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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Known history with this , from its purchase in Germany onwards, including
its original set of valves (not in there and used now, but will test out of curiosity). What are the main potential safety/reliability issues with an amp of this age? All the cotton covered wiring looks good but is there some test/procedure more convincing as to insualting value? Bakelite brittleness in the valve bases? metallurgical failure of springiness of valve contacts? Someone modified to 3 core mains cable and made an earth point, for 240V land, at some point in its history. Numerous caps replaced in 1991 and 1997 and some carbon R replaced with MO at some point. I've not checked the main caps yet. |
#2
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On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote:
Known history with this , from its purchase in Germany onwards, including its original set of valves (not in there and used now, but will test out of curiosity). What are the main potential safety/reliability issues with an amp of this age? All the cotton covered wiring looks good but is there some test/procedure more convincing as to insualting value? Bakelite brittleness in the valve bases? metallurgical failure of springiness of valve contacts? Someone modified to 3 core mains cable and made an earth point, for 240V land, at some point in its history. Numerous caps replaced in 1991 and 1997 and some carbon R replaced with MO at some point. I've not checked the main caps yet. No known safety issues other than mains wiring. These were pretty reliable amps. I own a 1970 Showman USA model. Someone tried to turn it into a 100 watt model by replacing the iron and adding two octals to the already blanked out chassis. I ripped all that stuff out and put new output iron in it. It's not worth much but it does sound sweet. -- Live Fast, Die Young and Leave a Pretty Corpse |
#3
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Meat Plow wrote in message
news ![]() On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote: Known history with this , from its purchase in Germany onwards, including its original set of valves (not in there and used now, but will test out of curiosity). What are the main potential safety/reliability issues with an amp of this age? All the cotton covered wiring looks good but is there some test/procedure more convincing as to insualting value? Bakelite brittleness in the valve bases? metallurgical failure of springiness of valve contacts? Someone modified to 3 core mains cable and made an earth point, for 240V land, at some point in its history. Numerous caps replaced in 1991 and 1997 and some carbon R replaced with MO at some point. I've not checked the main caps yet. No known safety issues other than mains wiring. These were pretty reliable amps. I own a 1970 Showman USA model. Someone tried to turn it into a 100 watt model by replacing the iron and adding two octals to the already blanked out chassis. I ripped all that stuff out and put new output iron in it. It's not worth much but it does sound sweet. -- Live Fast, Die Young and Leave a Pretty Corpse Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test |
#4
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On Wed, 22 Sep 2010 17:39:27 +0100, N_Cook wrote:
Meat Plow wrote in message news ![]() On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote: Known history with this , from its purchase in Germany onwards, including its original set of valves (not in there and used now, but will test out of curiosity). What are the main potential safety/reliability issues with an amp of this age? All the cotton covered wiring looks good but is there some test/procedure more convincing as to insualting value? Bakelite brittleness in the valve bases? metallurgical failure of springiness of valve contacts? Someone modified to 3 core mains cable and made an earth point, for 240V land, at some point in its history. Numerous caps replaced in 1991 and 1997 and some carbon R replaced with MO at some point. I've not checked the main caps yet. No known safety issues other than mains wiring. These were pretty reliable amps. I own a 1970 Showman USA model. Someone tried to turn it into a 100 watt model by replacing the iron and adding two octals to the already blanked out chassis. I ripped all that stuff out and put new output iron in it. It's not worth much but it does sound sweet. -- Live Fast, Die Young and Leave a Pretty Corpse Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Since the heater wiring is twisted it would be a good idea to replace if it is that poor of a state. I don't recall ever seeing the LV wiring in any Fender of that era in that state and the state of all the wiring is what I usually inspect first on any P2P wired vintage amp. -- Live Fast, Die Young and Leave a Pretty Corpse |
#5
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On 22/09/2010 17:39, N_Cook wrote:
Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Z&I Aero!!! I haven't heard that name for over 40 years. That was when their shop in Tottenham Court Road was worth visiting, followed by a stroll to Proops, and then onto Lisle Street. Are there any surplus places worth visiting today? -- Jeff |
#6
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![]() "Jeff Layman" wrote in message ... On 22/09/2010 17:39, N_Cook wrote: Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Z&I Aero!!! I haven't heard that name for over 40 years. That was when their shop in Tottenham Court Road was worth visiting, followed by a stroll to Proops, and then onto Lisle Street. Are there any surplus places worth visiting today? -- Jeff I still have a Z&I Aero (Zaerix) glossy covered catalogue / data book in near pristine condition. It has data on lovely old things like VCR97 'scope tubes, and has all the prices in pounds, shillings and pence ! Oh those lovely old days of skiving off school for the day and jumping on the train to London to go to Tottenham Court Road and Lisle Street. Into Henry's Radio .... I bought my first 'hifi' amplifier in Proops. It's a Teleton SAQ-307. It's here in the computer room with me, and I'm looking at it right now. Still works as good as the day it was bought. Only about 8 watts per channel as I recall, but punched way above that weight. It drives my EMI 13 x 8 cabs with 7 x 5 mids and Eagle dome tweeters. The EMIs came from Henry's and the Eagles from Maplin I think, but might have been Tandy (Radio Shack). I also have the matching Teleton GT-203 tuner, and then the Nikko ND-790 cassette deck. Remember those ? All together, it was the classic "poor man's" hifi rig of the early 70s. I think most of the wonderful old junk shops have pretty much gone now, but I think that Anchor Supplies up in Nottingham is still going. Remember AH Supplies ? They used to advertise every month in Practically Witless magazine, and I bought a lot of ex WW2 radios like 19 sets and an R1392 and a Wavemeter D from them. I have a feeling that they might still be going in one form or another. I'm also pretty sure that Birketts over in Lincoln somewhere are still going too. Then there was John's Radio, and Bull Electrical. Happy days ... Blimey. I've just looked up John's Radio, and they are still going ! Arfa |
