Tascam 38 R2R - newbie, hub question

[Ethan]

Hello,

I recently picked up a Tascam 38 that needed repair. My first reel to reel since I was young and had a hand me down 2 channel. I'm very excited over this machine.

I was told it had no audio, and the prior owner was trying to repair it. Dropped a snake on the motherboard (probably the backplane for the channel cards) and it no longer produced audio. Two fuses later, it's playing back audio.

First question is regarding hubs. The reels don't sit flat to the machine, they tend to have quite a bit of play in them. Looking at the hub adapters, they're spring loaded. There is a decent gap between the top and bottom parts of the hub adapter. I'm thinking it's supposed to sit together when it's not "unlocked" for removal. I took one apart but I can't figure out how the plastic would have separated or deformed to allow this play? Should these sit flat? I looked at pictures online but couldn't really tell.

TIA

 

[Ethan]

Okay, I'm an idiot. The hubs have two steps, I was only "tightening" it half way. Turning it further clamps down on the reel quite a bit more.

Now on to only half of the channels recording audio (erase head erases but no audio recorded.)

Fascinating!

 

[SkywaveTDR]

The 38 has a relay that switches from regular use to sync use. If the contact is not working that would stop recording. A fast look with a scope would tel you this.

 

[Ethan]

Ah thanks! It does record on some channels. not all channels. It just ends up erasing the channel but no audio recorded. I will test the two relays I see on each of the cards to see if the contacts are working. Thanks for the heads up on that!

I finally removed one of the rec-play PCBs today and made a capacitor list. I plan to replace the electrolytic caps.

Nichicon General Purpose 105 degree 2000hr is what I built on the BOM list with DigiKey. I didn't go with any audio capacitors, not sure if I should.

 

[Evgeny]

I plan to replace the electrolytic caps.

Are you sure it is neccessary? They can be a reason of sound absence, but I'm not sure they are.

 

[wkrbee]

Fix the recording problem first. The process of shotgunning the caps./poking around inside can create more problems. Keep the equation simple.

 

[-mjk-]

Are you sure it is neccessary? They can be a reason of sound absence, but I'm not sure they are.

Electrolytic caps dry out and go bad. They all do. It's only a matter of time. So, if you're going to change one or two, change all of them.

 

[Ethan]

Hello! The good news is, that with a few friend's help at a local LAN party/makerthing... 180 capacitors or so were replaced. All Nichicon or Panasonic high grade things.

Bad news? It made zero impact on the recording issues. I will need to do more research.

I will confirm the heads are clean. It does erase the tape when recording on 7 of the 8 channels. I also made sure to use outputs on my mixer that were the higher level that the unit expects, so the meters were moving pretty well.