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A Very Compact Hybrid Amp - Page 121

post #1801 of 2213
mhhhh - found the error, q4p was 550 instead of 560 - after powering on, still smoke. do you have any additions to "change q1s-q6s and remeasure"?

greets

dennis
post #1802 of 2213
umm..lets recap..
Q4P is an MPSA42 transistor for the B+ stage.

Can you check and tell me what you had mixed up?

And you'd want to remove Q1S-Q6S and then take some measurements before replacing them.
post #1803 of 2213
my fault, q4r, not q4p!
post #1804 of 2213
okay..
well best thing that I can suggest to you is replace all the buffer transistors Q4R-Q7R.
While I am there I would replace all the splitter transistors just to play it safe.

I would wait for Alex to chip in first.
post #1805 of 2213
the steps I would take are:

remove all splitter transistors Q1S-Q6S. Turn it on, measure opamp IC1S pin 3 and make sure it is reading 12 volts which means the splitter IC TLE2426 is working right. Turn it off, then I would remove and replace with new Q4R-Q7R transistors, plug in the new splitter transistors Q1S-Q6S and then give it a try again.
post #1806 of 2213
Think this thread is a better place for a query Erik made in the CTH tube & tweak thread, a result of CTH's good reception @ the last NY meet.

Quote:
Originally Posted by erikzen View Post
There is a small group of us in the New York area that wants to start having regular DIY mini-meets, primarily SiBurning. We had one meet in the spring with SiBurning, Kerry and one of SiBurnings friends from outside of Head-Fi. I have very little DIY experience myself but I'm trying to learn. I was thinking the CTH could be a good group project for us.
There are a lot of factors that should be considered when one is picking a project, such as going full kit or sourcing parts, build complexity, support, performance expectations, cost, tube vs solid-state, portability, etc. This is why there are so many projects to choose from (PPA, M3, SOHA II, MilletMax, etc.)

Based on one's experiences, preferences and biases, everyone has his/her own opinions on things. Here is mine in this case:
To give yourself some room to work in some upgrades (pots, jacks) & make for easier wiring, I'd suggest Bill's longer-than-std case & perf top offering if choosing this project.

As usually the case, it comes down to cost/benefit, risk/reward, trial/error they are what make life interesting

Other CTH builders can chime in if they wish, of course.
post #1807 of 2213
I use my CTH everyday. I really like it, I think if you build it you will too. Won't sit and gather dust as was said.
I purchased Bill's kit. It was great and everything was there. I would also recommend the longer case.
It is a great build, intermediate level, you have to be thorough and careful. If you put it together right it will come right up and sound great. If you don't you'll have the backing of a great community to help you get it going.
post #1808 of 2213
hmmm - sry for the long time without reply, "work sucks".

so, after removing q1s-q6s, pin 3 of ic1s is "dead"; no voltage. any suggestions?
post #1809 of 2213
Quote:
Originally Posted by speedbasslenny View Post
hmmm - sry for the long time without reply, "work sucks".

so, after removing q1s-q6s, pin 3 of ic1s is "dead"; no voltage. any suggestions?
Hmm,

Are you sure you have the regulator LM7824 in place?
Are you reading 24 volts on the pin 3 of the regulator?

If yes to both the above questions, what voltage are you reading at pin 1 of IC1S
post #1810 of 2213
mhhh - is it normal when q1s-q6s and lm7824 are removed, theres no voltage at pin1?
post #1811 of 2213
Quote:
Originally Posted by speedbasslenny View Post
mhhh - is it normal when q1s-q6s and lm7824 are removed, theres no voltage at pin1?
yes..there is no voltage crossing to the splitter if the regulator is removed.

power down, wait for a while (else there will be sparks when you try to put the regulator back in its place and we don't want that to happen and fry something else.)

SO put only the LM7824 regulator (Q1S-Q6S are all removed ) back in place, power on and measure pin 1 and pin 3 of IC1S.

Report back.

Cheers,
Sachu
post #1812 of 2213
not pin1 at the ic1s, pin1 of the lm7824-slot!
post #1813 of 2213
Quote:
Originally Posted by speedbasslenny View Post
not pin1 at the ic1s, pin1 of the lm7824-slot!
Hmm..no that isn't normal..you should be reading about 35-36 volts on pin1 of the regulator.
Very carefully, can you measure voltages at D1P and D3P. Be careful not to short them both when measuring.
post #1814 of 2213
Quote:
Originally Posted by sachu View Post
Hmm..no that isn't normal..you should be reading about 35-36 volts on pin1 of the regulator.
Very carefully, can you measure voltages at D1P and D3P. Be careful not to short them both when measuring.
hmm - measure between pin3 of the lm7824slot and d1p?
post #1815 of 2213
Quote:
Originally Posted by speedbasslenny View Post
hmm - measure between pin3 of the lm7824slot and d1p?
No..always measure with respect to SG (star ground).Since you have tombstoned the two diodes, D1p and D3p (they are right next to each other i believe), very carefully with the red probe on the exposed lead on top of the diode and the other black probe on SG..measure the voltages at these two diodes.
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