Avo vcm 163 - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Ed_Dinning · 13th Feb 2020, 8:32 am

Hi Folks, a bit of a pain, but with care the old contacts can be removed and a rescued on re fitted . The eyelets are not normally available nor their closing pliers, so use M1.8 or 8BA nuts and bolts

Ed

vintage_8bit · 13th Feb 2020, 11:06 am

Hi Ed, see post 4 for before and after repair pics.

Dekatron · 13th Feb 2020, 7:31 pm

When your tester has these kinds of problems I can recommend that you check every solder connection on the switches and elsewhere as there might well be more poor connections and in the worst cases unsoldered connections, or wires that have been trapped beneath mounting posts or that have chafed isolation resulting in shorts.

vintage_8bit · 13th Feb 2020, 10:34 pm

Will do Martin. Been unable to get in shack tonight. I did wonder if that black wire wasn't attached properly in the first place as there was bare wire at tbe end. If it had fractured you woud expect to be still covered in insulation. I will be reporting back on its first power up, after repair.

vintage_8bit · 20th Feb 2020, 1:56 pm

Posting delay due to touch of Man flu.
Well, it all went back together ok, after close inspection of everything. I have run a few output valves and a largest rectifier on it with believable results, not that I can rely on any results before its had a calibration of course. just had some very low results, both sides with a couple of ECH35's last night. Will check switch settings and check the thumb wheels are doing there job as I'm using positions not tried before. My valve data book is from 1978.

vintage_8bit · 22nd Feb 2020, 10:31 am

Trying a third ECH35 showed good results. So the tester was doing its job. I'm quietly confident that its working now as it should. Thank you all for your help and advice.

vintage_8bit · 23rd Feb 2020, 11:45 pm

One more question gents. I have just run 9 "807's" through the tester. Only 2 showed no problems. The rest showed varying degrees of leakage or showed some current on the gas test. I would assume that they are all destined for the bin.
I have run several different valves successfully up to now its just these 807's that have these problems.
So do they go in the bin or is some leakage acceptable. My view is the long term reliability would be in question. This particular batch has been sat in damp conditions so wondered if it might just be in the valve base?

vintage_8bit · 18th Mar 2020, 2:01 pm

Sorry if my last post was a bit off topic but just to tidy up.....
I left one of the 807's in an oven at around 80 degrees for about an hour, to see if moisture in the base was an issue. When it had cooled it went back on the VCM. I got the same results, so there binned now.

13th Feb 2020, 8:32 am	#21
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Avo vcm 163 Hi Folks, a bit of a pain, but with care the old contacts can be removed and a rescued on re fitted . The eyelets are not normally available nor their closing pliers, so use M1.8 or 8BA nuts and bolts Ed

13th Feb 2020, 11:06 am	#22
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 Hi Ed, see post 4 for before and after repair pics.

13th Feb 2020, 7:31 pm	#23
Dekatron Octode Join Date: May 2009 Location: Linkoping, Sweden Posts: 1,465	Re: Avo vcm 163 When your tester has these kinds of problems I can recommend that you check every solder connection on the switches and elsewhere as there might well be more poor connections and in the worst cases unsoldered connections, or wires that have been trapped beneath mounting posts or that have chafed isolation resulting in shorts. __________________ Martin, Sweden

13th Feb 2020, 10:34 pm	#24
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 Will do Martin. Been unable to get in shack tonight. I did wonder if that black wire wasn't attached properly in the first place as there was bare wire at tbe end. If it had fractured you woud expect to be still covered in insulation. I will be reporting back on its first power up, after repair.

20th Feb 2020, 1:56 pm	#25
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 Posting delay due to touch of Man flu. Well, it all went back together ok, after close inspection of everything. I have run a few output valves and a largest rectifier on it with believable results, not that I can rely on any results before its had a calibration of course. just had some very low results, both sides with a couple of ECH35's last night. Will check switch settings and check the thumb wheels are doing there job as I'm using positions not tried before. My valve data book is from 1978.

22nd Feb 2020, 10:31 am	#26
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 Trying a third ECH35 showed good results. So the tester was doing its job. I'm quietly confident that its working now as it should. Thank you all for your help and advice.

23rd Feb 2020, 11:45 pm	#27
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 One more question gents. I have just run 9 "807's" through the tester. Only 2 showed no problems. The rest showed varying degrees of leakage or showed some current on the gas test. I would assume that they are all destined for the bin. I have run several different valves successfully up to now its just these 807's that have these problems. So do they go in the bin or is some leakage acceptable. My view is the long term reliability would be in question. This particular batch has been sat in damp conditions so wondered if it might just be in the valve base?

18th Mar 2020, 2:01 pm	#28
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Avo vcm 163 Sorry if my last post was a bit off topic but just to tidy up..... I left one of the 807's in an oven at around 80 degrees for about an hour, to see if moisture in the base was an issue. When it had cooled it went back on the VCM. I got the same results, so there binned now.