Good fix for the sticky meter. I have had meters do that in the past, and it's usually been due to particles attracted to the magnet periodically jamming/slowing the meter movement. That hinged pcb construction used to be much more common back then I think - I've owned radio gear that was a joy to fix/modify because of this.
Kudos to you, for a great find and repair! Yes, part 2, please. Kudos to geirendre (hardened grease,) jim (tiny scope) and cashew (PCB face,) for their comments. Tip = Many drawing programs have a function that will expand an array into an arc. So, you could make your own meter face. Even some of the open source offerings do this. If you have a 3D printer, you could make a decorative name plate, to replace the black cardboard (however, it is perfectly fine.) Cheers.
sadly no 3d printing (yet), of course I could always find a place that allows me to do a 3d print job. I could make new scale (done it before, last time for a high voltage meter, there is a video...) but I am wondering if the small meter dimensions is making this worth the effort
Well done! That is a very interesting chassis, I have seen a few pieces of HP gear with fold-out cards but not hinged chassis sections. As someone else suggested, you might try backing off the jewel tensioning screw (just a few degrees at a time, front and/or rear) and see if the original meter movement improves - can't hurt it. Regards, David
Could also do 330 ohms R + 100 ohms trimpot. If the instrument uses 10x and 3x units full scale ranges, I would be tempted to take a photo of the new meter's scale backsheet and then photoshop up a custom one with with both scales.
Try to move the needle mechanically. If it drags, check the movement for the presence of ferromagnetic debris interfering with the movement of the coil frame. My old analog volt/amp meter (Avomet) had a similar problem. Tiny chip was removed with a steel wire to which the chip was attracted.
8:00 My TF2331 doesn't have a shield over the distortion PCB eighther. I'm considering taking the shield from the powersupply and moving it there. I will be running mine from a DC power source anyways. BTW the 4 transistors on the distortion pcb was placed in sockets and the legs was corroded, so I removed the sockets and soldered the transistors directly to the pcb. Also i replaced the banana input jacks with new high quality ones.
Good tips, many thanks. Yes I may move the shield from the power supply. So far ethe distortion part has not given any trouble and the wild deflections caused by the phase knob are getting better (probably because I am using the pot more)
@@TheHWcave Just finished recapping and servicing (cleaning switches etc) mine TF2331, and it works great now. The manual states a current draw of 25mA, and mine clocks in at 24mA. Connected to my Uni-T AWG supplying a 1KHz tone I'm now able to dial it down to around 0.015 - 0.02% distortion.
@@TheHWcave I ended up replacing all the orange/red caps. I measured the first few that I took out, and they all measured high, and with some level of leakage. So I decided to do them all. The only few I left was some small caps that I was not sure if where tantalum, they measured ok, so I left then in. There was also a few papercaps (Dubilier branded) that I replaces.
Nice, I Just got one og these meters myself. It worked on DC supply for 1 hour, then the notchfilter part stopped working. Havent had the time to look into whats wrong with it. Looking forward to part 2 of this. BTW did you try to loosen on the tiny screws on the needle in the instrument? Could be that it is stuck in old hardened oil.
@@TheHWcave Just take one screw at a time or else you risk that the movement falls out. Lossen one screw a tiny bit, flush the bearing with IPA, and tighten the screw until the movement starts to drag, then back it of "just a smidge". Then do the same on the other screw. Everything looked ok in your instrument, so it must be something with the bearings, lets just hope you can clean it up.
