Philips N4510 input / output RCA mod - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

NorfolkDaveUK · 25th Aug 2018, 8:03 pm

Yes you can , there are internal RCA plugs / sockets .

Edit , I`ll be swapping those for a 5 pin connector once it gets here

2nd edit , you would need 2 leads to be able to use it like this . You would need one for the monitor socket and one for the aux socket . Now you don`t need any .

julie_m · 25th Aug 2018, 8:34 pm

Oh, that's actually not too bad at all! It doesn't scream MODIFIED! even if you stare at it, but it definitely enhances functionality. The nearest thing to a "gold standard" for such a job is "Would a good dealer do it like that?"

Adaptors don't worry me (it's a necessary consequence of my younger days' quest to be able to connect anything audio-related to anything else!) so I wouldn't be bothered by having to use one or more just to get a signal into or out of a piece of equipment, but obviously others might be more put-off by the need for an adaptor than by an obvious, out-of-place alteration.

You've actually managed to do the job to the satisfaction of both schools of thought here, though! I'd call that a result

NorfolkDaveUK · 25th Aug 2018, 9:19 pm

Thanks Julie . My thinking is if someone can just get it home and plug it in then thats all they want to do . Us as geeky folk dont mine messing around with umpteen cables and keeping things as they were . After a year of selling and fixing these I come to the conclusion that the main market for these is people that have a loft / cupboard / drawer full of old tapes and they just want to get a bit nostalgic. I started off buying the revox`s and the teac`s etc and found out pretty quickly that that`s not what most of the market for these is . Sure there are lots and lots of people that will buy them but there are many more that just want a cheap , ready to go, hassle free player / recorder to "mess around" with that wont break the bank . Since changing to this mindset and buying accordingly , I`ve sold a lot more meaning I can buy a lot more and keep my hobby flowing pretty nicely . I`m not making a whole lot of money , BUT , that not why I started doing it . I have bipolar disorder and I live in my bedroom all day and night and havent left the house for a long time . So i needed something to occupy my mind and at the same time give me a sense of achievement . I have tried other things, I did reballing / reflowing games consoles for a while (not with a heat gun..hehe) but that really didnt keep my interest , so I sold my BGA machine and got into this . I just like it and I like the idea of giving people a piece of history that HOPEFULLY will go on and on ....wow...where did all that come from ...anyway , you get the picture ...lol .

NorfolkDaveUK · 26th Aug 2018, 10:55 am

OK I`m struggling a bit here . I decided to go ahead with the setup with all the old components in place . I`m trying to do the bit in the pic . I`m put a 333hz -100mV (peak to peak) signal into tape in , I`m reading the output at the monitor and its reading 1.7v rms and It wont go below 1.5v rms (using a scope). I have removed the osc card as stated in the manual . the adjustment is tiny , you can use the whole of the VR range and only get 0.4v attenuation . Any ideas anyone ?

ms660 · 26th Aug 2018, 10:58 am

RMS in....RMS out maybe.

What are you measuring the input test signal with and what are you measuring the output signal with?

Lawrence.

NorfolkDaveUK · 26th Aug 2018, 11:30 am

Hi Lawrence .
I tried that and it just made the whole situation much worse . 100mv in rms gave me something like 3v coming out rms .So it had to be P2P in rms out . I`m measuring it all with a scope . (hantech usb scope , crap but effective most of the time) I think the signal was a little hot going in . I have attenuated that a bit and now at 1v RMS the signal is just under the clipping so that`s about right I would think. I also re-capped the before tape boards which didnt help the situation but wont hurt.

NorfolkDaveUK · 26th Aug 2018, 11:43 am

The next bit is going WAYYYY over my head ..haha ... can someone explain what they are saying in laymans terms please ? "Input 333hz 1v ; Value to be measured , 1v + xV (x=max 0.8v) ; Halve the difference with R4 at before tape board" .

I`m seeing . put the 1v in , read the v at the designated point , if its over 1v reduce the difference by half using R4 , correct ? gotta love philips and their bizzare way of doing things huh ). .lol at least you dont need a test tape I guess .lol .

NorfolkDaveUK · 26th Aug 2018, 12:41 pm

So there is definitely an issue with this somewhere . The v`s are nothing like I should be getting so I'm going back to the original plan and going to re-cap the whole thing and then start over . Something is defo amiss. The output signal is really weak .

ms660 · 26th Aug 2018, 12:51 pm

Have you tried playing back a known good pre recorded tape?

