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Old 2nd Mar 2020, 9:52 pm   #21
Dick Glennon
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Default Re: 730A philips radio to get working.

Hi again, There is some confusion between the trader sheet 647 and the E.R.T service sheet regarding V 5 . The 647 has it at PM22A which has a 2volt filament, but the E.R.T. Sheet has it at PM24A which has a 4volt filament. Also could a 354V be substituted for the 244V. Filament amps are the same, and I would have a better chance of getting the afore mentioned at an affordable price. Any thoughts would be greatly appreciated. Regards, Dick.
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Old 3rd Mar 2020, 9:08 am   #22
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Default Re: 730A philips radio to get working.

Hi
My 647 sheet specifies a PM24A which I'm sure is the correct valve.

P
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Old 3rd Mar 2020, 10:34 pm   #23
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Default Re: 730A philips radio to get working.

Hi There,
According to the radiomuseum tube site the 244v can be replaced as a direct equivalent by types 41MHL, 4HLAC & MHL4

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Old 13th Mar 2020, 9:53 pm   #24
Dick Glennon
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Default Re: 730A philips radio to get working.

hi again, In stripping down the 730A the two electrolitic capacitors 3uf and 4uf, have instead 2 8uf capacitors in a cardboard box filled with wax. It seems to be the original box and the wires are completely disintegrated. Should I replace like with like or should I refer back to the schematic. Also will the resistors within tolerance be ok to leave in. What should the wattage be on replacements. Has anyone rebuilt the on/off volume control in this set. Thanks to all for your very helpful answers. Regards, Dick
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Old 13th Mar 2020, 10:45 pm   #25
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Default Re: 730A philips radio to get working.

Hi Dick, I would use a pair of 4.7uF. The resistor wattage depends where they are in the circuit. If you can id which ones need replacing it will be easier to advise. I have been looking through my valve spares to see if I can help out with the two 244V triodes. I don't have an 244V so looking up the data I offer the following for comment by you and by others for suitability as equivalents. Data from Radio Valve Guide Book 1 (G C Arnold Partners):
Type Vh (v) Ih (A) Va (v) Ia (mA) Vg (v) ra (kOhm) gm (mA/v)
244V 4.0 0.65 200 5.5 -5.5 9.25 2.75
354V 4.0 0.65 250 6.5 -4.5 11.5 3.5
41MHL 4.0 1.0 200 4.0 -3.0 11.5 4.5
HL4+ 4.0 0.65 250 5.0 -4.5 11.0 3.5
I would imagine any of the 3 equivalents would work after a fashion but I leave it for those more knowledgeable than me to advise which would be best. I have two 354V and one each 41MHL and HL4+. All 3 types are pin compatible with the 244V. I have also responded to your PM re: S4VB availability. Kind regards, Jerry
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Old 14th Mar 2020, 12:22 am   #26
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Default Re: 730A philips radio to get working.

The trader shows a can for these caps so the cardboard box is probably a replacement. Leave the old resistors that are in tolerance, I only replace ones that are +/-25%. V3 is a leaky grid detector so operating conditions are not 'normal'. V4 is an audio amplifier with fixed bias. I am sure any of these can be made to work but it would be wise to check the anode current as they may require changes to the bias circuit or anode load.
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Old 23rd Mar 2020, 3:49 pm   #27
Dick Glennon
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Default Re: 730A Philips radio to get working.

Hi again, Afew more questions on the 730A. The 6 capacitors in each of the cans are reading very good against service sheet. Should I replace them anyway. Also how will I know if the mains transformer is at the right setting for 240 mains volts on to the primary. Regards, Dick.
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Old 23rd Mar 2020, 5:27 pm   #28
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Default Re: 730A Philips radio to get working.

The only reasonably sure test of wax/paper capacitors is a combination of measured capacitance and leakage resistance at rated working voltage. Just capacitance on its own can be misleading since it provides no direct information about leakage which is the most likely failure method.


For electrolytics a similar combination is required, though leakage resistances can safely be rather lower- hundreds of kilohms rather than tens of megohms but also ESR as well, particularly for HT filter and cathode decoupling applications.

For the mains transformer, check the voltage out from a known voltage secondary. It should be within 10% or so of its expected value if the primary is tapped correctly for the applied mains. None of the circuits I can find (Trader, ERT and Philips) shows any primary tappings, though, and the nominal voltage input rating appears to be around 225Vac.
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Old 23rd Mar 2020, 5:38 pm   #29
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Default Re: 730A Philips radio to get working.

What have you measured? You need to measure leakage current at working voltage which would require setup of an HT PSU. Is it possible the capacitors inside have already been replaced?

I have one of these stored away and I don't think they ever had a back? Other Philips sets had a back with a cardboard wheel that gave the strap details. The Trader refers to other trader sheets for the mains selector details, this is from Trader 540. You might want to measure the primary resistance at various settings to make sure it appears to be correct.
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Old 13th Apr 2020, 8:32 pm   #30
Dick Glennon
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Default Re: 730A Philips radio to get working.

