Tascam 238 repair

[Studio-Integra]

Hi,

I just bought a Tascam 238 for 30 euro...
When I got it home, it was making a loud noise, like a jet engine.

I have replaced the SMT caps and the capstan is working fine now!

Sadly, channel 6 has no playback (record works fine)
Searching for the problem, I discovered U3 (LPF 19KHz) on the R/P PCB board is broken.

Does anyone have an idea where I can get a replacement?

 

[LUNE]

hey congratulations on the SMT cap fix!
are these the silver ones (c12, c14, c15 etc.)?

I've got a busted capstan motor card on mine as well, but its corrosion, not the usual speed / 'jet engine sound' problem.
I was cleaning it and inspecting to see what might be wrong and R11 came right off with my isopropyl soaked q-tip!
I'm guessing I'll have to replace the whole assembly, but i'm holding off on this project for a little. I would try replacing the resistor, but I don't know what it is (its tiny, black and says "682" on it) wish I could find schematics for this PCB! (anyone have schematics for the capstan motor pcb?!?)
these assemblies cost 90-100$

I can't really help you with finding your part though - the service manual that I found for this (you found this? they have pdfs at analogrules) does not have a parts list or pcb layout etc like some of the other tascam manuals I have. (which are very nice!) you could call / write to tascam parts and ask if they can look up "U3 (LPF 19KHz) on the R/P PCB board on the Tascam 238". or maybe they have replacement R/P PCB boards or can tell you what it is exactly so you can find an equivalent. they do still carry the capstan motor assembly (but you have to get the whole assembly, not just the pcb etc.) these machines seem to come right after the era where everything was exposed in the manual and there was a part number for each and every capacitor etc.

or maybe "LPF 19 KHz" means something to someone here...

best luck,
let us know how it goes.

ps, do you have these?

 

[Studio-Integra]

Yes, the little silver caps on the motor PCB.
It works fine now!

The SMD resistor on R11 schould be a 6k8

 

[Studio-Integra]

https://www.youtube.com/watch?v=3EWNe6sYLu4

Tascam 238 in action!

Don't mind the sound quality, my digicam just isn't better than this

 

[LUNE]

looks good! I took a look at your youtube of the 38 rebuild as well, looks like there was a lot to do on that one!

well I threw in a generic 6.8k resistor I pulled out of the junk pile and my capstan spins now (any reason i can't just use a regular 6.8k resister? not SMD) - the motor is making a difficult sound, it started up with a clean sort of 'rev' (which seemed ok), but then after a couple seconds it was sounding like rocks in an ice cream maker - a sort of semi-random grinding noise, not too loud, but it seemed mechanical and would change when i put just a little pressure here and there on the pcb. now the noise turned more into a low humming "zzzznnt...zzznnnt.....zzzzznnnt" anyway, i tried recording and there is terrible warble, so somethings quite off. it still could be rather corroded on the pcb in places, maybe the capacitors are off as well, or maybe I fried something else when putting in the resistor or I could have warped it somehow when i was handling it (at one point i unscrewed the pcb from the rest of the motor).
could extreme warble be caused by bad capacitors you think? or would it more likely be mechanical or something with the ic chips or something else? just curious if you have any offhand ideas - I doubt I'll really get thing going without buying a new motor assembly, but its fun to experiment anyway, and would be easy enough to replace the capacitors.

 

[Studio-Integra]

The story behind that Tascam 38 (not mine):

The machine has fallin of the stairs after years of collecting dust...
It is like new now and the owner is very happy with it


About the 238:

A normal resistor will do.

About the SMT caps... I have seen Tascam motors doing very strange things because of them...

You can replace them with normal capacitors (quality of capacitors is much better then 20 years ago)
My advice is to use 105 degrees Celcius caps, because it can be warm around the motor

I did not replace C12 and C14 on my PCB (Dont know why )

Just try it!

 

[LUNE]

well, I think I've mangled my pcb - it is rather corroded, i don't know if there is anything to attach my capacitors to anymore i can't really see what they're attached to or where they go anyway, what i think might have been the original terminals have come off the pcb...
If i had a pcb diagram or schematics perhaps i could find somewhere i could attach them, but as it is now i can hardly see the tracings, its a mess.
fun while it lasted though...
...without the capacitors it does the jet engine thing.

 

[Studio-Integra]

Can you post a photo of the PCB

 

[LUNE]

my camera just blurs with closeups, but maybe I can borrow a friends sometime.
it seems the metal terminals have mostly come up off the board with the old capacitors. perhaps if I was more careful when these came off I could have saved the terminals (I've never removed these smd capacitors before - I just tried to heat up and pull up each side at a time, - not knowing these capacitors, I didn't know at the time that the terminals came up as well) I don't know if the corrosion here is from capacitor leakage or from moisture/environment. if I could guess where the traces were going i could connect them directly to the next component with wire, but as I mentioned its a bit hard to see where they're going... maybe I can find a picture of a clean board - there was a blog somewhere where someone showed replacing these capacitors, but I think it was on a related machine, maybe a 234(?).

 

[Studio-Integra]

Are you sure the terminals came off?
On my PCB it looked like that also, but a little drop of soldeer learned me that it was still there

It looks a little gray and not shiny...

You can try it... afterall, if it did came off, you can't damage it further

 

[Zaldoran]

Hi you guys

I'm just warming up this thread. I have an 238 which formerly had the jet engine issue. I replaced the caps on the capstan board (except of C12 and C14, since I did not have any bipolar electrolytic caps). Now the Capstan is spinning up normally again, but runs with noticable jitter.

Now I thougt of replacing C12 and C14 too, unfortunatly mine are misprinted, and I'm not sure if they read 33µ/25V or 3.3µ/25V

Anyone can help? Anyone already had this jittering issue and knows if replacing those tho caps does help at all?

Thanks in advance
Zaldo

 

[Studio-Integra]

C12 and C14 are both 3,3uF

 

[chewbacaface]

Just out of curiosity, would this repair also fix problems with erratic motor speeds? My 238 records and plays but the speed is varies making the recording useless.

 

[organon1]

Sounds like the problem I'm having with my 238. Does anyone a qualified tech that could fix this on the west coast?