• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pioneer RT-707 service & rebuild

smurfer77

smurfer77

Super Member
Hi everyone,

I just picked up my first reel-to-reel machine, a Pioneer RT-707. Aside from a ding in shipping (sadly on the faceplate) and a couple of minor issues (see below) the machine looks in great shape. The heads are in outstanding physical shape. After playing a couple of tapes last night I'm very very happy with the sound; so happy that I'm motivated to do a full rebuild. I'm the type of person who only spends time on rebuilds of vintage gear that already sounds good pre-rebuild; I have zero motivation for spending time on old models that don't sound good and trying to make it sound good (let's face it, unless something is broken, replacing caps and stuff is mostly subtle, excepting some of the noisy transistors etc.) Of course, there are some exceptions where well known mods make a nice different to some vintage gear.

By full rebuild I mean not just mechanical servicing, but electronic as well. I dug around for similar threads, but didn't really find a detailed electronic rebuild (feel free to share some links, I'm sure they exist...), so I'm going to list the details in my thread here as I go along. Some of my previous detailed rebuilds went down well; here is my last detailed rebuild, on a Sansui AU-777A amp ( http://audiokarma.org/forums/index....xmas-break-rebuild.632026/page-5#post-8621968 ). I thought I might do a similarly detailed thread on my Pioneer, since I'm already in love with it. I'm new to tapes, so I will be learning as i go along, and hopefully sharing the knowledge I gain in an accessible manner for all to enjoy.

Aside from the mechanical servicing (the device audibly requires some lube, but all functions seem otherwise sound), head adjustment, and general electronic rebuilding, the two main issues I noticed last night were (1) reverse direction button is missing, and (2) the output is somewhat louder on the right channel than the left (note: that this was observed at both the RCA outputs and the headphone output, so the issue is upstream of the where these signal split off from one another).

Will post some pics soon.

Question for the forum: as I say, this is my first tape machine. I've got all the gear I need except the calibration tapes. Does anyone have a suggestion for where I can get the STD-154 (play system adjustment tape) and the STD-502 (record/play general adjustment tape) (or suitable substitutes)? I've seen a couple floating around on the web for about $150 but this seems a bit extravagant, no?

Cheers
David

EDIT 22 Oct 2017: There is now a rather detailed and excellent RT-707 thread, by Trevor White, which does have a lot of complementary info to my thread. It's particularly complementary because Trevor followed my thread when doing the rebuild, but his thread fills in some important blanks and brings in new info too. So check it out!
 
Last edited:
Register to hide this ad
Hi David,

I was the owner of a 707. Bought it in 1979. Ended up wearing it out. Another Audiokarmer has it now as a source of bits for one he has. They are fine machines. Give the mechanics a good clean and relube and take things from there. The condition of the pinch roller is critical for correct operation without crinkling tapes. If it looks barrel shaped when removed it is probably worthy of a rebuild and worth the expense of doing so. Dependent of the machine vintage, there may be holes in the reel motor end caps for inserting a dropper/syringe with fresh lubricant. The solenoid driven levers for the pinch roller/idler roller are also worth removing a cleaning/re greasing. The brake is just a matter of lubricating pivot points.

There is a white plug/socket on the bottom of the capstan servo PCB (the board on the RHS of the machine looking from the front). This is a known trouble spot for speed errors and instabilty. There are many mentions of this on the Forum.

When you have got the beast in a more servicable position, then consider the test tape. They are pricey as they are laboratory standard reference material. Pricey to produce in the first place and also they have to have traceabilty via other references they have used themselves in the reference tape production. If you have seen them for $150 then you will only get them cheaper if they are second hand. Then of course, the "Reference Tape" must be applied loosely!!!! There is no alternative for the test tape, it is the starting point for the whole machine calibration. It tends to follow the "garbage in/garbage out" rule of thumb. If you do intend to go down the route of a test tape. Get a head demagnetiser first!!!!!

GPS16
 
Thanks for the comments, especially the tips on mechanical servicing. Okay, I will check out the mechanics, lube it up, and get a feel for the overall condition before committing for the full rebuild and calibration. Will report back on condition, with some pics.

Cheers
David
 
A FYI.... Do not...... I repeat do not adjust the heads without a proper test tape. It will never be the same if you choose to adjust the heads with out a test tape. I have 2 707's and never had to adjust the heads. If there is a channel imbalance it is more like the playback board that could stand some minor tweaking of the pots. This deck is very reliable and problem free. One of the better 7 inch machines.
 
Eminence1963 said:
A FYI.... Do not...... I repeat do not adjust the heads without a proper test tape. It will never be the same if you choose to adjust the heads with out a test tape. I have 2 707's and never had to adjust the heads. If there is a channel imbalance it is more like the playback board that could stand some minor tweaking of the pots. This deck is very reliable and problem free. One of the better 7 inch machines.
Click to expand...

Thanks for the tip; head adjustment will now be last port of call with respect to the output channel imbalance. I will look into VRs (would be great if I can sort out the reverse playback button soon, so I can see if the issue is different for forwards and backwards play) shortly.

Cheers
David
 
Last edited:
Eminence1963 said:
A FYI.... Do not...... I repeat do not adjust the heads without a proper test tape. It will never be the same if you choose to adjust the heads with out a test tape. I have 2 707's and never had to adjust the heads. If there is a channel imbalance it is more like the playback board that could stand some minor tweaking of the pots. This deck is very reliable and problem free. One of the better 7 inch machines.
Click to expand...

+1 on the above. Additionally, if the heads have any wear grooves, which is nearly certain unless the deck has very few hours of use, means that adjusting of heads will damage your tape edges, as they rub against the head and it's wear grooves. Replacement or relapping of the heads is the only safe solution. All of those tempting little adjusters staring you in the face on the headblock-"Just Say No!"
 