Lawrence.

julie_m · 26th Aug 2018, 12:55 pm

The instructions seem to me to mean that the output will be 1v AC superimposed on x V DC, where the maximum value of x is 0.8.

If, while viewing the waveform with the input couplimg set to DC, you switch the input coupling to AC, the entire trace will shift down by an amount equal to x V. When displaying the waveform with DC coupling, the halfway line of the AC waveform (which you can also calculate by adding the minimum voltage in the "trough" and the maximum voltage in the "crest", and dividing the total by 2. This is so because there must by definition be exactly as much energy above the halfway line as below, and this occurs when the line is placed at the average as calculated above) will be x V above 0V.

This sort of waveform with AC "riding on" a DC bias is very common in all sorts of electronic equipment, so it's worth trying to get your head around it.

NorfolkDaveUK · 26th Aug 2018, 12:57 pm

Quote:

Originally Posted by ms660

Have you tried playing back a known good pre recorded tape?

Lawrence.

Yeah its quiet . The incoming signal is fine but but when you switch to tape monitor on record the signal drops significantly so something is wrong somewhere . Could be dead transistors or capacitors somewhere . If I need to I`ll change all the transistors too I have an abundance of 107`s and 550`s and 557`s that should work in here ok . The level is dropping 10 fold , I should be getting 1v out where I`m gettin 128mv so its not just poorly adjusted , theres definitely something dead somewhere .

NorfolkDaveUK · 26th Aug 2018, 1:00 pm

Quote:

Originally Posted by julie_m

The instructions seem to me to mean that the output will be 1v AC superimposed on x V DC, where the maximum value of x is 0.8.

If, while viewing the waveform with the input couplimg set to DC, you switch the input coupling to AC, the entire trace will shift down by an amount equal to x V. When displaying the waveform with DC coupling, the halfway line of the AC waveform (which you can also calculate by adding the minimum voltage in the "trough" and the maximum voltage in the "crest", and dividing the total by 2. This is so because there must by definition be exactly as much energy above the halfway line as below, and this occurs when the line is placed at the average as calculated above) will be x V above 0V.

This sort of waveform with AC "riding on" a DC bias is very common in all sorts of electronic equipment, so it's worth trying to get your head around it.

Thanks Julie . I will try and get my head round it . I`m using a pretty useless scope for anything too technical (hantech usb) so I`m not sure thats even possible with this scope(dc / ac coupling box is greyed out in the software)

julie_m · 26th Aug 2018, 1:52 pm

I doubt even the Chinese could make an oscilloscope that was actually worse than no oscilloscope .....

Even if the coupling is fixed on DC (it wouldn't make any sense for it to be fixed on AC) and switching can't be enabled in any of the settings (not inconceivable; the same software might well support more sophisticated hardware) you should still be able to find the halfway line by using the cursors to find the extreme values and calculating the average.

Using a 10nF capacitor in series with the probe will effectively simulate AC coupling. (If you've ever seen the circuit diagram for a simple oscilloscope kit, you will see exactly such an arrangement: the AC/DC switch connects the input to the probe tip either directly, or via a series capacitor.) But as long as you have sufficient room for measurement, you can manage with pure DC coupling for the time being

ms660 · 26th Aug 2018, 1:55 pm

There's no DC on the monitor output so far as I can make out, maybe that setup instruction means split the difference if there's a difference between the outputs (of up to 0.2 volts) when the signal is connected respectively to the two input sockets ?

Lawrence.

NorfolkDaveUK · 26th Aug 2018, 2:01 pm

Quote:

Originally Posted by julie_m

I doubt even the Chinese could make an oscilloscope that was actually worse than no oscilloscope .....

Even if the coupling is fixed on DC (it wouldn't make any sense for it to be fixed on AC) and switching can't be enabled in any of the settings (not inconceivable; the same software might well support more sophisticated hardware) you should still be able to find the halfway line by using the cursors to find the extreme values and calculating the average.

Using a 10nF capacitor in series with the probe will effectively simulate AC coupling. (If you've ever seen the circuit diagram for a simple oscilloscope kit, you will see exactly such an arrangement: the AC/DC switch connects the input to the probe tip either directly, or via a series capacitor.) But as long as you have sufficient room for measurement, you can manage with pure DC coupling for the time being

Thanks Julie thats great info thank you. Once I get it recapped and what have you I will start over and try and get my head around this . TA !

