Dansette RG31 radio not working. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

tracypaper · 9th Jul 2012, 12:58 am

Not working as a record player and KB radio stayed on when turning tuner. Now abandoned and will turn it into a Conquest Auto with spare C A amp I have.
RG31 number two had some caps changed a while ago but did not work, I have just sprayed the band selector as suggested and changed C19 (that Capacitor) and the radio works albeit quiet on full volume as is record player, R10 reads 10.45 and R18 reads 14.50, so I guess R18 needs changing??. Do I now change the MR1 as before

??
Cheers,
Gaz.

julie_m · 9th Jul 2012, 10:16 am

You only need to replace MR1 if the HT voltage is low. What are you measuring at the cathode of MR1?

tracypaper · 9th Jul 2012, 5:35 pm

As a novice I am not sure how to test it, I guess with power on connect red of Dmm to + of rectifier and black from DMM to chassis and read voltage?
Gaz.

julie_m · 9th Jul 2012, 6:05 pm

Yes, that's right.

Generally, unless otherwise stated, all voltage measurements are done with the black lead to chassis.

tracypaper · 10th Jul 2012, 12:20 am

Reading at cathode is HV 220

Station X · 10th Jul 2012, 10:04 am

HV?

Herald1360 · 10th Jul 2012, 12:03 pm

Probably just a DVM reminder that the voltage is high enough to be dangerous.

Steve_P · 10th Jul 2012, 2:46 pm

What should it be? Though I admit that 220v sounds OK.

If it's working but low everywhere, then check the voltages on the Output Valve and AF triode.

Don't scrap one by the way. There aren't many of these about.

Cheers,

Steve P.

tracypaper · 10th Jul 2012, 5:28 pm

Excuse my lack of knowledge please,
But how does one check voltage on output valve and AF triode.
If memory serves me right I take out the valve, turn on power, stick red lead from DMM in a pin socket and black lead to earth and take a reading.
But which pin of which valve
Gaz.

julie_m · 10th Jul 2012, 6:13 pm

No -- measure the voltages with the valves in place. You're unlikely to do much harm in the time it takes to get the measurements. Search for the pinouts online and measure the DC voltages on the cathode, G1 (control grid), G2 (screen grid) where applicable (also G3 of the ECH81 heptode) and anode of each valve section (you might as well do the early ones now, you'll probably have to later anyway). NB valve pin numbering increases clockwise from the gap, when viewed from below.

tracypaper · 11th Jul 2012, 6:16 pm

Still confused.com, would be easier for me (as I don't have your superier knowledge) to have the valve to test and pin number I.E Test the ECH81 pin 3, this I can work out.
Also Found a resistor, R9, that is on diagram at 330k but tested 550+ could this be the problem?
Gaz.

Steve_P · 11th Jul 2012, 7:57 pm

Well it's not right so change it!

We'll do one at a time. V4 is the Output Pentode, 6AQ5. (EL90 is an equivalent.) The sheet for it is here...

http://www.r-type.org/exhib/aag0003.htm

It has a 7 pin base, and going round clockwise from the gap...

Pin 2 is the cathode.
Pin 5 is the anode.
Pin 6 is the second grid.
Pin 1 and 7 are the first grid.

Measure these and report back.

Cheers,

Steve P.

9th Jul 2012, 12:58 am	#21
tracypaper Octode Join Date: Aug 2010 Location: Beeston, Leeds, West Yorkshire, UK. Posts: 1,234	Re: Dansette RG31 radio not working. Not working as a record player and KB radio stayed on when turning tuner. Now abandoned and will turn it into a Conquest Auto with spare C A amp I have. RG31 number two had some caps changed a while ago but did not work, I have just sprayed the band selector as suggested and changed C19 (that Capacitor) and the radio works albeit quiet on full volume as is record player, R10 reads 10.45 and R18 reads 14.50, so I guess R18 needs changing??. Do I now change the MR1 as before?? Cheers, Gaz.

9th Jul 2012, 10:16 am	#22
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Dansette RG31 radio not working. You only need to replace MR1 if the HT voltage is low. What are you measuring at the cathode of MR1? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

9th Jul 2012, 5:35 pm	#23
tracypaper Octode Join Date: Aug 2010 Location: Beeston, Leeds, West Yorkshire, UK. Posts: 1,234	Re: Dansette RG31 radio not working. As a novice I am not sure how to test it, I guess with power on connect red of Dmm to + of rectifier and black from DMM to chassis and read voltage? Gaz.

9th Jul 2012, 6:05 pm	#24
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Dansette RG31 radio not working. Yes, that's right. Generally, unless otherwise stated, all voltage measurements are done with the black lead to chassis. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

10th Jul 2012, 12:20 am	#25
tracypaper Octode Join Date: Aug 2010 Location: Beeston, Leeds, West Yorkshire, UK. Posts: 1,234	Re: Dansette RG31 radio not working. Reading at cathode is HV 220

10th Jul 2012, 10:04 am	#26
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Dansette RG31 radio not working. HV? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

10th Jul 2012, 12:03 pm	#27
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Dansette RG31 radio not working. Probably just a DVM reminder that the voltage is high enough to be dangerous. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

10th Jul 2012, 2:46 pm	#28
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Dansette RG31 radio not working. What should it be? Though I admit that 220v sounds OK. If it's working but low everywhere, then check the voltages on the Output Valve and AF triode. Don't scrap one by the way. There aren't many of these about. 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...?

10th Jul 2012, 5:28 pm	#29
tracypaper Octode Join Date: Aug 2010 Location: Beeston, Leeds, West Yorkshire, UK. Posts: 1,234	Re: Dansette RG31 radio not working. Excuse my lack of knowledge please, But how does one check voltage on output valve and AF triode. If memory serves me right I take out the valve, turn on power, stick red lead from DMM in a pin socket and black lead to earth and take a reading. But which pin of which valve Gaz. Last edited by tracypaper; 10th Jul 2012 at 5:38 pm. Reason: added question

10th Jul 2012, 6:13 pm	#30
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Dansette RG31 radio not working. No -- measure the voltages with the valves in place. You're unlikely to do much harm in the time it takes to get the measurements. Search for the pinouts online and measure the DC voltages on the cathode, G1 (control grid), G2 (screen grid) where applicable (also G3 of the ECH81 heptode) and anode of each valve section (you might as well do the early ones now, you'll probably have to later anyway). NB valve pin numbering increases clockwise from the gap, when viewed from below. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

11th Jul 2012, 6:16 pm	#31
tracypaper Octode Join Date: Aug 2010 Location: Beeston, Leeds, West Yorkshire, UK. Posts: 1,234	Re: Dansette RG31 radio not working. Still confused.com, would be easier for me (as I don't have your superier knowledge) to have the valve to test and pin number I.E Test the ECH81 pin 3, this I can work out. Also Found a resistor, R9, that is on diagram at 330k but tested 550+ could this be the problem? Gaz.

11th Jul 2012, 7:57 pm	#32
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Dansette RG31 radio not working. Well it's not right so change it! We'll do one at a time. V4 is the Output Pentode, 6AQ5. (EL90 is an equivalent.) The sheet for it is here... http://www.r-type.org/exhib/aag0003.htm It has a 7 pin base, and going round clockwise from the gap... Pin 2 is the cathode. Pin 5 is the anode. Pin 6 is the second grid. Pin 1 and 7 are the first grid. Measure these and report back. 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...?