A couple of pics of heads:

V6VbIwy.jpg

S72nXBp.jpg
 
oldvinyldude said:
+1 on the above. Additionally, if the heads have any wear grooves, which is nearly certain unless the deck has very few hours of use, means that adjusting of heads will damage your tape edges, as they rub against the head and it's wear grooves. Replacement or relapping of the heads is the only safe solution. All of those tempting little adjusters staring you in the face on the headblock-"Just Say No!"
Click to expand...
The pictures show some grooves.
 
While I had the covers off I checked out the mechanics (although everything functions smoothly, brakes do their job, etc, so it's just cleaning and lubing rather than adjusting or retensioning etc.). First of all i carefully vacuumed inside, although the unit doesn't look like it was in a dusty environment. I then use compressed air to get the bulk of fluff off of the mechanical pivot points. I have a machine oil syringe and put a few drops into the reel motors from the rear (looking from the rear you can (if you use a head lamp of some other directional lamp) see clearly inside and drop the lube wear it is needed (instead of on the coil of wires). I cleaned and lubed the mechanisms attached to the two solenoid drivers (the black rectangles left and right of the head block). At some points I used some machine oil (mineral oil) and at other points I used grease. I also put a bit of grease in between where the arms run close to the chassis. For the brake system I just dropped some mineral oil on pivot points.

All switches were of dust, lubed minimally, and electrical contacts given a deoxit treatment.

Before listening to a tape I made sure that any drips or drops of oil/grease were cleaned from tape path, guides, rollers, etc. Mechanically the machine worked great even before the clean and lube, but if definitely runs slightly quieter now - no more subtle squeaks.
 
oh, also i forgot to mention, the pitch potentiometer needed some deoxit too. I didn't do anything to the capstan motor - mine spins freely 'forever' so I think there is no need to mess with it for now.

I will be leaving original bulbs in until something blows, but posting this nice step-by-step for the play direction button LED substitute for future reference.
http://www.tapeheads.net/showthread.php?t=1912

I've seen some RT-707 on ebay with the meter lights replaced by LEDs, which I don't have a problem with, but I really do dislike the blue-white colour often chosen (I would try to use a yellow-white to match the original colour temp).
 
Last edited:
Regarding my reverse direction button, aside from the fact that the button is missing there is also an issue with the switch itself too. This is an electrical trigger switch, not a simple mechanical one.

What is happening with mine is that pressing the metal tab to switch to reverse always works when tape isn't playing. However, if play is then pressed the forward direction switch triggers, after a period of time ranging from practically instant, to (typically) a second or two, and sometimes as long as tens of minutes. (The same is true if the reverse direction switch is used during play. The direction will change to forward direction after some time). The first obvious thing to check is that the metal tab for the forward direction is not too close to the triggering contacts behind, but it's fine with a few mm spacing, same as for the reverse direction. So it's a false triggering of the forward direction, if that makes sense...

I will look at the switch/trigger circuit on the weekend, but I guess some folks here have had similar issues and adjusted these electrical switches and any advice in the meantime is greatly appreciated.
 
Last edited:
I've had a 707 for several years and never had to do anything to it other than a de-mag. When you say switching back to the forward direction, I wonder if that's related to switching to the forward direction when the counter gets to 0000???
Not sure but just a thought? I'm interested in what you find.
Bob
 
Hi,
on your photos, the one labelled "rear-top towards front". The rear of the takeup motor can be clearly seen. The hole which is at at about 27 mins past, needs to have a few drops of oil. Behind it is a felt pad to act as a reservoir for the sleeve bearings. While you are working on it, add a few drops, let it soak for a day and then add a few drops more. There are another 2 holes at the front of the motors but you may need to remove the brake drums to gain access. With the machine on it's back you may be able to drop oil into the holes with a long syringe. On no account get any oil on the brake drums or brake bands!!!!

With regard to the Fwd problem. The rev play switching is routed through the rec switch. Hold in the stop button and then shove the rec button in and release about 20 times. This will help to clean the switch contacts. This is too ensure that a recording cannot be attempted with the machine in reverse. The supply to RY602 (the reversing relay) goes via the rec switch. If this switch is high resistance, the relay will latch but then drop out after some indeterminate time. With a bit of regular use, this problem would magically disappear!!!

Keep going. So far you are in the realms of much required maintenance.

GPS16
 
Hi David,

looking at the photos again. The first ones which show the machine with the covers on, I notice that the Mic pots are mid scale. I hope this was for the pictures benefit only. If the mic sockets are not in use, the Mic pots should be left at zero. The mic inputs are high gain amps. With the pots left where they are you will be introducing unnecessary hiss onto ALL recordings made. The Mic and Line pots constitute a rudimentary mixer. With some phones in the front panel socket, set the MONITOR switch to Source and have a listen with no inputs connected. With the Mic pots advance the background hiss becomes quite pronounced. This will be part of your recordings if you do not take care.

Just a thought!!!

GPS16
 
GPS,

Yes, the knobs were set to mid but they are kept at zero otherwise. Thanks for the reminder though.

And, working the record button over a bit has indeed stopped the abormal triggering of the directional relays. The reverse direction now seems to hold nicely. So thank you for pointing out the link between the rec button and this relay. You are now the official RT-707 master.

Also thanks for the info about the holes on the front of the supply/take-up motors - will check that out and post some pics to make it clear for others. Anything to be done with the capstan motor? It seems sealed, at least from the rear, and is moving nicely.
 
You must log in or register to reply here.
Back
Top Bottom