Salas: try the JFET RDS resistance alternative test method shown in the video.
Just so we are on the same page as I follow the video: MJE15031 pin out (1) gate (2) source (3) drain.
As per the video, I measured the R value between Drain to gate & source bridge and both worrking/non-working board = 100.5 ohm.
Just so we are on the same page as I follow the video: MJE15031 pin out (1) gate (2) source (3) drain.
As per the video, I measured the R value between Drain to gate & source bridge and both worrking/non-working board = 100.5 ohm.
Not applicable to bipolar transistors like MJE Q1. Transistors have base collector emitter. That alternative resistance test method is for JFETS like J1.
So I took a deep breath and connect the single DCSTB to the DCG3, I must have check the whole thing 5 or 6 times to make sure the value/transistor orientation was correct. Then no smoke and the LED turn on. After 30 mins, both the DCSTB and DCG3 's heat sink were mildly warm. As mentioned in previous post, I am using a 15v transformer with dual output of 17.7 ac unloaded. I will leave it on for a few hrs. to make sure everything OK and then take it from there.
Attachments
Hi Salas,
Relay clicks, offset adjusted to about 1.2 mv on both channel with shorted input. I am not too fuzzy on dc at this moment as the whole thing is exposed and I understand it is temperature sensitive. Tomorrow I will feed a music signal through and listen through headphone, also I will order new J1,Q2,J1 for the non-working board. So you think its J1 that's short (post 6663).
Relay clicks, offset adjusted to about 1.2 mv on both channel with shorted input. I am not too fuzzy on dc at this moment as the whole thing is exposed and I understand it is temperature sensitive. Tomorrow I will feed a music signal through and listen through headphone, also I will order new J1,Q2,J1 for the non-working board. So you think its J1 that's short (post 6663).
DCSTB's J1 must have gone during the mishap that blew the fuses. Voltage across R10 divided by its Ohmic value will tell you each channel's output stage bias current by the way.
Salas: DCSTB's J1 must have gone during the mishap that blew the fuses The uneven voltage situation started way before the fuse was blown, it was during the fiddling (disconnect/connect the transformer) that the center tap was connected loosely. Speaking of the fuse, I am using a 1A SB fuse for the mono DCSTB. After I fixed the non-working board, I will put back the proper fuse (.4A). That said, I can only find .5 A Slow Blow locally, is that acceptable?
I will measure the bias current later today. Thanks for the heads-up.
I will measure the bias current later today. Thanks for the heads-up.
Uhm...
I just opened my (unconnected) DCG3 and had a look on how to commence.
I thought I'd first inspect the connections and here we are: The HP-out is completely shorted on the board (wiring seems good). That is, HP L/HP R and both Gnd are all returning ~1.x Ohm ...
I just opened my (unconnected) DCG3 and had a look on how to commence.
I thought I'd first inspect the connections and here we are: The HP-out is completely shorted on the board (wiring seems good). That is, HP L/HP R and both Gnd are all returning ~1.x Ohm ...
Aha! This is different. It's a conductive Plastic (instead of "Hybritron" whatever that is...
Looks good, although it isn't cheap... Why not giving it a try? (I won't before I tried various other types)
Looks good, although it isn't cheap... Why not giving it a try? (I won't before I tried various other types)
That looks like a linear mono pot. I have used a bourns 10 turn pot with a shunt resistor before, its a clean sound, too clean.
I have use TKD for the last 20yrs, like it, not the most neutral but smooth.
I have use TKD for the last 20yrs, like it, not the most neutral but smooth.
Thank you, Salas!
If I conclude correctly, there’s nothing wrong with the HP out being shorted, and the line out not?