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Good morning or whatever part of day you currently have, I have an Optonica RP-7100 turntable with a defective track detection phototransistor. How do I know it's bad? Well, I have two such record players and after swapping parts and some measurements I have found the problem to be the...

Hi, I am currently repairing a Technics SU-9070 preamplifier which has a dead channel in the MC preamplifier section. I have narrowed the problem down to the 2SC1406 (TR110) transistor (by switching it with the other channel). However, this part is almost unobtainable (there's one seller in...

Yes, they were made in Września, Poland by Tonsil which was part of the Unitra conglomerate. Late 1970s, possibly very early 1980s. They sound decent and have a cult following in Poland. A pair like that would cost more than $150 nowadays in Poland .

Here in Europe we have "Stylus Co. Japan" replacement styli for both Stanton 500 and Pickering V15. They are rather cheap (~$15) and sound really good for the price. The Pickering styli offered by Stylus Co. are rather low compliance and require about 3 grams tracking force, the Stanton...

So it took me a few months, but I'm still working on this Arcam amplifier. Eventually I found the culprit in the -15V node -> it was one of the DG413 ICs. I replaced it and now all the voltages in the power supply test points are correct. However, the amp is still stuck in standby/protection...

I can't see the schematic. Most likely your radio needs a complete overhaul as mine did. Start by replacing all electrolytics and checking every single resistor in the circuit. Also, I would replace the fuse holders if your radio has the original white ones - they are awful and a notorious...

I think I've measured the voltage drops between the output of the 7905 and everything that is fed -15V from this source. The results are inconclusive, at least for me. I've measured the following components: Z100 (pin 4) Z102 (pin 3) Z103 (pin 3) Z104 (pin 4) Z105 (pin 4) Z160 (pin 4) Z161 (pin...

I have since managed to repair the B&O radio but it still could use some proper tuning alingment. I would be very grateful if you could upload the schematic. I had to replace MANY components in my unit. The main problem was one of the bigger resistors that are close to the back cover - it...

That's a great advice! Thanks, will definitely use that.

I didn't mean that true mono is always 1 mil or 25um. Even lots of vintage LPs from the transistion era (1960s) were .7 mil. I meant that the dedicated mono carts with .6 mil are not always the best possible choice for mono records from the mono era.

One thing bugs me about those dedicated mono carts: the stylus size. I see that the Audio Technica monaural cartridge for LPs has a .6 mil conical stylus. True mono records were cut and meant to be played with 1 mil styli. From my experience there is a huge improvement when you play a 1 mil...

The zener diode seems OK. The 7905 gets -10V on the ground pin. I have rechecked the temperatures and the 7905 does get noticeably hotter than the 7805. I have checked the C316 capacitor and its resistance was noticeably lower (4 Megs) than the adjacent C315. I have replaced it. Nothing...

Yes, the other voltages are all within spec. The 7905 does get noticeably hotter than the 7805. I will check the zener diode closely.

I don't think it could cause any strange oscillation problems, but did you replace the death cap? It creates a "virtual ground" for the amplifier and it seems that at least some part of the problem is due to a grounding issue.

Hello! I've got this Arcam A65 amplifier that stopped working when a lightning struck near the house. There was a quick power surge and this amp didn't make it. It was in standby mode when this happened, connected via a surge protector that obviously didn't work. The amp now stays in standby...

Thanks, Tom. Those surplus prices are a lot better than Mouser's. Just to confirm - this kind of standoff terminal has the threaded part insulated from the turret part, right?

Hello dear AKers, Watching the Mr Carlson's YouTube video on his restoration of a beautiful Harman Kardon Citation tube preamp, I noticed he has a very interesting approach to replacing those multicap can capacitors in old tube gear. He uses some kind of ceramic insulators which allow to use...

Yes, they are around 800 ohms each. The dots on the stylus guard are the same color as the catridge body.

Well, the coil cover is chrome. But this cartridge doesn't sound like a regular run of the mill Grado. It sounds absolutely GREAT.

Hello dear AKers, a fellow dropped in a Luxman PD-131 turntable with SME 3009 S2 tonearm and this strange vintage Grado cartridge for me to setup and clean the potentiometers. I can't find any info on this Grado cartridge. The body looks like the Prestige series but seems older and is blue in...

Yes, I managed to dial a safe current of about 28-29mA per tube (plate voltage is 430V as per schematic) which results in 12-13W plate dissipation. After I've had it on for about 10 minutes the grid voltage slowly stabilized at 390V. The tubes (Sylvania) are well matched, apart from one which...

Thanks for chiming in, Dave. It works now. I appreciate your help. One last thing I noticed is that the grid voltage is a bit higher than on the schematic. It's 400V, the schematic calls for 375V. I don't think it's a big issue, is it? This also explains why someone wired an additional 390 ohm...

Well, I replaced the pot and wired it exactly as you described. Nothing changed. The negative DC voltage is still -23V on pin 5. And I think that current is flowing there, actually. There is no red plating on any of the tubes, and the plate current is low (about 10-12mA). I think I've had it...

Wow, big thanks, Larry! I wouldn't have thought about that! Will try that tomorrow. Best regards, Piotr

Thanks, this makes more sense than the pot being bad! R122 is missing (15k resistor to ground) but I was told to remove it. Other than that, I see no direct shorts. Neither does my multimeter. Will take a closer look. Could you tell me where can that missing connection be? The resistance...