Discatron Cartridge Replacement and General Questions - UK Vintage Radio Repair and Restoration Discussion Forum

Cameron · 28th Feb 2019, 10:24 pm

I've been after a Discatron for years, and I finally managed to get a really nice example on eBay. It came untested, but is cosmetically perfect at least.

I've stripped it down to service it and give it the once over, and the stylus is quite blunt. I read some advice online about sliding the stylus tip out, but instead it's just snapped in half. It appears that every thread I've found on this forum references the plastic cartridge found on the Discassette (sp?), which was a later 'improved' variant.

Mine appears to be an early model, with a red cartridge that needs to have the earth solder broken to be able to remove it. My stylus is blue, and appears to be reversible (one side plastic, one side metal), hence why I thought that it would just nicely remove. Even downloading the service manual, the procedure for removing the cartridge references removing the tabs at the back of the cartridge, which my set definitely doesn't have.

So what cartridge could it be? If I can attach some photos, I will.

Secondly, the Discatron was originally powered by two VT9 Batteries - what modern replacements can I use? I expect the original VT9 terminals will want swapping to accommodate the new battery too.

Here is a photo of the cartridge setup in my Discatron and the now broken stylus tip.

TonyDuell · 1st Mar 2019, 6:21 am

I think the VT9 is the Vidor equivalent of the Ever Ready PP9. PP9s are still available, or I think a holder with 6 AA cells will fit in the same space.

af024 · 2nd Mar 2019, 1:12 pm

There's an Acos GP79 cartridge/stylus assy in mine. I've never seen anything else fitted.
Yes, I concur, 2 x PP9s.

Regards

af024 · 2nd Mar 2019, 1:15 pm

This is one of them ...
https://www.musonic.co.uk/index.php?...ducts_id=19433

ekjdm14 · 2nd Mar 2019, 5:20 pm

This is another thread I was searching for after watching the video I linked to in this thread. https://www.vintage-radio.net/forum/...d.php?t=154354

I thought the stylus and red cartridge looked rather similar to the system used in the Wondergram.

af024 · 2nd Mar 2019, 6:42 pm

It does, but I don't think that's what was originally fitted to the Discatron.

Regards.

astro63 · 2nd Mar 2019, 6:55 pm

The red catridge/ stylus = power point is the same as the wondergram pick up Electro-voice EV51 power point, they are hard to get with the double tipped LP, the blue version EV56 is LP and 78 tipped. you will only get old stock now as they stopped making the red version few years back :-(

Herald1360 · 3rd Mar 2019, 1:04 pm

Quote:

Originally Posted by TonyDuell

I think the VT9 is the Vidor equivalent of the Ever Ready PP9. PP9s are still available, or I think a holder with 6 AA cells will fit in the same space.

Easily- in fact one will fit quite happily inside an emptied out PP9 case. Capacity is rather less- about half, but given that PP9s run to about £5 each and you can get decent AA alkaline cells for around 35p or less, and they're widely available in a hurry, the restuffed battery option is handy.

julie_m · 3rd Mar 2019, 1:52 pm

If you are building a replacement battery in the hollowed-out case of a dead one, you could use NiMH cells. Unless you can find someone selling 300 alkaline D cells for a quid*, rechargeable batteries work out cheaper than disposables.

* Assume 15Ah capacity for a D size alkaline cell. 15Ah * 1.5V = 22.5Wh = 0.0225 kWh (this is a very generous estimate, as the voltage will fall below 1.5V as the cell becomes spent). 1kWh of mains electricity costs 14.71p according to my meter, so £1 = 100 / 14.71 = 6.798kWh. 6.798kWh / 0.0225 kWh per cell = 302.1. Call it a nice round 300

