Trying to fix a non-working D100II.
I see a number of posts about schematics, but have been unable to find a working link for download.
Does anyone have them, and willing to share?
THANKS!
In the meantime, maybe I have a common problem? Power comes on, transistors get warm, but no output. Scoping out the final transistors, input level looks the same as output (very low). Power Supply seems to be fine, (32V both + and -).
I see a number of posts about schematics, but have been unable to find a working link for download.
Does anyone have them, and willing to share?
THANKS!
In the meantime, maybe I have a common problem? Power comes on, transistors get warm, but no output. Scoping out the final transistors, input level looks the same as output (very low). Power Supply seems to be fine, (32V both + and -).
Hmm.. Most of the replacements are TO-220 packages, mine look bigger.. Maybe TO-247??
Mouser has them listed, About $12 shipped to me for all 4. Probably worth the gamble. Going to sleep on it..
They have been offering them in TO-220 package's since ~ 8 years back. SoundStream used some of them in a few Rubicon models they had.
I have ~ 100 pieces < both N and P > of original NOS TO-218 1992 date code parts I bought long ago when these D series amps were still very popular. You might want to try and find the original package parts so the leads mount properly and the case thickness is not a issue since they rely on the PCB to clamp them down to the sink surface <I.E. the case height/thickness differences might cause interference fit issues > I have not ever modded one of these older D series amp to newer packages but its a possibility that the different cases may cause problems. The device internally should be the same, but its foot print will be smaller and its lead spacing in not the same, along with overall case dimensions being different. Just some food for though, and if you can't find them P.M. me, my stock runeth over...lol
Thanks for the correct drawing.. Looks pretty similar to the one I had, but clearly this one is more accurate.
Unfortunately, it had not helped me solve my problem.
All of the DC voltages seem correct (but, who knows.. I don't do this every day, and may have lost some understanding of transistor bias). Audio seems to flow through the entire circuit, but there is no gain in the final TIP142/147 output. I thought maybe one of the 3067 pairs popped and I was losing the feedback, but pulling it out of the circuit and doing the diode-test on it shows it is OK.
I was going to pull Q4 to test, but when looking for a spec sheet on it I see it has been discontinued. Is there a replacement for the PN4250??
Still considering the shot-gun approach to this, but I have a PPI amplifier in the pile that I never got back to after "throwing parts at it". I'd rather not make that mistake again.
Also broke one of the 1N914's when removing it for testing.. So, I am down to testing with 1 channel anyway (neither work).
Anyone up for providing some help/guidance?
Thanks
Unfortunately, it had not helped me solve my problem.
All of the DC voltages seem correct (but, who knows.. I don't do this every day, and may have lost some understanding of transistor bias). Audio seems to flow through the entire circuit, but there is no gain in the final TIP142/147 output. I thought maybe one of the 3067 pairs popped and I was losing the feedback, but pulling it out of the circuit and doing the diode-test on it shows it is OK.
I was going to pull Q4 to test, but when looking for a spec sheet on it I see it has been discontinued. Is there a replacement for the PN4250??
Still considering the shot-gun approach to this, but I have a PPI amplifier in the pile that I never got back to after "throwing parts at it". I'd rather not make that mistake again.
Also broke one of the 1N914's when removing it for testing.. So, I am down to testing with 1 channel anyway (neither work).
Anyone up for providing some help/guidance?
Thanks
Attached to a speaker, there is no output. I wonder if what I was seeing on the scope may have been signal coming back through the feedback (R11).
ON Semiconductor has a MSP4250 that looks to be similar to the PN4250.
I don't know if it is bad, but was just researching it. I know I need to order the diode I broke, and shipping is more than the part- Thought I may order some extra transistors too.
If you have any suggestions on diagnosing the problem, I'd appreciate it.
ON Semiconductor has a MSP4250 that looks to be similar to the PN4250.
I don't know if it is bad, but was just researching it. I know I need to order the diode I broke, and shipping is more than the part- Thought I may order some extra transistors too.
If you have any suggestions on diagnosing the problem, I'd appreciate it.
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