TASCAM 38 - Left Feed Motor Rust/Oxide

[Qete]

Hey all,

Got a 38 to work on. I got it in a town close to the ocean and it was fed plenty of SSS Ampex 456. As a result, there is buildup a plenty.

I think the heads have a 50/50 chance to be okay as the buildup was mostly on the metal parts of the tape path. Feel free to look at the pics and assess. I won't get to run any tape until I've cleared the rust.

I've cleared a majority of the rust with Q-Tips and 99% isopropyl. About to jump in on a second go over. The buildup on shaft on the left feed motor is being particularly stubborn. The motor runs well and has plenty lubrication thankfully.

How careful should I be about scratching the surfaces of the metal? Will superficial scratches (metal feels smooth) mess with tape alignment? At what point do I start replacing metal bits? Any metal cleaning tips and dos/donts appreciated.

I have Brasso, Isopropyl 99%, and acetone.

 

[Qete]

Doesn't seem like my images uploaded.

https://imgur.com/a/L7lS6CO

 

[wkrbee]

That's the Capstan motor shaft. A little cleanser- Comet/Ajax/bartenders friend- on a rag and held against the shaft while running will clean off the oxide. The alum. parts just look bad, probably not a problem.

 

[SkywaveTDR]

Forget Isopropyl alcohol as it is worthless for tape decks. I use Denatured. The Capstan shaft is first cleaned with Brasso on a cotton swab then if it is glazed after it is clean then put double sided tape on a pinch roller, cut a piece of sandpaper 150 grit about the width of the roller and tape it around the roller to meet end to end. Do not scratch the capstan shaft imprint it with the sandpaper by running it like that for 5-10 minutes then clean the shaft off with Denatured. I don't know where people get the idea to use Iso alcohol as it is for skin not tape decks

 

[Qete]

Thanks Skywave, I was able to use Brasso effectively. The parts are shiny and rolling, no tape shedding. I'll get me some denatured. I scratched the tension roller on the take up side and had to essentially respin it. I'll be careful if I ever use sandpaper.

It's currently recording six of eight tracks, didn't need much besides cleaning.

 

[SkywaveTDR]

The decks I work on all have the aluminum reconditioned. I have a number of screw and dowel rods that I put in a drill and am able to spin these parts with sandpaper lightly. The roller guides might be cleaned with brasso as I have seen then inside turn brass colored when either too much tension is on them over years or that someone is too aggressive in cleaning. You just need to remove the oxidation. That pictured pinch roller needs work as it looks glazed. People do not know the importance of the capstan shaft and pinch roller but when you watch phase - azimuth values bad parts make for a lot of variance. Terry will be doing work again if not someone else and so the business will continue.

 

[Qete]

@SkywaveTDR To turn the parts, I used a drill w/ precision screwdriver and some carefully placed tape. I have a ton of spare wood so I should make some rods like yours. Worked out in the end.

The pinch roller on this unit does have trouble engaging against the capstan - 30% of the time you need to tap it to engage. If you're talking about the tire, it was replaced.

 

[SkywaveTDR]

Pinch roller linkage on the 30 series is not all that common a problem. Maybe 2 of the many I have worked on. I don't think they used that same grease. Pinch rollers must be done by Terry as those stupid push on rubbers are a joke and do not work. The rubber must be bonded to the bearing and machined on it to be good. I have had Terry rebuild many 1/2" deck rollers as well as Tachometers and they all were like new. He just made me some A6600 roller that are rare.

The dowel rods are used for Pinch roller on A3300 and X series deck mostly, the smaller stuff like roller guides and other aluminum rollers are done with a Hex part that comes from a machine with a 3mm thread or some with a 4mm thread if larger. The length of screw changes depending on what you are working on. The hex parts were left over mechanical parts from deck that were wrecked by people before I got them and I just took them apart.