Philips N4510 flip flop transistors - UK Vintage Radio Repair and Restoration Discussion Forum

NorfolkDaveUK · 17th Aug 2018, 10:49 pm

Can I use BC550`s and BC557`s inplace of the BC147`s and AC128`s on this circuit. ? They are just being used as switches so I dont think its going to be critical what you use is it ? Voltage looks like its well within the specs of the BC 550 / 557`s range .

paulsherwin · 17th Aug 2018, 11:07 pm

I don't see why not. Just about any transistors should work.

NorfolkDaveUK · 17th Aug 2018, 11:24 pm

Thanks Paul . I kinda knew that but i`m still at that "i better just check " stage ..haha .

NorfolkDaveUK · 17th Aug 2018, 11:55 pm

Fixed !

Radio Wrangler · 18th Aug 2018, 4:16 am

Good that it's fixed, but it's worth pointing out that there is something fishy going on in that circuit. Now, why does each flip-flop have one Germanium transistor working against one Silicon one?

Without knowing what the thing does and what it gets connected to, it's impossible to guess what the designer was up to. I assume these flip-flops hold the tape drive status, play, fast forward, rewind.

It may be that the germaniul transistors are used for their larger rating for reverse base/emitter voltage than silicon devices. If so, silicon parts could prove unreliable on the left side of each flip-flop. And the plus two volt supply may not let the trick of having a protective diode in series with the base of a silicon transistor work.

Just a note of caution.

David

TonyDuell · 18th Aug 2018, 4:46 am

These flip-flops are odd (well, it's a Philips) and do indeed have a silicon NPN transistor cross-coupled with a germanium PNP one. The outputs (collector of the germanium PNP) drive the deck motors/solenoids.

Originally the NPN transistor was a BC148 (lockfit). Later production models seem to have a BC548 there (which is much the same in a TO92 package). The PNP transistor doesn't have to be germanium, but it does need to be able to switch a fairly high current. I found a BC640 to be a suitable replacement.

llama · 18th Aug 2018, 8:36 am

I wonder if it's to make it come up in a known state.
Graham

NorfolkDaveUK · 18th Aug 2018, 9:04 am

thanks everyone , i have replaced everything as i said and it is "fixed " but , the lights are certainly now dimmed , so i will be getting some 640`s as tony suggests (i know the pin-out is different)

Michael Maurice · 18th Aug 2018, 9:06 am

I've just repaired one of these in an N4418, I had an AC128 to hand anyway.

What I found very curious is that these machines were manufactured in 1974/5 long after Germanium technology was ditched in favour of silicon. There must have been higher powered silicon transistors in those days, or was it the PNP version that wasn't so readily available.

NorfolkDaveUK · 18th Aug 2018, 9:16 am

I was blown away when i opened mine up. The simplicity of the machine with the definite "respect" for the tech . The "bonnet prop" the way the boards connect to the mech , I just love this thing . Totally underrated machine . Sounds amazing too . Was stuck in Rew when I bought it , so I swapped the flip flop boards around and sure enough it started working so it had to be one of the transistors on the flip flop, other than that and the counter belt gone to goo , this thing is in fantastic condition . £40 paid .

Michael Maurice · 18th Aug 2018, 9:28 am

I dont know what these cost at the time, but i'm sure they weren't cheap, Certainly taking plug in modules to a new high! I personally would have preferred heavier duty reel motors directly driving the spools.

As has been said, it is a Philips who seem to love doing things in an unconventional manner.

NorfolkDaveUK · 18th Aug 2018, 10:09 am

I personally think I would recommend this for a beginner in electronics mainly because they have individual circuits on teeny boards and you can see exactly what each circuit looks like . I certainly found it very informative , sometimes breaking down individual circuits on a board can be quite difficult but not on this . Its a great learning tool for sure .

