Mullard MAS225 worth restoring? - UK Vintage Radio Repair and Restoration Discussion Forum

ted_ntsx · 22nd Dec 2008, 5:31 pm

I have been given this Mullard MAS225.

The Bakelite cabinet has a very bad crack on the top, the front is very tatty (LS cloth ripped and 'paintwork' poor), and the EBL21 is faulty (very microphonic).

Someone has already "replaced" the smoothing cap with some wire ended types suspended in mid-air.

It does work (after a fashion) on LW and SW, but MW is completely dead.

I think it is a lost cause, but wondered if it is rare enough to justify a lot of work (and some cost), or is it a just a run-of-the-mill common model, and better just used for spares?

Ted.

Steve_P · 22nd Dec 2008, 5:39 pm

Every radio is worth restoring. That's my view. And there aren't many Mullard sets about. Wonder what sort of valves are in it...?

The manufacturers service sheet is available up top there.

Valves, Speaker Cloth, Capacitors etc can be obtained - see here:

http://www.vintage-radio.com/contacts/index.html

As for the MW problem, clean the wavechange switch and take it from there.

Cheers,

Steve P.

ted_ntsx · 22nd Dec 2008, 9:14 pm

I am also reluctant to scrap any old radio, but I was beginning to wonder if I was likely to spend more in time and money than what it was worth. The time I can afford (I am retired), but not the money. Maybe I will put it aside until I have the time/inclination to restore it.

The wavechange switch seems ok. No bent contacts, cracking, etc. LW and SW are ok, but MW is just completely and utterly dead. Totally silent. Maybe one of the MW coils is O/C.

Valve set is ECH21, EAF41, EAF41, EBL21, AZ31. A bit of an odd collection...

A (very) quick Web search did not reveal a source of a replacement EBL21 at a *reasonable* cost. No point in paying more for one valve than what the whole radio is worth. It is a sad fact that some of these old sets are worth far more as spare parts than they are as complete working items.

Ted.

Steve_P · 22nd Dec 2008, 9:24 pm

If the EBL21 is microphonic, check the earthing of the paint around the can, the valveholder and the pins (heat them and try it).

Take the set out of the case, clean the Wavechange anyway (a visual inspection is not enough) and then determine whether the fault is in the oscillator or the aerial input circuits. by putting the aerial on the top cap of the ECH21 and seeing if you get anything then.

Cheers,

Steve P.

ted_ntsx · 23rd Dec 2008, 9:19 am

Thanks Steve. I will give your suggestions a try.

Ted.

Tim · 23rd Dec 2008, 12:52 pm

Hi Ted. If you are really stuck(although if the other bands work hopefully the EBL21 is OK, or at least reasonable) one could always try a 7C5 and two germanium diodes................
Some change will be needed to the valve socket. Sounds a similar set to the Philips 581A, of which there is a (not so )recent repair on Pau'ls main site.
ISTR mine worked on all bands.

http://www.vintage-radio.com/recent-...lips-581a.html

TimS · 23rd Dec 2008, 12:54 pm

Capacitors are not too pricey and hopefully after following Steve's suggestions the valve will turn out OK. That could leave you with a working but tatty radio (describe it in future as 'having the patina of age'

)

Got to be better than throwing it in the bin!

Merry Christmas,

-- Tim.

maitiustandun · 23rd Dec 2008, 3:28 pm

hello ted, any chance of a thum nail pic of your mas 225,i have a mullard mas 71. it
has a cream painted front that was badly scratched and paint missing etc , managed to mix up paint from artists tube type paints and matched the original nicely ,used yellow with plenty of white,

top of cabinet can be stuck with super glue or two part araldite,good luck with it , regards maitiu,

yestertech · 23rd Dec 2008, 4:38 pm

Looking at the service data , I suspect this uses the same ghastly wavechange switch as the 462A ( and others ? ) ie fixed outer wafer with spoon type contact touching rotating inner wafer with bridging contacts - Oh dear dear Philips !
Try rotating the switch slowly between the SW and LW clickstops and see if MW can be found. If it can, chances are it will disappear when the switch is in the "correct" position. You then have to work out which contact is troublesome ( usually the centre wafer ones from memory) and see if it can be adjusted. Due to years of wear, there's effectively too much play in the mechanism.
At this point it may all prove too much ....... Andy

ted_ntsx · 24th Dec 2008, 12:05 pm

Ok. Given all the comments here, I will persevere with this radio a bit longer.

The EBL21 is definitely faulty. There is bits of metallic and glass debris rattling about inside it, and the slightest vibration causes a lot of screeching. This is a problem but, as Tim suggested, it may be possible to fit an alternative.

The smoothing cap I can easily sort out, but the dead MW will require some more time to investigate, so will have to wait until after Christmas!

