Recent content by sweetbeats

And yeah okay I think if it was me I’d dismount the main power transformer, fuse PCB, and that sensor PCB mounted to the back of the takeup reel motor…take lots of pics, put hardware into different labeled baggies…those steps might help you make some gains with extracting the power supply PCB.

I wasn’t saying looking on the Mouser or Digikey website for cross-reference. Get old-school and call them…or open a live chat. Generally it’s possible to navigate PCB assemblies out around hard soldered wires…it’s not uncommon for the power supply to have to dismount the main transformer...

Thanks. I appreciate it. “Algorithmic Overlord”…lol Can you post a pic or some pics of what you are looking at as far as extracting your power supply? I looked at the exploded view and I see how it fastens, but it’s hard to know how things sit when assembled. It looks like there are two screws...

I need to revise my direction…transistors CAN be tested in circuit, I have just avoided doing it because I don’t trust the accuracy of the results I get…so my practice is to test them out of circuit with a transistor tester. To test a transistor in-circuit with a DMM you set it to diode check...

Transistors have to be tested out of circuit When you pull the PCB assembly, do it after it’s been unplugged and switched off overnight, or for at least several hours, to make sure the larger filter caps are all fully discharged.

So just because the voltage doesn’t seem correct at the base of Q801 does not necessarily mean Q801 is the cause of the fault. But it’s certainly suspect. If it was me I’d pull the transistor and test it. You can still find the 2SC1645 new-old-stock and if you shop a bit you can find somebody...

So you measured from pin 2 of J171 to pin 1 of Q801, which is the pin closest to the edge of the power supply PCB? I just want to make sure because you made the statement “Base is not in the middle”, and I never said anything about it being in the middle. And if you measured this with J171...

Measure for DC volts between J171 pin 2 and the base of transistor Q801. The base pin is the first one, the one closest to the edge of the power supply PCB.

600mV is very not right for pin 3 after startup. Yes, reference to pin 2 for ground is correct. Did you get that measurement with J171 connected or disconnected from the motherboard?

Too many posts. I can’t keep up with the blasts. Please let’s take things one step at a time.

Think about this…how can it be the heads, or only the heads? You connected a source to an input and got nothing at the output. No heads involved there. So logically the issue is further upstream. Yes the power mute circuit mutes all audio at all outputs for a couple seconds +/- at power...

Turn on the 34B. Give it a few seconds, and then measure for DC volts at pin 3 of J171. What do you get?

You’ve got your hands full and I’m not sure if I’m going to be able to help. Again if it is global then it has to be something high up in the chain. I would verify power is actually getting to the opamps…like check for DC volts at pin 4 or pin 8 of any of the 4558 or 4559 opamps. The other...

I think they’re accessed via a removable panel on the bottom of the deck…looking at the service manual (which is available for free on the internet, and if you don’t have a copy you should get it and study it, because I’m going to steer you toward that every time…) it looks like you remove the...

Post some pics of the headblock assemblies and heads if you want some feedback on condition and completeness.