EKCO AD75 restore - UK Vintage Radio Repair and Restoration Discussion Forum

thejazzageuk · 15th Mar 2019, 11:55 am

Hi
I've just picked up a fairly poor condition example of these lovely radios. Unfortunately there is a crack on the top in the bakerlite and the chassis is very dirty and the knobs are missing.

I was just looking for advice regarding whether to just do a cosmetic restore or whether to try and get it working again. I saw an earlier post from JimMac53 who did a fantastic job restoring one of these, but not sure if I have the time of expertise for such a comprehensive restore. Here are some photos..

Cobaltblue · 15th Mar 2019, 1:41 pm

The cosmetic restore is probably more work than getting it going

It looks like an early one with side contact valves.

The rectifier has been replaced as well with a resistor and metal rectifier.

I think the only thing that would concern me is are the coils OK.

Cheers

Mike T

thejazzageuk · 17th Mar 2019, 1:07 pm

Thanks CobaltBlue. I've removed the chassis and dusted it off to get a better idea about the level of work required to get some function back. Here are some more pics...

JimMac53 · 17th Mar 2019, 2:56 pm

I agree with CobaltBlue, I'd first check if the coils, IF transformers, & output transformer are ok. Not that they can't be fixed, but life will be easier if they don't have to be. This is certainly a big job. This one is in worse condition than the one I restored. But I don't want to discourage you. Break it down into little jobs. Perhaps tackling the cosmetic jobs first - fixing the case and speaker grill cloth. I'm in favour of a full restore.

Lloyd 1985 · 17th Mar 2019, 3:02 pm

That looks a good project, I’ve got one of these myself. The crack should repair quite nicely, especially if it’s a clean break. I know I’ve said it many times before, but careful preparation of the joint to make sure the surfaces are level, followed by decent brand super glue, allowing it to overflow a bit, then careful sanding back with fine grade wet and dry, should make a near invisible repair, which can also be further strengthened with fibreglass on the inside of the cabinet. Brown Bakelite is one of the easiest to repair this way, as it already has patterns in the finish! The chassis looks in good order under the dirt, so won’t need much other than a clean. I recently restored the chassis of an Ekco RS3, which I thought was rusty, no amount of foam cleaner was making it look any better! Rust remover treatment didn’t shift all the ‘rust’ either, turned out it wasn’t rust, well, not all of it, some was just dirt and nicotine, I ended up using Gunk traffic film remover in a pump up spray bottle from RS, I used it neat, and it brought the chassis up like new, apart from the few rusty spots that were actual rust! It did a really good job on the aluminium cans that housed the RF could under chassis, obviously I removed all the wound components before cleaning.

Talking of round Ekco’s, there’s a brown AC76 sat in my roundtuit pile, with a cracked case and the bar that goes over the speaker missing!

Regards
Lloyd

thejazzageuk · 1st Jun 2020, 5:06 pm

Thanks all for your helpful responses. Apologies for the delay in getting back onto this. However I now have a bit of time so here goes.

As suggested perhaps I will start with the cosmetic aspects first. I order of priority these could be:
1. Crack on case
2. speaker/speaker cloth
3. Dial display
4. replacing knobs
5. Pointer mechanism

For (1) I have started the repair by super-gluing the two sides together. I've ordered a fibreglass repair kit to strengthen it on the inside but you will see there are some tiny chips on the edges of the crack. Can this be best repaired by using some epoxy resin with brown pigment mixed in? If anyone has done this before I'd be grateful for any advice. What pigment suits brown Bakelite, do I need to open the crack more etc?
For (2) I've ordered some replacement speaker cloth but notice that part of the paper cone is missing from the speaker- is it possible to glue a cone from a similar speaker in place?

I'll go through the rest as I progress.

