's not reformed. If in doubt, cut wire to it and measure current. If it's more than 1mA after an hour or two, then it's too leaky. The other problem is Electrolytics drying out. Symptoms are hum (HT) or lack of gain (Cathode decouplers) or no FM (4uF approx Discriminator cap, +Ve usually to 0V!).