National NV-850-A Hi-Fi Stereo VCR (1984 Model)

[derek92994]

That is very unusual for a transformer...

Maybe those higher voltage caps? I don't see it as a problem, as I will be running the unit with the top off at all times, may even throw a fan near the transformer.

 

[derek92994]

Not surprised, these units ran very hot even when stock.

Ok I've elevated it and put a big ass fan at the back blowing air up through the Power supply section. Some air comes out the front from underneath out the front too so good air flow all round. The unit is functioning better than my previous one even when it was only 5 years old.

 

[derek92994]

Any other ideas on why the transformer would get that hot? I'd say its around 75c.

 

[derek92994]

Down to 50-60c now with cool air blowing over the top.

 

[laatsch55]

They get warm when they are loaded up. I think that dome phase issues can cause heat but Joe would know for sure.

 

[Gepetto]

Any other ideas on why the transformer would get that hot? I'd say its around 75c.

Several ideas why:

Cheap transformer with lots of eddy, core and winding losses
Saturation, are you running a transformer at 50Hz that was only designed for 60 Hz?
Are you running it at the wrong input voltage than what it was designed for?

 

[derek92994]

They get warm when they are loaded up. I think that dome phase issues can cause heat but Joe would know for sure.

Well the machine was working at its hardest (recording) and I got the temp down enough to be comfortable with it. I will idle the machine for the rest of the day as I am done recording for now. Just checked the start and finish of the recording and its fine, did around 2 hours. I'll turn it off when I'm not in the house though just to be safe. Will check temp after an hour of idling. I also have to touch up the solder on those diodes tomorrow.

 

[derek92994]

Several ideas why:

Cheap transformer with lots of eddy, core and winding losses
Saturation, are you running a transformer at 50Hz that was only designed for 60 Hz?
Are you running it at the wrong input voltage than what it was designed for?

Nope it is running at what its supposed to. Hz and Voltage. Back says 240 volt - 50-60hz - 41 Watts

 

[derek92994]

Cooled down real quick after recording stopped, running with power on at idle now.

 

[Gepetto]

Cooled down real quick after recording stopped, running with power on at idle now.

You are not running it on one of those crappy UPSes are you?

 

[derek92994]

You are not running it on one of those crappy UPSes are you?

Both my UPS died a week or two ago, batteries only last 3-4 years, they are also full sine wave. I'm running surge protection only now.

 

[Gepetto]

Both my UPS died a week or two ago, batteries only last 3-4 years, they are also full sine wave. I'm running surge protection only now.

I don't care what the UPS maker advertises, unless you pay a lot, the UPSes are piecewise linear sine wave approximation units at best. The only thing I run on UPSes are line operated switching PSU's with PFC inputs on them because they don't care what you give them. On the other hand, 50-60 Hz transformers care a lot about the input being a real sine wave. We see data center class UPSes with crest factors as low as 1.1 from time to time...ouch!!

 

[derek92994]

I don't care what the UPS maker advertises, unless you pay a lot, the UPSes are piecewise linear sine wave approximation units at best. The only thing I run on UPSes are line operated switching PSU's with PFC inputs on them because they don't care what you give them. On the other hand, 50-60 Hz transformers care a lot about the input being a real sine wave. We see data center class UPSes with crest factors as low as 1.1 from time to time...ouch!!

So you're saying its best to stick to UPS only with computers and leave the audio gear off them?

 

[Gepetto]

So you're saying its best to stick to UPS only with computers and leave the audio gear off them?

Absolutely, I never run any audio gear on a UPS.

 

[derek92994]

Absolutely, I never run any audio gear on a UPS.

I'll take your advice. I have been running all my audio gear through UPSes for about 4 years except the amplifiers, without any issues at all. Its more to save the gear from fast off/on black/brownouts. Turntables, Cassette decks, reel to reels, cd players, eqs, vhs/beta machines, even an old CRT TV, no issues ever.

Could there have been stuff going on that I didn't know about that may cause problems if I continue to run them through UPS when batteries are replaced?

 

[Gepetto]

I'll take your advice. I have been running all my audio gear through UPSes for about 4 years except the amplifiers, without any issues at all. Its more to save the gear from fast off/on black/brownouts. Turntables, Cassette decks, reel to reels, cd players, eqs, vhs/beta machines, even an old CRT TV, no issues ever.

Could there have been stuff going on that I didn't know about that may cause problems if I continue to run them through UPS when batteries are replaced?

I don't, UPSes are for computer data not for music. In normal cases they are just pass through devices anyway, unless the power fails. Consumer grade UPSes are not double conversion types so you get no isolation benefits.

In my main system I run a Topaz 2.5KVA ultra-isolation transformer with Faraday shield which outputs balanced power. It does not alter the input power characteristics except to shunt off trash on the line. In the lab, I run straight AC.

 

[BlazeES]

In my main system I run a Topaz 2.5KVA ultra-isolation transformer with Faraday shield which outputs balanced power. It does not alter the input power characteristics except to shunt off trash on the line. In the lab, I run straight AC.

Something that looks similar to this ?

 

[Gepetto]

Something that looks similar to this ?

View attachment 18990

Yes, very good item. Can find them on Craigslist inexpensively.

 

[derek92994]

Here are the specs of my high end UPS - APC Smart UPS SUA1500I

Output Power Capacity
980 Watts / 1500 VA

Max Configurable Power
980 Watts / 1500 VA

Nominal Output Voltage
230V

Output Voltage Note
Configurable for 220 : 230 or 240 nominal output voltage

Output Voltage Distortion
Less than 5% at full load

Output Frequency (sync to mains)
47 - 53 Hz for 50 Hz nominal, 57 - 63 Hz for 60 Hz nominal

Topology
Line Interactive

Waveform Type
Sine wave

Surge energy rating 480 Joules

Filtering: Full time multi-pole noise filtering : 0.3% IEEE surge let-through : zero clamping response time : meets UL 1449

 

[Gepetto]

Here are the specs of my high end UPS - APC Smart UPS SUA1500I

Output Power Capacity
980 Watts / 1500 VA

Max Configurable Power
980 Watts / 1500 VA

Nominal Output Voltage
230V

Output Voltage Note
Configurable for 220 : 230 or 240 nominal output voltage

Output Voltage Distortion
Less than 5% at full load

Output Frequency (sync to mains)
47 - 53 Hz for 50 Hz nominal, 57 - 63 Hz for 60 Hz nominal

Topology
Line Interactive

Waveform Type
Sine wave

Surge energy rating 480 Joules

Filtering: Full time multi-pole noise filtering : 0.3% IEEE surge let-through : zero clamping response time : meets UL 1449

That is the same one I have on my computer system.