Left my class A amp on overnight...

[nzoomed]

If its a decently built amp you only took 8 hours off the tube life

Well thats what im hoping, not normally something I would do. Didnt think my friend would switch it on when i went to bed as he must have stayed up for a bit, would have told him to make sure to switch it off if i knew he was going to use it lol

Anyway, here is the schematic, amp seems to still be performing OK.

 

[nzoomed]

If an amp could not run 8 hours continuously, it needs fixing. Some folks warm up their amp for 8 hours before start listening

yes that did cross my mind about "burning in" new tubes.

 

[Wavebourn]

I leave my amps for as long as possible, to set stationary temperatures, then take IR pictures. Then I decide, if it needs some improvements in terms of heat dissipation.

 

[hpeter]

stay in specs and u will be fine

 

[Alastair E]

ECL/PCL82, probably the most reliable of the bunch. PCL82 SE class A used in practically every British mono TV set and rarely if ever failed.

--Unlike the PCL86, used in later colour sets, its slightly higher power replacement, Those things were awful-- changed dozens, but never changed a PCL82!

 

[nzoomed]

ECL/PCL82, probably the most reliable of the bunch. PCL82 SE class A used in practically every British mono TV set and rarely if ever failed.

--Unlike the PCL86, used in later colour sets, its slightly higher power replacement, Those things were awful-- changed dozens, but never changed a PCL82!

wow thats amazing, good to know!
All i know is the transformer gets really hot with this thing running, especially after being on overnight.

 

[Galu]

--Unlike the PCL86, used in later colour sets, its slightly higher power replacement, Those things were awful-- changed dozens, but never changed a PCL82!

I have no experience of the PCL86 but the four original Mullard ECL86 valves in my 50 year old Rogers amp are still going strong and still sounding as sweet as new.

 

[JoeAlders]

Looking at the given circuit diagram and the DC operating currents and restricting
my rough calculations to the pentode output stage:
Plate dissipation : 4.7 Watts (presuming the OT primary resistance at 2k5)
The specification (Philips) gives max.: 7Watts for A.F. appllications.
Grid No.2 dissipation: 1.5W
The specification (Philips) gives average: 2Watts
So not much to worry about I think.

 

[scottjoplin]

All i know is the transformer gets really hot with this thing running, especially after being on overnight.

This is possibly more important, it was a power transformer that started to burn in my left on amp, thankfully I was at home at the time, never left an amp on since

 

[JoeAlders]

This is possibly more important, it was a power transformer that started to burn in my left on amp, thankfully I was at home at the time, never left an amp on since

That is indeed what I could not calculate because Hammond gives only the Max. DC-bias current which is 60mA and sadly enough not the primary resistance of that type of OT.
And I completely overlooked that part of nzoomed comments.


http://www.hammondmfg.com/pdf/5c0054.pdf

 

[daqvin_carter]

I have a low power (10 watts) 845 amplifier.
My boiler died so it has been on for the last week.

 

[Alan4411]

nzoomed,
Question, the mains transformer on the schematic is a Hammond 270EX, that's a 117 volt US transformer.
I was under the impression that NZ was 240 volt ac mains like the UK.
Do you use a drop down transformer or is something else fitted to your amp?
Alan

 

[JoeAlders]

I have a low power (10 watts) 845 amplifier.
My boiler died so it has been on for the last week.

Wow, if that's enough to warm your (living)room, I think my new to build amp will be that 845 amplifier .

 

[kodabmx]

This is possibly more important, it was a power transformer that started to burn in my left on amp, thankfully I was at home at the time, never left an amp on since

The only time that happened to me was when I was overloading a 60 year old 150VA transformer to about 250VA. It smoked but didn't catch on fire

 

[kodabmx]

I have a low power (10 watts) 845 amplifier.
My boiler died so it has been on for the last week.

I have electric baseboard heat. I haven't used it in years. Apparently, computers, TV, and tube amps make lots of heat? Who knew! Usually by the evening, I have the windows open (Yes, even when it's -10c out). In the summer, I have 17,000 BTUs of a/c for my 380sqft apartment... Electric is included

 

[nzoomed]

nzoomed,
Question, the mains transformer on the schematic is a Hammond 270EX, that's a 117 volt US transformer.
I was under the impression that NZ was 240 volt ac mains like the UK.
Do you use a drop down transformer or is something else fitted to your amp?
Alan

Just so you know, i used a 230V transformer out of a Bell colt radio that was the same spec. Is still working perfectly