Philips N4404 record no erase - UK Vintage Radio Repair and Restoration Discussion Forum

NorfolkDaveUK · 20th Jan 2019, 1:43 pm

This is another machine I`m not all that familiar with ,

This one is recording , but its not erasing , I have checked the head and there is resistance there (0.6 & 0.6) , I checked another one I have here and that has a resistance of 1.0 and 1.0 so I think the head is ok .

There is no voltage at the head , and there should be 15 vac , Does anyone have experiences with these machines . I know they have an issue with the switches but I have cleaned all those so its not that , I THINK I can seen on the schematic that T202 is the one I should be looking at and that`s out on a little satellite board and that tested fine . Any help would be greatly appreciated . I picked this up for next to nothing £23 and I had to "de-goo" it , but it did come with all the new rubber , so it was a bargain really and it sounds really great playing I just need to sort out this erase issue .

Thanks in advance.
David

NorfolkDaveUK · 20th Jan 2019, 2:21 pm

Ahh no it`s TS201. I just found the schematic inside the machine ....Thought it was a little odd . lol ...

ms660 · 20th Jan 2019, 2:58 pm

Yes, T201 is the oscillator transistor, it's supplied from the voltage doubler via a resistor, down stream of that resistor should be 15 volts stabilized.

Lawrence.

NorfolkDaveUK · 20th Jan 2019, 4:06 pm

No something is amiss here , I`m getting 40 vdc on all three legs of the transistor and there is 40v all over the board . Which resistor are we talking about here lawrence ? R205 ? Thats coming up good but its passing 40 straight through .

Red to black · 20th Jan 2019, 4:42 pm

If you are getting 40V all over the board then check any ground/0V/ chassis returns, it sounds like you have a broken/O/C return line.

NorfolkDaveUK · 20th Jan 2019, 4:55 pm

Thanks Red I`ll check it out . I`ve put it away for a bit now , you know how it is , it was getting to "big hammer" time ..hehe

ms660 · 20th Jan 2019, 5:07 pm

Quote:

Originally Posted by NorfolkDaveUK

No something is amiss here , I`m getting 40 vdc on all three legs of the transistor and there is 40v all over the board . Which resistor are we talking about here lawrence ? R205 ? Thats coming up good but its passing 40 straight through .

On the schematic I'm looking at....bridge rectifier (18.5 volts out)...voltage doubler (37 volts out)….as well as other circuits the voltage doubler feeds R301, the downstream side of R301 supplies the oscillator, that supply is stabilized by the Zener diode X304 (15 volt)

The schematic I'm looking at appears to show two different switching arrangements for connecting the osc to the supply and for grounding the anode of the Zener diode, one is in the +ve rail (the dotted circuit) the other is in the -ve rail, obviously all the switches connected in series shown in those arrangements would have to make contact in order to make the supply available to the osc.

The manual I'm referring to is in German (elektrotanya)

Lawrence.

NorfolkDaveUK · 20th Jan 2019, 5:59 pm

Yeah i have the German one too but the schematic I have is the original one that i found inside the machine so thats got to be the right one . OK , I have diddly Squat going into or coming out of R301. I`m going to change C303 and see if that improves things , the resistor is ok .

NorfolkDaveUK · 20th Jan 2019, 7:09 pm

OK I tested the resistor again with somewhat more patience . I have 39vdc both sides of R301 , resistor is good .

ms660 · 20th Jan 2019, 7:11 pm

Check that the grounding of the Zener (its anode) is adequate.

Lawrence.

NorfolkDaveUK · 20th Jan 2019, 7:20 pm

GL305 is adequately grounded , GL304 isnt (does it need to be ?)

ms660 · 20th Jan 2019, 7:37 pm

Yes. (X304 on the elektrotanya schematic)

Lawrence.

NorfolkDaveUK · 20th Jan 2019, 7:40 pm

Yes i`ve just found a crack in the board Lawrence . Let me repair it and see where that takes us . \...

