Seeburg DS100/160 Ear Speaker Noise & Low Volume

I have one DS that has low volume on the left channel speaker only.

On the other DS I have one speaker that has a lot of noise including cracking and hissing sounds, most records at low volume will sound OK, if there is a lot of sax then the speaker goes crazy, once again this is only on the left speaker!

I have moved both of these speakers to other DS models and the problem is not with the speakers.

I suspect that the amps may need to be rebuilt. Are there any tubes I should trade out to se if that is the problem or any other things I should check before I have the amps rebuilt?

Thanks

Darrell

Well since no one else has answered yet I'll suggest a few things:

That sort of noise is often from deteriorating transistor junctions. those amps use germanium transistors and as they age their internal impedance lowers and finally they become noisy with excessive collector-emitter leakage.

Given that the amp has not been rebuilt (?) there may be other causes, some of which can be destructive.

1) Remove the driver tube (7199) from the noisy channel. If all noise goes away proceed to the next test. If noise does not go away --stop using the amp-- until at least the bias supply and output tube couplers are rebuilt.

2) Find pins 1&5 on the five pin muting/squelch plug those two are the signal from the preamp. in-turn short each to ground and note if noise goes away. In fact, if the noise goes away during the normal changing cycle you can skip this and try #3

3) Swap out the 6EU7 tube with a known good one. If problem goes away, you found the solution.

4) If that fails try grounding the 6EU7's grids. see schematic: http://www.verntisdale.com/schem/shfa5.jpg Also, test for voltage on the grids -there should be no dc on them.

That last test will eliminate all but the transistor preamp. Too bad they aren't removable as on the earlier models.
you can do these steps in any order and you might just start with #4.

These last tube amps were really super-simple and while some would say they lacked the belching bass power of the older ones, the lack of huge feedback and simple path does give a noticeably purer and less slewed sound.

FWIW: On those old amps i have out I bypassed the existing pre and used a better two stage external. this gives a big improvement in both bass, gain and noise. Seeburg's transistor pre's were mediocre at best.

Rob

Rob

To my knowledge neither DS160 has had the amp rebuilt.

All noise disappeared when I emoved the driver tube (7199) from the noisy channel, easy it was the left tube!

Skipped step 2 as problem is not there during normall changing cycle.

I do have the service parts and service manual, however, I am challenged when it comes to reading schematics. For the 6EU7 tube, there are two of them one upper (V101) and one lower (V109). Which one goes to the left channel?

Also, what would be the purpose of leaving either one out of the phono all together? I ask this, because when I went to a DS100 that I thought sounded fine to get a known good 6EU7 tube , the lower 6EU7 tube was absent????

Any ideas what could be causing the low volume on the other DS160 left channel only?

Thanks for your help.

Darrell

Darrell,
Plain and simple--both amps should be re-built !
Running them "as is" is just looking for an expensive rebuild sometime in the near future.
The lower tube is the AVC control circuit, and it is a "common trick" of a cheap operator, or his route "mechanic" to remove it, when there are complaints of "low volume". Ron Rich

Darrell, if one tube is missing and you still have sound, that is the AGC amp tube. As Ron mentioned people often removed them to squeeze out a few more db's from a dying amp.

The other 6EU7 is shared between both channels. At this point my verdict would be a bad transistor in the preamp, but as Ron again points out, this amp needs to be properly rebuilt -it is fifty years old. The capacitors used in these amps were never intended to be used for this long a period. The large electrolytic cans were high quality and may still be serviceable --but ALL the interstage caps must go for safe operation. You'll probably be pleasantly surprised at how much better a rebuilt amp sounds.

There are capacitor kits available and aside from also replacing several diodes, the job is pretty straight-forward.

Rob

Ron & Rob

Sorry for confusion. The DS100 that had a missing the lower 6EU7 tube does not have a low volume problem and has a bill of $446.24 in April of 2004 and it looks like it incuded work on the receiver ($175.00) and Amp ($150.00). The person I bought this phono from said she was told he rebuilt both of them? She also told me that he told her that he could set up something like 10 slots to play 33 1/3 records for $50.00 and if he had to come back because she wanted more slots it would be something like $10.00 per slot. This is the same unit in which the TASU2 was missing the Q754 and Q755 transistors. Almost seems like someone decided to use this TASU2 for spare parts, but, who knows. This unit should not need to have the Amp rebuilt, but, I still can't understand why the lower 6EU7 tube was missing after being rebuilt? The sound in this unit is great.