TonyDuell · 18th Aug 2018, 11:16 am

I also love this series of machines. I have an N4510 and an N4450. The former has 2 boards with 3 flipflops on each. The latter is an autoreverse machine with 6 heads (erase, record, play for each direction) and has 2 boards with 4 flip-flops on each one.

Mine both needed a complete set of belts. In the case of the N4510 one of the reel belts had turned to go, the goo has got into the motor and I could not get it to run. In the end a friend in the Netherlands got me a replacement motor (how I do not know!). The other main fault on these machines are the slide switches. It's worth getting the sliders out (they come out and go in from the opposite end to the actuator, if you get it wrong you can damage contacts) and cleaning them with IPA.

I fitted BC640s to all the flipflops in both machines and they work well. With 2N3906s (my normal 'TUP' (as Elektor used to put it)) I had odd faults.

There are pictures of my machines (in bits) in my flickr account (tony_duell).

paulsherwin · 18th Aug 2018, 11:29 am

Quote:

Originally Posted by Michael Maurice

I've just repaired one of these in an N4418, I had an AC128 to hand anyway.

What I found very curious is that these machines were manufactured in 1974/5 long after Germanium technology was ditched in favour of silicon. There must have been higher powered silicon transistors in those days, or was it the PNP version that wasn't so readily available.

There was certainly reasonably priced medium power PNP silicon available by then (most obviously the BC464 in Lockfit), but I wouldn't put it past Philips to seize the opportunity to clear their inventory of obsolete AC128s. That would be a perfectly defensible thing to do if the AC128s were up to the job. The previously large market for AC128s in radio output stages was shrinking rapidly at the time.

NorfolkDaveUK · 18th Aug 2018, 11:35 am

Quote:

Originally Posted by TonyDuell

I also love this series of machines. I have an N4510 and an N4450. The former has 2 boards with 3 flipflops on each. The latter is an autoreverse machine with 6 heads (erase, record, play for each direction) and has 2 boards with 4 flip-flops on each one.

Mine both needed a complete set of belts. In the case of the N4510 one of the reel belts had turned to go, the goo has got into the motor and I could not get it to run. In the end a friend in the Netherlands got me a replacement motor (how I do not know!). The other main fault on these machines are the slide switches. It's worth getting the sliders out (they come out and go in from the opposite end to the actuator, if you get it wrong you can damage contacts) and cleaning them with IPA.

I fitted BC640s to all the flipflops in both machines and they work well. With 2N3906s (my normal 'TUP' (as Elektor used to put it)) I had odd faults.

There are pictures of my machines (in bits) in my flickr account (tony_duell).

I`ve become really quite fond of Philips machines . I now have a 4307 , this 4510 and the top of the range Black Tulip 4520 . The latter is an amazing piece of kit, I`m waiting at the moment for the IC for the counter to arrive from America as it was borked when I bought it. Its a beast of a thing but the sound quality from it is absolutely incredible . Its very very rare too so I`m glad I managed to land one . They have their "issue" being Philips , they certainly don`t like playing by the rules , but you can`t argue with the end results , they work brilliantly .

AC/HL · 18th Aug 2018, 3:45 pm

Philips were well known for their "adventurous" designs, but to me our particular interests would have been much the poorer without their influence. However, as one of the driving forces behind semiconductor design and manufacture, they had access to any device they wanted. They would have chosen any particular one for a reason. Whether those reasons are still valid is another matter of course. For the same reason, they were driving the demise of obsolete devices. They would be unlikely to be caught with other than normal levels of surplus, and would have had established channels for disposal.

TonyDuell · 18th Aug 2018, 4:33 pm

I must admit to liking (old-ish) Philips designs. This is partly nostalgic -- I learnt electronics from the Philips EE series kits, my first cassette recorder was Philips, so was my first minicomputer (!). But it's more that I like unconventional designs that make me think, particularly (as in the case of the N4510, etc) they work well.

Anyway... I have no idea why they used AC128s in these flip-flops. But I will confirm that, now, they are a common failure and that fortunately a common silicon transistor can be used to replace them.