Hi again, I have a few more questions to ask about the 730A. Firstly, I want to know if the settings I have on the mains transformer are correct. Please see attachment. Secondly, does the earth wire from C26 pickup the centre tap on L14 and proceed to L11. Thirdly, please see R21 in attachment it has gone open circuit. Would a 2watt of the same resistance suffice? Lastly, is R7 available in an on/off plus potentiometer of the same ohms value. Please see all attachments. Thank you in advance. Regards, Dick.
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Old 23rd Jul 2020, 6:45 am   #31
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Default Re: 730A Philips radio to get working.

Hi,
I just registered here to reply on this post.

I just started restoring a 730A, made in Holland in 1931.
This unit is in very good condition, no rust or corrosion on chassis and everything (except an added electrolytic cap dated 1944) is clean and untouched. As for now, I'll only restore the caps (put new caps in the old boxes) and do some cabinet touch up. Transformers and speaker all fine.

If anyone has doubt about how things are wired, what parts are original etc. I can post some pics. This unit also have tube types stamped on the chassis (Philips/Dutch types, not Mullard types as on some schematics) and came with the original tube set, so it is a fine unit to use as reference.

I can mention that I am a valve/tube distributor and tubeamp service center by trade, but I am not here to promote myself. I just have a weak heart for 20's and 30's amplifiers, and especially Philips stuff.

Cheers
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Old 16th Dec 2020, 1:50 pm   #32
Dick Glennon
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Default Re: 730A Philips radio to get working.

Hi again, I have been lucky enough to come on another 730A not working and with some repairs carried out some time ago. As I investigated I found that capacitors no 19,23 and 25 are gone to chassis . Would this be right for C25 as I read it as going from V5 to HT. I must be wrong as this is original wiring. Any thoughts would be very much appreciated. Dick.
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Old 16th Dec 2020, 2:17 pm   #33
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Default Re: 730A Philips radio to get working.

Quote:
Originally Posted by Dick Glennon View Post
Hi again, I have been lucky enough to come on another 730A not working and with some repairs carried out some time ago. As I investigated I found that capacitors no 19,23 and 25 are gone to chassis . Would this be right for C25 as I read it as going from V5 to HT. I must be wrong as this is original wiring. Any thoughts would be very much appreciated. Dick.
In a Philips 1932 manual the circuit reference equivalent of C25 in the Trader sheets is connected between anode and chassis, in the Trader sheets it's connected between anode and HT, the latter connection would prevent damage to the output transformer should that capacitor fail short circuit.

Lawrence.
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Old 16th Dec 2020, 7:50 pm   #34
Dick Glennon
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Default Re: 730A Philips radio to get working.

hi again, Thank you very much Laurence for setting me straight, regards,Dick.
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Old 5th May 2021, 12:17 pm   #35
Dick Glennon
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Default Re: 730A Philips radio to get working.

Hi again, I have good news on the Philips 730 A . I have it working very well ,I am even getting B.B.C coming in on Longwave with a long wire aerial. I want to thank all on the forum for their patience and perseverance with me over what has been a long time. I also got the Lady Margaret (Vidor) working, both IF transformers were open circuit, and I managed to to fit Paul's battery eliminator into the case. Once again thanks, I have pics of the eliminator if anyone wants to have a look.

Regards, Dick.

Last edited by Station X; 5th May 2021 at 12:22 pm. Reason: typo
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Old 25th May 2021, 9:04 pm   #36
Dick Glennon
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Default Re: 730A Philips radio to get working.

hi again, I had the Philips 730 A working very well, so I decided to get the second one working .My mistake was that being the fool I am I disconnected the two capacitors C20 and C22 on the working one to get a better view of the connections to valve bases of V4 and V5. I oviously did not put them back right as I have no stations coming through. I have no reaction when I connect/disconnect the ariel but I am getting a loud click in the speaker when I flick the tone correctoin switch. I have it connected through the lamp limiter. Any thoughts would be very much appreciated. Dick.
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Old 8th Jun 2021, 12:01 pm   #37
Dick Glennon
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Default Re: 730A Philips radio to get working.

Hi agan, I now have RTE radio 1 coming in on L.W. But only by connecting a short wire to the top cap of V1. I have no reaction when I plug in the long wire Ariel to its socket. Also is it possible to fit a speaker and if so what resistance would I require. Any help would be very much appreciated . Regards Dick.
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Old 8th Jun 2021, 1:56 pm   #38
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Default Re: 730A Philips radio to get working.

You are not alone Dick, we can all make errors over the years and regardless of experience.
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Old 8th Jun 2021, 6:40 pm   #39
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Default Re: 730A Philips radio to get working.

Do you have your aerial plugged into the A2 socket? The A1 socket is only for very strong transmissions. If the aerial is in the A2 socket then there's a problem between there and V1.

If you are asking about connecting an extension speaker, the sockets on this set (and a few other 1930s sets) are connected to the output transformer primary and so are at HT potential. I usually isolate this type of socket to prevent a shock hazard. They were intended for use with the type of early extension speaker that had an output transformer inside the cabinet.
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