Lawrence : thats what I took it to mean but I`m not expert to be fair ..lol .

I`ve just looked at these boards and someone had willy nilly changed some of the transistors . Some or most of the boards in here are paired with another and most have different transistors in them , so I`m going to go through and pair them all up properly with 550`s and see what I get once thats done.

TonyDuell · 26th Aug 2018, 2:32 pm

Philips did change the transistor types used in these machines during the production run. Originally, for example, a lot of the transistors were BC148 (Silicon NPN in a 'Lockfit' package). Later machines had BC548 transistors in the same positions (Silicon NPN in a TO92 package). These are essentially the same part in a different package and there is no problem in having a mix of both types in the same machine.

NorfolkDaveUK · 26th Aug 2018, 2:44 pm

Yeah thanks tony, I could pull them all out and test them , but if I have them out I may as well put a new one in there . They cost next to nothing when you buy them 1000 at a time so its quicker and way simpler to just shotgun them all . There are two or three in here that are neither 148`s or 548/9`s and the 550`s are the same as the 548/9`s (pretty much) so these are ok got the job . Sometimes when you test them they can come up OK but still be distorting or crackly as you know so I like to just get rid. I know that`s rare but it does happen I have a desoldering gun now so it only takes a second to get them out with no damage to the boards so its all good . I know the pro`s think I`m wasting my time and parts , but it keeps me amused ..haha.

julie_m · 26th Aug 2018, 3:49 pm

Be very careful if changing components "blind", without testing between each change. If you know it was working before you replaced (let's say) C9, and now it's not working, then it's reasonable to suppose you made a mistake with C9 -- perhaps it is mis-wired, or you fit the wrong value.

But the more parts you touched between tests, the harder it is to be sure what might have caused any newly-introduced fault.

NorfolkDaveUK · 26th Aug 2018, 4:24 pm

Thanks Julie , the good thing about these little philips units are all the circuits are on little tiny plug in boards . So I just do one and compare it to the other before doing it , and then it eliminates the possibility for error. (usually ..lol)

So I`ve replaced all the transistors in the universal input board , the rec board and the before tape board (along with the caps ) and now the input level is REALLY hot (overly so , distorted to hell and I`m unable to adjust the input level up much ). The transistors shouldn`t have caused it to do that because the ones I`ve put in are virtually the same with the same pin out , As Tony said earlier , the ones in there were 149b which were later changed to 549b which is the same pretty much as the BC550 , so something is definitely amiss in here some place . The caps I replaced like for like . All orientated correctly and none of them are short .

NorfolkDaveUK · 10th Sep 2018, 4:13 pm

Right I`m back to normal now with this one . The power supply was the issue with the output .

I still have the same problem though . I have VERY low record and the trimmers on the record cards do nothing (neither of them)

Can someone help me with this please . I`ve been over it with my signal tracer and I have a low input going into the "before tape" card and a high output coming out and simularly I have the same with the record card with the exception I have a low output coming out of the output to the pre-emphasis card .

I have checked the voltage at the record head and I have 21v on the bottom coil and only 4v on the top one . What should they be ?

it plays tapes recorded on other machines just fine so the problem is definitely within the recording circuit somewhere .

Tapes recorded on this machine play extremely quiet on other machines also .

Thanks as always for any assistance .

25th Aug 2018, 8:03 pm	#21
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Yes you can , there are internal RCA plugs / sockets . Edit , I`ll be swapping those for a 5 pin connector once it gets here 2nd edit , you would need 2 leads to be able to use it like this . You would need one for the monitor socket and one for the aux socket . Now you don`t need any . Last edited by NorfolkDaveUK; 25th Aug 2018 at 8:24 pm.

