AR88 - What has happened and how to cure it? - UK Vintage Radio Repair and Restoration Discussion Forum

JanWra1 · 19th Mar 2018, 4:44 pm

Hi guys

Following the advise of many on this forum I have started to renovate the infamous oil filled triple capacitors starting with the 2 on the front side, i.e. C103,106 and c107 (1:st attempt) which was a success, then moving on to C71,C95 and C102, here I managed to let C102 get to close to the case of the AF-gain which I didn't notice at first. Simultaneously I hade removed and refitted C119 to check what kind it is (Aerovox 0,003 MFD 1000 V) When refitting there was an excess of solder closing the gap between pins 3 and 4 on V11 (6V6GT) but not a solid closure.
When starting the radio there was just a hum from the speaker but the S-Meter indicated that the radio received signals as I scanned the bands.
Turned off the radio and started to look for problems where I hade been working and found both shorts.
Then turned it on again and now there was noise on all bands and the S-meter was going up and down s I scanned the bands, the noise increased with increased value on the S-meter - BUT no readable sound - neither talk, music or CW could be identified.
Tried to replace V10 and V11 but it didn't help.

Any idea what to look for next anyone?

Jan

HamishBoxer · 19th Mar 2018, 6:32 pm

If you have a noise (as in lack of aerial type noise) than the delicate o/put transformer is ok,however I think you have made a wiring error somewhere.

Just a thought try headphones.

turretslug · 19th Mar 2018, 8:16 pm

Make sure that the noise limiter is switched off, too- it's pretty good at removing all modulation at maximum setting!

JanWra1 · 21st Mar 2018, 12:37 am

It's alive again! Have replaced R30 with a new 10W resistor of 2.5K, the old one had a value of 1.3 K. It worked before with the 1.3 k resistor so I don't know why the change fixed it - anyway it's up and running again and have just enjoyed an hour of Radio Scotland at 810 Khz.
Jan

19th Mar 2018, 4:44 pm	#1
JanWra1 Tetrode Join Date: Jan 2018 Location: Stockholm, Sweden Posts: 78	AR88 - What has happened and how to cure it? Hi guys Following the advise of many on this forum I have started to renovate the infamous oil filled triple capacitors starting with the 2 on the front side, i.e. C103,106 and c107 (1:st attempt) which was a success, then moving on to C71,C95 and C102, here I managed to let C102 get to close to the case of the AF-gain which I didn't notice at first. Simultaneously I hade removed and refitted C119 to check what kind it is (Aerovox 0,003 MFD 1000 V) When refitting there was an excess of solder closing the gap between pins 3 and 4 on V11 (6V6GT) but not a solid closure. When starting the radio there was just a hum from the speaker but the S-Meter indicated that the radio received signals as I scanned the bands. Turned off the radio and started to look for problems where I hade been working and found both shorts. Then turned it on again and now there was noise on all bands and the S-meter was going up and down s I scanned the bands, the noise increased with increased value on the S-meter - BUT no readable sound - neither talk, music or CW could be identified. Tried to replace V10 and V11 but it didn't help. Any idea what to look for next anyone? Jan

19th Mar 2018, 6:32 pm	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: AR88 - What has happened and how to cure it? If you have a noise (as in lack of aerial type noise) than the delicate o/put transformer is ok,however I think you have made a wiring error somewhere. Just a thought try headphones. __________________ G8JET BVWS Archivist and Member V.M.A.R.S Last edited by HamishBoxer; 19th Mar 2018 at 6:52 pm.

19th Mar 2018, 8:16 pm	#3
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,398	Re: AR88 - What has happened and how to cure it? Make sure that the noise limiter is switched off, too- it's pretty good at removing all modulation at maximum setting!

21st Mar 2018, 12:37 am	#4
JanWra1 Tetrode Join Date: Jan 2018 Location: Stockholm, Sweden Posts: 78	Re: AR88 - What has happened and how to cure it? It's alive again! Have replaced R30 with a new 10W resistor of 2.5K, the old one had a value of 1.3 K. It worked before with the 1.3 k resistor so I don't know why the change fixed it - anyway it's up and running again and have just enjoyed an hour of Radio Scotland at 810 Khz. Jan