Hello,

I'm looking for the circuit diagrams for the two radiogram chassis. I'm hoping you guys may be able to help.

I saw in the forum that someone has already asked for the HMV one but I know the Philips will be quite hard to find as they have no presence online for the furniture units.

I have also got a suitably technical question too, on the 1950's 1960's stereograms I seem to find the same issue every time if they work, the left channel is low on output when connected to a modern source such as a cd player or ipod. I have done the usual including new valves and checking the signal path and transformers, I even put a spanking new set of tubes and transformers in the rf8 but had the same issue.

Thanks in advance.

I have an RF6, It is the same as an RF8 Except it dosnt have the extra preamp tube for the mic/guitar/organ i/p.

I have not found any problem with the channel being down in volume. There is sometimes bad hum (well I found this anyway) with different types of 12AX7s. Also the difference between the two sections in that tube will give different gain to each channel, Probably what you are finding.

Get your hands on a tube checker or someone to test your 12ax7 and the 6GW8s and make sure they have the same amplification factor (GAIN).

If you un hide your email address I can send the diagrams to you.

If you unhide your email address in your member profile, I'll send you the RF8 material.

As for the general left channel attenuation issue you mention, I can only guess that it's a bad joint or a bad component. If a meter isn't helping, then I'd probably check each path with an oscilloscope.

This assumes that the source player isn't the problem. Obviously, swapping the input L & R channel plugs would highlight a problem there.

I expect there could be an impedance mismatch between a modern source and the old stereograms, but that effect ought to be consistent in each channel.

I have checked what has been mentioned here, it's not the source nor is it the tubes, I swapped the left and right transformers and output tubes and ran several pin matching preamp tubes and some preamp tubes that needed heater rewires to no avail the issue stays, new coupling caps, cathode resistors and such also don't help.

^ I have checked what has been mentioned here,

Have you tried a CRO with input source, or a signal injector by itself, monitoring the signal stage by stage?

I have emailed you the RF8 material.

Thank you for the e-mail I can now make a new chassis for the philips I am restoring.

I don't have a cro anymore the best I have been able to find is that it only happens with stereograms with a modern source so I am currently fiddling in the tone and volume controls to see if it's an issue there, on record the hmv has equal volume per channel but on say cd left is low.

Since this appears to be a general problem, could it be an impedance matching issue? Is the output impedance of modern equipment matched to the input impedance of valve equipment?

"on record the hmv has equal volume per channel but on say cd left is low."

Through what type of input socket is the CD player being connected?

Also, I expect there is an input mode/source switch involved? If so, check the contact resistance.