488mkII Phantom Power cable

[DamienC]

I have a 488mkII that I'm in the process of attempting to repair. Long story short, it was in working order then improperly put into storage, and now it has a ton of blown caps and needs a new belt. But I have the maintenance manual and can solder/desolder so I'm okay with all that work.

One other issue the unit has is that cable P3, the one that supplies +48v phantom power, was partially severed. I could make a cable myself, but I'd much rather replace it with something genuine if I can rather than desoldering the existing jacks.

Anyone know where I can source one, and if not, what type of cable I should use?

 

[SkywaveTDR]

Product that use special cables are a pain. The DC going through a Phantom is DC so it is very basic so use whatever you can find. The use of a standard hunk of wire will most likely be fine.
When dealing with heads leads and erase head wires is an entirely different situation.
If you need ribbon cable there was a lot of that used for floppy drives in the olden days. just get one and cut the number of conductors off of it as needed. Even 22 or 24 gauge stranded wire twisted of contained in a heat shrink would be just as good. no need to go looking for a special part like that- repair people would not and I am one of them.
Who blew up that many caps and how did you see them blown up- you mean physically? I would be worried that there will be other damage when people treat machines like this.

 

[DamienC]

Good to know I can pretty much use what I have. I wasn't looking forward to trying to source an original part and I can build a cable easily enough. I will NOT cannibalize a floppy ribbon cable however; I also have an affinity for vintage PCs and those are hard to come by.

Well as for the caps... I guess it's story time. I have had multiple Tascam multitracks and other recording equipment and I like to think I treat them pretty well. I moved into an old victorian back in 2013 and didn't have time for anything music for a few years. Without thinking, I stored the 488mkII in an attic crawlspace for probably two years, not taking into account the extreme temperatures the machine would experience at both the high and low ends. In addition, my attic became infested with bats. Getting rid of the bats was a task in and of itself, but then I removed my poor 488 and when I check it out it didn't power on. Obviously this was my own blunder and a serious regret. Since then, I've had two kids and several job transfers so I haven't had time to repair it, and in the meantime I also had a regular 488 that worked just fine and also a digital DP-008EX unit that I could use for recording.

Now with covid and having nowhere to go and nothing to do, I decided it would be a fun project to try and revive this thing. When I first rescued it from the attic I didn't notice any obvious blown caps, so I wrote that off as being an issue. I honestly thought it was something with the power transformer, but after checking it out it wasn't shorted at the primary and it was outputting the proper voltages. Then I got a bright LED light and looked a little closer inside, and I realized that most of the larger caps had ruptured from the bottom (I was previously only looking for ruptures and bulges at the top of the caps), and the material that leaked out was somewhat transparent and blended in very well with the PCB color. Every large cap on the Power PCB looked like it was affected, as well as the C12 cap on the Control PCB.

I couldn't see any other damaged caps or components, and I stared at each of the boards for quite a bit of time. I'm fairly confident that after replacing the caps I can get the unit to at least power on.

 

[SkywaveTDR]

Large caps do not just leak or explode. What you may be looking at is glue and it may not be bad caps at all. I have had no 488 Mk II decks with bad caps in them but always the Gear C is cracked or frozen up. The mechanism need cleaning and new grease and I apply Lubriplate 105 type. The capstan belt is a 8" belt and I also oil the capstan bearing with AMSoil that I suggest all the time for the last three years. As I tell my trainee do not jump to conclusion without actual proof as in the leaked caps conclusion. This is a more recent unit not from the 60's so these caps may not be bad yet.
Bats in the attic sound like Grandpa of the Munsters (Al Lewis) was always a fun one to watch with his expressions and lines. Car 54 was again the same pair.

 

[DamienC]

I plan on disassembling the whole unit anyway to give it a thorough proper cleaning, so I'll take a closer look at all the PCBs before I do anything.

Gear C looks okay (I can't see any broken teeth) but I really can't start troubleshooting any of that until I get power to the unit. So we'll see. I may very well need a new one considering how long it's been since it ran.