To make progress towards getting it working, as suggested by CobaltBlue and JimMac53 I removed the cap on L8/L9/C33/C34 and did a quick check on pins 2-6 and 3-7. If these represent L8 and L9 I am reading 11.7 and 12.4 ohms- does that look OK? I've attached part of a schematic that may be of interest.

thejazzageuk · 9th Jun 2020, 1:48 pm

I've started removing the valves to clean the chassis a bit. I notice that V3 (see photo) makes a tinkling sound as you turn it upside down and sounds like tiny bits of metal are loose. I guess that probably means it needs replacing. According to the spec sheet, V3 is a mullard CBL31. However the removed valve shows 3BL plus some numbers I can't read. Can anyone suggest where I can get a replacement. Thanks

Lloyd 1985 · 9th Jun 2020, 2:42 pm

It’s probably just loose bits in the Bakelite base, bits of the adhesive that hold the base on break loose over time, probably nothing to worry about, unless you can see bits of loose metal floating about inside the glass. I’d wait and see if it works before condemning it, especially as these older valves are getting harder to find, and more expensive!

Regards
Lloyd

thejazzageuk · 11th Jun 2020, 6:50 pm

Thanks Lloyd 1985. I hope you are right. However I also checked the actual valve V3 (removed from chassis) for resistance across the heater contacts. It appears O/C between pins 2 and 7, i think these are the heater pins.

Initial checks showed O/C between the mains pins. However when I cleaned the the on/off switch with contact cleaner I got:
970ohms between the mains pins
0.9ohms between chassis and N
970 ohms between chassis and L
Not sure if this is encouraging.

I plugged it in with a safety lamp. Lamp glows dimly. No sound at all from temp speaker I connected, R19 gets warm. No valves light up as far as I can see.

I also checked some voltaes on the valve pins

V3
Pin 1 15V A/C but 0 DC
Pin 2 12.8V A/C but 0 DC
Pin 3 10.4V A/C but 0 DC
Pin 4 15.4V A/C but 0 DC
Pin 5 15.8V A/C but 0.1 DC
Pin 6 16.5V A/C but -0.3 DC
Pin 7 15.9V A/C but 0 DC
Pin 8 16.9V A/C but 0 DC

V2
5.7V AC between 2 and 6 ( which I think are the heater pins)
Pin 1 207V A/C but 0 DC
Pin 2 207V A/C but 0 DC
Pin 3 190V A/C but 0 DC
Pin 4 180V A/C but 0 DC
Pin 5 2.9V A/C but 0.1 DC
Pin 6 165V A/C but -0.3 DC
Pin 7 & 8 not measured

V1
5.4V AC between 2 and 7 ( which I think are the heater pins)
Pin 1 0V A/C but 0V DC
Pin 2 6.7V A/C but 0V DC
Pin 3 10V A/C but 0V DC
Pin 4 1mV A/C but 0V DC
Pin 5 1mV A/C but 0V DC
Pin 6 165V A/C but -0.5V DC
Pin 7 1mV A/C but -0.7V DC
Pin 8 16.9V A/C but -0.5V DC

Any suggestion for next steps very welcome. Thanks

Heatercathodeshort · 11th Jun 2020, 7:55 pm

Just a note. Remember that the chassis will be live if the mains is connected incorrectly. Sorry if your aware of this. The output valve is a CBL1. The number on the base has probably little to do with the actual number that has probably rubbed off the glass.
Your picture certainly looks like a CBL1. The CBL31 has an octal base. Quite a lot of work by the look of it and don't expect too much performance wise but an interesting project. John.

PJL · 11th Jun 2020, 9:28 pm

It's a bit too soon to be connecting it to the mains.

First step is to understand what has been changed and get the heater chain working. If you say that V3 pin 2 to pin 3 of the CBL1 is showing as open circuit then none of the heaters are going to work as they are wired in series. It is often difficult to make a reliable connection with meter probes so worth checking again. You should also check the heaters of the other valves: V1 (ECH3?) and V2 (EF9?).

The replacement of V4 (CY1) will also mean the loss of the drop in the heater chain of the 20V heater and that should have been replaced with a resistor of around 100 ohms.

You can do the checks in circuit: Clean the valve base and socket connections first; Set your meter for resistance and connect one end to the live mains on the switch (not connected to mains!); measure the resistance to pin 2 and pin 3 of each valve V3, V2 then V1 in turn.

thejazzageuk · 12th Jun 2020, 1:07 pm

Thanks Heatercathodeshort and PJL

Now it starts to make sense! The spec sheet shows V4 to be a CY31, which I think has heater terminals on pins 2 and 7- so the circuit just did not make sense.

