Yacht-Boy 210 - UK Vintage Radio Repair and Restoration Discussion Forum

Johnnyboy73 · 12th Sep 2019, 8:46 pm

Dear All
I was recently gifted this set one that my father had when I was a child. While circa 1970s it still worked fine on FM. Today after a few weeks use it has died. It runs on the original mains power supply, output was good and the bulb still lights on the set but no sound. There is a slight hiss/crackle when depressing the red on button through the speaker but otherwise nothing. I removed the internal tray with the mounted PCB, checked for loose wires and cleaned with compressed air and contact spray but nothing. I am handy with a multimeter but pretty clueless where to start. I also have a copy of the schematics.
Any hope for this ?
Best
John

orbanp1 · 13th Sep 2019, 12:12 pm

Hi John,

Welcome to the forum!
That is a nice radio, well worth fixing it!

First thing is to check the current draw of the radio. The battery voltage is 9V.
When the circuits are fine the current draw should be somewhere between 10mA to 20mA or so.
Next thing is to check if the output of the final amplifier stage, the common emitter point of T9 and T10, before the output coupling capacitor (C66, 1000uF) is at half supply voltage.
You could also check the idle current of the final stage, the schematics gives 5.5mA at that link marked with "X" at 7.5V battery voltage (a bit higher at 9V).
If not, do check the other DC voltages in the audio amplifier (T7 - T10), as marked on the schematics.

If the above is alright, do add some external audio signal to the audio amplifier and see if the amp works.
According to the schematics, if both LW and MW band switches are engaged, the audio amp takes the input from the 5-pin DIN audio jack. For esternal source you could use an MP3 player or similar.

If the above works, we can continue from there.

Regards, Peter

Johnnyboy73 · 13th Sep 2019, 9:25 pm

Hi Peter
Thanks for your reply. I tried running off a 9v battery with no difference.
I tried to check the draw but was unsure where on the board. As the light was lit I selected the two terminals across the battery meter. A slight crackle and the bulb has now gone off?
Back on battery c66 had no voltage or amperage. I found T10 and just touching the middle and lower contact with the probes was enough for the set to spark into life! When testing is COM best earthed on either chassis or antenna.
Presume this is a dry joint. Is it best to resolder all the T terminals ?
Also with an old set like this is it best left on for long periods rather than on and off for short ones ?
Many thanks for help, much appreciated.

'LIVEWIRE?' · 14th Sep 2019, 8:20 am

To measure the current drawn, the meter, set to a suitable milliampere range, must be connected in series with either the battery, which means, e.g., connect the red meter probe to the positive terminal of the battery, and the black terminal to the positive supply point on the radio, i.e. the poit where the battery positive terminal usually connects, or in series with the collector of one of the output transistors. On most of the Yacht Boy series there is a link on the circuit board for this purpose. This may be a deliberately provided gap in a PC Track, bridged by solder or a wire link.

orbanp1 · 16th Sep 2019, 11:53 am

Hi John,

I do not think there is a need to touch up all the solder joints of the transistors, it is enough to find and "fix" the bad ones!

If you look at the schematics, the negative pole of the battery is not the radio ground, but that is "away" by R43, a 100 Ohm resistor. When you measure voltages be aware of this!
On the schematics the voltage measurements are depicted by arrows, showing both ends of the contacts, and that should help.

The link mentioned by Livewire for the final transistor current measurement is shown on the PCB, and it is also incidentally the negative pole of the battery.

As Livewire mentioned, you measure the total current draw of the radio with the am-meter in series with the battery.

It probably does not make much difference if you leave on or turn off the radio for long periods, only in battery consumption.

If anything, it is probably the condition of the electrolytic capacitors that is affected by age, and you find the bad ones by measuring the ESR (equivalent series resistance) of those caps. Depending on the ESR-meter, the caps can be measured in-situ, without taking them out.
It is quite simple to build an ESR-meter by yourself, and it is one of the most useful test equipment, in my opinion.

Regards, Peter

Johnnyboy73 · 19th Sep 2019, 10:03 pm

Great. Many thanks for all the help. The dry joint as marked seems to have fixed this set. I also opened the original power supply and replaced the 2 glass fuses that had blow. A couple of the wires were also loose so resoldered those too and carefully managed to wiggle it back into its case and eventually got a nice 9v output again. So all good.

