I have the opportunity to buy an ind teisco checkmate combo for cheap. But i have to drive quite far to get there. It doesnt work. The owner tells me it went more and more quiet, and at last completely silent. Does this point anyone in a direction to finding out what is wrong with it?
Best regards
Kasper
Best regards
Kasper
If it's similar to the Checkmate 20, check the anode loads (100K) of the 12AX7's (and the first half of the 12AU7), it's by FAR the biggest cause of faults in valve amplifiers.
Well?
Recieved the AMP today.
Have been starting out by checking the PT, because none of the filaments light up. My meter reads 7v ac on the Heater winding, so I Think its a bit weird that they dont light up?
Especially because the Heater Wiring is ok.... Have checked for continuity All the Way around the AMP?
Recieved the AMP today.
Have been starting out by checking the PT, because none of the filaments light up. My meter reads 7v ac on the Heater winding, so I Think its a bit weird that they dont light up?
Especially because the Heater Wiring is ok.... Have checked for continuity All the Way around the AMP?
Did you have the valves unplugged when you checked?, otherwise it just reads through the valves.
Best thing is to check the voltage on each valve, double triodes use 4/5 and 9 (9 is the centre tap if wired for 12.6V), pins 4 and 5 are joined for 6.3V.
Nigel, you should just put this info in your signature 🙂
As for heaters not lighting up, not all tubes have really bright heaters, or even ones that you can see at all. Most of the dual-triodes I have right now are very dim or not visible at all. Do they get warm? You should be able to feel warmth in less than a minute.
Last edited:
Unfortunately most of the people playing with valve amps don't come from the valve days 😀
This is true. Technically I'm among them (I'll be 37 this year), but my Dad weened me off baby bottles with valve bottles for sure. 🙂
It´s wired for 6,3 v, with pins 4 and 5 joined. With all tubes unplugged, I read 7 volts ac on every socket. Plugged all tubes back in, they don´t light up, and they do not get warm at all? I dunno what this amp has been through, but the tubes are OLD man...they are from the "good old valve days" as you guys mention. I tried putting in a pair of old el84s in the powersection, just to see if they would light up, but no luck there either.
I was on day release at college in the early 70's, we only covered valves one afternoon - and that was because the normal lecturer was away, and a different guy took over. I suspect that without that, they wouldn't have even been mentioned.
This is despite the fact that we did almost all our practical work at college on valve TV's 😀
That is very strange... it could be possible that the sockets are not making contact, and need to be cleaned... but ALL of them? I could believe one being that dirty, but not all, especially after you've removed and reseated a few times.
Exactly. It is strange....but probably obvious when I find out what it is...going away for the weekend today. I´ll try replacing one of the sockets, and try with some spare tubes when I get home...
Thanks for the replies
Thanks for the replies
Back in the day we used to take the valve out, give the pins a quick squirt of switch-cleaner, immediately plug it back in and rotate it round in the socket (to give both pins and socket a good coating).
I suspect either the voltages are missing (pretty unlikely) or he just can't see them glowing (try in a dark room).
Well, i have tried the dark room. No light. I will try the contact cleaner though....
Thanks again
Thanks again
The switch cleaner worked...after several attempts. They must have been really dirty🙂 All of the old tubes light up, and get warm now. One of the power tubes is redplating! Output is very low! And I have to admit that the switches of this amp is a bit more advanced than the ones I usually put in an amp? The amp has a power switch on the backside of the amp. Then there is a 3 position rotary switch on the front labeled: Off- Standby - On. No matter how this 3 position switch is put, the amp is in on-mode. The on-indicator is lit, even though I flip it to OFF? But the switch does turn of the indicator when turned to standby-mode....but even here, I can play the amp? I´m confused...Something must be wrong with this switch?
Glad to your you're making progress! It sounds like there may be other issues with the old girl. I wonder if some more contacts are still dirty. At least you have some output!
- Status
- Not open for further replies.