I've buzzed out the heater circuit and it looks OK up to the heater output from V1. I can't find where this goes to. The area under V1 is very busy. I can see a yellow/red wire going down from Pin 2 of V1 but can't find where it goes to. It dissapears into the mass of components and I can't trace it. It does not go to chassis though as there is OC showing. I've tried buzzing all the terminals nearby and no lick. Any suggestion as to where it may go?
I've attached a couple of photos that may help.

Lloyd 1985 · 12th Jun 2020, 2:28 pm

I do wonder if there is another service sheet available, as your set doesn’t use the octal valves shown on the service sheet. I’m sure my set also has the same side contact valves as yours. Your set should have a CY1 valve if it’s all side contact type valves fitted, in which case the heater will be on pins 2 and 3.

Regards
Lloyd

Ah, I see that the CY1 rectifier has been removed and replaced with something else!

David G4EBT · 12th Jun 2020, 2:36 pm

Quote:

Originally Posted by thejazzageuk

Thanks Heatercathodeshort and PJL

I've buzzed out the heater circuit and it looks OK up to the heater output from V1. I can't find where this goes to. The area under V1 is very busy. I can see a yellow/red wire going down from Pin 2 of V1 but can't find where it goes to. It dissapears into the mass of components and I can't trace it. It does not go to chassis though as there is OC showing. I've tried buzzing all the terminals nearby and no lick. Any suggestion as to where it may go?
I've attached a couple of photos that may help.

If you look at the circuit you will see that pin 2 of V1 completes the series heater chain for all four valves and should go to the chassis.

To confirm that, (with the set switched off an all valves in situ) if you clip a test lead onto Pin 2 V1 and the other end of the lead to the chassis, provided that the valve heaters are all intact, that should complete the heater circuit. Another way of checking it (with the test lead still in place from V1 pin 2 to the chassis), with your multi-meter on the Ohms range, connect one test lead to pin 7 of V4 and the other test lead to the chassis, that should confirm that the heater chain is now complete. You can then make a permanent connection from pin 2, V1 to chassis.

Hope that helps.

ms660 · 12th Jun 2020, 2:39 pm

V4 is no more, when it was there it was probably a side contact job as this appears to be an early version of the model, all the details are in the Trader sheet.

Lawrence.

PJL · 12th Jun 2020, 4:15 pm

What is the lower of the resistances from the live connections to V3 pin 2 or pin 3 with the valves in place? We need to know this so we can check if the missing CY1 has been properly allowed for. You need to have the voltage set to the highest tap on the dropper. The total should read about 915 ohms (815 + 100) ohms.

From your measurement above of 970 ohms from live to neutral, it suggests the heaters are all OK but the additional 100 ohms for the CY1 may not have been added. The dropper is located in the correct position but appears to be a replacement.

Can you also measure the resistance from the live connection to both ends of the metal rectifier.

There are many capacitors in the set that will need replacing before the set will work reliably.

Station X · 12th Jun 2020, 4:51 pm

The heater chain.

If V1 pin 2 isn't connected to chassis, I can't see how it's possible to measure 970R between the pins of the mains plug.

thejazzageuk · 13th Jun 2020, 1:09 pm

Thanks all. I have re-checked pin 2 from V1 and it DOES go to chassis. I've measured the voltages following the heater circuit on the attached photo.

R19 is currently connected to the second pin and R=930 ohms. If I move it to the top ointhe resistance would be 997 ohms.

After following the voltages along the heater circuit I did a direct measuremnt for each valve.

Here are ther results:

V3= 29.6V
V2= 4.4V
V1= 3.1V

PJL · 13th Jun 2020, 7:00 pm

The resistance sounds OK, the voltages are I assume AC measurements but look a bit low as they should be 6.3, 6.3 and 44.0, however, the valve heaters take quite a while to warm up and when cold they are a lower resistance.

Last time you did not get any DC measurements. Did you measure the resistance from live to the metal rectifier?

thejazzageuk · 14th Jun 2020, 12:22 pm

Thanks PJL- yes I have taken some measurement on the rectifier. Here are what I got:

Gnd to Rectifier top=1K ohm
Gnd to Rectifier base=1.8M ohm

Plugged in
Gnd to Rectifier top=-1.4VDC, 202V AC
Gnd to Rectifier base=257VDC, 200mV AC

With the safety lamp bypassed, the heater voltage across V3 rises from 29V to 39V.