#7
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On Sep 22, 2:17*pm, Jeff Layman wrote:
On 22/09/2010 17:39, N_Cook wrote: Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Z&I Aero!!! *I haven't heard that name for over 40 years. *That was when their shop in Tottenham Court Road was worth visiting, followed by a stroll to Proops, and then onto Lisle Street. *Are there any surplus places worth visiting today? -- Jeff Tottenham Court Road... Proops... Lisle Street... Brings back memories! Cheers, Roger (in Canada since 1970...) |
#8
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Meat Plow wrote in message
news ![]() On Wed, 22 Sep 2010 17:39:27 +0100, N_Cook wrote: Meat Plow wrote in message news ![]() On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote: Known history with this , from its purchase in Germany onwards, including its original set of valves (not in there and used now, but will test out of curiosity). What are the main potential safety/reliability issues with an amp of this age? All the cotton covered wiring looks good but is there some test/procedure more convincing as to insualting value? Bakelite brittleness in the valve bases? metallurgical failure of springiness of valve contacts? Someone modified to 3 core mains cable and made an earth point, for 240V land, at some point in its history. Numerous caps replaced in 1991 and 1997 and some carbon R replaced with MO at some point. I've not checked the main caps yet. No known safety issues other than mains wiring. These were pretty reliable amps. I own a 1970 Showman USA model. Someone tried to turn it into a 100 watt model by replacing the iron and adding two octals to the already blanked out chassis. I ripped all that stuff out and put new output iron in it. It's not worth much but it does sound sweet. -- Live Fast, Die Young and Leave a Pretty Corpse Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Since the heater wiring is twisted it would be a good idea to replace if it is that poor of a state. I don't recall ever seeing the LV wiring in any Fender of that era in that state and the state of all the wiring is what I usually inspect first on any P2P wired vintage amp. -- Live Fast, Die Young and Leave a Pretty Corpse The conductor size, under the insulation, is only 0.7mm presumably not enough for the current plus localised heating. Will replace with silicon sleeved wire with "Refrasil" glass sleeving over that , dulled down with dark green permanent ink felt tip pen, gives a very convincing contemporary look, and surprisingly does not wipe off the glass |
#9
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On 23/09/2010 02:18, Arfa Daily wrote:
"Jeff Layman" wrote in message ... On 22/09/2010 17:39, N_Cook wrote: Closer look and the cotton covering to the wiring between the output heaters is "perished", crumbling to dust, and needs replacing. Strange having a load of Mullard, Brimar and Z&I Aero valves to test Z&I Aero!!! I haven't heard that name for over 40 years. That was when their shop in Tottenham Court Road was worth visiting, followed by a stroll to Proops, and then onto Lisle Street. Are there any surplus places worth visiting today? -- Jeff I still have a Z&I Aero (Zaerix) glossy covered catalogue / data book in near pristine condition. It has data on lovely old things like VCR97 'scope tubes, and has all the prices in pounds, shillings and pence ! Oh those lovely old days of skiving off school for the day and jumping on the train to London to go to Tottenham Court Road and Lisle Street. Into Henry's Radio ... I bought my first 'hifi' amplifier in Proops. It's a Teleton SAQ-307. It's here in the computer room with me, and I'm looking at it right now. Still works as good as the day it was bought. Only about 8 watts per channel as I recall, but punched way above that weight. It drives my EMI 13 x 8 cabs with 7 x 5 mids and Eagle dome tweeters. The EMIs came from Henry's and the Eagles from Maplin I think, but might have been Tandy (Radio Shack). I also have the matching Teleton GT-203 tuner, and then the Nikko ND-790 cassette deck. Remember those ? All together, it was the classic "poor man's" hifi rig of the early 70s. I think most of the wonderful old junk shops have pretty much gone now, but I think that Anchor Supplies up in Nottingham is still going. Remember AH Supplies ? They used to advertise every month in Practically Witless magazine, and I bought a lot of ex WW2 radios like 19 sets and an R1392 and a Wavemeter D from them. I have a feeling that they might still be going in one form or another. I'm also pretty sure that Birketts over in Lincoln somewhere are still going too. Then there was John's Radio, and Bull Electrical. Happy days ... Blimey. I've just looked up John's Radio, and they are still going ! Arfa Teleton SAQ-307! yes I had one o them. Marvelous amplifier, didn't it have some unusual feature for it's day, slider control or something? I had mine in my shop driving a stack consiting of a 15" Gauss in a home made Altec Voice of the Theatre copy, a 12" Gauss VotT copy and a whopping great Vitavox multicell horn (courtesy of the recently closed local ODEON). No electronic crossovers in those days! Even tho it was only a few watts, it could visibly make the shop window shake in time to the music (Dark Side of the Moon - Most impressive) Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 2512 of my spam emails to date. Get the free SPAMfighter he http://www.spamfighter.com/len The Professional version does not have this message |
#10
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At least not best wiring practise, wires not looped thru tags (2 passes)
before soldering. Although original wiring , a 6L6 socket has been replaced at some time. Did he swap around the wires and so the heater pinning is different? . The original "push" pair have opposite polarity pinning for the heaters of each but the "pull" pair, with the replaced socket, are same "polarity". I'm inclined to replace the wiring with both pairs having alternate polarity |
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