28th Feb 2019, 10:24 pm	#1
Cameron Retired Dormant Member Join Date: Oct 2010 Location: Nottingham, Nottinghamshire, UK. Posts: 56	Discatron Cartridge Replacement and General Questions I've been after a Discatron for years, and I finally managed to get a really nice example on eBay. It came untested, but is cosmetically perfect at least. I've stripped it down to service it and give it the once over, and the stylus is quite blunt. I read some advice online about sliding the stylus tip out, but instead it's just snapped in half. It appears that every thread I've found on this forum references the plastic cartridge found on the Discassette (sp?), which was a later 'improved' variant. Mine appears to be an early model, with a red cartridge that needs to have the earth solder broken to be able to remove it. My stylus is blue, and appears to be reversible (one side plastic, one side metal), hence why I thought that it would just nicely remove. Even downloading the service manual, the procedure for removing the cartridge references removing the tabs at the back of the cartridge, which my set definitely doesn't have. So what cartridge could it be? If I can attach some photos, I will. Secondly, the Discatron was originally powered by two VT9 Batteries - what modern replacements can I use? I expect the original VT9 terminals will want swapping to accommodate the new battery too. Here is a photo of the cartridge setup in my Discatron and the now broken stylus tip. Attached Thumbnails

1st Mar 2019, 6:21 am	#2
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,213	Re: Discatron Cartridge Replacement and General Questions I think the VT9 is the Vidor equivalent of the Ever Ready PP9. PP9s are still available, or I think a holder with 6 AA cells will fit in the same space.

2nd Mar 2019, 1:12 pm	#3
af024 Octode Join Date: Jan 2003 Location: Ashby-de-la-Zouch (it's not by the sea) Posts: 1,255	Re: Discatron Cartridge Replacement and General Questions There's an Acos GP79 cartridge/stylus assy in mine. I've never seen anything else fitted. Yes, I concur, 2 x PP9s. Regards __________________ Now where on earth did I remove that from?

2nd Mar 2019, 1:15 pm	#4
af024 Octode Join Date: Jan 2003 Location: Ashby-de-la-Zouch (it's not by the sea) Posts: 1,255	Re: Discatron Cartridge Replacement and General Questions This is one of them ... https://www.musonic.co.uk/index.php?...ducts_id=19433 __________________ Now where on earth did I remove that from?

2nd Mar 2019, 5:20 pm	#5
ekjdm14 Banned Join Date: Feb 2019 Location: Congleton, Cheshire, UK. Posts: 609	Re: Discatron Cartridge Replacement and General Questions This is another thread I was searching for after watching the video I linked to in this thread. https://www.vintage-radio.net/forum/...d.php?t=154354 I thought the stylus and red cartridge looked rather similar to the system used in the Wondergram.

2nd Mar 2019, 6:42 pm	#6
af024 Octode Join Date: Jan 2003 Location: Ashby-de-la-Zouch (it's not by the sea) Posts: 1,255	Re: Discatron Cartridge Replacement and General Questions It does, but I don't think that's what was originally fitted to the Discatron. Regards. __________________ Now where on earth did I remove that from?

2nd Mar 2019, 6:55 pm	#7
astro63 Pentode Join Date: Mar 2013 Location: Norfolk, UK. Posts: 248	Re: Discatron Cartridge Replacement and General Questions The red catridge/ stylus = power point is the same as the wondergram pick up Electro-voice EV51 power point, they are hard to get with the double tipped LP, the blue version EV56 is LP and 78 tipped. you will only get old stock now as they stopped making the red version few years back :-(

3rd Mar 2019, 1:52 pm	#9
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Discatron Cartridge Replacement and General Questions If you are building a replacement battery in the hollowed-out case of a dead one, you could use NiMH cells. Unless you can find someone selling 300 alkaline D cells for a quid, rechargeable batteries work out cheaper than disposables. Assume 15Ah capacity for a D size alkaline cell. 15Ah * 1.5V = 22.5Wh = 0.0225 kWh (this is a very generous estimate, as the voltage will fall below 1.5V as the cell becomes spent). 1kWh of mains electricity costs 14.71p according to my meter, so £1 = 100 / 14.71 = 6.798kWh. 6.798kWh / 0.0225 kWh per cell = 302.1. Call it a nice round 300 __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.