25th Aug 2018, 8:34 pm	#22
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Philips N4510 input / output RCA mod Oh, that's actually not too bad at all! It doesn't scream MODIFIED! even if you stare at it, but it definitely enhances functionality. The nearest thing to a "gold standard" for such a job is "Would a good dealer do it like that?" Adaptors don't worry me (it's a necessary consequence of my younger days' quest to be able to connect anything audio-related to anything else!) so I wouldn't be bothered by having to use one or more just to get a signal into or out of a piece of equipment, but obviously others might be more put-off by the need for an adaptor than by an obvious, out-of-place alteration. You've actually managed to do the job to the satisfaction of both schools of thought here, though! I'd call that a result __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

25th Aug 2018, 9:19 pm	#23
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Thanks Julie . My thinking is if someone can just get it home and plug it in then thats all they want to do . Us as geeky folk dont mine messing around with umpteen cables and keeping things as they were . After a year of selling and fixing these I come to the conclusion that the main market for these is people that have a loft / cupboard / drawer full of old tapes and they just want to get a bit nostalgic. I started off buying the revox`s and the teac`s etc and found out pretty quickly that that`s not what most of the market for these is . Sure there are lots and lots of people that will buy them but there are many more that just want a cheap , ready to go, hassle free player / recorder to "mess around" with that wont break the bank . Since changing to this mindset and buying accordingly , I`ve sold a lot more meaning I can buy a lot more and keep my hobby flowing pretty nicely . I`m not making a whole lot of money , BUT , that not why I started doing it . I have bipolar disorder and I live in my bedroom all day and night and havent left the house for a long time . So i needed something to occupy my mind and at the same time give me a sense of achievement . I have tried other things, I did reballing / reflowing games consoles for a while (not with a heat gun..hehe) but that really didnt keep my interest , so I sold my BGA machine and got into this . I just like it and I like the idea of giving people a piece of history that HOPEFULLY will go on and on ....wow...where did all that come from ...anyway , you get the picture ...lol .

26th Aug 2018, 10:55 am	#24
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod OK I`m struggling a bit here . I decided to go ahead with the setup with all the old components in place . I`m trying to do the bit in the pic . I`m put a 333hz -100mV (peak to peak) signal into tape in , I`m reading the output at the monitor and its reading 1.7v rms and It wont go below 1.5v rms (using a scope). I have removed the osc card as stated in the manual . the adjustment is tiny , you can use the whole of the VR range and only get 0.4v attenuation . Any ideas anyone ? Attached Thumbnails

26th Aug 2018, 10:58 am	#25
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4510 input / output RCA mod RMS in....RMS out maybe. What are you measuring the input test signal with and what are you measuring the output signal with? Lawrence. Last edited by ms660; 26th Aug 2018 at 11:19 am. Reason: addition

26th Aug 2018, 11:30 am	#26
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Hi Lawrence . I tried that and it just made the whole situation much worse . 100mv in rms gave me something like 3v coming out rms .So it had to be P2P in rms out . I`m measuring it all with a scope . (hantech usb scope , crap but effective most of the time) I think the signal was a little hot going in . I have attenuated that a bit and now at 1v RMS the signal is just under the clipping so that`s about right I would think. I also re-capped the before tape boards which didnt help the situation but wont hurt.

26th Aug 2018, 11:43 am	#27
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod The next bit is going WAYYYY over my head ..haha ... can someone explain what they are saying in laymans terms please ? "Input 333hz 1v ; Value to be measured , 1v + xV (x=max 0.8v) ; Halve the difference with R4 at before tape board" . I`m seeing . put the 1v in , read the v at the designated point , if its over 1v reduce the difference by half using R4 , correct ? gotta love philips and their bizzare way of doing things huh ). .lol at least you dont need a test tape I guess .lol . Last edited by NorfolkDaveUK; 26th Aug 2018 at 11:48 am.

26th Aug 2018, 12:41 pm	#28
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod So there is definitely an issue with this somewhere . The v`s are nothing like I should be getting so I'm going back to the original plan and going to re-cap the whole thing and then start over . Something is defo amiss. The output signal is really weak .

26th Aug 2018, 12:51 pm	#29
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4510 input / output RCA mod Have you tried playing back a known good pre recorded tape? Lawrence.

