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Thanks for the suggestions. I'm a younger guy, I'm not familiar with things like those patch matrix boards. They seem outdated but look cool and there's a langevin attenuator. I'm going to recycle the enclosure this weekend and I don't want to leave anything that I might find useful later on...

I dont find too many rated at 2 watt. Maybe a guitar amp volume control?

I bought a relic from the nephew of the uncle who stored this in his garage. Very nice wiring, high quality parts, and a bunch of preamps. Unfortunately I will be stripping it for parts because it has no use otherwise on its own. I'm going to build some mic pre's with the cards but I was...

Tapping on it causes the audio signal to drop in and out, Im absolutely sure. What's the story with the restoring relay contact plating now? Definitely do not use sandpaper or contact cleaner, if I remember. I might just purchase a new one, apparently MY4-02-DC24 is a replacement for the MS4U...

It has these annoying push button switches that are hard to penetrate, but I think it's the relay. Im hearing cut outs at lowest volume, and after exhaustive and precision chop stick poking I think the relay contacts are the cause.

Back on it, Pete. Here's the situation. Tone Defeat on. I'm getting changing results. While doing these tests, I'm moving balance L-R, volume and pushing in selection buttons FM: Getting some distortion to total drop out intially on the R channel (the one I blew the transistor on) but it then...

Just finished another one petehall347, everything but the tuner went really well - I wish I knew more about troubleshooting and aligning heterodyne circuits. But thanks to your advice, They're coming out of the woodwork around here to get serviced. One more and you'll qualify for a free gift..

:beerchug:

Still mystified how I messed that up, what a bummer. I don't have any resistors of that value, they'll be in later this week. I'll be using 1/2 watt metal film resistors. The crispy ones still measure the correct resistance out of circuit but I can wait. Shouldn't TR505 collector be -43.2V? It's...

B // Right side ECB TR501 is -.724 V // 42.9 V // -.117 V TR502 is -.723 V // 43.8 V // -.111 V TR503 is 43.7 V // 1.107 V // 43.2 V TR504 is .549 V // 43.9 V // 1.11 V TR505 is -.596 V // -.600 V // -1.25 V Much better!

Not sure how that happened but I've fixed it with a new set including the proper replacement for TR504 - KSC2690. Should I take another look at the voltages now?

Whelp, carelessness strikes again - I installed a KSA1220AYS in TR504B by mistake and TR505 is shorted as well. TR503B is OK.

I'll check on that resistor. The picture has the measurements of A / Left on the top, the B / Right on the bottom. I did my best to match the transistors, I looked again and it seems to line up..These are measurements I took today, right now

I took measurements from the other side to compare. I also took out the Pre/Main jumpers and I still measure 6V DC at the input (pin 1) of the B board.

I double checked TR503, original part - E is going to R509, B connects to R504. Here are the measurements of the B for the transistors TR501B 5.3V TR502 14.6V TR503 43V TR504 42V TR505 39V TR508 -43V

Went back over your posts, Pete. Checked the input from the tone board to the Right/B channel - more than half a volt DC coming in!

I forgot my needle probe, dammit. Wont be able to really do this until tomorrow. Oh crap, my mistake. Those measurements were WITH the new outputs and a 60W DBT. My notes from last week say the B channel is still putting out 8V DC on the output. The 100W bulb probably pushed it all over the edge.

Considering the fact that I missed the difference between those .33 ohm and 3.3 ohm resistors on that G-5500 I just finished it definitely could be my mistake.

There's 3 sets from the transformer - the primary from the wall, then 2 big red ones and a ground that go from the rectifier directly to the main filter caps and another 3 that go directly to the power supply. No output transistors - no short. Way ahead of you.. this was with a 60W DBT and with...

OK, when I tested the AC votlage at the rectifier by removing the transformer secondary the light went dim so I think that eliminates a short in the power supply (still powered by the transformer)

Yes, nothing has been on the speaker outs or inputs. It's an unusual input selection - no AUX, just 2 tape and phono. I'm busing reassembling the recitfier for the moment.. no rush!

I am at the point where I'm generally identifying TR roles but couldnt look and tell you. I pulled and tested TR508 and D504 and they seem to behave normal with a diode test.

It was at the lowest value, Pete. I pulled it and tested the sweep of the resistance. It seems fine (and I've had no luck finding a 500 ohm VR with a 10mm pin width.) Then I put it at 50%, that's when the resistor kept smoking. Your advice from yesterday was making me think how the high current...

Started this morning firing up the 6 new transistors in the power amp (KSC2690 / KSA1220 & new sets of MJ21193G/MJ21194G for both channels). I used a 100W DBT limiter and experienced some results that are hard to trace because A) I don't know how to use an oscilloscope effectively yet and B) too...