Welcome to Audiokarma, Dave. I gather your ASC deck is one of those radio-oriented machines intended to be operated from a mixing console, without any form of level control, no pots, no vu-meters, right? In order to make a standard PR99 out of this machine you would need to change the lower front plate, the motherboard, and possibly a good deal of the internal wiring, and add all the missing knobs. As a first step you would need to buy those parts, and that would not necessarily be less expensive than a working PR99. You would probably be better off by finding a good mixer to use it with, or just using this deck as a player (no levels to set in this case). Another obvious option is to sell it and use the money to buy a standard PR99. Also, many ASC Revoxes are mono, but I guess you have already checked this.
As for the refurbishing job (assuming you choose not to sell it), yes, you can just change a few capacitors if you have skills. However these particular radio machines were usually operated 24/7 and the Rifas rarely need replacement since they were shorted all the time, thus didn't see any voltage, and thus never had a chance to suffer. A quick visual check will tell you the condition: a Rifa that needs changing is heavily scattered with cracks, it's only when those cracks become deep enough to let the air reach the internals that the dielectric dies in a puff of smoke. Almost all the Revoxes that I've opened were used this way and had perfect, or close to perfect, Rifas. Other than that, the caps that tend to not age well are the motor caps (aluminium cylinders screwed to the chassis), and all the chemicals and tantalums. Don't change the others: not only don't they change with time, they are critical to the performances so you have nothing to gain but problems by replacing them. In fact, as soon as you open a Revox you expose yourself to a bunch of problems, especially with the aging trimmers (more on this below), so it's not necessarily a good idea to do anything in the first place.
On the other hand, if you want to have a PR99 running at its full potential, it's a good idea to make a full overhaul, which doesn't mean just changing a few capacitors but also the trimmers (those that they used in Revoxes fail much more often than the caps: the wiper becomes brittle and breaks like glass by just looking at it - so they are your #1 priority for any overhaul on a Revox), the motor and tape path bearings, the pinch roller, quite possibly the heads (you didn't mention the conditions of yours), cleaning everything, lubricating the capstan motor (use PDP65 only, please!), checking everything (you'd be surprised by how many diodes and transistors I had to change on Revoxes) and completely recalibrating the deck with a proper calibration tape. Anything short of this is a waste of your time, and likely to cause more problems than you can solve. Needless to say, this is both very time-consuming and fairly expensive. Whether or not you should engage into this depends widely on your motivation, technical skills, and equipment. But if you are able to properly carry out such an overhaul, you will be rewarded by performances that very (I mean, VERY!!!) few of those machines can offer in their current condition.
Welcome to Audiokarma, Dave. I gather your ASC deck is one of those radio-oriented machines intended to be operated from a mixing console, without any form of level control, no pots, no vu-meters, right? In order to make a standard PR99 out of this machine you would need to change the lower front plate, the motherboard, and possibly a good deal of the internal wiring, and add all the missing knobs. As a first step you would need to buy those parts, and that would not necessarily be less expensive than a working PR99. You would probably be better off by finding a good mixer to use it with, or just using this deck as a player (no levels to set in this case). Another obvious option is to sell it and use the money to buy a standard PR99. Also, many ASC Revoxes are mono, but I guess you have already checked this.
As for the refurbishing job (assuming you choose not to sell it), yes, you can just change a few capacitors if you have skills. However these particular radio machines were usually operated 24/7 and the Rifas rarely need replacement since they were shorted all the time, thus didn't see any voltage, and thus never had a chance to suffer. A quick visual check will tell you the condition: a Rifa that needs changing is heavily scattered with cracks, it's only when those cracks become deep enough to let the air reach the internals that the dielectric dies in a puff of smoke. Almost all the Revoxes that I've opened were used this way and had perfect, or close to perfect, Rifas. Other than that, the caps that tend to not age well are the motor caps (aluminium cylinders screwed to the chassis), and all the chemicals and tantalums. Don't change the others: not only don't they change with time, they are critical to the performances so you have nothing to gain but problems by replacing them. In fact, as soon as you open a Revox you expose yourself to a bunch of problems, especially with the aging trimmers (more on this below), so it's not necessarily a good idea to do anything in the first place.
On the other hand, if you want to have a PR99 running at its full potential, it's a good idea to make a full overhaul, which doesn't mean just changing a few capacitors but also the trimmers (those that they used in Revoxes fail much more often than the caps: the wiper becomes brittle and breaks like glass by just looking at it - so they are your #1 priority for any overhaul on a Revox), the motor and tape path bearings, the pinch roller, quite possibly the heads (you didn't mention the conditions of yours), cleaning everything, lubricating the capstan motor (use PDP65 only, please!), checking everything (you'd be surprised by how many diodes and transistors I had to change on Revoxes) and completely recalibrating the deck with a proper calibration tape. Anything short of this is a waste of your time, and likely to cause more problems than you can solve. Needless to say, this is both very time-consuming and fairly expensive. Whether or not you should engage into this depends widely on your motivation, technical skills, and equipment. But if you are able to properly carry out such an overhaul, you will be rewarded by performances that very (I mean, VERY!!!) few of those machines can offer in their current condition.
Hi JLB2
thanks for your reply, you are correct the machine was a radio studio job but although there are no input controls there are twin VU`s. There are a few tiny cracks on the rifa`s so will probably change them, What are your thoughts on the motor caps? i have seen the plastic ones for sale but read somewhere that they are indented for washing machines etc, is this an issue?
cheers
Dave