Ferrograph 633 Problem - UK Vintage Radio Repair and Restoration Discussion Forum

untune87 · 2nd May 2016, 5:33 pm

Hi all

I have a Ferrograph 633H which I'm having a slight issue with. It has always been fine and I've not used it a great deal, but as of late I've tried to do some recording and noticed that the run lever keeps springing back, so it won't play continuously.

Holding the lever (hard) in the downward position seems to keep it going, but letting go causes the auto stop arm to spring back and shut it off again. Could it be a bad connection somewhere or a mechanical issue? It was driving me mad the other night, right when I was in the middle of recording something! Any ideas are appreciated.

Cheers

saxmaniac · 2nd May 2016, 9:11 pm

The lever is held by a solenoid powered by the HT so I suppose that's the first thing to check?

untune87 · 2nd May 2016, 9:55 pm

Hi saxmaniac

Certainly sounds like it could be the culprit, although opening it up and repairing it is a little beyond my abilities unfortunately, and I love this machine too much to risk any permanent damage!

Is there anyone on here in the Bolton/Manchester area qualified to repair? It's probably due a service by now anyway, and I'd like to keep it working well

AC/HL · 2nd May 2016, 11:58 pm

Try a post in this section: https://www.vintage-radio.net/forum/...play.php?f=145

untune87 · 3rd May 2016, 7:45 am

Cheers, I'll try that

flywheel · 7th May 2016, 10:03 pm

Quote:

Originally Posted by saxmaniac

The lever is held by a solenoid powered by the HT so I suppose that's the first thing to check?

Actually on the 633 the solenoid is powered from the DC heater supply, and this could be running low due to a power supply component problem (the most likely suspect would be the smoothing capacitor).

Also, the solenoid gets its power via a 100 ohm resistor mounted on the tag board that sits on the metal strap between the two reel motors. You might prefer to leave this to someone else, but if you can, check the value of this (I think it's at the end of the board nearest the supply reel motor).

untune87 · 11th May 2016, 11:30 am

Sorry for the delay, thanks for the info. No luck on finding anyone to look at this so I may be forced to do it myself. My only real worry is that, if I open it, I may disturb the deck to the extent that I can't put it back together. If I can get to the electronics mentioned without having to remove/disturb any of the mechanical elements, I might be in with a chance. Can anyone tell me if there's a particular method or anything to watch out for when opening up a series 6 Ferrograph, from experience?

Ted Kendall · 11th May 2016, 11:36 am

It's easy enough to loosen the thumbscrews and hinge the deck up so you can get a firm grasp of the interior layout without having to dismantle anything.

untune87 · 11th May 2016, 11:48 am

Thankyou Ted, just been studying the manual and didn't realise it was quite that easy!

I have something in the back of my mind that I must have read once, that removing particular screws on the face can be disastrous...

AC/HL · 11th May 2016, 9:39 pm

Always better to err on the side of caution than risk disaster.

untune87 · 13th May 2016, 7:18 am

Thanks all, I've opened it up but one of my multimeter leads broke earlier this week, so I decided it was time to get a better one. Should arrive this weekend. I've only had time for a quick peek inside, but which points should I be testing in regards to the solenoid, and looking for potential problems? I couldn't find that 100 ohm resistor but like I said, I've only had a brief look, it's probably hidden behind wires

Stevie342000 · 14th May 2016, 10:35 pm

The solenoid should be at full or near to HT potential, if I have read the thread correctly the unit does not hold once you put it in motion.

Which suggests your HT is low, not got the manual in front of me but all the machines are pretty much the same only the record/replay electronics varied, so they are pretty much standard from one model to another.

I am assuming that you have the tape in position so that the auto stop is not engaging, I.E. have you got the tape threaded up correctly, sorry if that has been covered, that will be in the front of the manual, it is also in the fault analysis section, item 2 in Ferrograph 420 manual.

According to the 420 manual the solenoid is in series with the 100 Ohm resistor (R77), it is connected across the DC supply, with the junction of the two connected to the chassis, R77 prevents a short circuit of the PSU when the stop button is brought into action, as the solenoid is shorted.

You should be looking at about 250 volts DC on one side of the solenoid, if it is not then the culprit is the power supply. There is a video on YouTube which shows how a Ferrograph 4 is brought back to life, it includes work on the power supply it is in four parts.

You will find it useful, I would suggest replacing all the out of specification components i.e. coupling capacitors and electrolytics and take a look at the odd resistor or two, the pointers as to which and how are in the video.

