Groove Tubes CL1s HELP!!

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Hayman

Well-known member
Joined
Dec 1, 2004
Messages
91
Hi,

I just got a nice (but dead) Groove Tubes CL1s compressor in. I'm just taking a look at it for a friend. It's not working anymore. One of the two fuses (in the fuse holder) blows after two seconds at power up.

I think they have experimented a little with the fuses so I really don't know what values those fuses shold be. They are now 2A/250v and 0,5A/250v. The 0,5A blows, the other is fine.

The compressor is a opto tube compressor.


Does anyone have a scematic for this unit?

Any tips on what to check first?


Thanks in advance.


Richard
 
Thanks,

6 tubes. 3 on each channel.

I found a loose regulator (maybe a transistor. Have not checked yet) on the power supply card. RPS-101 card. I thought I had the problem tracked down, but when I took out the card I found that someone had been there before. A diode was soldered on the underside of the card. Also a pice of wire (jumper). The wierd thing was that they were both soldered on one end only. The other end was just hanging there. One track on the board was also scraped off.

I'll have to take a closer look tomorrow. I'll take some pictures too.


Thanks

Richard
 
Ok,

Here is a picture of what i found:
bypass.gif



Looks like some sort of "bypass" that has fallen apart.


Richard
 
Might be an in/out voltage limiter diode - look at the TL783 in the G9 psu for reference. Without this, the regulator tends to fail at first power-down..
 
[quote author="gyraf"]Might be an in/out voltage limiter diode - look at the TL783 in the G9 psu for reference. Without this, the regulator tends to fail at first power-down..[/quote]

Yes, that makes sense.

The regulator in the 325v line is a LM317. The scematic says it's a LM317LZ but when I got those in the mail I found that they are not the right ones. They are to small to handle the current I think. I have a few LM317T's here. Can I use those?

...and I thought the LM317 was adjustable to 37v (max). How does that turn into 325v?

Thanks

Richard
 
I replaced the LM317 and put in a 2A fuse instead of the 0,5A that blows all the time. Now I have two 2A fuses in there.

I powered up and it worked!!! After a minute or so it started to smell a little from the power board so I shut it down. At least I have the chance to measure the thing now.

Richard
 
Smells funny means your burning something most likely a resister or 2. if your blowingt your .5a fuses from the get go then there has to be a short. chcek your voltage regulators and make sure they are not shorting out. As well as chcek your trasistors. If you run it with a 2amp fuse and it works thats one thing but running it with a 2amp fuse when it's not working correctly will make more problems. its a bad idea IMO
 
I have replaced the regulators and all the BUX85 transistors.

I measured B+ (should be 325v) at power up last night. My DMM shows that the volt rise up to 325v but it does not stop. It goes to about 400-450v. Then it falls to almost 0v.

I found that what was really getting hot in there was the big power transformer. It has three different outputs. 15VAC, 330VAC and 30VAC.

I'm starting to think that there is a problem with the 330VAC secondary. When I use my DMM in "beep-mode" I get nothing on that 330VAC. It beeps on the other two.

Richard
 
Still working on this thing, and there has been progress the last few days. :grin:

I think I found the short that caused the fuse to blow. I feel a little stupid but I found there was no isolation between a transistor and a regulator that is mounted to the chassis for cooling. It's a BUX85 and a LM350T-regulator and I guess they should be isolated. :oops:

While I'm waiting for the isolation-kits I just make sure they are not touching the chassis...and it works now....well at least the fuse Is not blowing anymore and the trafo stays cool.

The problem now is I can't get my voltages right.

The board outputs should be:

325v (tubes)
+-15v (opamps)
12v or something (heater and lamps)


What I have on the outputs are:

0v (325v outputs)
260mV (heater)
-15v and +0v (+-15v)

This is not good. :?

I think I can fix the +15v by replacing the regulator.

I have replaced all rectifier diodes and all caps. I have a new LM317 in there.

DC voltages after the rectifiers are 21vDC (heater), 450vDC and 19,4vDC (opamp lines).

When I measure right before the LM317 the the voltage has dropped to 0,39vDC. This brings me to Q503 in the schematic. It's not there!! Someone took it out for some odd reason. The schematic says it's a "25A 1486". That PNP is in the same arrangement as two BUX85's that goes to the LM317 input.

What I have also done is: There are two 2W resistors and a variable resistor in series with the LM317 adj. pin (to ground). The schematic says it should be two 16k and a 5k VR in series. On the board I found two 101R and the 5k VR. I changed those 101R's to 15k's (could not find 16k's). Could this cause the voltage to drop?

Sorry for my norwegian newbie-way of explaining things. :wink:

Any suggestions?

Thanks again.

Richard
 
Hi,

Just wanted to say that, thanks to you guys, it works!!! :green:

I had to give up fixing the original plate voltage circuit. Instead I made a small board based on Jacobs G9 power supply....and it works. No problems so far. I now have 12v heater and +-15v from the original board and 310v from the new.

Thanks again


Richard :grin:
 
[quote author="gyraf"]:thumb: Good solution, Richard..![/quote]


Thanks Jacob,

One problem today. I only get about 5mA of current to the tube plates. There are six tubes and I need about 12mA of current. Should I change some of the resistors?

Richard
 
[quote author="gyraf"]if the voltage is correct, the tubes should draw whatever current they need..?

Jakob E.[/quote]


Well, suddenly my votages are wrong. Yesterday I accidently got a short between R33 (470r) and R34 (100k). There was smoke and I replaced both. After this I get around 400V on my plate supply (it was 310V) and 6V on heater (was 12V). I changed to a new TL783....same thing happens.

I really don't know what is going on.


....and one more question.

I put in a 390R resistor where G9 schematic have 470R+47R (Adj pin). This should give me about 320V. The question is: Why is R34 100K? I have seen others use lower values. I was just wondering why you picked 100K?

....and...also the value of R33 and R37. They are 470R. I'm a newbie and I'd just like to know why 470R? The Groove tubes schematic use a 82R in front of the regulator input.


Thanks again Jakob.


Richard
 
Well, changed my heater regulator (LM350T) again and I have the right voltages now. How the plate voltage got "fixed" after changing the heater regulator I do not know.


Richard
 

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