Did anyone measure a residual voltage on the filter caps in a JCM2000 DSL100?
I never did.
Found this thread about bleeding the filter caps:
DSL100 | Bleeding Filter Caps
I measured for voltages on R71, as said in the article, but no residual voltage at all.
My guess is that R73 and...
Thanks for the reply.
The problem is not in the fuses I measured them.
Yeah, a bad soldering or the fuse socket could be it. I have soldering skills, but I doubt it is possible to measure voltages while the amp is on ... this is quite tricky and traces may be very hard to reach.
Anyway...
Well, after a couple of months the problem is back.
Today the amp made no sound at all, and I saw the first tube was dead again.
The other three happy and glowing.
I took off the back cover, took the dead tube out (the first power tube from left, next to the pre amp tubes), took out the...
Guys
strange thing is, I took the amp home, checked all fuses HT, main, then opened the amp and checked all fuses inside. All fine.
Put the amp back together and guess what: all is fine. I'm using the amp for 2 weeks now and still no problems.
I guess a loose contact or so ... :hmm:
Ok, thanks! Will check and replace the HT fuse.
Replacing only the dead tube will result in a non-matched tube amp ... if this is a good idea or not will be a whole other forum thread, I suppose ;-)
(I will bias them, though)
I have a DSL100, and today I got no sound from the amp.
So I opened up the back side, and found out that one power tube is not glowing.
It's the first power tube from the left.
(looking in the amp from the back-side, on the left are the pre-amp tubes and on the right the 4 power tubes)...
There might be another cause for the popping: no diode across the relays.
I think I will insert diodes across the coils of relay 2 and 3 to cut out high voltage clips when switching.
That seems to be a relais. I also see a diode across it; that's also an indication.
(the diode short cuts peak voltages when the relais is switched).
I'm not sure about optocouplers versus relais; I guess it's different versions of the amplifier.
About the switching sounds ... a bit of a...
I order to solve the switching channels noise (pops) problem I did the optocoupler check as indicated in this thread.
green channel: 1411 ohm
red channel: 1.5 MOhm, and this value increased to 2.4 MOhm during 1 minute or so.
What does this say?
I am not sure it I measured the right component...
I installed the mod too, option 3 and added the volume knob on the front of the amp. Neat! :lol:
It all works great (tested only at low volumes), but there seems to be one strange thing:
I get a 'pop' sound (in the speaker) when switching from green to red channel back an forth.:(
It seems...
I think he was referring to the power-divider which indeed is R67/R73 in the schema.
If you take out the EL34tubes, and measure from pin 2 or pin7 to ground, you should find 50 ohms.
Good news!
The F1 fuse was the problem after all.
The fuse itself was ok, ... however its socket had a bad soldering.
I re-soldered it and now all tubes are glowing happily.
Thanks for the input guys! :wave:
sorry guys, I wasn't clear on this.
Yes, I checked the fuses with a meter. All good.
PS I have a degree (engineer) in electronics, but I have not much experience in repairing a DSL100. But thanks for your warnings anyway. It is always good to be carefull with tube amps!
Ok I finally got 5 minutes to open up the amp ... to my surprise all fuses are ok :confused:
There are no burned areas as far as I could see ... so I'm a bit confused (funny: con-fused :-) )
Anyone a bright idea for me to check?:hmm:
Today I switched on my JCM2000 DSL100 but no sound!:(
Looking inside (removed back cover) I found that all preamp tubes were dead (not glowing) plus V1 of the power tubes.
So tubes 1-5 are dead, 6 7 and 8 are glowing. :confused:
Anyone ideas?
The power tubes were recently replaced, the...