I would replace the silicon rectifiers as well, they are going on 50 plus years old, as the electrolytics today they make them much smaller but you can re-stuff the old cans it's in the video.

Sorry about that senior moment realised I had a Ferrograph 420 manual open in front of me, opps....not in Manchester down the road from you in Salford though, the smart city end.

Oh yes finally replace the resistors in the PSU or certainly take one end out of circuit and measure to see if they are still on specification and check all the high value resistors especially those in the HT or anode parts of the circuit. Valve electronics is simple to follow, but do be aware there are voltages in there both AC and DC that can and may kill you so keep one hand out and away from the unit preferably the left but best not to go poking around in there with a probe too much, be very careful with the unit powered up and with the deck top plate up they have a tendency to tip and your first reaction is to try and catch it...ouch if it is powered up, as there are sharp bits not just nasty elastic trickery in there as well.

You may be looking at more than 250 volts for the DC straight off the HT, not located it manual but do suggest you give yours a good read if you have not already done so before you go back in there. There should be a table with volts at various parts of circuit worth giving that a go over to check overall performance in all areas.

There is not much to go wrong in these machines and there is little that can not be fixed unlike modern equipment which has unobtanium in it by the time you buy it in some cases and built in obsolescence.

flywheel · 16th May 2016, 12:54 am

Quote:

Originally Posted by Stevie342000

The solenoid should be at full or near to HT potential,,,

You should be looking at about 250 volts DC on one side of the solenoid...

Please look at the circuit diagram! On neither the 633 nor the 420 is the solenoid powered by the HT supply (it is on the older mono models like the Series 4 or 5). It is powered by the low voltage DC heater supply.

Stevie342000 · 16th May 2016, 9:36 am

You are absolutely right, I had not looked at the winding volts on main transformer. Opps that is what happens when you are doing these things late at night.

Well either way if it is not holding in then that would still suggest a power supply issue, look at those capacitors and the diodes.

Plus still go see the YouTube video on repairing Series 4 machine, it will point you in the right direction plus clean all the switches, sockets and lubricate the machine carefully.

untune87 · 16th May 2016, 12:49 pm

Thanks for your input Steve, lots of useful info - I've found that Youtube video, I'll have to watch it properly when I have time. I'm starting to think I'll need a better soldering iron, plus I'll have to factor in the replacement components I might need. Not a great deal of confidence beyond small hobby projects and at the moment I barely have time to get those done!

Oh I'm actually in Salford too, but the Walkden/Worsley area. Small world eh

flywheel · 16th May 2016, 10:46 pm

Quote:

Originally Posted by Stevie342000

Plus still go see the YouTube video on repairing Series 4 machine, it will point you in the right direction plus clean all the switches, sockets and lubricate the machine carefully.

Indeed, they're good videos. But I've realised over the years that correct choice of lubricant is a whole subject in itself! At least on the Series 6 models the capstan and capstan motor can often be left well alone, but correct oil for reel motors may not be so straightforward. I gather 3-in-1 should be avoided because additives can evaporate, leaving a sticky residue. But even if that advice is misplaced, a universal message to everyone new to this is: avoid putting WD40 on anything!

Stevie342000 · 17th May 2016, 12:26 am

I did not want to throw the spanner in to the works in saying avoid WD40. But yes small world. As the machine is modular to a degree take it one step at a time, but starting off with the power supply unit may be of greater benefit.

Given that there seems to be reduced juice which is why the hold in solenoid is not holding, it seems to make sense to me to start there. Once the PSU is sorted any other issues may or may not show up.

I tend to agree with the non wholesale approach to replacing parts but there are certain parts such as the 0.1uF and electrolytics which should be replaced. The 0.1uF will probably have Hunts on them, if however they are Mustard coloured then they are Mullards and those are usually fine to leave it but they do fail. Anything that is in pF range was selected at works and should be fine.

Take it slowly, these are not difficult machines to service just be careful with hands probing inside when power is on.

untune87 · 21st Nov 2016, 11:53 pm

Hi all, I posted back in May regarding an issue I was having with my Ferrograph machine https://www.vintage-radio.net/forum/...d.php?t=126058 - obviously now closed, not had a chance to sort it out yet but since I have a few projects out of the way, it might be on the cards.

In the linked discussion, flywheel posted the following:

Quote:

Originally Posted by flywheel

Actually on the 633 the solenoid is powered from the DC heater supply, and this could be running low due to a power supply component problem (the most likely suspect would be the smoothing capacitor).

Also, the solenoid gets its power via a 100 ohm resistor mounted on the tag board that sits on the metal strap between the two reel motors. You might prefer to leave this to someone else, but if you can, check the value of this (I think it's at the end of the board nearest the supply reel motor).

