The Fostex R8 and other products you use every day were certainly offered in the manual set. Many instructions, immediately after the purchase, go into the trash along with the box, which is a mistake. Get acquainted with the information concerning the manual for Fostex R8, which will help you to avoid troubles in the future. If you do not want to read brochures every time concerning a Fostex R8 or other products, it is enough to read them once only - just after buying the device. You will then acquire basic knowledge to maintain Fostex R8 in good operating condition to make it easily reach the intended life cycle. Then you can put away the manual on a shelf and use it again only in a situation where you're not sure whether you perform maintenance of the product appropriately.
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User Name Remember Me? Hey guys, This is my first thread so bare with me. A couple months ago i fell in love with tape. So i decided to introduce some r2r into my studio. I bought a Fostex R8, and then an other for spare parts. Change all the parts that were'nt up to snuff, cleaned and demaged-it.
Unfortunatly, being the way i am, i wanted to make sure that everything was in order before i start recording. So i got myself a calibration tape from MRL. So i started the calibration process, which, let me tell you isn't so easy on that machine.
Ok, i'll admit it's my first time, but the service manual is badly written and confusing. So here's what i did so far: - I could'nt check the speed and flutter since i don't have the test tape or the equipment. First the service manual says to check for Bias leakage, which i did for the Repro section but not for the Record section.
I just can't find the test point 5 that they're talking about. Then we move on to, Section 4. I'm really confused but the whole "Core of T-1" and how do i make it reach peak level. Last but not least, my real problem hehehe. Section 4. Bias Current Adjustment.
All the manual says is: "Put all 8 tracks in the record mode. That's all fine, easy enough to do but, the manual suggest to use Quantegy , so my guess is that's the set up for that type of tape. I think, but i'm not sure that SM as to be set up at 3db overbias i might be wrong there. How do i make a proper reading of the bias level i'm setting. This machine is pretty non-standard. It's only got 2 heads so i can't monitor the repro head while the machine is in record.
And the VU meter does'nt do that fun little thing where the needle rise t'ill it peaks and then you can set your overbias. Sorry for the super long thread Hope somebody has the knowledge i seek I know it's not the best machine in the world but i gave it a lot of love already and would love to see it run like it did 20 something years ago.
Thank you! The bias peaking was needed to get the lvel of the erase current at the right position at least that was what was needed in a B16 I worked on. The bias leakage should be made minimal the bias needs to be adjusted withe r Dolby C off and make Hz level adjustments and then switch to 10 KHz and adjust bias for a like level.
The levels you set already will need to be reduced by the amount of the offset that is from the tape you have to the tape you are suppose to use. It tells in the manual what tape to use for reference level. Find all posts by Skywavebe. Originally Posted by Skywavebe. The bias setting procedure doesn't sound like it is a tape level but a means of peaking the bias oscillator.
It might make more sense if you had a schematic and found where the test points are in the circuit. Originally Posted by speaker dave. The peak and over bias method spoken about in manuals is an approximate setting but does not take into account wear and other circuit change parameters as well as the manual may have been written too many years ago for the tape that was available then. This was used on the assembly line for a number of companies but is not all that accurate.
In the manual they give you guide lines to follow and they expect that a person working on such a unit has experience and previous knowledge of tape decks. This means that you must use an external meter like a LMVA or something like it to get the output readings in dB. Then when everything is well adjusted the meters are set to 0Vu after that. They are still just as inaccurate but for music OK. For calibration of tape with tones they will drive you crazy.
A MHz vertical amplifier scope is also needed on ever test bench for phase comparisons, Bias trap settings and many other measurements but not dB measurements as well as troubleshooting. The B16 I had sent to me had been adjusted by an amateur and it showed in that many of the channel pots were at their extremes with signals still insufficient.
Then I was setting it up and got to the bias adjustment for the setting of erase- it was not erasing well either. Once that setting was done and it was a DC measurement, the correct value dialed in was then allowing the erase function to work.
The bias seting was then also working well where before it worked poorly. What I have not mentioned before that in a test bench set up for 4, 8, or 16 channels, you need to have a switch device to allow you to switch to any of the channels.
This has to be a switch device that when used does not alter the signal going through it buy more than 1 dB to 28KHz. These are mostly done at the facility that you are working at and the people building them have a good knowledge of electronics, stray capacitance and what the wrong cables will do to your measurements.
This same wiring in the switches are done with shielded wire and the lengths kept short. Then when they are made previous to use they are checked for problems in sweeping from 30Hz to 30KHz to see if they alter the signal. Many of the ones I built over the years would sweep up into the 50 to KHz area. So besides screw drivers, meters, AC Millivolt meters Leader LMVA and scope, you may also need special items as switchers and a device like a Tentelometer or a digital bikes scale.
The Digital bike scale would be used instead of fish spring scales for brake tension setting and Pinch Roller pressure adjustments. Last edited by Skywavebe; at PM. Originally Posted by Dertodesking. Yeah that's exactly what is says in the manual So what, i would never change this, even if i changed tape formula?? I am pretty sure the deck we are talking about just like the TSR8 Tascam unit is a two head unit. Yes, it takes twice as long to work on these and so you will save money going in but not when it comes to service.
The 15MHz scope might work but will not allow you to do some of the more advanced troubleshooting. I get the idea this is not your purpose for it anyway so that is that. The switch box design is a trouble saving device.
This means you can switch channels by turning a knob and get instant results. Otherwise and I have done it many times you need to go and switch the cable around and after a few times this get old very fast. This adds to the time that is already 2X from a two head system and so if you are retired or have all day to fool around with this you don't have to build such a device. I would say a AC millivolt meter with dual dB scales on it hat is easy to read is a must but the switcher is a thing a service person would use as too much time is wasted fooling around with cables.
Cut to the quick- once a AC millivolt meter is hooked to the output of the unit put in Hz and adjust levels, put in 10 KHz and adjust bias for equal level of the Hz, go back and forth until the Hz and 10 KHz is about the same level.
Check you recording also up higher as at 16 KHz and 20 KHz to see what hey are returning. It is often necessary to allow 10KHz to be 1 to 1. Attached Images Sweep reel Ea. Last edited by Skywavebe; at AM. Yeah, its not really making sense to me. Sometimes you set the oscillator for best erasure, then bias is how much of that is syphoned off into the record head. Bias for a tape is never set by a voltage but rather as peak or over peak of the output from tape.
It is related to tape sensitivity vs. So all a little confusing. You don't have a schematic? You would definitely set bias for the individual tape type. The instructions must say something about "set to peak output" or "x dB over peak output". Sounds like this uses a combined record play head. That complicates bias setting as you have to tweak blind and then rewind and replay. Maybe that is why the procedure is different? Attached Images page Last edited by speaker dave; at AM.
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Fostex R8 Service Manual
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User Name Remember Me? Hey guys, This is my first thread so bare with me. A couple months ago i fell in love with tape. So i decided to introduce some r2r into my studio. I bought a Fostex R8, and then an other for spare parts.
Forum Rules. Remember Me? Results 1 to 6 of 6. Thread: Fostex r8 doesn't power up. Fostex r8 doesn't power up Sign in to disable this ad. Hi everyone, I'm new to this forum but came here a lot of times.