Tascam Portastudio 414 MK II | tear down part two - remove door and PCBs

[@fabiannacht1784]

Many thanks!

[@MJHarris-q9f]

Hi Tetrakan! My second hand Tascam 414 Mk 2 will not record on any of the 4 channels but there is a signal going through the mixer section which I can hear via the headphones socket. Would be grateful for a steer of where to go next please !

[@kevinbudjones6888]

Very helpful video. I'm about to buy one today and wonder if there is a toggle switch modification to reduce the transport speed by 1/2 - still allowing for the use of the pitch control.

[@williamjones9706]

I have one and the 4th channel is not recording. Any common issues you have seen? I have started breaking it apart but wondered if there is a cap or other frequent failure. Channels 1-3 are OK.

[@Tetrakan]

I haven't worked on this model frequently enough to tell you which components are more prone to failure, but based on my experience with other Tascam portastudios causes of that sort of problem in order of likelihood are or cracked solder joint (especially around switches etc); leaky electrolytic capacitor; dead opamp. The schematic is on my blog for free download so it should be fairly easy to identify which sections are the ch4 record and playback amplifiers. You could do some probing with a multimeter, 'scope or audio probe if you know how, but even if not, if you try first reflowing the solder or failign that replacing all the electrolytic caps and opamps in that part if the circuit the chances that your issue will clear up as a result are good.

[@zer0return000]

Super helpful video! When I was marking up my board I noticed that mine has little pictures of screw on the board showing which holes take screws. They're hard to see but there if you forget

[@robertbuccat9240]

hi i just wanna ask if whats the problem with my portastudio rew button not working and also ffw button is not funtionaly workin if you press it it wont allow you to do it so is it a belt problem hope to hear from you asp tnx..?

[@Tetrakan]

Can you confirm which model you have? If its the 414 there's a separate belt which drives the reel mechanism (reel mechanism = all the moving parts that turn the reel tables) I point it out in the previous video in this series, replace that rubber part and see where you are?

[@seantennett9174]

Thank you for making this video it’s great. I just got one of these off eBay and when I record onto the first track when I play it back it sounds very quiet and I know I’m not doin anything wrong when recording or playing I want to know if there is something electronically that could be causing this problem. Thank you

[@Tetrakan]

The simplest thing would be either the record or playback trimpot has slipped or got dirty, turning down the gain on that channel; these are on the bottom PCB and labelled somewhat clearly. Ideally you would have a playback calibration tape and calibrate the playback levels before adjusting the record level but such tapes are expensive and rare....so long as you're not too fussed about higher noise floor you could just try turning those trimpots up a little anyway. I have a playlist of videos on calibration accessible from my homepage if you want to learn how to do it properly.

[@edmundmoon556]

Awesome resource! Do you know what pitch 8pin connector is the right one for the erase head connection?

[@Tetrakan]

I’ve crimped on jst connectors in the past, pretty sure it was 2mm pitch, but desolder the header and measure the space between holes with a ruler before you sink a bunch of money into it!

[@fabiannacht1784]

I have an interesting question... Are there any digital parts of any kind in this machine? (I'm thinking of digital chips) and if so - do they play any part in the processing of sound before it reaches the tape? Many thanks

[@Tetrakan]

No digital chips in the audio path.

[@kylecovan]

Thanks for all your informative videos. I have an issue with a 414 I’m trying to solve. The input on channel one has a signal, however when I try to record with it there is nothing on the playback. The other three channels properly record to the tracks though. Any thoughts on how to solve the issue with channel one? Thank you!

[@Tetrakan]

First establish whether the record play head is at fault or the record or playback amplifier- if you play a pre recorded tape, do you get signal from tape on channel 1? If you don’t have a pre recorded tape, record to track 4 and turn the tape over - if your head is healthy, you should be able to hear what you recorded play backwards

[@kylecovan]

@@Tetrakan Thank you for the guidance! I’ll put a pre recorded tape in there and let you know if I get a signal.