The other night, just looking round I located the 100ohm resistor at the end of the tag board. Looking at the attached pic, it would appear to me that there are two 100ohm resistors (5% and 10%) in parallel across points marked F and X on the tag board. I checked the circuit diagram and manual and it's meant to be a 5% 100ohm resistor - I measure about 41ohms between the two points. Is there a reason for there being two?

untune87 · 24th Nov 2016, 2:38 pm

Hi all, can anyone confirm that I am indeed looking at a pair of resistors here and not a resistor plus something unusual, ie an inductor, fuse, cap etc... not that there should be anything like that there in the first place but I'm a bit confused if this is perhaps something that has been added/repaired and if so, how it has managed to work until now considering the incorrect value

peter_sol · 24th Nov 2016, 3:01 pm

Yes it looks like you have 2 100 ohm resistors in parallel
41 ohms is within tolerance.
The solenoid will pull in more strongly but why was the extra pull needed?

2nd May 2016, 5:33 pm	#1
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Ferrograph 633 Problem Hi all I have a Ferrograph 633H which I'm having a slight issue with. It has always been fine and I've not used it a great deal, but as of late I've tried to do some recording and noticed that the run lever keeps springing back, so it won't play continuously. Holding the lever (hard) in the downward position seems to keep it going, but letting go causes the auto stop arm to spring back and shut it off again. Could it be a bad connection somewhere or a mechanical issue? It was driving me mad the other night, right when I was in the middle of recording something! Any ideas are appreciated. Cheers

2nd May 2016, 9:11 pm	#2
saxmaniac Heptode Join Date: Oct 2007 Location: Birmingham, West Midlands, UK. Posts: 618	Re: Ferrograph 633 Problem The lever is held by a solenoid powered by the HT so I suppose that's the first thing to check?

2nd May 2016, 9:55 pm	#3
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Hi saxmaniac Certainly sounds like it could be the culprit, although opening it up and repairing it is a little beyond my abilities unfortunately, and I love this machine too much to risk any permanent damage! Is there anyone on here in the Bolton/Manchester area qualified to repair? It's probably due a service by now anyway, and I'd like to keep it working well

2nd May 2016, 11:58 pm	#4
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Ferrograph 633 Problem Try a post in this section: https://www.vintage-radio.net/forum/...play.php?f=145

3rd May 2016, 7:45 am	#5
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Cheers, I'll try that

11th May 2016, 11:30 am	#7
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Sorry for the delay, thanks for the info. No luck on finding anyone to look at this so I may be forced to do it myself. My only real worry is that, if I open it, I may disturb the deck to the extent that I can't put it back together. If I can get to the electronics mentioned without having to remove/disturb any of the mechanical elements, I might be in with a chance. Can anyone tell me if there's a particular method or anything to watch out for when opening up a series 6 Ferrograph, from experience?

11th May 2016, 11:36 am	#8
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: Ferrograph 633 Problem It's easy enough to loosen the thumbscrews and hinge the deck up so you can get a firm grasp of the interior layout without having to dismantle anything.

11th May 2016, 11:48 am	#9
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Thankyou Ted, just been studying the manual and didn't realise it was quite that easy! I have something in the back of my mind that I must have read once, that removing particular screws on the face can be disastrous...

11th May 2016, 9:39 pm	#10
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Ferrograph 633 Problem Always better to err on the side of caution than risk disaster.

13th May 2016, 7:18 am	#11
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Thanks all, I've opened it up but one of my multimeter leads broke earlier this week, so I decided it was time to get a better one. Should arrive this weekend. I've only had time for a quick peek inside, but which points should I be testing in regards to the solenoid, and looking for potential problems? I couldn't find that 100 ohm resistor but like I said, I've only had a brief look, it's probably hidden behind wires Attached Thumbnails

