----------
Digi-Beta DVW-500 series.
Pretty reliable so far as long as you keep them clean. Wipe over the drum and guides using a lint free cloth with a little isopropyl alcohol on it. Scrub the pinch roller and capstan with the same materials. If the pinch roller shows signs of cracking or developing a ring around it after cleaning, change it. Oh, and remember to replace the little paper-disk filter on the top of the head drum assembly.
----------
Several common points of failure have shown up so far.
The first causes high errors and leads the hapless engineer to assume that the heads are worn out. Before changing the heads, give the chips along the top edge of the EQ45 board a dose of freezer spray. If the errors go away, you've got galloping chip-rot.
If you have more than one machine, you can swap the EQ45 boards and see if the high-errors problem stays with the board or the machine. It's a bit fiddly because of all the cables but it's better than doing an unnecessary head change!
The early chips (IC401,501,601,701) have plastic tops and no heat-transferring material between the chip and its top. Sony did stick a nice heatsink on the top but it only cools the plastic! The chips tend to run hot, especially if you block the vent holes in the top cover, and they die.
The new chips have nice golden metal tops and run cooler but they cost £100 each and are a pig to change.
Another way to solve the problem is to fit the new version of equaliser board, it costs close-on £1000 and the machine needs a software upgrade. They do run much cooler though, so should be more reliable.
----------
The second common fault I call "mad panel syndrome".
Various erroneous indications are given by affected front panels. The record light comes on and scares the s**t out of you, two lights illuminate when only one should, timecode display is corrupted etc. etc. Although this is usually just an indication problem, serious cases can also affect the operation of the machine.
The faults are caused by some sort of corrosive material emenating from the rubber holders supporting the LEDs behind the panel. This rots through the circuit tracks and plated-through holes beneath.
The cure is to remove all the LEDs, clean and repair the circuit tracks underneath them and replace with new LED holders. You can re-use the old ones if you're sure they won't release any more nasty stuff. I give them a coat of silicone grease to seal them.
----------
Now that these machines are 10 years old a further problem is showing its head; the dreaded leaking electrolytics fault!
Despite the general good quality of Sony's Cs, some of the small dark blue radial electrolytics have started to deposit a nasty black gunge around their legs. This gunk is conductive and corrosive, not a good thing to have on your expensive panels!
I've recently had two instances of this, one caused the FM demodulator to stop working (for analogue audio track 3) and the other caused a fire! The conductive goo had shorted across the legs of the C, in the fist case upsetting the bias of the demodulator by presenting a resistance of 60 Ohms to earth. In the second case the C in question was a decoupler next to an 8V regulator and the whole force of the PSU was dissipated through the low resistance gunge causing the board to burn up. Fixable but messy.
The Cs were a 10uF and a 47uF so there isn't a particular value to look out for I'm afraid. It is very difficult to see the problem from above the C so inspection to prevent future damage may be a waste of effort but if you do come across a board fault, suspect the electrolytics..
----------
Mechanical mayhem.
The DVW 500 series are now also starting to suffer from "sticky-lever" problems, like the BVW series below. If your tape comes out with a loop hanging out of the shell, or won't unthread, check them as for the '75 series.
Cassette up/down compartments can lose the plastic end pieces from the sliders inside. These then get into the works and jam the brakes, reel tables etc. Glue them back on if you can find them.
----------
BVW 60/65, 70/75 series.
These have been around for ages and loads of problems have been identified. Below are the most common ones.
----------
"Error 09"
Caused by the threading ring failing to move when required, usually leaving your precious tape stuck in the works.
First change the little belt on the gearbox to the right of the threading ring, it goes slack with age...
If there are still problems; lube the threading ring lightly where it touches the rollers, align the back roller so the ring is held reasonably firmly and can't wobble about. Then change the gearbox assembly.
If unthreading fails after the ring has partially unlaced, it's probably a worn idler roller which operates the levers and cams just in front of the gearbox. If the lever doesn't clear the ring in time it will jam causing error 09.
----------
"Error 20"
Cassette load timeout error. It's either a problem with the "cassette up" mechanism (check belts etc.) or the reel tables not moving between large and small tape sizes (lube and adjust). Also sometimes due to foreign bodies in the machine, Post-Its are a favourite!
----------
Various fluctuating luma or chroma levels.
Almost always caused by one of the block filter units on the DM56, TBC7, DEC42, EN48 etc. boards. The machine is full of them, rectangular tin cans with the part number usefully printed on the top. Treat with great suspicion!
----------
"Sticky lever syndrome"
This causes tapes to be mangled in various ways, usually at the most inconvenient time. Gives a "reel trouble" error (as in, "you're in reel trouble now!").
With the machine switched off and the cassette-up compartment removed, check the freeness of movement of all the levers and cams to the front and right of the threading ring. If any of them don't spring back with enthusiasm when released, they need to be freed up. This includes the pinch roller.
Hint. Rotate the gearbox motor pulley a few times by hand so that the threading ring turns about 20 degrees. This will give most levers room to move.
Any sticky levers should be removed, cleaned, lubed and re-fitted. If you just don't have the time or inclination, it's usually possible to free them by trickling a small quantity of very light oil (WD40 is good) down the bearing shaft of the suspect lever whilst waggling it back and forth. Be very careful not to get any oil on the tape path!
In serious cases you can free a reluctant lever by heating the bearing with a soldering iron. Usually this melts the grease and further waggling will allow you to get it off. Be very careful that you don't damage any plastic parts with the iron!
----------
Bad RF, as in "bearding" and chroma flashing.
Usually a sign of the heads being on the way out but it's worth just checking the RF levels. When heads wear down they actually become more efficient at putting a signal onto the tape and so need less record drive. This is shortly before they suddenly become a lot LESS efficient when they wear out completely!
Back off the record current slightly and see if that helps. Then order a new drum assembly for when the inevitable happens...
----------
A "don't quote me on this" production. (c) Dave Pick 2009.