Monthly Archives: January 2016

Woodwork

Decided today to carry on with the Teac.

sides off

Stripped it of its’ sides. It’s a well-built machine.

oil soap

Pre-work, ready to be cleaned.

wiped down

Cleaned up, and dried off.

prep

Preparation to oil the veneer.

upside down

Odd angle but, applying the Tung oil.

freshly oiled

Letting the oil soak in.

shiny

Left until tacky then buffed down to a uniform finish. Typically this attracts lint, which will mostly come out once it’s drier later, with a second buffing. I think, looking at it, that’ll be adequate as it’s come up nicely.

Tape

Ordered some reel to reel tape off eBay. Shall see how (if) it works. That is, if the tape deck isn’t toast. I’m going to go ahead and plot through the schematic then the circuit diagram to see what, in terms of electrolytic capacitors, are in the sound path and get a list of replacements together.

Reel to-gether

Reassembled and tested the functions of the deck. Pinch roller now snaps in nicely, rest of it seems ok. Just needs a clean on the outside and the transport path is still grubby. Shopping for tapes now 🙂
Found a copy of the service manual and a copy of the user manual for the A-2300SX (similar machine in function and setup).

Reel to bits.

Continuing on with the Teac. Took a look at how it’s assembled.

flywheel off

Removed the flywheel and clamp plate.

pink screwdriver

Had a bit of a fight getting in at the right angle with enough torque (ended up with a small wrench on a drill-driver bit) to undo the solenoid finger-bar.

dry grease

With a bit of a fight, wiggling and swearing the lever arm came free, showing the culprit. 40-year old dry grease.

solvent

With a suitable solvent on a Q-Tip, the old grease was removed. A rag on the shaft got the rest.

lube

Choice of lubricant for this task, regular grease.

smear

All mating surfaces given a light coat of grease before reassembly.

broken bit of switch

There are a pair of microswitches operated by a cam, attached to the tape-run lever on the front. When I undid one screw to move the switches out of the way, this piece of the lower switch fell away. Someone in the past has over-tightened the screw.

switches

Out with the superglue. Glued the corner back on, waiting for it to set right now before continuing.

Reel to Reel

Collected a nice Teac A-2300S reel to reel deck yesterday. Cosmetically very good, needing a bit of TLC to get working again.

r2r

Started by seeing how the paint would respond to a bit of a scrub, as it was all bit dusty.

head cover

The cover over the heads came up nicely after a quick scrub with a bit of soap.

tape path

The tape path is filthy with oxide. Started cleaning it up with tape head cleaner and Q-Tips.

back off

Popped the back off. All pretty good inside, the main capstan motor was stuck but after a quick spin by hand now rotates freely. You can see the original NEMA-1 power connector on the back that I didn’t have the cord for. It’s bit outdated now and hard to find correct cords for. Decided to change it out.

iec

Nice new IEC connector from a dead computer PSU. Came with a nice Y1 type safety cap and an RF choke. Left that all in the circuit, connected the hot to the fuse and the N to the power board, and ran the ground to the back panel. Nice that it’s now grounded.

first run

Brought it gently up on the Variac. Both needles gave a bit of a wobble as the circuits charged up.

spin

Set it to fast forward.. it all spins up properly.

scrub

Gave the back panel a bit of a scrub also, it was dusty.

motor bearing

The capstan pinch roller had jammed solid, which also moves the tape pressure pins. In short, this machine, as it stands, would move the tape but never play.
Took the back bearing plate off and tried dripping some solvent onto the bearing arm.

bearing

Unfortunately it’s a very tight fit and I think it’ll be futile attempting that method. It needs the arm taken off the bearing, the bearing cleaning of the old grease thoroughly and some new grease applied. That’ll necessitate removal of the capstan flywheel to get at the mechanism.

Phase shift

I’d been having a bit of trouble with the matrix quad audio positions on the QX-747. As in, the quad wasn’t working.

I sat down, thought critically about the operational description, looked at the block diagrams logically and studied the circuit diagrams.

2-CH worked properly, as did 4CH CD-4 but RM and SQ were marginal at best and RM favored the left channel, and both were a bit muffled sounding.

Determined that the cause must be early on in the decoder board, most likely the left channel. Popped the lid off, removed the CD-4 matrix board (sits on a bracket above) and inspected the decoder board.

pnp

Aha yes. Spot the culprit. There’s a PNP transistor early on in the left channel circuitry with the B and C legs transposed. It’ll pass current but not how it’s meant to!

board up

Popped the board off the plastic lugs, did a bit of surgery and put a brand new KSA992 in.

Result? Now it works properly, sounds clean and albums like Dark Side of the Moon play in another added dimension. Currently listening to Billy Joel. Impressive to listen to now. This is recorded (mostly) as if you’d be sat in the middle of the recording studio, listening to the band play. I like that. Worth the $0.12 transistor!

Stereo stuff and lights

Back to the Pioneer QX-747. I’d always been disappointed with the reception on the set. I had managed to tweak the AM reception, which is greatly improved now; the FM requires a plastic hexagonal tool to adjust the coil slugs.

Ordered a set of plastic tools, got them in. There’s a number of strong and some marginal stations locally, and one or to that have really picky stereo subcarrier signals, so a tweak here and there and I’m pulling in probably close to 20 stations. Happy with it now, adjusting by ear. Need to get a distortion meter ideally to get it set up fully and peaked, but right now it doesn’t pop, crackle or overdrive so it’ll be alright for the time being.

Trimming RF coil 2

Decided to set about redoing the indicator lights with LED’s, as the colors are still rich on the front gel. The holders are this funny rubber stuff which is going gooey due to the heat mostly. Pulled the lights out as best as I could and took apart the holders to rebuild them for LED’s.

twist

Decided to twist the wires on rather than solder so as not to damage the insulation.

trimmed and tucked

Trimmed the legs and tucked the wires in.

rubber bungy

Added the rubber holster

metal can

Finally slotted it into the metal can.

resistance

Added appropriate resistance. You can see the IR coming up through the board from the scale lights- the camera picking it up as purple.

Finally, together. the speaker option lights are now the correct light green, the mode lights a nice deep green.

lit up

Camera eats the colors unfortunately but it does look nice.