New Clarinet...Help

avahifi · « **Reply #40 on:** 13 Jun 2013, 09:24 pm »

If you get discouraged and would welcome some hands on help, just pack the preamp up, along with the tubes and the build instructions and send it to me. I will fix it and not charge you for my troubleshooting and repair time. Necessary expensive parts will be at whatever they cost me. Note that I will not use $20 each resistors that do not fit the circuit boards, but I always use quiet and stable 1% tolerance metal film resistors which cost about 10 cents each.

I am making this offer because it would be fun to compare a working Clarinet with our best tube preamp on our ABX box, which does not lie, for better or for worse.

E-mail me if you are interested avahifi@comcast.net

Best regards,

Frank Van Alstine

Quicksilverproac · « **Reply #41 on:** 14 Jun 2013, 12:57 am »

Thanks for the offer Frank, however I think I will keep going. I built a Cornet a few years ago....it turned out perfect. I have been a ham for a good many years and have some experience with building RF amps....but not much with audio. Thanks again, Allan

bregez · « **Reply #42 on:** 14 Jun 2013, 01:52 am »

One last easy thing to check:
1) The R302 leads toward the center should be grounded. Your multimeter should beep between these and the ground lug on the back of the clarinet.
2) Remove V300 and test both R302 again. You should get 330K ohms

Quote from: Quicksilverproac on 13 Jun 2013, 09:02 pm

The inside cap wires beep all the time...with the volume pot all the down and all the way up.

This may just be a instrument parameter setting in the fluke, as long as you are able to see the sweep between 0-50K things should be ok.

Quote from: avahifi on 13 Jun 2013, 09:24 pm

If you get discouraged and would welcome some hands on help, just pack the preamp up, along with the tubes and the build instructions and send it to me. I will fix it and not charge you for my troubleshooting and repair time.
Best regards,

Frank Van Alstine

This is a great opportunity. You may want to consider it if we can't pound the problem flat in a few days.

Quote from: avahifi on 13 Jun 2013, 09:24 pm

If you get discouraged and would welcome some hands on help, just pack the preamp up, along with the tubes and the build instructions and send it to me.

Build Instructions: http://www.hagtech.com/pdf/clarinet.pdf

Quote from: avahifi on 13 Jun 2013, 09:24 pm

I am making this offer because it would be fun to compare a working Clarinet with our best tube preamp on our ABX box, which does not lie, for better or for worse.

I think it would also be fun to do a ABX comparison, I have a semi-stock working Clarinet to participate if Allan declines.

Brad

poty · « **Reply #43 on:** 14 Jun 2013, 02:20 pm »

Quote from: Quicksilverproac on 13 Jun 2013, 05:27 pm

I removed the jumpers from C302... The Volume pot seems ok 50K and tuns down to near zero.

It means that the volume pot is out of question.

Quote from: Quicksilverproac on 13 Jun 2013, 05:27 pm

the inside cap wires beep to gnd. R302 measures 330Ohm...not K however I removed one yesteday and it was 330K....not sure ...

This is very strange. It seems that something wrong with the 3 parts ("inside" wire of C302, R302 or R303). May I ask you to remove the R302 (either L or R) and thoroughly check its value -
AND!!!
- while the resistor, jumper C302 and V300 is out - measure the resistance (not beep) across empty R302 place?

Quicksilverproac · « **Reply #44 on:** 14 Jun 2013, 03:21 pm »

With R302 out it reads 330K ... I can not get a reading on R302 on the PCB ...Zero

poty · « **Reply #45 on:** 14 Jun 2013, 04:28 pm »

Just fantastic!
Allan, I suggest to restore C302 jumpers and remove both R302s. Without C302 they (R302s) are not necessary. I think you Clarinet will start to work!

Quicksilverproac · « **Reply #46 on:** 14 Jun 2013, 04:43 pm »

Just a few minutes ago I thought I would try to bypass the switch...jumper RCA to volume pot...It WORKS! I am not sure if the switch or the balance or the soldering is bad. Poty, I would like to thank you very much for sticking with me through all this. Allan

poty · « **Reply #47 on:** 14 Jun 2013, 05:02 pm »

Hm... As far as I understand the place I pointed to was wrong, so I'm not deserve any thanks.

But your measurements were very funny really. I don't know exactly why you cannot read the right values in such simple circuit.