Also there is a loose wire (see photo) the wire highlighted next to the rectifier runs to L13. Should it be connected to the base of the rectifier?

Still no sound even after warm up.

15th Mar 2019, 11:55 am	#1
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	EKCO AD75 restore Hi I've just picked up a fairly poor condition example of these lovely radios. Unfortunately there is a crack on the top in the bakerlite and the chassis is very dirty and the knobs are missing. I was just looking for advice regarding whether to just do a cosmetic restore or whether to try and get it working again. I saw an earlier post from JimMac53 who did a fantastic job restoring one of these, but not sure if I have the time of expertise for such a comprehensive restore. Here are some photos.. Attached Thumbnails

15th Mar 2019, 1:41 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: EKCO AD75 restore The cosmetic restore is probably more work than getting it going It looks like an early one with side contact valves. The rectifier has been replaced as well with a resistor and metal rectifier. I think the only thing that would concern me is are the coils OK. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

17th Mar 2019, 1:07 pm	#3
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore Thanks CobaltBlue. I've removed the chassis and dusted it off to get a better idea about the level of work required to get some function back. Here are some more pics... Attached Thumbnails

17th Mar 2019, 2:56 pm	#4
JimMac53 Hexode Join Date: Apr 2009 Location: Naples, Florida, USA Posts: 255	Re: EKCO AD75 restore I agree with CobaltBlue, I'd first check if the coils, IF transformers, & output transformer are ok. Not that they can't be fixed, but life will be easier if they don't have to be. This is certainly a big job. This one is in worse condition than the one I restored. But I don't want to discourage you. Break it down into little jobs. Perhaps tackling the cosmetic jobs first - fixing the case and speaker grill cloth. I'm in favour of a full restore. __________________ Jim Mac

17th Mar 2019, 3:02 pm	#5
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,818	Re: EKCO AD75 restore That looks a good project, I’ve got one of these myself. The crack should repair quite nicely, especially if it’s a clean break. I know I’ve said it many times before, but careful preparation of the joint to make sure the surfaces are level, followed by decent brand super glue, allowing it to overflow a bit, then careful sanding back with fine grade wet and dry, should make a near invisible repair, which can also be further strengthened with fibreglass on the inside of the cabinet. Brown Bakelite is one of the easiest to repair this way, as it already has patterns in the finish! The chassis looks in good order under the dirt, so won’t need much other than a clean. I recently restored the chassis of an Ekco RS3, which I thought was rusty, no amount of foam cleaner was making it look any better! Rust remover treatment didn’t shift all the ‘rust’ either, turned out it wasn’t rust, well, not all of it, some was just dirt and nicotine, I ended up using Gunk traffic film remover in a pump up spray bottle from RS, I used it neat, and it brought the chassis up like new, apart from the few rusty spots that were actual rust! It did a really good job on the aluminium cans that housed the RF could under chassis, obviously I removed all the wound components before cleaning. Talking of round Ekco’s, there’s a brown AC76 sat in my roundtuit pile, with a cracked case and the bar that goes over the speaker missing! Regards Lloyd

1st Jun 2020, 5:06 pm	#6
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	EKCO AD75 restore -continued Thanks all for your helpful responses. Apologies for the delay in getting back onto this. However I now have a bit of time so here goes. As suggested perhaps I will start with the cosmetic aspects first. I order of priority these could be: 1. Crack on case 2. speaker/speaker cloth 3. Dial display 4. replacing knobs 5. Pointer mechanism For (1) I have started the repair by super-gluing the two sides together. I've ordered a fibreglass repair kit to strengthen it on the inside but you will see there are some tiny chips on the edges of the crack. Can this be best repaired by using some epoxy resin with brown pigment mixed in? If anyone has done this before I'd be grateful for any advice. What pigment suits brown Bakelite, do I need to open the crack more etc? For (2) I've ordered some replacement speaker cloth but notice that part of the paper cone is missing from the speaker- is it possible to glue a cone from a similar speaker in place? I'll go through the rest as I progress. To make progress towards getting it working, as suggested by CobaltBlue and JimMac53 I removed the cap on L8/L9/C33/C34 and did a quick check on pins 2-6 and 3-7. If these represent L8 and L9 I am reading 11.7 and 12.4 ohms- does that look OK? I've attached part of a schematic that may be of interest. Attached Thumbnails

