HF100G amp and contact problem

Hi all: 2 problems. this 100G has an MRA1 amplifier. We have Recapped it and have made sure all the tubes are good. The amp sounds good but just cannot get the volume up. it is ok for a small living room only. I have cleaned all the rotary switches the volume pot with De-ox it. this has the original mono redhead cartridge. I need to get an idea where in the amp I should look for off value components. I suspect a resistor but not sure.
The 2nd question is about the S and SC contacts. I just cannot seem to get the correct adjustment. it was energizing the circuit continuously and burned out the b cancel coil. Now it fires the circuit, but not strong enough to fire the coils reliably and will get repeat selections. What it the size of the contact points on these contacts as I am thinking they have worn off too much to get a proper activation. any help would be great. Thanks Mark

Mark, as far as the amp is concerned there are two things to check first;

1) What styli are in the cart. If they are the angled, stereo compatible type there was a run for sale a few years ago that was made with poor magnetic material and thus doesn't generate enough output from the cart. If you have a regular magnetic cart on a turntable, plug that in to the Seeburg amp and check the level. That, or just remove the pickup plug during play and touch the center contact in the RCA plug. A loud hum should result if you are not also touching the chassis.

2) If this machine has an AGC section, remove the 6SK7 tube. If the volume rises it indicates that the squelch contacts on the vertical mech stack are not closing during play or there is a broken connection in that circuit.

Beyond those checks, you'll need to check voltages on the tube plates and get an idea of where the signal goes weak in the various stages. You didn't mention if the sound was at all distorted at maximum. If it is, suspect either lot plate voltages or shorted turns in the output transformer.

I goes without saying (but I will anyway): Double check your work after replacing caps.

Rob/NYC

Thanks Rob:
The amp has no AGC but I have another G completed so I just swapped the amps. I did not consider a cart problem as we got new needles just a few months ago. But that is what it is. I cannot swap those with the other G as it has a Thorp cart.
Now I need some more direction. What carts can be used in a G? We will be at the Chicago show next weekend and would like to see if we can get a replacement.
Still have the S, SC contact question too.
Thanks Mark

Mark, if I understand correctly, you have determined that it is a problem with the red cart's styli? If so theanswer is simply to buy a pair of the newly made styli from Europe offered through Victlory Glass and probably other too.

These are the products:
http://www.jukebox-world.de/en/Current- ... 7-mil.html
http://www.jukebox-world.de/en/Current- ... 1-mil.html

Beyond those the alternatives are either an older "blackhead" cart which will probably need rebuilding internally, or to change the tonearm and pickup to use the cart that Seeburg used beginning in 1966 with the SS160. That is a lot more involved but produces excellent sound.
Yet another option is this homemade version: http://www.needles4jukeboxes.com/Seeburg-Cartridges.htm Scroll down to "Pickering Redhead Mono Cartridge Replacement"

I suggest just getting the new styli for the redhead. Even though it is expensive, if the arm is properly balanced and tracking at approx 3 grams with washed records, you'll probably never need to replace them for home use.

For the contacts: Look at these pic's: viewtopic.php?f=3&t=6813&start=15 (scroll down) the set in-question are the third from the top with three blades and the short one in center. When in the play (up) position, the top and bottom of that set are to make but the center one must not touch either one. They don't look correctly adjusted in that top shot as there doesn't appear to be enough of a gap and the popularity meter and cancel coil look like they would remain energized.

Remember that Seeburg switches at the ground (chassis) return. This means power is always present in the coils and only when the other end of the coil is grounded do that conduct. this also means that any short of that return lead to chassis will pull-in those coils continuously.

Rob

Guys,
The photo of the S-SC contacts referred to above ARE defiantly adjusted incorrectly --that adjustment WILL burn up a cancel coil--real fast !!! Hint, when adjusted properly, you should hear a nice loud "snap/buzz", from the pop meter coil just before the needle sets down--the "buzzing" sound should/must, stop, prior to the needle landing ( a VERY short amount of time)! Ron Rich

Is there any reason why I shouuld not use the red head cartridge out of my Seeburg KS200 to test the Seeburg HFG100?

Best
Darrell

ds100h wrote:Is there any reason why I shouuld not use the red head cartridge out of my Seeburg KS200 to test the Seeburg HFG100?

Best
Darrell

No problem,

Rob

Thanks Rob. Just got back from Mark's house and the G works great with the cartridge out of the KS200. So now we need to determine what cartridge we will be getting, appreciate all your help.

Best
Darrell

Darrell,
Did you try just swapping needles ?? Before you do, take a small "Q-stick" moistened with "rubbin' alkehaul", and clean out the area that holds the needles, on the redhead, that's not loud enough. I have seen "stuff" impacted in there stopping a needle from seating properly, which results in low volume. Ron Rich