Latest Mend It Mark video

[agardiner]

https://www.youtube.com/watch?v=NeRfJrpvB74

An interesting watch and only Part 1. There is no way Mark could have tackled this Revox 4 track reel to reel without the service manual, as someone had been fiddling! Great watch as always.

[Radio Wrangler]

He doesn't finish this one, there will be a part 2 which might be delayed by a shift to new premises. No cliff-hanger.

David

[lesmw0sec]

Hmm. A much more complicated machine than the old A77. I wonder if it sounds any better.

[Radio Wrangler]

Possibly not much, though it is a 7.5/15 ips one. It has a less easily fixable look to it, and parts won't be so common. Mark getting a pinch wheel tyre was interesting.

It does have closed-loop tension control which is a useful improvement on the A77.

Both big phase shift capacitors for the motors were left alone as they measured OK. With a 3 phase drive to the capstan, it won't need a phasing capacitor, so those there are for the spool motors. Wonder why one had Rifas tagged across it? Mark would have spotted if it wasn't in the manual....

David

[lesmw0sec]

I converted mine to 7.5/15, there was a substitute spindle available quite cheaply at the time. It always impressed me how easy they were to get at - just take the back screws off and shake the works out on to the bench. I was wondering about that cap as well...

[Kentode]

Originally Posted by lesmw0sec

just take the back screws off and shake the woks out on to the bench.

Thank you, that's the best thing I've read today!
But, £30 for a capstan tire? Yikes!
Mark is one of the best on t'web...

[jamesperrett]

I must admit that I got nearly 4 minutes into the video and gave up. He made so many rookie mistakes with a machine like this and seemed to take delight in being ignorant of all the features that this machine offers. I'm a bit surprised because usually he's pretty good.

What is he doing try to play an Ampex tape? It will make a big mess of the machine unless he has taken the precaution of baking it first. Why is he so amazed that the take up reel spins in the forward direction whichever mode he selects (all Revoxes do this AFAIK)? Plus, white leader tape isn't always opaque enough to prevent the auto stop from working. It is also obvious what the 7.5 means to anyone who knows reel to reels.

Maybe it gets better but I didn't stick around to find out...

[Radio Wrangler]

He's obviously not experienced with open-reel tape machines, and was feeling his way around. There is a lot of general knowledge on servicing Revox mechanisms available for a little searching, and people on here prepared to impart, if asked. He was surprised by a non-rotating guide and wasn't aware as their use as dampers. As you said, he wasn't aware of how back-tension is done and that the motors can only create torque in one direction. Whenever tape is moving in either direction, the spool it is moving from gets gentle torque opposing that motion. Doing it this way avoids wear on brakes or clutches. It all makes sense once you know. He might be OK on consumer level machines with loads of spinning idler wheels, slipping clutches and drag from brakes.

He's simply not had any exposure to three-motor decks.

I'd have had a scope on the heads fairly early on to see if it was worth continuing.

David

[Sideband]

Mark is a brilliant engineer but can't be experienced in everything! It's unlikely he's had many, if any, r to r's in since he's been running his repair service. Look at the stuff he HAS repaired.....many things of which a lot of us would have turned away.

Most of the experienced engineers on here are a lot older than Mark and have worked on r to r's when they were common (including myself) and understand about back-tension etc.

I eagerly await the next instalment when I have no doubt the Revox will be repaired and it's operation will become obvious to Mark and will be another chapter in the book of experience!

[McMurdo]

Sometimes experienced career-youtubers make mistakes on purpose as they attract a glut of corrections in the comments, pushing the video up the ratings

[jamesperrett]

Originally Posted by Sideband

Mark is a brilliant engineer but can't be experienced in everything! It's unlikely he's had many, if any, r to r's in since he's been running his repair service. Look at the stuff he HAS repaired.....many things of which a lot of us would have turned away.

I've enjoyed the other videos that I've seen of his and would find them useful if I had to dive into something that he has looked at. I guess I'm a bit fed up with all the other ignorance on some of the open reel and recording forums and feel that we don't need more misinformation from a normally reliable source.

I'm grateful for all the good knowledge that we have here.