It is very similar to the Philips 581. I have uploaded a picture (not actually my set. Mine is rather more tatty).

Ted.

ted_ntsx · 1st Jan 2009, 2:48 pm

Just a follow-up, in case anyone is interested...

I replaced the EBL21 valve with a 6V6 and it works well, but it did require a extra cathode bias resistor to limit the current to a reasonable value.

The dead MW band was traced to an open circuit oscillator coil inside a sealed metal can. I managed to break it open, repair the coil, and reseal it. Some "leaky" waxy capacitors were replaced and some iffy looking previous repairs tidied up.

I replaced the torn speaker cloth and re-glued the cracked cabinet. The cabinet still requires a bit more work, but is acceptable.

I now have a MAS225 that looks reasonable and works very well.

Ted.

TimS · 2nd Jan 2009, 8:19 pm

Good to hear that its been a success.

I wouldn't worry about the cabinet being perfect. Its a radio after all - it was never bought in the first place to be looked at!

-- Tim.

Tim · 3rd Jan 2009, 1:03 am

Hi glad it works. Another one saved!!
ISTR the 7C5 is electrically equivalent to 6V6 but with the "Loctal" base. If it is similar to the Philips 581 , I can't remember if the diodes in the EBL21 were actually used. There are two more available , one in each EBF41/2, which I think were used for detection/ AGC etc. Another point to bear in mind, which may save lots of cursing, is the negative connection (in the Philips)of the two main smoothers(50uF) DOES NOT CONNECT DIRECTLY TO CHASSIS, but via a low value resistor shunted by a capacitor(25-50uF).

ted_ntsx · 3rd Jan 2009, 9:43 am

Yes, the 7C5 and 6V6 are similar. I had a 6V6 to hand, so used that. The diodes in the EBL21 were not used and were just strapped to the cathode. Makes you wonder why they picked that valve?

I was aware of the slightly odd arrangement of the way the HT -ve is used to provide a bias for the valves. It did not produce enough for the 6V6 (it gor VERY hot), so I added it's own extra cathode resistor/capacitor.

Ted.

22nd Dec 2008, 5:31 pm	#1
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Mullard MAS225 worth restoring? I have been given this Mullard MAS225. The Bakelite cabinet has a very bad crack on the top, the front is very tatty (LS cloth ripped and 'paintwork' poor), and the EBL21 is faulty (very microphonic). Someone has already "replaced" the smoothing cap with some wire ended types suspended in mid-air. It does work (after a fashion) on LW and SW, but MW is completely dead. I think it is a lost cause, but wondered if it is rare enough to justify a lot of work (and some cost), or is it a just a run-of-the-mill common model, and better just used for spares? Ted.

22nd Dec 2008, 5:39 pm	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Mullard MAS225 worth restoring? Every radio is worth restoring. That's my view. And there aren't many Mullard sets about. Wonder what sort of valves are in it...? The manufacturers service sheet is available up top there. Valves, Speaker Cloth, Capacitors etc can be obtained - see here: http://www.vintage-radio.com/contacts/index.html As for the MW problem, clean the wavechange switch and take it from there. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

22nd Dec 2008, 9:14 pm	#3
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Mullard MAS225 worth restoring? I am also reluctant to scrap any old radio, but I was beginning to wonder if I was likely to spend more in time and money than what it was worth. The time I can afford (I am retired), but not the money. Maybe I will put it aside until I have the time/inclination to restore it. The wavechange switch seems ok. No bent contacts, cracking, etc. LW and SW are ok, but MW is just completely and utterly dead. Totally silent. Maybe one of the MW coils is O/C. Valve set is ECH21, EAF41, EAF41, EBL21, AZ31. A bit of an odd collection... A (very) quick Web search did not reveal a source of a replacement EBL21 at a reasonable cost. No point in paying more for one valve than what the whole radio is worth. It is a sad fact that some of these old sets are worth far more as spare parts than they are as complete working items. Ted.

22nd Dec 2008, 9:24 pm	#4
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Mullard MAS225 worth restoring? If the EBL21 is microphonic, check the earthing of the paint around the can, the valveholder and the pins (heat them and try it). Take the set out of the case, clean the Wavechange anyway (a visual inspection is not enough) and then determine whether the fault is in the oscillator or the aerial input circuits. by putting the aerial on the top cap of the ECH21 and seeing if you get anything then. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

23rd Dec 2008, 9:19 am	#5
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Mullard MAS225 worth restoring? Thanks Steve. I will give your suggestions a try. Ted.

