Recent content by gillygilbert

This is the picture of the board's solder side. Hopefully the board doesn't compress it too much. I didn't get to check the above voltages, but will hopefully have time tomorrow to do that. I corrected a couple dodgy solders along the top edge, those were behind the chassis.

Having a closer look at the solder side I noticed some additional dodgy looking solders hidden by the chassis on the side the output transistors are located. I decided I was going to remove the board and to get a better look and my butter fingers "may" have accidentally dropped the power supply...

I got a chance to look at it yesterday. Fired it up to test the voltages (off dot) and as I was observing voltages and it started to smoke from what looked like underneath the board. I quickly turned it off and unplugged. What looks like a power rail looks like it got hot. The scorch mark...

Yes, been off the DBT for a bit now. Yes, been off the DBT for a bit now. Yes I've mirrored the other channel with both the KSC2383/KSA1013 and KSD1845/KSA992 I have gone through and looked at the soldering a few times, the previous owner made a bit of a mess of the soldering and killed off...

OMG now that's a typo, I guess I shouldn't have waited until almost bed-time to post! Embarrassing considering I even proofread this last post! The correct answer is -14.3. Yes the TR715 and 717 are new transistors.

Didn't get a ton of time to test things out but did check on a few things. Here's some observations. Used the ground header on the board to ground my multimeter. I tested TP-1 shortly after it came out of protection. And it started in the positive 5vm but the voltage was declining rapidly...

I'll look for a higher wattage bulb. Incandescent bulbs are getting tougher to find. As for the the positive and negative probes, they are placed correctly in the meter. I'm using chassis ground with the black terminal and red on the test points. I tried another meter last night and got a...

Yes. With the trimmers on the highest resistance I can get it to -17mV or at its lowest resistance -21mV. Should the whole channel be a negative voltage, or should it be positive like the other channel? I also forgot to mention that the DBT starts bright, as normal and then dims but...

Thanks to all your help the amp now comes out of protection after following the above noted plan and on the dbt. I do get undistorted sound, though a problem still remains. When testing the idle voltage is when things go sideways. Test point 1&2 have a negative voltage of -18 mV, whereas TP...

So last night I had time to pull the output transistors and diode test them. Results below: TR725 - 2SB531 PNP B→E forward: OL B→E reverse: OL B→C forward: OL B→C reverse: 0.0012V C→E forward: OL C→E reverse: OL TR723 - 2SD371 NPN B→E forward: 0.1329 B→E reverse: 0.1329 B→C forward: 0.133...

Neither Mouser nor Digikey have the KSA1015 in stock (both have the KSC1815 in stock however). Digikey does have it in marketplace. Seems this was a popular transistor. Is this something that's worth stocking up on from Marketplace, or is there another option? I did a bit more searching...

Had some time this evening so I got a few things replaced and tested. Replaced 721 & 719 as outlined in the previous post. Tested 719 out of circuit and it tested fine. Pulled transistor 717 as it showed short while in circuit. I'm not sure exactly what to make of the results but I'm...

Thanks for that info. Since 721was already out of circuit I can add that c --> e is shorted as well so will need to be replaced. What are your thoughts on these replacements? 721 - 2SB560 --> KSA1013YTA 719 - 2SD438 --> KSC2383OTA I have these on hand and I got the suggested replacement from...

I'll hopefully have time to revisit the c-e testing on these in the coming days. For the transistors that I pull to test is it okay if I replace with a new, closely matching transistor (regardless of test results), or will that throw off any diagnostics?

So I built a DMB tester, then that lead to setting up a proper workbench with much improved lighting...and life happened between that...but I'm back. Tested all driver transistors in-circuit with the amp unplugged and caps discharged. Here are the diode test readings (multimeter in diode...