As PRR says, I think it will be a lot less than that. If you have a wattmeter, or just an AC ammeter, you could plug it into a 120V mains outlet long enough to measure the current draw.
Since the chassis might be live (and potentially lethal), this would have to be done with proper precautions. Place the amp in an insulating box with the lid on (say a big plastic storage box) so there is no chance of accidentally touching its chassis. Make up an adapter box with an IEC inlet and regular wall outlet, wired in between so that you can put your ammeter in series with the mains power going to the amplifier. Make all connections in advance, so that you are ready for the measurement.
Then, touching only the AC plug, insert it into the wall, wait long enough for the heaters to warm up, read the current draw, and unplug it from the wall.
The chassis itself is safe as soon as you unplug from the wall, but make sure all caps are fully discharged before touching anything inside the chassis...
If 50 watts proves to be sufficient, the Triad N68-X is economy king at about $16 USD, and it's well proven: Blocked
(The N-68X can be wired for either 115V or 230V primary operation).
If you need 100 watts, the Triad N-76U at just under $33 USD looks like a good option: Blocked
And if you really need a whole 150 watts, there's the $44 USD N-73A: Blocked
-Gnobuddy
I will revise my estimate to 80VA. The 100VA part is fine.
No, Prather's books are not about an English detective. He is known for the 'Shell Scott' books, a smart-mouth Los Angeles dick. But Pattern for Panic is not originally a Scott, but a one-off set among Mexican bad-guys (I'll avoid the heavy political overtones). Anyway, they get film of the General's wife, naked, and are about to show it on the Filmosound Model 385. The book has a detailed description: '...all the gadgets. Switches to start, stop, or reverse the film, a switch for showing single frames'...
No, Prather's books are not about an English detective. He is known for the 'Shell Scott' books, a smart-mouth Los Angeles dick. But Pattern for Panic is not originally a Scott, but a one-off set among Mexican bad-guys (I'll avoid the heavy political overtones). Anyway, they get film of the General's wife, naked, and are about to show it on the Filmosound Model 385. The book has a detailed description: '...all the gadgets. Switches to start, stop, or reverse the film, a switch for showing single frames'...
I say Holmes! Mexican bad guys and naked women? Should we call Scotland Yard? On the contrary my Dear Watson. There is nothing illegal going on there.
It's good to have a bit of banter now and then. Some people take life far to seriously. Us Limeys do come across as being a bit pompous sometimes but that isn't the case with me. Though I do like Sherlock Holmes. I didn't mean to come across that way. I had just come back from a gig, tired and still in full banter mode from the band mates.
On a more serious note, I have taken on board what you said and you are indeed correct. I have seen some of your posts on here and you are clearly a very knowledgeable person. The most important thing is to get it right and I have got things right from people sharing their knowledge with me as I have shared my musical knowledge with others.
You stay safe and take care because it's not good out there. Whilst I don't do panic I do have a problem dealing with loosing good people and I have lost far to many these past two years and it won't do Holmes. It just won't do.
It's good to have a bit of banter now and then. Some people take life far to seriously. Us Limeys do come across as being a bit pompous sometimes but that isn't the case with me. Though I do like Sherlock Holmes. I didn't mean to come across that way. I had just come back from a gig, tired and still in full banter mode from the band mates.
On a more serious note, I have taken on board what you said and you are indeed correct. I have seen some of your posts on here and you are clearly a very knowledgeable person. The most important thing is to get it right and I have got things right from people sharing their knowledge with me as I have shared my musical knowledge with others.
You stay safe and take care because it's not good out there. Whilst I don't do panic I do have a problem dealing with loosing good people and I have lost far to many these past two years and it won't do Holmes. It just won't do.
I did once see a statement that B&H overcame the 110/240V problem using what was in effect an early form of SMPS. If that is really true then there will be a transformer in there, just not as big as you would expect. @nglcom, have you been able to disentangle the circuit enough to figure out how the power supply works?
Hello Gnobuddy. I will pop the insulation gloves on when I test it. I have a watt meter to test the draw. Thank you for the heads up on the transformers. I will have a look at them.
Hello wg_Ski
I had thought about that too. I should really get one for test purposes. Thank you.
Perfect, as they say in these parts.
I'm glad to hear from another person who actually uses insulating gloves to work on dangerously high voltages. On more than one tube / valve forum, I've advocated for the use of electrician's insulating gloves, safety goggles, and maybe a leather welder's apron (in case a "live" chassis falls onto your chest or into your lap!)
Somewhat to my surprise, none of those threads ever gained any traction. I got the impression some respondents were actually offended at the idea that our grandparent's rather primitive safety measures ("only use one hand") could be improved upon.
High-voltage machismo. Who knew.
I hear you on the loss of too many people. It's been a huge emotional weight on me, to the point where I couldn't find any joy in DIY electronics for most of the last eighteen months.
-Gnobuddy
I just found a three-part article about fixing up and converting a Bell & Howell 621 Filmosound projector into a guitar amplifier, on Guitar.com.
It's not exactly the same model as yours, but maybe it will be useful to you.
Part 1: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part One) | Guitar.com | All Things Guitar
Part 2: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part Two)
Part 3: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part Three)
-Gnobuddy
It's not exactly the same model as yours, but maybe it will be useful to you.
Part 1: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part One) | Guitar.com | All Things Guitar
Part 2: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part Two)
Part 3: DIY Workshop: Bell & Howell Filmosound Amp Conversion (Part Three)
-Gnobuddy
I used that article for a Filmosound 179 conversion (very similar to the 621) and found it very useful.
Attached is the schematic that I used from another forum site, which I adapted to use with 5Z4, 6SL7, 6SJ7 and a pair of JJ 6V6 all power with a Hammond 290BEX transformer.
I also found a decent source of information on the various B&H amps, so have a gander and see if your 626 is among them.
Attached is the schematic that I used from another forum site, which I adapted to use with 5Z4, 6SL7, 6SJ7 and a pair of JJ 6V6 all power with a Hammond 290BEX transformer.
I also found a decent source of information on the various B&H amps, so have a gander and see if your 626 is among them.
Attachments
I made that schematic a few years ago. The amp and cabinet actually has been sitting on a shelf for a few years now. I should go fire it up and make sure it still works. After a few years i often ask myself "why did you do that", this one is probably going to be why did i use 400v caps for the bias and if my voltages are so much higher than stock, are the filament voltages ok? I often use a .22 ohm or whatever is required in the filament strings to bring it down to 6.3vac, i may have done that but not updated the schematic. Some of these octals often are microphonic and don't show that until the amps is on for a hour. I think there are mil spec tubes of the 6sl7, 6sn7,6sj7 (red painted) i picked up at a few antique radio shows which should be a lot quieter.
EDIT: i do have a old prewar Supro i may have copied some parts from(except it had a 80 rectifier). I do remember the grid cap 6J7, and the pentode front end. Also think the underside of the amp was pretty tight and packed with wire and components, probably get cursed at in 30 years if someone else ever has to work on it. I should hook it up to a EVM12L to hear it without speaker coloration.
EDIT: i do have a old prewar Supro i may have copied some parts from(except it had a 80 rectifier). I do remember the grid cap 6J7, and the pentode front end. Also think the underside of the amp was pretty tight and packed with wire and components, probably get cursed at in 30 years if someone else ever has to work on it. I should hook it up to a EVM12L to hear it without speaker coloration.
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