Portastudio 424 mk2 erase head not erasing one track

Y

yun

New member
Hi everyone! I seem to be having a problem with my portastudio 424 mk2 erasing one of my tracks; track 2 never seems to erase properly. If I try to record over track 2, the original recording gets half erased/new recording is recorded over. My quick solution is to just turn over the track and erase it via track 3. It works but it is pretty inconvenient.

At first, I thought the erase tape head was being defective but since track 2 is not on the outside of the tape track layout, I feel that the tape head is not totally screwed up yet. This is what I've done with negligible improvements:
- Cleaned the tape heads with isopropyl alcohol
- Run a demagnetizer on the tape heads.
- Opened up the unit and checked the erase signals. I probed the erase signals and each one showed a healthy bias signal

The only thing I haven't done is try to realign the tape heads but I'm not even sure how to do that properly (can't find a service manual anywhere...). Any tips on how to fix this? I will supply more info if needed and will understand if the tape head really is screwed up! Thanks!
 
Just a few thoughts since no one else has replied yet - you are using type II tape? Do you have the same effect with other tapes? I only mention this as I once tried metal tape on my 244 and found - not surprisingly - that it couldn't erase it. But the fact it is only only track 2 might mean that the erase head is defective on this track - especially as you have measured the signal to it. They do have to handle a fairly large amount of power and heat up a bit. Sorry I can't be of much help.
 
Findlay said:
Just a few thoughts since no one else has replied yet - you are using type II tape? Do you have the same effect with other tapes? I only mention this as I once tried metal tape on my 244 and found - not surprisingly - that it couldn't erase it. But the fact it is only only track 2 might mean that the erase head is defective on this track - especially as you have measured the signal to it. They do have to handle a fairly large amount of power and heat up a bit. Sorry I can't be of much help.
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Yes I am using type II tape!

And ugh if that's the case then that would suck. I will admit I trusted the seller too much when he told me he had sent it in for calibration before he sold it to me so I didn't really think anything of it (I had only tested the unit to see if I could get healthy playback on each channel). I guess I'll have to stick to my track 3 erase workaround if that's truly the case.

Thanks! Hopefully someone else can come in here and dispute your erase head comments so I can fix it haha.
 
Maybe worth an experiment using Type 1 tape to see if it can erase on track 2 (should be easier than type 2 if I remember correctly and if the erase head is only partially shot it might cope. If so , you could then re-bias for recording on Type 1 - I've found it works better !
 
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Findlay said:
Maybe worth an experiment using Type 1 tape to see if it can erase on track 2 (should be easier than type 1 if I remember correctly and if the erase head is only partially shot it might cope. If so , you could then re-bias for recording on Type 1 - I've found it works better !
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Good idea! I'll try it out later tonight. Luckily have one type 1 tape laying around here!
 
Findlay said:
Maybe worth an experiment using Type 1 tape to see if it can erase on track 2 (should be easier than type 2 if I remember correctly and if the erase head is only partially shot it might cope. If so , you could then re-bias for recording on Type 1 - I've found it works better !
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Ah didn't work :(

I guess the only thing I can try is to realign the tape heads but I highly doubt that would work. If anyone here can give me some tips on adjusting them, it would be much appreciated!!! Thanks everyone!
 
Worth a try anyway.... I can't see how it can be an alignment problem. I guess you could try to measure how much current is going to the track 2 erase head - and at the same time try to get some idea of the impedance of this is compare to the other tracks.

PS Have you checked the bias frequency? A slight variation from the spec can have a big effect - I think it should be 85kHz for the 424 - I read a while back somewhere that a drift of just a few kHz led to incomplete erasure.
 
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