Fostex PD2 Service Report

The Fostex PD2: Are They Still Serviceable?

by Steve George

We still get requests to repair the venerable PD-2, and although we will take them in for repair, we try to first inform the customer that such a task is never as straightforward as it first seems.

Lack of Replacement Parts

First of all, there is the lack of replacement parts. As there are little or no parts available from Fostex, component-level repair is really the only way to repair a failed board. This means that labor costs for the repair are going to be much higher than if we could just pop in a new PC board.

Age and Heat

Secondly, age and heat takes its toll. As PD-2 owners already know, the PD-2 gets quite hot under normal use. In fact, it’s this heat damage that contributes to many of the failures. Of all the gear we service, the PD-2 is by far the “oldest” with regard to solder and component aging. Aside from water damage corrosion, nothing reduces the lifespan of an electronics circuit faster than long term overheating.

On the PD-2, even some mechanical parts are affected. The most common is the reel brake pads migrating out of position as the heat causes the self-adhesive glue to liquefy. (We clean ‘em and Epoxy them back on so they’re good for the remaining life of the machine).

During its lifespan, all the parts under the PD-2 hood have been subjected to heat induced rapid aging at the same rate. Any deviations in value of the components have pretty much occurred across the board so for years of operation, all is well. Longer term, however, the oil-filled electrolytic capacitors start to boil out their caustic contents onto the printed circuit board and failures start.

The Domino Effect

Now, let’s say that during a repair we introduce a brand new component to this finely cured mix, and now a different value is in the circuit (as this component as yet has no age deviation). This strong, young component could actually cause problems in the circuit it now resides, as it alone is capable of operating at rated capacity. Oftentimes complete recalibration of a circuit’s function is required after a single component replacement, and this starts a Domino Effect that requires further adjustments of values down the line. Some replacement parts induce such a change to the calibration that the adjustments no longer have enough range to compensate!

I can honestly say that in at least half of the PD-2 repairs we perform, the unit’s symptoms get worse during the repair procedure! It’s like opening Pandora’s box!

For example, a common PD-2 problem is high PCM Error rates in both Playback and Record after warm up. Symptoms are easily duplicated on the bench with no other apparent problems. Inspection of the unit finds several blown capacitors on the Transport Controller board. These are replaced, the PCM’s are great, but now the PD-2 randomly loads and unloads the Transport tape guides even though there’s no tape installed (when power is first applied). Further troubleshooting finds that several more leaky caps are on the Transport Controller, but their flaws were totally benign until those first capacitors were replaced! Even worse is that sometimes the secondary symptoms mentioned above may take weeks to manifest! This means you’ve already gotten it back and could lose hours on location and have at least one more trip to the shop to contend with! (Believe me, it’s frustrating for us, too.)

Leave it on

We test repair PD-2 units for at least a full day before returning the machine to the customer, but not all heat damage shows up right away.

We have several PD-2’s in our shop for use as parts machines, but as these are just as old as the units needing service, we often have to replace the leaky capacitors on the replacement boards before they can be installed.

So, you can see that there is some hope for the PD-2, but not without its own set of problems. The decision to have your old warhorse repaired rests with you, but the benefits may barely justify the means. Be prepared for high labor costs to get you there.

A word of advice to anyone who gets their PD-2 serviced or buys a used one: upon receipt, power it up and leave it on for a full day minimum. During this time, randomly test for both playback and record PCM Errors with different tapes, listen to the Phones monitoring and phantom-powered mic inputs, and see how it behaves during cycling of the Power Switch. If it’s going to be a lemon, it’ll most likely fail after it’s been on for several hours. If it runs fine for a full day, you’re probably good to go.


The Fostex PD2: Are They Still Serviceable?
by Steve George
We still get requests to repair the venerable PD-2, and although we will take them in for repair, we try to first inform the customer that such a task is never as straightforward as it first seems. Lack of Replacement Parts First of all, there is the lack of replacement parts. As there are little or no parts available from Fostex, component-level repair is really the only way to repair a failed board. This means that labor costs for the repair are going to be much higher than if we could just pop in a new PC board. Age and Heat Secondly, age and heat takes its toll. As PD-2 owners already know, the PD-2 gets quite hot under normal use. In fact, it’s this heat damage that contributes to many of the failures. Of all the gear we service, the PD-2 is by far the “oldest” with regard to solder and component aging. Aside from water damage corrosion, nothing reduces the lifespan of an electronics circuit faster than long term overheating. On the PD-2, even some mechanical parts are affected. The most common is the reel brake pads migrating out of position as the heat causes the self-adhesive glue to liquefy. (We clean ‘em and Epoxy them back on so they’re good for the remaining life of the machine). During its lifespan, all the parts under the PD-2 hood have been subjected to heat induced rapid aging at the same rate. Any deviations in value of the components have pretty much occurred across the board so for years of operation, all is well. Longer term, however, the oil-filled electrolytic capacitors start to boil out their caustic contents onto the printed circuit board and failures start. The Domino Effect Now, let’s say that during a repair we introduce a brand new component to this finely cured mix, and now a different value is in the circuit (as this component as yet has no age deviation). This strong, young component could actually cause problems in the circuit it now resides, as it alone is capable of operating at rated capacity. Oftentimes complete recalibration of a circuit’s function is required after a single component replacement, and this starts a Domino Effect that requires further adjustments of values down the line. Some replacement parts induce such a change to the calibration that the adjustments no longer have enough range to compensate! I can honestly say that in at least half of the PD-2 repairs we perform, the unit’s symptoms get worse during the repair procedure! It’s like opening Pandora’s box! For example, a common PD-2 problem is high PCM Error rates in both Playback and Record after warm up. Symptoms are easily duplicated on the bench with no other apparent problems. Inspection of the unit finds several blown capacitors on the Transport Controller board. These are replaced, the PCM’s are great, but now the PD-2 randomly loads and unloads the Transport tape guides even though there’s no tape installed (when power is first applied). Further troubleshooting finds that several more leaky caps are on the Transport Controller, but their flaws were totally benign until those first capacitors were replaced! Even worse is that sometimes the secondary symptoms mentioned above may take weeks to manifest! This means you’ve already gotten it back and could lose hours on location and have at least one more trip to the shop to contend with! (Believe me, it’s frustrating for us, too.) Leave it on We test repair PD-2 units for at least a full day before returning the machine to the customer, but not all heat damage shows up right away. We have several PD-2’s in our shop for use as parts machines, but as these are just as old as the units needing service, we often have to replace the leaky capacitors on the replacement boards before they can be installed. So, you can see that there is some hope for the PD-2, but not without its own set of problems. The decision to have your old warhorse repaired rests with you, but the benefits may barely justify the means. Be prepared for high labor costs to get you there. A word of advice to anyone who gets their PD-2 serviced or buys a used one: upon receipt, power it up and leave it on for a full day minimum. During this time, randomly test for both playback and record PCM Errors with different tapes, listen to the Phones monitoring and phantom-powered mic inputs, and see how it behaves during cycling of the Power Switch. If it’s going to be a lemon, it’ll most likely fail after it’s been on for several hours. If it runs fine for a full day, you’re probably good to go.