NorfolkDaveUK · 20th Jan 2019, 7:53 pm

Thats got it Lawrence . This board has a chunk out of it . it wasn`t there when I started so what I think happened is there was a crack in it ,a bad one , and as i`ve been working on it , the chunk has fallen out . Anyway , All repaired , voltage back at the head . I just need to secure the board and jobs a good`n . Thanks mate !! Much appreciated as always !

Also thanks to Red to Black who was also spot on !!

Many thanks all ...I`m going to have a cuppa !

20th Jan 2019, 1:43 pm	#1
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Philips N4404 record no erase This is another machine I`m not all that familiar with , This one is recording , but its not erasing , I have checked the head and there is resistance there (0.6 & 0.6) , I checked another one I have here and that has a resistance of 1.0 and 1.0 so I think the head is ok . There is no voltage at the head , and there should be 15 vac , Does anyone have experiences with these machines . I know they have an issue with the switches but I have cleaned all those so its not that , I THINK I can seen on the schematic that T202 is the one I should be looking at and that`s out on a little satellite board and that tested fine . Any help would be greatly appreciated . I picked this up for next to nothing £23 and I had to "de-goo" it , but it did come with all the new rubber , so it was a bargain really and it sounds really great playing I just need to sort out this erase issue . Thanks in advance. David

20th Jan 2019, 2:21 pm	#2
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase Ahh no it`s TS201. I just found the schematic inside the machine ....Thought it was a little odd . lol ...

20th Jan 2019, 2:58 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4404 record no erase Yes, T201 is the oscillator transistor, it's supplied from the voltage doubler via a resistor, down stream of that resistor should be 15 volts stabilized. Lawrence.

20th Jan 2019, 4:06 pm	#4
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase No something is amiss here , I`m getting 40 vdc on all three legs of the transistor and there is 40v all over the board . Which resistor are we talking about here lawrence ? R205 ? Thats coming up good but its passing 40 straight through .

20th Jan 2019, 4:42 pm	#5
Red to black Nonode Join Date: Mar 2010 Location: Sunderland, Tyne and Wear, UK. Posts: 2,474	Re: Philips N4404 record no erase If you are getting 40V all over the board then check any ground/0V/ chassis returns, it sounds like you have a broken/O/C return line. __________________ I don't suffer from Insanity. I enjoy every minute of it.

20th Jan 2019, 4:55 pm	#6
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase Thanks Red I`ll check it out . I`ve put it away for a bit now , you know how it is , it was getting to "big hammer" time ..hehe

20th Jan 2019, 5:59 pm	#8
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase Yeah i have the German one too but the schematic I have is the original one that i found inside the machine so thats got to be the right one . OK , I have diddly Squat going into or coming out of R301. I`m going to change C303 and see if that improves things , the resistor is ok .

20th Jan 2019, 7:09 pm	#9
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase OK I tested the resistor again with somewhat more patience . I have 39vdc both sides of R301 , resistor is good .

20th Jan 2019, 7:11 pm	#10
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4404 record no erase Check that the grounding of the Zener (its anode) is adequate. Lawrence.

20th Jan 2019, 7:20 pm	#11
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase GL305 is adequately grounded , GL304 isnt (does it need to be ?)

20th Jan 2019, 7:37 pm	#12
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4404 record no erase Yes. (X304 on the elektrotanya schematic) Lawrence.

20th Jan 2019, 7:40 pm	#13
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase Yes i`ve just found a crack in the board Lawrence . Let me repair it and see where that takes us . \...

20th Jan 2019, 7:53 pm	#14
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4404 record no erase Thats got it Lawrence . This board has a chunk out of it . it wasn`t there when I started so what I think happened is there was a crack in it ,a bad one , and as i`ve been working on it , the chunk has fallen out . Anyway , All repaired , voltage back at the head . I just need to secure the board and jobs a good`n . Thanks mate !! Much appreciated as always ! Also thanks to Red to Black who was also spot on !! Many thanks all ...I`m going to have a cuppa !