9th Jun 2020, 1:48 pm	#7
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore I've started removing the valves to clean the chassis a bit. I notice that V3 (see photo) makes a tinkling sound as you turn it upside down and sounds like tiny bits of metal are loose. I guess that probably means it needs replacing. According to the spec sheet, V3 is a mullard CBL31. However the removed valve shows 3BL plus some numbers I can't read. Can anyone suggest where I can get a replacement. Thanks Attached Thumbnails

9th Jun 2020, 2:42 pm	#8
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,818	Re: EKCO AD75 restore It’s probably just loose bits in the Bakelite base, bits of the adhesive that hold the base on break loose over time, probably nothing to worry about, unless you can see bits of loose metal floating about inside the glass. I’d wait and see if it works before condemning it, especially as these older valves are getting harder to find, and more expensive! Regards Lloyd

11th Jun 2020, 6:50 pm	#9
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore Thanks Lloyd 1985. I hope you are right. However I also checked the actual valve V3 (removed from chassis) for resistance across the heater contacts. It appears O/C between pins 2 and 7, i think these are the heater pins. Initial checks showed O/C between the mains pins. However when I cleaned the the on/off switch with contact cleaner I got: 970ohms between the mains pins 0.9ohms between chassis and N 970 ohms between chassis and L Not sure if this is encouraging. I plugged it in with a safety lamp. Lamp glows dimly. No sound at all from temp speaker I connected, R19 gets warm. No valves light up as far as I can see. I also checked some voltaes on the valve pins V3 Pin 1 15V A/C but 0 DC Pin 2 12.8V A/C but 0 DC Pin 3 10.4V A/C but 0 DC Pin 4 15.4V A/C but 0 DC Pin 5 15.8V A/C but 0.1 DC Pin 6 16.5V A/C but -0.3 DC Pin 7 15.9V A/C but 0 DC Pin 8 16.9V A/C but 0 DC V2 5.7V AC between 2 and 6 ( which I think are the heater pins) Pin 1 207V A/C but 0 DC Pin 2 207V A/C but 0 DC Pin 3 190V A/C but 0 DC Pin 4 180V A/C but 0 DC Pin 5 2.9V A/C but 0.1 DC Pin 6 165V A/C but -0.3 DC Pin 7 & 8 not measured V1 5.4V AC between 2 and 7 ( which I think are the heater pins) Pin 1 0V A/C but 0V DC Pin 2 6.7V A/C but 0V DC Pin 3 10V A/C but 0V DC Pin 4 1mV A/C but 0V DC Pin 5 1mV A/C but 0V DC Pin 6 165V A/C but -0.5V DC Pin 7 1mV A/C but -0.7V DC Pin 8 16.9V A/C but -0.5V DC Any suggestion for next steps very welcome. Thanks

11th Jun 2020, 7:55 pm	#10
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: EKCO AD75 restore Just a note. Remember that the chassis will be live if the mains is connected incorrectly. Sorry if your aware of this. The output valve is a CBL1. The number on the base has probably little to do with the actual number that has probably rubbed off the glass. Your picture certainly looks like a CBL1. The CBL31 has an octal base. Quite a lot of work by the look of it and don't expect too much performance wise but an interesting project. John.

11th Jun 2020, 9:28 pm	#11
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: EKCO AD75 restore It's a bit too soon to be connecting it to the mains. First step is to understand what has been changed and get the heater chain working. If you say that V3 pin 2 to pin 3 of the CBL1 is showing as open circuit then none of the heaters are going to work as they are wired in series. It is often difficult to make a reliable connection with meter probes so worth checking again. You should also check the heaters of the other valves: V1 (ECH3?) and V2 (EF9?). The replacement of V4 (CY1) will also mean the loss of the drop in the heater chain of the 20V heater and that should have been replaced with a resistor of around 100 ohms. You can do the checks in circuit: Clean the valve base and socket connections first; Set your meter for resistance and connect one end to the live mains on the switch (not connected to mains!); measure the resistance to pin 2 and pin 3 of each valve V3, V2 then V1 in turn. Last edited by PJL; 11th Jun 2020 at 9:38 pm.