Maarten · 18th Aug 2018, 6:50 pm

Quote:

Originally Posted by NorfolkDaveUK

so i will be getting some 640`s as tony suggests (i know the pin-out is different)

Actually the BC640 pinout depends on the make, so be sure to check the datasheet and/or measure it.

NorfolkDaveUK · 18th Aug 2018, 9:22 pm

The ones I bought are ECB so they just need rotating one stop clockwise .

Cheers

NorfolkDaveUK · 20th Aug 2018, 2:14 pm

OK just to draw a line under this one , 640`s arrived and fitted . All transport working perfectly even with the wrong belts in there so hopefully once I get the correct belts , we should be all good as far as operating goes .

One strange thing . The machine will FF whether I press FF or REW . Is this likely to be a transistor issue also or do you think its just because the reel belts are shot and the right one has a bit more ooomph (technical term) than the left ? Neither FF OR REW works with the tape in the path (the belts just slip), I have to lift it out to get any movement so the belts are definitely shot . I didnt think the Right motor would operate in REW though and it does .

17th Aug 2018, 10:49 pm	#1
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Philips N4510 flip flop transistors Can I use BC550`s and BC557`s inplace of the BC147`s and AC128`s on this circuit. ? They are just being used as switches so I dont think its going to be critical what you use is it ? Voltage looks like its well within the specs of the BC 550 / 557`s range . Attached Thumbnails

17th Aug 2018, 11:07 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,941	Re: Philips N4510 flip flop transistors I don't see why not. Just about any transistors should work.

17th Aug 2018, 11:24 pm	#3
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors Thanks Paul . I kinda knew that but i`m still at that "i better just check " stage ..haha .

17th Aug 2018, 11:55 pm	#4
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors Fixed !

18th Aug 2018, 4:16 am	#5
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,868	Re: Philips N4510 flip flop transistors Good that it's fixed, but it's worth pointing out that there is something fishy going on in that circuit. Now, why does each flip-flop have one Germanium transistor working against one Silicon one? Without knowing what the thing does and what it gets connected to, it's impossible to guess what the designer was up to. I assume these flip-flops hold the tape drive status, play, fast forward, rewind. It may be that the germaniul transistors are used for their larger rating for reverse base/emitter voltage than silicon devices. If so, silicon parts could prove unreliable on the left side of each flip-flop. And the plus two volt supply may not let the trick of having a protective diode in series with the base of a silicon transistor work. Just a note of caution. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

18th Aug 2018, 4:46 am	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Philips N4510 flip flop transistors These flip-flops are odd (well, it's a Philips) and do indeed have a silicon NPN transistor cross-coupled with a germanium PNP one. The outputs (collector of the germanium PNP) drive the deck motors/solenoids. Originally the NPN transistor was a BC148 (lockfit). Later production models seem to have a BC548 there (which is much the same in a TO92 package). The PNP transistor doesn't have to be germanium, but it does need to be able to switch a fairly high current. I found a BC640 to be a suitable replacement.

18th Aug 2018, 8:36 am	#7
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: Philips N4510 flip flop transistors I wonder if it's to make it come up in a known state. Graham __________________ Half my stuff is junk - trouble is, I don't know which half!

18th Aug 2018, 9:04 am	#8
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors thanks everyone , i have replaced everything as i said and it is "fixed " but , the lights are certainly now dimmed , so i will be getting some 640`s as tony suggests (i know the pin-out is different)

18th Aug 2018, 9:06 am	#9
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,223	Re: Philips N4510 flip flop transistors I've just repaired one of these in an N4418, I had an AC128 to hand anyway. What I found very curious is that these machines were manufactured in 1974/5 long after Germanium technology was ditched in favour of silicon. There must have been higher powered silicon transistors in those days, or was it the PNP version that wasn't so readily available. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

18th Aug 2018, 9:16 am	#10
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors I was blown away when i opened mine up. The simplicity of the machine with the definite "respect" for the tech . The "bonnet prop" the way the boards connect to the mech , I just love this thing . Totally underrated machine . Sounds amazing too . Was stuck in Rew when I bought it , so I swapped the flip flop boards around and sure enough it started working so it had to be one of the transistors on the flip flop, other than that and the counter belt gone to goo , this thing is in fantastic condition . £40 paid . Last edited by NorfolkDaveUK; 18th Aug 2018 at 9:24 am.