Theeeen we have two DS160's. One that has low volume on one channel (left). This unit was purchased from a selle that his father had it for 25 or so years and then he had it about 5 years. No mention was made of the amp being rebuilt.

The second DS160 which has a rattle sound when a sax or some song with a heavy low bass tone is being played and volume is raised. At low volume it sounds OK. I sprayed the volume control pot with Deoxit and worked it in well. There is no hissing or cracking sound now.

I think you are correct and the Amps need attention.

Thank you
Darrell

"She also told me that he told her that he could set up something like 10 slots to play 33 1/3 records for $50.00 and if he had to come back because she wanted more slots it would be something like $10.00 per slot."

That is just disgusting. If someone tried that on me, I'd don my rarely-used work boots and kick him in the ass..If he objected I'd do it again.

Thankfully, I don't need to call for help from cruds like that.

Just to be clear on this: There is NO need to "set up" any slot for 33 operation. If a working speed unit is installed any small hole record will switch to 33. Only when different pricing was desired for the albums was it necessary to set jumpers in the keyboard for a certain group.

BTW: In fall 1990 I installed an HLPC in a diner out in Queens NY. I'd gotten several used 7" 33's from an op and put them in just for fun. Same price etc. They sounded a bit thinner than the current 45 pressings but were well received. I had to take them out when we went over to 200's and an HVL three years later.

Rob/NYC

Rob,
I agree 100% with you--and PM'd Darrell about this--BUT, upon thinking further about it--
If you wanted to set up LP PRICING, it was quite a bit more work on an AYxxxU, or DSxxx model phono. There was a kit that needed to be installed in the USPU, to make it a UDPU, and the TES, also required a kit. If used, the RCSU, needed some work too. However, once the kits were installed, it was simple to "add" rows of ten selections to premium pricing.

I have found out the problem with the ear speakers on one Seeberg DS160 is the Pickering Red Head Stereo cartridge is bad. Is there anything available that replaces the original Pickering Red Head Stereo cartridge or does someone know where I could get a good one?, I know the usual places to look for them.

Thank you
Darrell

There is sound coming through the Pickering Red Head Stereo cartridge, however it is distorted. The copper plate the needles sit on have a lot of corrosion on them. Would it be advisable to use emery cloth and attempt to remove some of this corrosion to see if the distorted sound will clear up? Open for suggestions, tried spraying the copper plated with DEOXIT, that did not seem to help.

Thank you Darrell

Darrell,
I suspect it's more then a tube--however, since you have more then one amp--pull both bottom tubes from one amp and install them in the "bad" amp. If that makes no difference, pull the two 6973's and the 7199 from a known good right side of one amp, and place them in the "bad" left side of another--If that makes a difference, replace one good tube at a time till you determine which one is causing problems-- CAUTION the 6973's GET HOT-- enough to burn the skin off your fingers--even more so, if there are "problems", internal to the amp ! Ron Rich

Hi Ron

I have done all those things including exchanging one tube at a time plus I have exchanged entire amps and speakers. The only thing I have found that will eliminate the distortion entirely is exchanging the Pickering Red Head Stereo cartridge. When I do this with a known good Pickering Red Head Stereo cartridge the problem comletely goes away. If I then place the suspect Pickering Red Head Stereo cartridge into a known good DS 100 the problem now is in that DS100 Juke Box.

Thank you

Darrell

Hi Darrell,
Then the problem "has gotta be" with the cartridge or needles---Does the problem follow one needle, if you swap it ? Does it only happen on one side of the cartridge, no matter which needle is installed ? Ron Rich

I replaced the needles one at a time and the problem is still there. There is alot of corrosion on the copper(?) plate that the needles sits on. I have sprayed the copper with DEOXIT and that gas not helped. I was thinking that maybe I could try emery cloth to remove the corrosion and see if the cartridge would then be OK. I hate to throw away a cartridge that is no lnger made, if there is some way to revive this one. In any event before I toss it I will try something to remove the corrosion which I believe casues the distorted sound coming from the cartridge.

Thank you for your houghts on this subjevt

Darrell

Try "Brasso" it's brass Also, clean the connectors-- Ron rich