12th Jun 2020, 1:07 pm	#12
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore Thanks Heatercathodeshort and PJL Now it starts to make sense! The spec sheet shows V4 to be a CY31, which I think has heater terminals on pins 2 and 7- so the circuit just did not make sense. I've buzzed out the heater circuit and it looks OK up to the heater output from V1. I can't find where this goes to. The area under V1 is very busy. I can see a yellow/red wire going down from Pin 2 of V1 but can't find where it goes to. It dissapears into the mass of components and I can't trace it. It does not go to chassis though as there is OC showing. I've tried buzzing all the terminals nearby and no lick. Any suggestion as to where it may go? I've attached a couple of photos that may help. Attached Thumbnails

12th Jun 2020, 2:28 pm	#13
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,818	Re: EKCO AD75 restore I do wonder if there is another service sheet available, as your set doesn’t use the octal valves shown on the service sheet. I’m sure my set also has the same side contact valves as yours. Your set should have a CY1 valve if it’s all side contact type valves fitted, in which case the heater will be on pins 2 and 3. Regards Lloyd Ah, I see that the CY1 rectifier has been removed and replaced with something else!

12th Jun 2020, 2:39 pm	#15
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EKCO AD75 restore V4 is no more, when it was there it was probably a side contact job as this appears to be an early version of the model, all the details are in the Trader sheet. Lawrence. Last edited by ms660; 12th Jun 2020 at 2:45 pm. Reason: additional info

12th Jun 2020, 4:15 pm	#16
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: EKCO AD75 restore What is the lower of the resistances from the live connections to V3 pin 2 or pin 3 with the valves in place? We need to know this so we can check if the missing CY1 has been properly allowed for. You need to have the voltage set to the highest tap on the dropper. The total should read about 915 ohms (815 + 100) ohms. From your measurement above of 970 ohms from live to neutral, it suggests the heaters are all OK but the additional 100 ohms for the CY1 may not have been added. The dropper is located in the correct position but appears to be a replacement. Can you also measure the resistance from the live connection to both ends of the metal rectifier. There are many capacitors in the set that will need replacing before the set will work reliably.

12th Jun 2020, 4:51 pm	#17
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,286	Re: EKCO AD75 restore The heater chain. If V1 pin 2 isn't connected to chassis, I can't see how it's possible to measure 970R between the pins of the mains plug. Attached Thumbnails __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

13th Jun 2020, 1:09 pm	#18
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore Thanks all. I have re-checked pin 2 from V1 and it DOES go to chassis. I've measured the voltages following the heater circuit on the attached photo. R19 is currently connected to the second pin and R=930 ohms. If I move it to the top ointhe resistance would be 997 ohms. After following the voltages along the heater circuit I did a direct measuremnt for each valve. Here are ther results: V3= 29.6V V2= 4.4V V1= 3.1V Attached Thumbnails

13th Jun 2020, 7:00 pm	#19
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: EKCO AD75 restore The resistance sounds OK, the voltages are I assume AC measurements but look a bit low as they should be 6.3, 6.3 and 44.0, however, the valve heaters take quite a while to warm up and when cold they are a lower resistance. Last time you did not get any DC measurements. Did you measure the resistance from live to the metal rectifier?

14th Jun 2020, 12:22 pm	#20
thejazzageuk Pentode Join Date: Feb 2014 Location: Carmarthen, Wales, UK. Posts: 238	Re: EKCO AD75 restore Thanks PJL- yes I have taken some measurement on the rectifier. Here are what I got: Gnd to Rectifier top=1K ohm Gnd to Rectifier base=1.8M ohm Plugged in Gnd to Rectifier top=-1.4VDC, 202V AC Gnd to Rectifier base=257VDC, 200mV AC With the safety lamp bypassed, the heater voltage across V3 rises from 29V to 39V. Also there is a loose wire (see photo) the wire highlighted next to the rectifier runs to L13. Should it be connected to the base of the rectifier? Still no sound even after warm up. Attached Thumbnails