14th May 2016, 10:35 pm	#12
Stevie342000 Hexode Join Date: Jan 2006 Location: Greater Manchester, UK. Posts: 373	Re: Ferrograph 633 Problem The solenoid should be at full or near to HT potential, if I have read the thread correctly the unit does not hold once you put it in motion. Which suggests your HT is low, not got the manual in front of me but all the machines are pretty much the same only the record/replay electronics varied, so they are pretty much standard from one model to another. I am assuming that you have the tape in position so that the auto stop is not engaging, I.E. have you got the tape threaded up correctly, sorry if that has been covered, that will be in the front of the manual, it is also in the fault analysis section, item 2 in Ferrograph 420 manual. According to the 420 manual the solenoid is in series with the 100 Ohm resistor (R77), it is connected across the DC supply, with the junction of the two connected to the chassis, R77 prevents a short circuit of the PSU when the stop button is brought into action, as the solenoid is shorted. You should be looking at about 250 volts DC on one side of the solenoid, if it is not then the culprit is the power supply. There is a video on YouTube which shows how a Ferrograph 4 is brought back to life, it includes work on the power supply it is in four parts. You will find it useful, I would suggest replacing all the out of specification components i.e. coupling capacitors and electrolytics and take a look at the odd resistor or two, the pointers as to which and how are in the video. I would replace the silicon rectifiers as well, they are going on 50 plus years old, as the electrolytics today they make them much smaller but you can re-stuff the old cans it's in the video. Sorry about that senior moment realised I had a Ferrograph 420 manual open in front of me, opps....not in Manchester down the road from you in Salford though, the smart city end. Oh yes finally replace the resistors in the PSU or certainly take one end out of circuit and measure to see if they are still on specification and check all the high value resistors especially those in the HT or anode parts of the circuit. Valve electronics is simple to follow, but do be aware there are voltages in there both AC and DC that can and may kill you so keep one hand out and away from the unit preferably the left but best not to go poking around in there with a probe too much, be very careful with the unit powered up and with the deck top plate up they have a tendency to tip and your first reaction is to try and catch it...ouch if it is powered up, as there are sharp bits not just nasty elastic trickery in there as well. You may be looking at more than 250 volts for the DC straight off the HT, not located it manual but do suggest you give yours a good read if you have not already done so before you go back in there. There should be a table with volts at various parts of circuit worth giving that a go over to check overall performance in all areas. There is not much to go wrong in these machines and there is little that can not be fixed unlike modern equipment which has unobtanium in it by the time you buy it in some cases and built in obsolescence.

16th May 2016, 9:36 am	#14
Stevie342000 Hexode Join Date: Jan 2006 Location: Greater Manchester, UK. Posts: 373	Re: Ferrograph 633 Problem You are absolutely right, I had not looked at the winding volts on main transformer. Opps that is what happens when you are doing these things late at night. Well either way if it is not holding in then that would still suggest a power supply issue, look at those capacitors and the diodes. Plus still go see the YouTube video on repairing Series 4 machine, it will point you in the right direction plus clean all the switches, sockets and lubricate the machine carefully.

16th May 2016, 12:49 pm	#15
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Thanks for your input Steve, lots of useful info - I've found that Youtube video, I'll have to watch it properly when I have time. I'm starting to think I'll need a better soldering iron, plus I'll have to factor in the replacement components I might need. Not a great deal of confidence beyond small hobby projects and at the moment I barely have time to get those done! Oh I'm actually in Salford too, but the Walkden/Worsley area. Small world eh

17th May 2016, 12:26 am	#17
Stevie342000 Hexode Join Date: Jan 2006 Location: Greater Manchester, UK. Posts: 373	Re: Ferrograph 633 Problem I did not want to throw the spanner in to the works in saying avoid WD40. But yes small world. As the machine is modular to a degree take it one step at a time, but starting off with the power supply unit may be of greater benefit. Given that there seems to be reduced juice which is why the hold in solenoid is not holding, it seems to make sense to me to start there. Once the PSU is sorted any other issues may or may not show up. I tend to agree with the non wholesale approach to replacing parts but there are certain parts such as the 0.1uF and electrolytics which should be replaced. The 0.1uF will probably have Hunts on them, if however they are Mustard coloured then they are Mullards and those are usually fine to leave it but they do fail. Anything that is in pF range was selected at works and should be fine. Take it slowly, these are not difficult machines to service just be careful with hands probing inside when power is on.

24th Nov 2016, 2:38 pm	#19
untune87 Pentode Join Date: Oct 2010 Location: Greater Manchester, UK. Posts: 161	Re: Ferrograph 633 Problem Hi all, can anyone confirm that I am indeed looking at a pair of resistors here and not a resistor plus something unusual, ie an inductor, fuse, cap etc... not that there should be anything like that there in the first place but I'm a bit confused if this is perhaps something that has been added/repaired and if so, how it has managed to work until now considering the incorrect value

24th Nov 2016, 3:01 pm	#20
peter_sol Octode Join Date: Aug 2003 Location: Welwyn Garden City, Herts. UK. Posts: 1,906	Re: Ferrograph 633 Problem Yes it looks like you have 2 100 ohm resistors in parallel 41 ohms is within tolerance. The solenoid will pull in more strongly but why was the extra pull needed?