12th Sep 2019, 8:46 pm	#1
Johnnyboy73 Diode Join Date: Sep 2019 Location: Glasgow, Scotland, UK. Posts: 3	Yacht-Boy 210 Dear All I was recently gifted this set one that my father had when I was a child. While circa 1970s it still worked fine on FM. Today after a few weeks use it has died. It runs on the original mains power supply, output was good and the bulb still lights on the set but no sound. There is a slight hiss/crackle when depressing the red on button through the speaker but otherwise nothing. I removed the internal tray with the mounted PCB, checked for loose wires and cleaned with compressed air and contact spray but nothing. I am handy with a multimeter but pretty clueless where to start. I also have a copy of the schematics. Any hope for this ? Best John

13th Sep 2019, 12:12 pm	#2
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Yacht-Boy 210 Hi John, Welcome to the forum! That is a nice radio, well worth fixing it! First thing is to check the current draw of the radio. The battery voltage is 9V. When the circuits are fine the current draw should be somewhere between 10mA to 20mA or so. Next thing is to check if the output of the final amplifier stage, the common emitter point of T9 and T10, before the output coupling capacitor (C66, 1000uF) is at half supply voltage. You could also check the idle current of the final stage, the schematics gives 5.5mA at that link marked with "X" at 7.5V battery voltage (a bit higher at 9V). If not, do check the other DC voltages in the audio amplifier (T7 - T10), as marked on the schematics. If the above is alright, do add some external audio signal to the audio amplifier and see if the amp works. According to the schematics, if both LW and MW band switches are engaged, the audio amp takes the input from the 5-pin DIN audio jack. For esternal source you could use an MP3 player or similar. If the above works, we can continue from there. Regards, Peter

13th Sep 2019, 9:25 pm	#3
Johnnyboy73 Diode Join Date: Sep 2019 Location: Glasgow, Scotland, UK. Posts: 3	Re: Yacht-Boy 210 Hi Peter Thanks for your reply. I tried running off a 9v battery with no difference. I tried to check the draw but was unsure where on the board. As the light was lit I selected the two terminals across the battery meter. A slight crackle and the bulb has now gone off? Back on battery c66 had no voltage or amperage. I found T10 and just touching the middle and lower contact with the probes was enough for the set to spark into life! When testing is COM best earthed on either chassis or antenna. Presume this is a dry joint. Is it best to resolder all the T terminals ? Also with an old set like this is it best left on for long periods rather than on and off for short ones ? Many thanks for help, much appreciated. Attached Thumbnails

14th Sep 2019, 8:20 am	#4
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Yacht-Boy 210 To measure the current drawn, the meter, set to a suitable milliampere range, must be connected in series with either the battery, which means, e.g., connect the red meter probe to the positive terminal of the battery, and the black terminal to the positive supply point on the radio, i.e. the poit where the battery positive terminal usually connects, or in series with the collector of one of the output transistors. On most of the Yacht Boy series there is a link on the circuit board for this purpose. This may be a deliberately provided gap in a PC Track, bridged by solder or a wire link.

16th Sep 2019, 11:53 am	#5
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Yacht-Boy 210 Hi John, I do not think there is a need to touch up all the solder joints of the transistors, it is enough to find and "fix" the bad ones! If you look at the schematics, the negative pole of the battery is not the radio ground, but that is "away" by R43, a 100 Ohm resistor. When you measure voltages be aware of this! On the schematics the voltage measurements are depicted by arrows, showing both ends of the contacts, and that should help. The link mentioned by Livewire for the final transistor current measurement is shown on the PCB, and it is also incidentally the negative pole of the battery. As Livewire mentioned, you measure the total current draw of the radio with the am-meter in series with the battery. It probably does not make much difference if you leave on or turn off the radio for long periods, only in battery consumption. If anything, it is probably the condition of the electrolytic capacitors that is affected by age, and you find the bad ones by measuring the ESR (equivalent series resistance) of those caps. Depending on the ESR-meter, the caps can be measured in-situ, without taking them out. It is quite simple to build an ESR-meter by yourself, and it is one of the most useful test equipment, in my opinion. Regards, Peter Attached Thumbnails

19th Sep 2019, 10:03 pm	#6
Johnnyboy73 Diode Join Date: Sep 2019 Location: Glasgow, Scotland, UK. Posts: 3	Re: Yacht-Boy 210 Great. Many thanks for all the help. The dry joint as marked seems to have fixed this set. I also opened the original power supply and replaced the 2 glass fuses that had blow. A couple of the wires were also loose so resoldered those too and carefully managed to wiggle it back into its case and eventually got a nice 9v output again. So all good.