Quicksilverproac · « **Reply #48 on:** 14 Jun 2013, 09:03 pm »

Maybe its my meter, the Fluke was not reading K's, I used a cheap Hatbor Freight meter and it read the 330K. I have been listening for the past several hours with the makeshift setup and it sounds great. I have 2 other preamps and I think it sounds better than both of them. I am not sure how to correct the switch problem. Its not working. I am not sure if its the switch or the way I installed it. Thanks for all the help.

poty · « **Reply #49 on:** 16 Jun 2013, 01:51 pm »

As far as I know the switch can be "set" to different number of positions. Please check for mistakes in stuffing the pin into the switch.

Quicksilverproac · « **Reply #50 on:** 18 Jun 2013, 07:48 pm »

I could not get the switch to work...I ordered a new one. The pins came out when I removed it from the pcb. The new one should be here on Wed. I have about 50 hours use ....sounds great. I am using clips from the rca's to the volume pot.

Quicksilverproac · « **Reply #51 on:** 21 Jun 2013, 02:45 pm »

Well the switch came and I installed it...still not working.....however somehow I think the C302's touched or shorted. I have no sound on either side. I first thought it could be a B+ short..transformer but the fuse is ok ....nothing looks burnt and no smell and all the tubes light up. I am not sure what it could be. Allan

poty · « **Reply #52 on:** 22 Jun 2013, 11:49 am »

Quote from: Quicksilverproac on 21 Jun 2013, 02:45 pm

I think the C302's touched or shorted.

I don't really understand your words. C302s are already jumpers. Did you mean they are shorted to ground? While it is possible, the previous measurements suggest that at least the input sides of the jumpered C302s are not on ground. The funny measurements from the tube side can probably say something like shorting to ground, but as you had sound just before you restored the C302 jumpers, I doubt that something wrong here too. I'd check continuity from the RCA center pin to the switch, then to the balance pot, then to the C302 (this can be affected by balance pot, so either you should measure kOhms or turn the balance to measuring side).

Quicksilverproac · « **Reply #53 on:** 22 Jun 2013, 12:11 pm »

This is a new problem.I had jumpers from the rca's to the the wire jumper....all was fine. I think one of the jumpers touched something or the two big caps touched. I heard a pop and then no sound. I checked the voltages ....349 for the 375 112 for the 145 and 247 for the 280.

poty · « **Reply #54 on:** 22 Jun 2013, 06:32 pm »

The voltages are not dramatically sagged. I doubt it can affect something.
The only problem I can think of is tubes. You should check if the following gear (preamplifier, power amplifier, acustic systems) are working. The source should be also checked.

Quicksilverproac · « **Reply #55 on:** 22 Jun 2013, 07:13 pm »

I moved the Clarinet to a different system ...still did not work. I then hooked up my dac to the amps I was using when this whole thing started. It appears I blew something in the amps....no sound. Could some sort of surge have damaged the power amps. Could it be an open resistor. I changed all the tubes and checked the rca's.

poty · « **Reply #56 on:** 22 Jun 2013, 08:40 pm »

All is possible, the exact reason is to be determined. I'd not hook up the Clarinet to anything until it becomes clear what had happened and in what state the Clarinet is now.
You provide very small info what did you do just before the "pop", was the sound from AS or from devices themselves? What did you do after that? Why do you think it's from short-circuiting something? It's very strange the problem duplicates to another channel, especially in the power amp. Maybe there is only a fuse blowed (in the power amp)? There are many questions... Sorry... But guessing without more info is very unproductive.
meanwhile...
I'd started to check the output caps.
And maybe buy a new multi-meter to be shure you measure correct values. It will help to fight the initial problem too.

Quicksilverproac · « **Reply #57 on:** 22 Jun 2013, 09:08 pm »

The sound was from the Clarinet and not the speakers. I had alligator clips between the rca's and C302...I think the clip touched the wires of the input caps. I have a Fluke 77, and 2 other inexpensive meters. I am not sure how to check the output caps.

hagtech · « **Reply #58 on:** 23 Jun 2013, 04:31 am »

It could be if the CLARINET outputs were connected to the power amp - and the clip shorted something - that could put a huge AC transient on the output. At least until the output coupling cap settles to a new DC operating point. So my guess would be the input opamps need to be replaced on the power amp.

jh

poty · « **Reply #59 on:** 23 Jun 2013, 08:03 am »

Quote from: Quicksilverproac on 22 Jun 2013, 09:08 pm

The sound was from the Clarinet and not the speakers.

Then I'd recheck everything.

Quote from: Quicksilverproac on 22 Jun 2013, 09:08 pm

I am not sure how to check the output caps.

If your meters do not have capacitance measurements you can remove tubes and anything connected to output and try to measure resistance across the C303s. The meter should slowly drop from initial zero Ohms to indefinite. To repeat the measurements - exchange probes (because the capacitors will be charged by the meters otherwise).
And try to measure continuity as I suggested before.