[@kylecovan]

@@Tetrakan I just tested the 414 with a pre recorded tape I made with an MF-P01. I do get a good signal on channel 1. From your previous comment, I guess I now need to test the record and playback amplifier? This is all new to me, so I appreciate you walking me through this as much as you are willing to.

[@Tetrakan]

This shows the playback amp and head are working. Try replacing all electrolytic caps associated with the record amplifier. The schematic is on my blog. Dm me on fb or ig if you’re not sure.

[@vhsvicTv]

Hey dude! Love your vid. It really helped me through the opening process. My 3rd track isn't working properly, there is a loud buzZ when I press play and the output volume is really low. Do you know how to solve this problem? Thanks Tetrakan!

[@Tetrakan]

Check the cables at the base of the rec/playback head are still intact. Failing that try signal tracing to establish where the cassette audio goes from healthy to buzzy and quiet, this would give you a clearer idea of where the fault lies and which components might be causing the issue. If you're not set up to signal trace you could just replace all electrolytic capacitors and reflow the solder at the base of all components associated with the playback amp of Ch 3, you'd only need a soldering iron and £5 worth of caps for that, the schematic is up on my blog for free download.

[@vhsvicTv]

@@Tetrakan Thanks for your reply! It looks like a small white & red cable was disconnected at the playhead so I was able to solder the cables back to the little board underneath the playhead and now playback on track 3 is working! So thanks for your help! There is a new problem now... the playback seems to be really fast on tapes i've multitracked on this machine. It sounds like I put in a normal commercial tape and is now playing my song chipmunk style. Do you know what the reason might be for this? Thanks again Tetrakan!

[@vhsvicTv]

Dude I fixed it! Turns out there was another small Track 2 cable attached to the playhead that had come un-soldered that was affecting track playback and tape speed for some reason I soldered all wires and adjusted the internal amplifier knobs that I found on the schematic manual off your blog and now it seems to be working properly! Thanks again for your help!

[@Tetrakan]

Check the blue and yellow cables running to the motor, if one is disconnected the motor will run as fast as possible and the pitch control won't work

[@vhsvicTv]

​@@Tetrakan Thanks! Yes exactly, correct diagnosis. The cables running to the socket input from the motor weren't completely pushed in Once I pushed them down and the socket clipped together with the pins the problem was solved! Do you have any tips on adjusting the internal amplifier knobs? Thanks man!

[@ianhall481]

Thanks for the vids, I have a 414 coming soon, could you tell me where I can get the belts you mentioned in one of your vids. Thanks. Ian

[@Tetrakan]

I know I already answered this already via facebook but for the benefit of anyone else reading these comments wondering which keyboards to enter into ebay/ali express/ etc the wording of the item I bought was " 60+ Pcs Universal Mix Cassette Tape Machine Belt Common Square Belt Assorted"

[@fspotrecords]

Great videos! Quick question, do you know what the big blue capacitor near the power jack is? Recently picked up a 414mkii and it has a very noticeable hum only while in record or play mode though. Just took a quick look in side and noticed that big blue one was covered in junk and seemed like it leaked. Rest of the inside is very clean. Might try to replace it and see if it helps though can't seem to find what kind of capacitor it is. Any thoughts?

[@Tetrakan]

It's an electrolytic capacitor, it's almost certainly the main filter capacitor following the rectifier (Google linear power supply if you're not sure what I'm talking about) the capacitance and voltage ratings are written on the side. What you're seeing might be leaking fluid, but it could be just glue to stop it rattling around. It isn't difficult it expensive to replace. Here's a video about it. kzbin.info/www/bejne/mX6QnqtmlJWjqdU. Also check the black earth connection from the record/playback head to the bottom PCB since that is another common cause of the sort of symptoms you describe. Good luck!

[@fspotrecords]

@@Tetrakan Thanks much. Going to try replacing the cap(s) on the power sections. Seems like the case. Checked the ground wires but couldn't notice anything off. All seems connected and very clean on the inside. Good to know about the glue. Possible it's a combination of that and some leaked fluid as it's slightly crusty and runs up the side of the capacitor.. Cheers!