U sing W ith U SB and O ther Tu rntab les Equipped W ith Built-in Pream ps
So m e tab les (inclu ding M M m od els w ith U SB) have built-in p h ono pream ps.
Exte rn al p re a m ps like ours can be u sed w ith th e se, b u t the in ternal p ream p M U ST
be tu rned off o r byp asse d . Failin g to d o th is w ill resu lt in m assive overlo ading and
distortion . M o st p re a m ps bu ilt into turntab les p ro du ce inferior qu ality a u d io an d
are very n o isy (typ ically <50d B S/N ); even our lea st expe n sive m od e l easily
ou tp erform s th ese. B yp ass sw itch e s th a t turn o ff the in te rn al p re a m p a n d allo w
use of an e xtern a l prea m p instead vary in la b eling an d location dep end in g o n
turntab le bran d. T o use on e of ou r pream ps instead of y o u r tu rntab le's in ternal
on e , se t th e tab le's bypa ss sw itch a s sh o w n in RED . If in do ub t, try bo th po sition s;
the o ne th at so un d s g o od is the righ t settin g ...
G round W ires (and w h at to do w hen th ere isn't one)
So m e turntab les h a ve rem ovab le gro un d w ires; usu ally these have a gro u n d scre w
term inal o r binding p o st near th e R CA ca ble o r jacks as at the righ t. Tech nics
bran d tables for m an y y e ars featured plu g-in gro u n d w ires; th e low er im ag e at
righ t sho w s the jack for the se circle d in red. These tab le s w ill H U M if n o grou n d
w ire is co n ne cted (as w ill a n y ta b le w ith a b uilt-in gro u n d w ire tha t is le ft
un co n ne cted). Y o u can m ak e yo ur o w n Techn ics g ro un d w ire from a len gth o f
braide d ho oku p or speake r w ire; sim ply b a ll u p the bared end so th a t it fits snu gly
in to th e gro un d ja ck, a n d secu re w ith electrical or o ther ta p e.
M ost tab les w hich h ave b u ilt in pream ps a n d/or U SB also h ave N O gro un d w ire,
and do n o t re q u ire on e . A few m an ufactu re rs (m ost n otab ly JV C ) w ire the ir ta b le s
so th at the sign al (RC A ) cab le also carrie s the chassis grou n d co n ne ctio n, a nd so
they h ave n o sep a rate grou n d w ire. A d ding on e creates a grou n d loop and w ill
actu a lly C A USE h um ; d o no t do this. La stly, gro u n d w ires o ccasion ally ge t
am pu tated o r b re a k off, esp e cially if em bed d ed in the R CA ca b le a s w as co m m on
w ith A R an d som e o th er table bran d s (see im age a t righ t). If you r table hu m s, th is
m ay b e the rea son . If in su fficie n t 'stum p' rem ains to a llow splicin g a n ew gro u n d
le a d , yo u m ay ne e d to go in sid e th e tab le to co nn ect a rep la cem ent.
The next p age pro vides troublesh o o tin g in fo fo r p o w e r and audio issues.
Typical byp a ss sw itch lab e ling;
PH O N O / LIN E
EQ O FF / O N
BY PA SS O N / O FF
TH R U / O N
Troublesho otin g G u ide
Channel M issing, Low or H as H um
These issues are EA SY to diagno se a n d loca lize ; all that's requ ire d is a m eth od ical, step -by-step a p p ro ach . M o st
ch a nn e l o u t an d oth e r ch a n n e l sp e cific issues a re du e to prob lem s a t th e au dio sou rce, no t w ith th e pream p. O ften
turntab les an d cartrid ge s be ing use d w ith o u r p ream ps are d eca d es o ld, and have sa t un use d for years. O xida tion o f
co n n e ctio n s (cartrid ge w irin g, head sh e ll plug -in s, p atch co rd plugs) is the m ost com m on cau se o f m issin g o r
in term itten t aud io . T o determ in e w he re the fault lies, p erform a sim ple step-by-step test. Tu rn th e vo lu m e do w n
w hen con nectin g or d isco n ne ctin g cab le s as follow s.
If n o chan ge, retu rn the inp u t cab les to th eir prop er jacks
and then p roceed next to sw ap the left and righ t p lugs at
the p ream p's O UTP U T. If th e prob le m no w sw itche s
sp e a k e rs, th e pream p is m ost like ly a t fa u lt. If n o ch a n ge,
ch e ck th e ou tp ut cable a nd am p/receiver fo r a prob le m .
A ll of ou r p re a m p m od e ls excep t th e TC -450 have eithe r a po w er LED o r sou rce indicator
LED s w hich con firm the p resen ce of p o w er. If n ot lit, m ake sure th at the p o w er sw itch (if so
equ ip pe d ) is on . Som e m odels have th is sw itch in tegrate d w ith th e level con trol w hile on
othe rs it is stan d -alone . Co nfirm th a t the D C po w er p lug is fully in serted in its jack , and that
the D C ja ck is no t spru n g o u t o f its h o le in the p ream p rear p a n el (see illustratio n a t right). If
the jack is d isplace d, yo u can re m ed y this b y insertin g th e D C p lu g an d gently p re ssu ring
sid ew ays o r vertically as n eed e d un til th e jack pop s b ack into p lace. Lastly, try the ad ap to r
in a differen t A C o utlet. M o st verified no p o w er issue s resu lt from ad apto r failure, n o t a
fau lt w ith th e pream p itself. P ow er a d apto rs le ad h ard lives, being exp ose d to lightning and
othe r po w er m ain s irregu la rities; th e u p side to th is is that th e y serve as b u ffers, preven tin g
su rges from re ach ing an d dam agin g the p ream p. R ep lacem en t A C ad ap to rs are a v a ilab le on
ou r w eb site .
R
L
R
L
N o Pow er (LED not lit)
Pow er B ut N o A udio
N o aud io is ra re ly a ph on o prea m p issue. U su ally it's th e resu lt o f m isco nn ection (reve rsing the p ream p inp uts and
ou tp uts), o r co n ne ctio n to a "d ead " inpu t on the receiver o r am plifier. M any h om e theater re ceivers h ave b oth
digita l and an alog inpu ts w ith the sam e lab els (CD , D A T, etc); o n m ost, o nly o ne o r the other can b e u sed . If a C D
player is alre a dy con n ecte d to th e To slink o r P C M C D in p u t, the an alo g C D inp u t w ill usu a lly b e in active an d w ill
pro d uce n o so u n d . If yo u alre a dy h ave a w orking analog so u rce co n ne cted, try tem po ra rily h o oking up yo ur
turntab le and pream p to th at in p u t. A ssum in g th is pro du ces go od sou nd , you can the n m ove o n to figure o ut w hy
othe r in pu ts do n 't fun ction. A th oro u gh re a d in g o f yo ur re ceiv e r's user m anu al w ill usu a lly p rovid e th e solutio n .
Sta rt b y sw ap p in g the left and righ t p lu gs (from the tab le )
go ing into th e pream p inp ut. W h en yo u p lug th e left plug
in to th e right inpu t (an d vice versa ), d oes the p rob lem
sw itch spe a k e rs? If it d oe s, th e cau se is d e fin itive ly n o t
the p ream p; ch eck yo ur cartrid ge , the tab le an d its cable.
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