26th Aug 2018, 12:55 pm	#30
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Philips N4510 input / output RCA mod The instructions seem to me to mean that the output will be 1v AC superimposed on x V DC, where the maximum value of x is 0.8. If, while viewing the waveform with the input couplimg set to DC, you switch the input coupling to AC, the entire trace will shift down by an amount equal to x V. When displaying the waveform with DC coupling, the halfway line of the AC waveform (which you can also calculate by adding the minimum voltage in the "trough" and the maximum voltage in the "crest", and dividing the total by 2. This is so because there must by definition be exactly as much energy above the halfway line as below, and this occurs when the line is placed at the average as calculated above) will be x V above 0V. This sort of waveform with AC "riding on" a DC bias is very common in all sorts of electronic equipment, so it's worth trying to get your head around it. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

26th Aug 2018, 1:52 pm	#33
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Philips N4510 input / output RCA mod I doubt even the Chinese could make an oscilloscope that was actually worse than no oscilloscope ..... Even if the coupling is fixed on DC (it wouldn't make any sense for it to be fixed on AC) and switching can't be enabled in any of the settings (not inconceivable; the same software might well support more sophisticated hardware) you should still be able to find the halfway line by using the cursors to find the extreme values and calculating the average. Using a 10nF capacitor in series with the probe will effectively simulate AC coupling. (If you've ever seen the circuit diagram for a simple oscilloscope kit, you will see exactly such an arrangement: the AC/DC switch connects the input to the probe tip either directly, or via a series capacitor.) But as long as you have sufficient room for measurement, you can manage with pure DC coupling for the time being __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

26th Aug 2018, 1:55 pm	#34
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philips N4510 input / output RCA mod There's no DC on the monitor output so far as I can make out, maybe that setup instruction means split the difference if there's a difference between the outputs (of up to 0.2 volts) when the signal is connected respectively to the two input sockets ? Lawrence.

26th Aug 2018, 2:32 pm	#36
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Philips N4510 input / output RCA mod Philips did change the transistor types used in these machines during the production run. Originally, for example, a lot of the transistors were BC148 (Silicon NPN in a 'Lockfit' package). Later machines had BC548 transistors in the same positions (Silicon NPN in a TO92 package). These are essentially the same part in a different package and there is no problem in having a mix of both types in the same machine.

26th Aug 2018, 2:44 pm	#37
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Yeah thanks tony, I could pull them all out and test them , but if I have them out I may as well put a new one in there . They cost next to nothing when you buy them 1000 at a time so its quicker and way simpler to just shotgun them all . There are two or three in here that are neither 148`s or 548/9`s and the 550`s are the same as the 548/9`s (pretty much) so these are ok got the job . Sometimes when you test them they can come up OK but still be distorting or crackly as you know so I like to just get rid. I know that`s rare but it does happen I have a desoldering gun now so it only takes a second to get them out with no damage to the boards so its all good . I know the pro`s think I`m wasting my time and parts , but it keeps me amused ..haha.

26th Aug 2018, 3:49 pm	#38
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Philips N4510 input / output RCA mod Be very careful if changing components "blind", without testing between each change. If you know it was working before you replaced (let's say) C9, and now it's not working, then it's reasonable to suppose you made a mistake with C9 -- perhaps it is mis-wired, or you fit the wrong value. But the more parts you touched between tests, the harder it is to be sure what might have caused any newly-introduced fault. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

26th Aug 2018, 4:24 pm	#39
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Thanks Julie , the good thing about these little philips units are all the circuits are on little tiny plug in boards . So I just do one and compare it to the other before doing it , and then it eliminates the possibility for error. (usually ..lol) So I`ve replaced all the transistors in the universal input board , the rec board and the before tape board (along with the caps ) and now the input level is REALLY hot (overly so , distorted to hell and I`m unable to adjust the input level up much ). The transistors shouldn`t have caused it to do that because the ones I`ve put in are virtually the same with the same pin out , As Tony said earlier , the ones in there were 149b which were later changed to 549b which is the same pretty much as the BC550 , so something is definitely amiss in here some place . The caps I replaced like for like . All orientated correctly and none of them are short . Last edited by NorfolkDaveUK; 26th Aug 2018 at 4:29 pm.

10th Sep 2018, 4:13 pm	#40
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 input / output RCA mod Right I`m back to normal now with this one . The power supply was the issue with the output . I still have the same problem though . I have VERY low record and the trimmers on the record cards do nothing (neither of them) Can someone help me with this please . I`ve been over it with my signal tracer and I have a low input going into the "before tape" card and a high output coming out and simularly I have the same with the record card with the exception I have a low output coming out of the output to the pre-emphasis card . I have checked the voltage at the record head and I have 21v on the bottom coil and only 4v on the top one . What should they be ? it plays tapes recorded on other machines just fine so the problem is definitely within the recording circuit somewhere . Tapes recorded on this machine play extremely quiet on other machines also . Thanks as always for any assistance .