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Hi Straycat23, Be careful leaving this running with the servo out of control. The capstan motor will be running at full power. The motor will get hot as it is receiving way more power than is required to achieve speed and also the RPM will be as fast as the mains frequency can spin it. Even...

I have sent you one. Just reply to it! GPS16

Hi Paul, A word of advise. Do not put personal information into a thread. There are a lot of creepy people out there and your last post has gone worldwide!! There is a PM section where you can put messages privately. I do have spare 2 Track heads but the same heads fit a C270. I use this...

Hi Paul, I am a fellow A700 owner and live in Prestwich near Manchester. I started with a NS 2 Track B77 which I converted to 4 Track. Working on this machine showed me what good machines the Revoxes were. I then got the chance of a 2 Track A700 and jumped at it. Later on I bought another A700...

Hi Guys, with regard to the replacement of the TBA931 Op Amps. After a bit of Net Research, I settled on a surface mount package for an Analogue Devices AD8672. I wanted the small package so that I could mount it on a DIL Header 14 Pin. I did this mod back in 2007 and the 4 Track A700 has been...

Hi PorkyB, I think you are in error here!! 15/16 inches per minute would make a recording that would be so muffled due to lack of treble that they would be useless. The standard speeds for tape recorders start at 15 IPS (30 IPS) and then get repeatedly divided by 2. Hence 15/2 - 7.5 IPS, 15/4...

Hi Straycat23, had a peruse of the circuit to check for the "pairs". V3 and V4 are a pair. These valves follow S6a and both Triodes in the valve are used in a single channel. V9 and V11 are a pair. These tubes are in the final stages of the Head Amps. Again, both Triodes in the valve are used...

Hi Stratcat23, From the information I have on the beast........ V 1 ECC83 Double Triode V 2 ECC81 Double Triode V 3 ECC81 Double Triode V 4 ECC81 Double Triode V 5 ECC81 Double Triode V 6 ECC83 Double Triode V 7 ECL86 Triode-Pentode V 8 ECL86 Triode-Pentode V 9...

Hi DJDDay, for the front holes, there are slots in the front panel (if memory serves). The oil hole should be visible through one of the slots. GPS16

Hi DJDDay, In the following thread from Smurfer77, there is a photo. https://audiokarma.org/forums/index.php?threads/pioneer-rt-707-service-rebuild.702717/ The rear side of the take up motor can be seen. The oil hole is at about 25 minutes past. With the machine sat on it's back the front...

Hi Steerpike, From the Service manual for a C270, the over bias for LPR35 is given as follows:- 3 3/4 IPS 6dB 7 1/2 IPS 5dB 15 IPS 4dB The C270 also uses the "22" and "27" heads. Hope this helps. GPS16

Hi Medio_Mutant, By cutting the tape at an angle you have introduced a HUGE azimuth alignment error. A small fraction of a degree will kill of the high frequencies as they will cancel out at the head gap. A large error such a you have introduced will make much lower frequencies cancel out as...

Hi Jomo1960, Check first that the capstan speed is adjustable and not locked to the mains frequency. If you have a reel of leader tape, mark it with a pen at appropriate distances and get hold of a good stop watch. Tedious but accurate!! The longer the tape with the marks is the more accurate...

Hi Drjonfrockit, these Rifa Caps are well known as bombs. The value is 0.1uf and not 0.47uf. On any of the drawings for the power supplies, it is the cap following the mains fuse. It is on the drawing but I haven't found it in any parts list either. Whist you are in there, also replace the Rifa...

Congratulations. You have one of the best sounding consumer decks on the planet!! I hope you get as much enjoyment from this machine as I got from my RT707. Cheers GPS16

Hi jdwk, Yes, the pause button needs to be held in. There is a guy in Germany (I think) who sells a small PCB which is inserted between the control PCB and the front panel buttons. The PR99 differs from the B77 with functions which are more suited to a studio environment. Fader Start, Tape...

Hi O.Friend, Your issue is just with reverse and it is common to both channels, from information given. Cable 33 looks to be a supply rail so it must be OK. From the video, the muting releases and then there is a click followed by silence. You now need to check the voltages on the bases of the...

Hi Titanstats, this is purely a personal opinion. This issue goes along with the "digital is harsh, analogue is warmer" debate. To me, the white LED will seem to be too cold and harsh visually. I would have picked the yellow LED instead. Much easier on the eye and more in keeping with the B77...

Hi O.Friend, this problem is most likely to be an electrolytic which has dried out and gone leaky. Have you got the schematic? My first port of call would be C128 and C127. They give the delay on the bases of transistors Q101/3 (L) and Q102/4 (R). The reverse relay RY602 grounds the bases of...

My thoughts exactly OldVinylDude!! As mentioned in a previous post, the monitor PCB does (should) not affect the Audio Level in any way. It just shorts it out during the power up pause. Now that you have removed it and restored normality, the monitor PCB needs attention!! Next question. Are...

Hi Jotape1960, The relay on the monitor PCB shorts the output from the Reproduce Amp to ground during the power up delay. It does not affect the level in any way. When the relay has clicked the contacts are O/C!! The monitor amp electronics run the VU Meters and the Headphones only. The risk to...

Hi Jotape1960, No!!!!! It would be a bad idea to do this. The audio circuits are AC coupled with Electrolytics. There is only a single 21V regulated supply, so all amps are approx 10V when silent. On power up these caps all need to be charged to approx 10V. Power up the machine after it has...

Hi Irv, this is cut/pasted from a personal message to another AKer. On ANY tape recorder the Azimuth adjustment is CRITICAL to the HF performance. The Zenith and Tilt are also important but are more to do with transport stability and the progression of head wear. At 19 cm/s a 15 kHz signal...

Hi Guys, the Autostop on a RT707 is done with a tape loop which is held up by the tape in all modes. The loop has a viscous damped pivot and takes 1.5 to 2 secs to drop to the bottom of travel where it changes the state of a microswitch. The switch then discharges a capacitor into a solenoid...

Hi xpert911, for high frequency issues like this the Azimuth of both the playback and record heads needs to be verified. This is CRITICAL to the high frequency performance of the machine. For the electronics to adjust the response the mechanical adjustments must be correct as the "foundations"...