Sudden drastic loss in sound quality

[Modplod]

I have a Pioneer RT-707 which up to recently has been working like a dream The sound quality was great.

Recently however when I have tried to record to it the sound is muffled or on one recorded tape which I know works one channel has dropped while the other sounds good.

I have cleaned the heads with 99.6% isopropyl alcohol until the cotton bud stays clean but this has made no difference.

I was wondering if these symptoms were being caused by magnetized heads? or if it is something more serious

Thanks for any help

 

[eddisc]

has it been quite a while since you've recorded? Might be dirty RECORD sw. ?? Spray & exercise *all* those associated w/RECORD - include the RCA's, bias, tape type.... Is the PLAY fine? Do you get OK meters when in REC.? How about in PAUSE? Last thing I would do is demag the heads - and I mean LAST THING.... Try different tape(s); YMMV

 

[Modplod]

Thank you for the reply

I have recorded fairly regular until a couple of days ago when the sound quality really dropped off, like dropped off a cliff...nothing gradual about it.....muffled, channel missing, low volume. the meters when recording are fine but on playback are very low. I have tried a bunch of different tapes with much the same result.

 

[Modplod]

Update

Took the front panel off, deoxited (is that a word?) all the front panel button and rotary knobs. I also cleaned the heads with a lot more force. Result everything appears to be working....Thank you for all the advice

 

[eddisc]

Update

Took the front panel off, deoxited (is that a word?) all the front panel button and rotary knobs. I also cleaned the heads with a lot more force. Result everything appears to be working....Thank you for all the advice

Good on YOU !!
One of the problems with 'shotgun' approach, is you end up not knowing what fixed the issue(s). But HEY! it works now...
MY educated guess is that there was a TINY speck of foreign material on the REC head. You'd be surprised how little it takes!!

Roll 'em...........

 

[Modplod]

I was very nervous about using more force to clean the heads but I see now that there are not as fragile as I thought

 

[Modplod]

I spoke too soon

now on playback: muffled highs and no movement on VU meters this with a previously recorded good tape

recording: VU meters moving on record, on playback of new recording barely audible and no movement on VU meters

The speed appears to be ok as what I can hear is at the correct speed

 

[oldvinyldude]

I still suspect oxidation of a switch.

Would not hurt to treat the tape\source switch on your preamp, as well. If you note the channel affected, and switch the cables on the preamp\tape out side, and the problem moves to the other channel, then your preamp is likely an issue. You mentioned good VU response on recording, suggesting tape in side is ok. Look at the tape out side of things.

Head magnetization is not the issue, given the sudden nature of the change. Speed setting has no bearing here, as well.

 

[nbndtrain]

Try working the Tape/Source button on the 707 about 50 times and see if it improves. They seem to oxidize quite a lot. It may need another shot of Deoxit.

 

[Pio1980]

Also record/playback switches.

 

[Grenadeslio]

Poor pressure on the heads would explain this, check for tape tension.

 

[Pio1980]

Poor pressure on the heads would explain this, check for tape tension.

I don't know if this deck used pressure pads on the heads, if so, check for lost ones.

 

[Modplod]

So.....took the faceplate off again and took the black cover off as well to get better access to the buttons

Deoxited again and pressed every button at least fifty times.....

cleaned the heads again.

Watched the tape go through it's path....seemed to be flat against the tape heads with no bowing or cupping..

Put it back together and it seems...finger crossed....to be working both record and play...

Thank you again for all of your advice


(though if I do keep having problems it might be going on craigslist)