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Help with tubes for stereo receiver!

Hi!

I have a stereo receiver I use for listening only to vinyl that I was given as a gift by a relative. This relative built this amp from scratch. It sounds awesome and I love it, but today I started getting some hissing and high pitched noises, so I cooled down the 4 tubes, opened it up, turned it back on, taped the tubes with a pencil, and got lots of scratching and noise. I've had this thing for maybe 6 years and have never had an issue, so it made sense to me that the tubes might finally have gone.

When I opened it up, I saw 4 tall, slender tubes that I'd never seen before. I play guitar so I have minimal experience with pre-amp tubes for guitar amps, but these look nothing like them. The only marking on them is as follows:

Left Tube - Ge Electronic Tube - IN 188-5 (on the side)
Left Center - No markings whatsoever
Right Center - No markings whatsoever
Right Tube - GE Electronic Tube - EA 188-5 (on the side)

This amp is a completely DIY build and has no markings at all as far as company or parts. The green board where the tubes sat has markings but they see pretty generic. I'm gonna try to add some images below, sorry if they don't work, see Username.

h4ctwUq.jpg


19oNXFW.jpg


GD1rR4k.jpg


At this point I just want to replace the tubes so I can use my amp again for tunes, but I've spoken to 4 different amp repair places and tube experts and they are just baffled, so i am turning to the forums here. Are there tubes that are readily available that can replace these? Just what the hell are these tubes? All help is greatly appreciated.

Thank you!
 

pcan

Member
Paid Member
2015-12-31 4:57 pm
They seems to be ECL86 / 6GW8 or PCL86 / 14GW8. Check the pinout and the filament voltage to be sure. Use the advanced editor and attach the pictures directly to your post. We can open your externally linked pictures only by manually pasting the url on the browser address bar, and this is very cumbersome to do on some devices.
Have you already tried to clean the tube pins and the sockets?
 
If the tubes are bad and you can't find 10GV8 tubes, the 9GV8 might be used with a small value dropping resistor. A 6GV8/6F5P might be possible with a larger dropping resistor, but I don't know if the power transformer is up to the task of twice the heater current. The 6GV8 could probably be used safely if the heaters were rewired from all parallel to a parallel/serial arrangement, but that would involve cutting traces and running jumpers, something that may be beyond your comfort level.
 
They seems to be ECL86 / 6GW8 or PCL86 / 14GW8. Check the pinout and the filament voltage to be sure. Use the advanced editor and attach the pictures directly to your post. We can open your externally linked pictures only by manually pasting the url on the browser address bar, and this is very cumbersome to do on some devices.
Have you already tried to clean the tube pins and the sockets?

My apologies for the incorrect posting of the pics. I have not cleaned the pins and sockets, should I just use canned air for that?
 
If the tubes are bad and you can't find 10GV8 tubes, the 9GV8 might be used with a small value dropping resistor. A 6GV8/6F5P might be possible with a larger dropping resistor, but I don't know if the power transformer is up to the task of twice the heater current. The 6GV8 could probably be used safely if the heaters were rewired from all parallel to a parallel/serial arrangement, but that would involve cutting traces and running jumpers, something that may be beyond your comfort level.

Yes, unfortunately I am not up to the task of rewiring or changing anything. So I'll seek out 10GV8 tubes. Is that correct?
 
The print may have been rubbed off, but there still should be a visible type number on the tube.

Breathe on the tube so that your breath condenses on it, and as the condensate evaporates, look closely at the the tube for the type marking. Keep repeating this on different parts of the tube until you find the type number.

Probably 11BM8 tubes.

edit: about 7.75 seconds with Google revealed this page regarding the S-5 electronics Type M amplifier.

http://diyaudioprojects.com/Tubes/K-12M/audioXpress-review-of-S5-Electronics-K-12M-Tube-Amp-Kit.pdf

11MS8 tubes.
 
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