23rd Dec 2008, 12:52 pm	#6
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: Mullard MAS225 worth restoring? Hi Ted. If you are really stuck(although if the other bands work hopefully the EBL21 is OK, or at least reasonable) one could always try a 7C5 and two germanium diodes................ Some change will be needed to the valve socket. Sounds a similar set to the Philips 581A, of which there is a (not so )recent repair on Pau'ls main site. ISTR mine worked on all bands. http://www.vintage-radio.com/recent-...lips-581a.html __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

23rd Dec 2008, 12:54 pm	#7
TimS Pentode Join Date: Jun 2005 Location: Forres, Moray, UK. Posts: 194	Re: Mullard MAS225 worth restoring? Capacitors are not too pricey and hopefully after following Steve's suggestions the valve will turn out OK. That could leave you with a working but tatty radio (describe it in future as 'having the patina of age' ) Got to be better than throwing it in the bin! Merry Christmas, -- Tim.

23rd Dec 2008, 3:28 pm	#8
maitiustandun Pentode Join Date: Aug 2005 Location: Dublin, Ireland. Posts: 157	Re: Mullard MAS225 worth restoring? hello ted, any chance of a thum nail pic of your mas 225,i have a mullard mas 71. it has a cream painted front that was badly scratched and paint missing etc , managed to mix up paint from artists tube type paints and matched the original nicely ,used yellow with plenty of white, top of cabinet can be stuck with super glue or two part araldite,good luck with it , regards maitiu,

23rd Dec 2008, 4:38 pm	#9
yestertech Nonode Join Date: Dec 2002 Location: Coulsdon, Surrey, UK. Posts: 2,135	Re: Mullard MAS225 worth restoring? Looking at the service data , I suspect this uses the same ghastly wavechange switch as the 462A ( and others ? ) ie fixed outer wafer with spoon type contact touching rotating inner wafer with bridging contacts - Oh dear dear Philips ! Try rotating the switch slowly between the SW and LW clickstops and see if MW can be found. If it can, chances are it will disappear when the switch is in the "correct" position. You then have to work out which contact is troublesome ( usually the centre wafer ones from memory) and see if it can be adjusted. Due to years of wear, there's effectively too much play in the mechanism. At this point it may all prove too much ....... Andy

24th Dec 2008, 12:05 pm	#10
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Mullard MAS225 worth restoring? Ok. Given all the comments here, I will persevere with this radio a bit longer. The EBL21 is definitely faulty. There is bits of metallic and glass debris rattling about inside it, and the slightest vibration causes a lot of screeching. This is a problem but, as Tim suggested, it may be possible to fit an alternative. The smoothing cap I can easily sort out, but the dead MW will require some more time to investigate, so will have to wait until after Christmas! It is very similar to the Philips 581. I have uploaded a picture (not actually my set. Mine is rather more tatty). Ted.

1st Jan 2009, 2:48 pm	#11
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Mullard MAS225 worth restoring? Just a follow-up, in case anyone is interested... I replaced the EBL21 valve with a 6V6 and it works well, but it did require a extra cathode bias resistor to limit the current to a reasonable value. The dead MW band was traced to an open circuit oscillator coil inside a sealed metal can. I managed to break it open, repair the coil, and reseal it. Some "leaky" waxy capacitors were replaced and some iffy looking previous repairs tidied up. I replaced the torn speaker cloth and re-glued the cracked cabinet. The cabinet still requires a bit more work, but is acceptable. I now have a MAS225 that looks reasonable and works very well. Ted.

2nd Jan 2009, 8:19 pm	#12
TimS Pentode Join Date: Jun 2005 Location: Forres, Moray, UK. Posts: 194	Re: Mullard MAS225 worth restoring? Good to hear that its been a success. I wouldn't worry about the cabinet being perfect. Its a radio after all - it was never bought in the first place to be looked at! -- Tim.

3rd Jan 2009, 1:03 am	#13
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: Mullard MAS225 worth restoring? Hi glad it works. Another one saved!! ISTR the 7C5 is electrically equivalent to 6V6 but with the "Loctal" base. If it is similar to the Philips 581 , I can't remember if the diodes in the EBL21 were actually used. There are two more available , one in each EBF41/2, which I think were used for detection/ AGC etc. Another point to bear in mind, which may save lots of cursing, is the negative connection (in the Philips)of the two main smoothers(50uF) DOES NOT CONNECT DIRECTLY TO CHASSIS, but via a low value resistor shunted by a capacitor(25-50uF). __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

3rd Jan 2009, 9:43 am	#14
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Mullard MAS225 worth restoring? Yes, the 7C5 and 6V6 are similar. I had a 6V6 to hand, so used that. The diodes in the EBL21 were not used and were just strapped to the cathode. Makes you wonder why they picked that valve? I was aware of the slightly odd arrangement of the way the HT -ve is used to provide a bias for the valves. It did not produce enough for the 6V6 (it gor VERY hot), so I added it's own extra cathode resistor/capacitor. Ted.