18th Aug 2018, 9:28 am	#11
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,223	Re: Philips N4510 flip flop transistors I dont know what these cost at the time, but i'm sure they weren't cheap, Certainly taking plug in modules to a new high! I personally would have preferred heavier duty reel motors directly driving the spools. As has been said, it is a Philips who seem to love doing things in an unconventional manner. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

18th Aug 2018, 10:09 am	#12
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors I personally think I would recommend this for a beginner in electronics mainly because they have individual circuits on teeny boards and you can see exactly what each circuit looks like . I certainly found it very informative , sometimes breaking down individual circuits on a board can be quite difficult but not on this . Its a great learning tool for sure .

18th Aug 2018, 11:16 am	#13
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Philips N4510 flip flop transistors I also love this series of machines. I have an N4510 and an N4450. The former has 2 boards with 3 flipflops on each. The latter is an autoreverse machine with 6 heads (erase, record, play for each direction) and has 2 boards with 4 flip-flops on each one. Mine both needed a complete set of belts. In the case of the N4510 one of the reel belts had turned to go, the goo has got into the motor and I could not get it to run. In the end a friend in the Netherlands got me a replacement motor (how I do not know!). The other main fault on these machines are the slide switches. It's worth getting the sliders out (they come out and go in from the opposite end to the actuator, if you get it wrong you can damage contacts) and cleaning them with IPA. I fitted BC640s to all the flipflops in both machines and they work well. With 2N3906s (my normal 'TUP' (as Elektor used to put it)) I had odd faults. There are pictures of my machines (in bits) in my flickr account (tony_duell).

18th Aug 2018, 3:45 pm	#16
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Philips N4510 flip flop transistors Philips were well known for their "adventurous" designs, but to me our particular interests would have been much the poorer without their influence. However, as one of the driving forces behind semiconductor design and manufacture, they had access to any device they wanted. They would have chosen any particular one for a reason. Whether those reasons are still valid is another matter of course. For the same reason, they were driving the demise of obsolete devices. They would be unlikely to be caught with other than normal levels of surplus, and would have had established channels for disposal.

18th Aug 2018, 4:33 pm	#17
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Philips N4510 flip flop transistors I must admit to liking (old-ish) Philips designs. This is partly nostalgic -- I learnt electronics from the Philips EE series kits, my first cassette recorder was Philips, so was my first minicomputer (!). But it's more that I like unconventional designs that make me think, particularly (as in the case of the N4510, etc) they work well. Anyway... I have no idea why they used AC128s in these flip-flops. But I will confirm that, now, they are a common failure and that fortunately a common silicon transistor can be used to replace them.

18th Aug 2018, 9:22 pm	#19
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors The ones I bought are ECB so they just need rotating one stop clockwise . Cheers

20th Aug 2018, 2:14 pm	#20
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Philips N4510 flip flop transistors OK just to draw a line under this one , 640`s arrived and fitted . All transport working perfectly even with the wrong belts in there so hopefully once I get the correct belts , we should be all good as far as operating goes . One strange thing . The machine will FF whether I press FF or REW . Is this likely to be a transistor issue also or do you think its just because the reel belts are shot and the right one has a bit more ooomph (technical term) than the left ? Neither FF OR REW works with the tape in the path (the belts just slip), I have to lift it out to get any movement so the belts are definitely shot . I didnt think the Right motor would operate in REW though and it does .