Fostex Model 250 Service Manual

[bsco]

Good morning to everybody...hope everybody is doing good....I have this 4 track mixer/recorder for repair and was looking for a service manual....the problem with this one is when you select the recorder/ mixer function switch to the recorder position, the VU meter for track 1, (which is the meter located on the far left), pegs to the right and sort of bounces as if there is some sort of oscillation.....I have checked other functions and everything appears to be ok.....any help would be greatly appreciated.....
Cheers,

[g1]

Get that email account yet? https://music-electronics-forum.com/...track-recorder

[bsco]

I can't get signed up for some reason......it says the account is already in use but apparently not by me......I will try that site again just to see what happens this time......thanks for the reply...cheers...

[dmeek]

I have a copy but the size is too large to post here.
Here are the schematics
Fostex 250_shematics.pdf

[bsco]

Get that email account yet? https://music-electronics-forum.com/...track-recorder

OK. I got it to finally work..I have no idea what the problem was....anyway it's all good now.....thanks...

[bsco]

I have a copy but the size is too large to post here.
Here are the schematics
[ATTACH]n996362[/ATTACH]

Thank you...I did finally manage to get registered at that site....I take it that you have repaired these before..if so I have a question....did you have an issue with the clip led light in the 1st VU meter assy coming on and the needle pegging as if there was some sort of signal being detected...when the mixer / recorder meter switch was placed in recorder mode....even with no inputs connected and all other three position switches in their off position...and all controls turned down......the meter needle also slightly bounces while pegging out.....but it does NOT happen when in mixer mode.....very strange indeed......any thoughts are kindly welcome....thank you for those schematics....much appreciated...

also just discovered that when you activate the record button on the tape mech and activate track 1 the led goes out and the needle returns to zero....very strange indeed....take it out of record mode and the issue returns.....

[g1]

They were prone to relay issues. Possibly a trk1 relay that is supposed to ground something isn't, and the needle is peaking because of it. Don't recall if these relays have covers that would allow a shot of cleaner to the contacts.

[dmeek]

Yes, the relays were often a problem with this model. The transparent cover can be popped off with a knife blade. Try to carefully rub the contacts together with some isopropyl alcohol.

[bsco]

They were prone to relay issues. Possibly a trk1 relay that is supposed to ground something isn't, and the needle is peaking because of it. Don't recall if these relays have covers that would allow a shot of cleaner to the contacts.

strange...the problem went away after and so far hasn't returned...if it does I will check the relays.....Thanks....

[bsco]

Yes, the relays were often a problem with this model. The transparent cover can be popped off with a knife blade. Try to carefully rub the contacts together with some isopropyl alcohol.

g1 said the same thing...the problem went away on it's own...so far it hasn't returned....but something did cause it.....if or should I say when it happens again, I will check out the relays....thank you for the info...much appreciated....
cheers....

[bsco]

well the problem has happened again....when I listen to the audio output from the recorder on track one, it sounds like a motorboating sound....if it was power supply related you would think that it would happen on all tracks....if I put the recorder in record standby and arm track 1 but not the play button, the problem goes away......also if the mixer is in mixer mode the issue is not there.....very strange......I already have tracks 1,2, and 3 recorded...the problem happened after I I finished recording them....I have also noticed that if I take track 1and route it to any of the other VU meters, the meters in question will also peg and oscillate and it is definitely a motorboating sound....