- Valve amp standby - 1 Update
- Voltages too far out of spec? - 3 Updates
| Gareth Magennis <sound.service@btconnect.com>: Dec 02 01:55PM -0800 Hi, in a previous post of mine about a faulty Engl amp I had that destroyed all its valves, I believe it was suggested by Phil Allison that Standby mode can be inmplemented in a push/pull configuration simply by removing the Screen Grid HT. Since this grid does not pull much current, switching it off is fairly trivial, as opposed to the trauma of switching the whole HT in and out. I posted that I had never come accross such an implementation and wondered why, but yesterday I finally did. It is in this thing: https://www.fryette.com/power-station-integrated-reactance-amplifier/ Interestingly, this HT switching is done by a solid state device - this one: http://www.cosmo-ic.com/object/products/KAQV216.pdf The switching is done via the switched speaker jack. No speaker lead, no Screen Grid HT. Gareth. |
| three_jeeps <jjhudak@gmail.com>: Dec 02 10:26AM -0800 On Sunday, December 1, 2019 at 8:15:26 PM UTC-5, John Robertson wrote: > schematics and voltage test points... > Nice chatting with you! > John :-#)# I dealt with troubleshooting and repairing a lot of consumer tube TV, stereos, and radios during the 60's and 70's. (Still have a collection of service manuals filling 4 large bookcases from my fathers shop). One of the most cited volt meters in the service manuals and schematics in that era was the B&K 177 VTVM. On occasion, I would see a Sencore or Simpson 260 multimeter. As consumer electronics moved to all solid state (80s), I saw a B&K 3-1/2 digit DMM specified (cant remember the model). At some point we went with HP gear. I think they speced equipment that was what the TV technicians were buying, as lab bench gear was quite a bit more expensive and did not require the lab quality accuracy & repeatability numbers. Occasionally I would run across a voltage tolerance spec on a schematic or SM, something like 5%, but dont recall exactly... J |
| Fox's Mercantile <jdangus@att.net>: Dec 02 12:45PM -0600 On 12/2/19 12:26 PM, three_jeeps wrote: > on a schematic or SM, something like 5%, but don't recall > exactly... > J Hewlett Packard isn't consumer grade. If they say 80v on a power supply, they mean 80v. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| John Robertson <spam@flippers.com>: Dec 02 11:14AM -0800 On 2019/12/02 10:45 a.m., Fox's Mercantile wrote: >> J > Hewlett Packard isn't consumer grade. > If they say 80v on a power supply, they mean 80v. Yes, I would have agree, His readings indicate power supply regulation issues not VOM errors. My mistake for going off on this tangent! Sorry about that wild goose chase, John :-#(# |
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