Machine in shed for 15yrs - 1/4" audio tape PR99 Revox

[carolmaille]

Hello again. I have recently collected some machines from a terrace shed. They are analogue audio. One is an oscilloscope. All seem to have lights on to begin with, but I just put them on for a few seconds. The Revox PR99 1/4" tape machine was once a good machine I bought it from a redundant plant:
On the back next to the socket I lowered the power to 140V from 220 and switched it on; the LED display came on the Record light came on - then it all went off: The fuse on the machine seems to have blown
So - would this be because something went short circuit after switching it on for so long ? Would it be a capacitor but that would go open circuit ? So do you have any ideas of why this happens or/and of how to proceed please ?
With the oscilloscope I read to switch it on progressively for longer times while leaving it for 30 min in between ? Many thanks for suggestions, Have a good day Carol

 

[Tony Stewart]

I grew to enjoy electronics in the 60's with my vacuum tube tape recorder, modifying it as conference phone and also an electric guitar or violin amp. Then I had a ssssSony and many others before the VCR could be used to store hours of high quality digital audio.

 

[liamjerr]

If you've applied massively too much voltage (as it seems you have) the most common problem is just blowing the mains fuse, however, if you're unlucky (or the fuse has been replaced by a nail?) the transformer will blow. Parts on the secondary (bridge rectifier, capacitors etc.) have a fairly low probability of being damaged.

As you're presumably in Europe? (although it looks like you're using a VPN) then why did you turn it down to 140V?.

OK, I've downloaded the service manual, it looks a really nice machine - the mains fuse is on the back panel, so no need to take anything to pieces - just take the fuse out and check it. As 230V uses a smaller fuse than 120V, it's hopefully blown before any damage was done. I would suggest checking the fuse, replacing it with the correct type, making quadruply sure it's set to the correct mains voltage! - and try it again.

If the mains transformer has blown, you're pretty well stuffed, it's a very complicated multi-winding transformer, and even if available would cost a fortune.

Don't get too worried about capacitors, it's a 'relatively' new machine, all transistors and IC's - it's the old valve equipment where you tend to need to reform the electrolytics.

It's a nice looking machine, and odds are replacing the fuse (and checking the voltage setting yet again) will restore operation - mechanically it could be a different story, as belts, pulleys and pinch rollers machine embroidery deteriorate over time and lack of use.

Yes i have notice it is just the fuse